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1
Rivera, Gomez Franco Wilfrido. "Heat transformer technology and steam generation." Thesis, University of Salford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360445.
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2
Ambrosson, Fredrik, and Markus Selin. "Solar Concentrating Steam Generation in Alberta, Canada." Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-191492.
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In the context of climate change the world is facing an increasing need to become more environmentally sustainable, and a concerted effort to use renewable energy is required in order to decrease emissions, meet climate goals and prepare for the post-oil era. Solar energy is an area with great potential, and developments in solar energy technologies have increased rapidly. Concentrating solar technologies have existed for more than one hundred years, and have largely been applied in the context of direct power generation. However, solar energy technologies can also be used for purposes other than power generation, such as generating steam for alternative applications. This work investigates the steam generating potential of a solar steam generation system located at the Southern Alberta Institute of Technology (SAIT) campus in Calgary, Alberta, Canada and the potential for utility scale implementation in Alberta’s Oil Sands for steam demanding enhanced oil recovery (EOR) methods. Furthermore, this thesis also validates weather data for the SAIT campus. Both of the proposed systems use parabolic troughs as solar collectors. The SAIT system also incorporates a two-tank direct thermal energy storage and Therminol 62 as the heat transfer fluid, while the utility scale system uses water as the heat transfer fluid. The results show that the SAIT system can provide saturated steam at 0,7 MWh 155 times which amounts to a total steam output of 90 MWh annually. The results for the utility scale system show that solar steam generation from a 500 MW thermal plant implemented for enhanced oil recovery in an EOR facility becomes economically feasible, as compared with steam production from natural gas, at a natural gas delivery price of approximately $7 USD/GJ. Furthermore, an installed 500 MW thermal plant can reduce carbon emissions by 180,000 tonnes of CO2 equivalents annually. Conclusions drawn in this thesis are as follows: the technology is technically feasible however there are both political and economic obstacles to its use; solar EOR should be seen as an add-on to existing plants due to the intermittence of solar energy in Alberta; the GHG reduction potential is great and consequently there is a possibility of receiving carbon credits by using the technology; and by tilting the solar collector field total output can be increased by over 25%.<br>I dagens växande miljömedvetna samhälle behövs en kraftfull ansträngning mot förnybar energi för att minska växthusgasutsläpp, uppnå klimatmål och förbereda samhället för en era efter oljan. Solenergi är ett område med stor potential där utvecklingen inom området ökat lavinartat den närmsta tiden. Termisk solkraft (engelska: Concentrating Solar Power) är en teknologi som funnits tillgänglig i över ett sekel men det är först på senare tid som det börjat användas kommersiellt. Historiskt sätt har termisk solkraft använts för att generera elektricitet men teknologin kan även fördelaktigt användas för att tillverka ånga för andra syften än el-produktion. Detta examensarbete undersöker ånggenereringspotentialen för ett solånggenereringssystem placerat på campus tillhörande Southern Alberta Institute of Technology i Calgary, Alberta, Kanada. Arbetet undersöker även potentialen för denna teknologi storskaligt i oljeindustrin inom området förbättrad oljeutvinning (engelska: Enhanced Oil Recovery) som används i norra delen av Alberta i oljesanden (engelska: Oil Sands). För SAIT systemet har arbetet inkluderat val av komponenter, design av dessa och en validering av väderparametrarna som påverkar den möjliga ångproduktionen av systemet. I det storskaliga systemet har arbetet varit mer fokuserat på att undersöka när teknologin blir ekonomiskt gångbar och hur mycket växthusgasutsläpp som kan minskas genom att använda teknologin. SAIT systemet utgörs av två paraboliska trågkollektorer (engelska: parabolic trough collector) placerade på taket av Cenovus Energy Centre-byggnaden. Systemet innefattar även en termisk energilagring (engelska: thermal energy storage) som möjliggör ångproduktion på begäran. Värmeöverföringsfluiden är Therminol 62 som även används i energilagringen. Det storskaliga systemet är fokuserat på den sydligaste delen av oljesanden, Cold Lake och utnyttjar också paraboliska trågkollektorer som kollektorer. I detta system verkar vatten som värmeöverföringsmedium och ånga är producerad genom direktånggenerering och injicerade i oljereservoaren. Resultaten av arbetet visar att SAIT systemet kan producera 0,7 MWh mättad ånga 155 gånger vilket ger en total produktion om 90 MWh årligen. För det storskaliga systemet visar resultaten att termisk solkraft för ångproduktion blir ekonomiskt gångbart vid ett naturgaspris på $7 USD. Vidare visar resultaten att för ett termiskt solkraftverk på 500 MW kan reducera växthusgasutsläppen mot motsvarande ångproduktion från naturgas med 180 000 ton CO2-ekvivalenter. Slutligen visar arbetet att ångproduktionen kan öka genom att luta kollektorerna mot söder. Slutsatser och framtida arbete inkluderar: • Lutning av kollektorerna kan öka ångproduktionen med över 25 %. • Båda systemen är tekniskt genomförbara och hindren är främst politiska och ekonomiska. • Anläggningar för termisk solkraft för ånggenerering bör implementeras som tillägg till redan existerande anläggningar för förbättrad oljeutvinning och hållas operativt mellan mars till oktober. • Möjligheterna att minska utsläpp och erhålla utsläppsrätter är stora. • Idag är termisk solkraft för ånggenerering inte ekonomiskt gångbart i Alberta på grund av låga priser för naturgas. • Platsspecifika undersökningar av existerande anläggningar för förbättrad oljeutvinning för att se var termisk solkraft har potential att implementeras behöver utföras. • En undersökning för att se hur stora inkomster utsläppsrätter kan generera behöver genomföras.
3
Cairns, Paul-Emanuel. "High Pressure Oxy-fired (HiPrOx) Direct Contact Steam Generation (DCSG) for Steam Assisted Gravity Drainage (SAGD) Application." Thesis, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24329.
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Production in Canada’s oil sands has been increasing, with a projected rate of 4.5 million barrels per day by 2025. Two production techniques are currently used, mining and in-situ, with the latter projected to constitute ~57% of all production by that time. Although in-situ extraction methods such as Steam Assisted Gravity Drainage (SAGD) are less invasive than mining, they result in more greenhouse gas (GHG) emissions per barrel and require large amounts of water that must be treated and recycled with a make-up water requirement of about 10%. CanmetENERGY is developing a steam generation technology called the High Pressure Oxy-fired Direct Contact Steam Generator (HiPrOx/DCSG, or DCSG for short) that will reduce these water requirements and sequester GHGs. This study evaluates the technical feasibility of this technology using process simulations, bench-scale testing, and pilot-scale testing.
At first, a method in which to integrate the DCSG into the SAGD process was presented and process modeling of expected system performance was undertaken. The process simulations indicated that DCSG decreased the energy intensity of SAGD by up to 7.6% compared to the base SAGD case without carbon capture and storage (CCS), and up to 12.0% compared to the base SAGD case with CCS.
Bench-scale testing was then performed using a pressurized thermogravimetric analyzer (PTGA) in order to investigate the effects of increased pressure and high moisture environments on a Canadian lignite coal char’s reactivity. It was found that under reaction kinetic-controlled conditions at atmospheric pressure, the increased addition of steam led to a reduction in burning time. The findings may have resulted from the lower heat capacity and higher thermal conductivity of steam compared to CO2. At increased pressures, CO2 inhibited burnout due to its higher heat capacity, lower thermal conductivity, and its effect on C(O) concentrations on the particle surface. When steam was added, the inhibiting effects of CO2 were counteracted, resulting in burnout rates similar to pressurized O2/N2 environments. These preliminary results suggested that the technology was feasible at a bench-scale level. Conflicting literature between bench-scale and pilot-scale studies indicated that pilot-scale testing would be advantageous as a next step.
At the pilot-scale, testing was performed using n-butanol, graphite slurry, and n-butanol/graphite slurry mixtures covering lower and upper ends in fuel reactivity. It was found that stable combustion was attainable, with high conversion efficiencies in all cases. With the n-butanol, it was possible to achieve low excess oxygen requirements, which minimizes corrosion issues and reduce energy requirements associated with oxygen generation. With graphite slurry, it was found that it was possible to sustain combustion in these high moisture environments and that high conversion was achieved as indicated by the undetectable levels of carbonaceous materials observed in downstream equipment.
Overall, these studies indicate that DCSG is technically feasible from the perspectives of energy and combustion efficiencies as well as from a steam generation point of view. Future work includes the investigation of possible corrosion associated with the product gas, the effect of CO2 on bitumen production, the nature of the mineral melt formed by the deposition of the dissolved and suspended solids from the water in the combustor, and possible scaling issues in the steam generator and piping associated with mineral deposits from the dissolved and suspended solids in the produced water is recommended.
4
Kysel, Stanislav. "Energetický paroplynový zdroj na bázi spalování hutnických plynů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229801.
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The main goal of my thesis is to carry out thermic calculations for adjusted conditions of electric and heat energy consumption. The power of the generator is 330 MW. In the proposal, you can find combustion trubines type GE 9171E. Steam-gas power plant is designed to combust metallurgical gases. Effort of the thesis focuses also on giving a new informations about trends in combinated production of electric and heat energy.
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Kysel, Stanislav. "Energetický paroplynový zdroj na bázi spalování hutnických plynů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230245.
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The main goal of my thesis is to carry out thermic calculations for adjusted conditions of electric and heat energy consumption. The power of the generator is 330 MW. In the proposal, you can find combustion trubines type GE 9171E. Steam-gas power plant is designed to combust metallurgical gases. Effort of the thesis focuses also on giving a new informations about trends in combinated production of electric and heat energy.
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Hagos, Dejene Assefa. "Techno-Economic Assesment of Parabolic Trough Steam Generation for Hospital." Thesis, KTH, Energiteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-42720.
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Hospitals are one of the most energy consuming centers in which thermal energy is utilized for different medical equipments and others. Sterilizers, laundry and kitchens are the main thermal energy utilizing equipments. In addition, large amount of hot water is utilized mainly for showering and dish washing. The main sources of this thermal energy are fossil fuel for oil fired boilers and solar irradiation for solar thermal steam generation system. This project aims in analyzing the Technical performance of parabolic trough steam generation and oil fired boiler steam generation system for Black lion general specialized hospital which is located in Addis Ababa and to perform economic assessment on both systems so as to make comparison test. The result from technical feasibility study shows the parabolic trough can meet the steam demand of the hospital at the required time, more than 8hour per day, as the hospital currently require steam for different activities during the day time for 8hour per day. During cloudy day the conventional back up steam generation system will meet the daily demand for few days of the year. The economic assessment result shows that although the initial investment of concentrated solar steam generation is high as compared to convention steam generation system, the reverse is observed in operation and maintenance cost, resulting solar thermal steam generation break even (payback) to occur early, after 7 year the system let to operate over the conventional oil fired steam generation. In addition the levelized cost of energy for concentrated solar steam generation is found to be 58% higher than conventional steam generation. Hence, the result shows that parabolic trough is found to be more economical for steam generation than oil fired boiler. If solar thermal steam generation (parabolic through) is implemented, the fuel consumption and operational cost of the boiler can be reduced appreciably.
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Rwezuva, Onekai Adeliade. "Solar Augmentation of Process Steam Boilers for Cogeneration." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33898.
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In this study, the techno-economic feasibility of converting an existing process steam plant into a combined heat and power plant, using an external solar thermal field as the additional heat source was studied. Technical feasibility entailed designing a suitable heat exchanger, which uses hot oil from the solar field to raise the steam conditions from dry saturated to superheated. The solar field was sized to heat a selected heat transfer fluid to its maximum attainable temperature. A suitable turbine-alternator was chosen which can meet the required plant power demand. For this to be a success, the processes which require process steam were analysed and a MathCAD model was created to design the heat exchanger and check turbine output using the equations adapted from various thermodynamics and power plant engineering texts, together with the Standards for the Tubular Exchanger Manufacturer's Association. The U.S. National Renewable Energy Laboratory system advisor model was used to size the suitable solar field. A financial model was developed in Excel to check the economic feasibility of the project, using discounted payback period as the economic indicator. It was found out that amongst loan interest rates, variation of system output and the electricity output, the profitability of the project was largely influenced by the electricity tariff. An optimum size for the heat exchanger of 30ft was established from the sensitivity analysis and it was concluded that the project is currently not economically viable on an independent investor financing model, unless either the electricity tariff improves or the solar thermal energy and turbine technology costs decrease.
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Schlaifer, Perrine. "Performance Calculations and Optimization of a Fresnel Direct Steam Generation CSP Plant with Heat Storage." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-116806.
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This master thesis deals with the performance calculations of a 9MW linear Fresnel CSP plant withdirect steam generation built by the Solar Division of the CNIM Company. The aim was to calculate theannual electricity production taking into account the weather conditions as well as some steam storage.At first, a steam accumulator model was developed with Excel, in order to estimate the pressureevolution in the tanks during the charging, storage and discharging processes. The data obtained withthis model was then integrated to the thermodynamic cycle model, programmed with Excel, whichcalculated the electrical power production knowing the thermal power available in the solar field. Theelectricity production calculations were made every 600 seconds during one year.To improve the results accuracy, the influence of the plant location slope was estimated, calculating theequivalent azimuth and elevation angles in a new spherical coordinates system. For an average slope of4.21° at the plant location, the annual thermal energy gain is 14.4% (with a gain up to 60% duringwinter days) and the annual electricity production is increased by 12.59%. The influence of frost on themirrors during cold and humid nights was also estimated with a simple model of the energy needed toheat up a constant layer of ice. Depending on the assumptions, the electricity production losses werebetween 1.27 and 2.84% of annual electricity production. The losses due to plant shutdowns set by theelectrical network manager RTE during the snowmelt months were also estimated. The annualelectricity production could decrease by 8.02 to 11.57 % because of the load management, dependingon the days during which the plant is shutdown.Finally, an economic optimisation was led with prices estimated by CNIM, which gave an optimal solarfield design with 31 lines and 5 steam accumulators. The payback time would then be 9.887 years.
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Somasundara, D. H. G. S. R. "Waste from instant tea manufacturing as a fuel for process steam generation." Thesis, Högskolan i Gävle, Energisystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-25094.
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An existing furnace oil fired boiler is used to supply process steam to an instant tea manufacturing factory. The instant tea is manufactured the Broken Mixed Fannings (BMF) through extraction and other required processes. The average steam consumption of the plant is 6000 kg/h at 10 barg pressure. During the process, tea waste is generated at a nominal rate of 50,000 kg/day, about 2000 kg/h at around 70% MC content on wet basis. At the moment this waste tea is either dumped in the surrounding area by spending money or sent to landfilling purposes, which create environmental issues. The tea waste coming out at 70% MC wet basis, is looked at to press through continuous belt press to reduce the moisture content to about 55% on wet basis. The water removed from this pressing process is sent to effluent treatment plant at the factory. The output from the belt press is sent to a steam operated The average generation of tea waste from the instant tea manufacturing process process is about 2000 kg/h, after pressing in the belt press an output rate of about 1,400 kg/h at 55% MC. This amount of tea waste at 55% MC is sent to a rotary steam tube dryer and the MC is reduced from 55% to 30% and the output rate from the steam tube dryer is about 857 kg/h. The amount of steam consumed by the rotary steam tube dryer at 6 barg pressure is 760 kg/h. Then the tea waste from the rotary tube dryer is mixed with firewood of 30% MC and fed to the boiler to generate process steam, out of which 857 kg/h steam at 6 barg pressure is sent back to the rotary steam dryer. From tea waste alone, a steam amount of 2,472 kg/h can be supplied after giving steam to the rotary steam dryer. The balance steam amount of 3,528 kg/h for the process requirement is supplied by burning additional firewood at 30% MC content. The tea waste fuel and firewood in combination have an overall moisture content of 30% on wet basis. The boiler is rated at 10,000 kg/h F & A 100 deg C with an actual generating capacity of about 9000 kg/h at 10 barg operating pressure at 70 deg C feed water temperature. By implementing the combination of belt press, rotary steam tube dryer and firewood boiler in place of the existing furnace oil fired boiler, an annual monetary saving of 168 Mn SLR/year can be achieved with a simple payback period of 21 months which is a highly feasibly project.
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Bond, Nicole. "Inorganic Phase Characterization, Corrosion Modelling and Refractory Selection for Direct Contact Steam Generation." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41951.
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Technological advances are required to reduce the environmental impact of the Canadian oil sands. Oxy-direct contact steam generation (DCSG) is one such way to move toward this goal, by producing steam for oil sands operations with a higher efficiency, lower fresh water consumption, and lower CO₂ emissions than traditional once-through steam generators. For DCSG, untreated process water, which may contain a variety of inorganics, is injected directly into the combustor to produce steam. The inorganic material that may deposit in the combustor as a result of that process water was studied for two applications of DCSG in the Canadian oil sands: (1) steam assisted gravity drainage (SAGD), and (2) mining, in order to inform refractory material selection for the combustor.
For SAGD, free water knockout tank discharge was used as the process water and resulting deposits in the combustor were predicted to be high in silica and sodium oxide, and enriched with sodium sulfate as the potential operating temperature of the combustor was lowered. At the lowest combustor temperature studied (1075 °C), a low viscosity molten salt phase rich in sodium sulfate was also expected to form. It is recommended that the operating temperature of the combustor be as low as possible while still remaining above the formation temperature of this potentially corrosive salt phase, thus in the range of 1200-1250 °C in the regions of the wall where solids are expected to impact it. A number of candidate refractory materials were assessed through corrosion models and corrosion tests. Aluminosilicate based refractory materials should be avoided due to their potential reaction with the sodium oxide in the slag. This can result in formation of low density solid phases such as nepheline, which can damage the refractory material through volume expansion. Of the three refractories tested, mullite zirconia yielded the worst corrosion resistance, with dissolution of the binder phase and full penetration by sodium oxide. Chromia corundum yielded the greatest resistance to penetration of the materials tested, though some dissolution of the chromia in the slag was still evident. Further investigation into high chrome refractory materials is recommended for this application.
For mining applications, mature fine tailings water (MFT) combined with an oil sands processing water (OPW) was used as the process water for injection. Due to the high liquidus of the resulting inorganic deposits, co-injection of a fluxant is recommended to reduce the liquidus and viscosity of the resulting slag solution, thereby maximizing the combustor efficiency by reducing the required operating temperature. Dolomite was identified as the optimal fluxant, at a concentration of 20 wt % CaMgO₂ in the fluxed slag. This mixture was found to have a viscosity of just under 25 Pa·s at 1300 °C, making this a good operating point for the DCSG combustor, as the slag should flow freely and not cause plugging. The corrosion resistance of several candidate refractory materials was assessed through modelling and laboratory scale testing for both the fluxed and non-fluxed slag. Similar to the results for SAGD, of the refractories tested, chromia corundum offered the greatest resistance to penetration, while mullite zirconia was most deeply penetrated by sodium oxide. Again, a chromia-containing refractory is recommended for further investigation for use in the DCSG combustor. Other candidate refractories investigated in the models that warrant testing are chromia spinel and magnesium aluminate spinel. For future work, further corrosion tests at multiple durations are recommended, as well as characterization of refractory samples from CanmetENERGY’s DCSG pilot plant and quantification of the effects of slag exposure on the mechanical strength of the refractory materials.
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Cuthbertson, Grant. "An experimental investigation of dropwise and filmwise condensation of low pressure steam in tube banks." Thesis, Heriot-Watt University, 1999. http://hdl.handle.net/10399/1246.
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Research to date has highlighted a number of conditions where dropwise condensation may offer heat transfer enhancements over filmwise condensation. Previous studies have shown at pressures above or around atmospheric, dropwise condensation offers significant benefit over filmwise. However, some of this research suggests that as the system pressure is reduced below atmospheric, the benefits of dropwise condensation diminish rapidly, to the extent that, at pressures around 50mbar the benefits of dropwise over filmwise are minimal. This thesis details a series of experiments which were conducted to investigate the heat transfer and pressure drop distributions in tube bundles during both dropwise and filmwise condensation of steam. The primary objective of the work was to determine the design implications associated with switching the mode of condensation of a electricity generating steam turbine condenser from the current filmwise mode, to dropwise. Experimental data were obtained from a new purpose build apparatus containing seventy-five, 150mm long titanium tubes, arranged in an in line configuration of five columns and fifteen rows. Dropwise and filmwise data were recorded from each row at test cell inlet pressures down to 50mbar using both pure steam and steam air mixtures. Filmwise heat transfer data indicated that, under most conditions, heat transfer coefficients were generally in agreement with those obtained by previous workers. Heat transfer data obtained during dropwise condensation suggested that the benefits of dropwise condensation are not significantly diminished at low pressure, and that, unlike filmwise condensation, inundation has little or no effect in a fifteen row bundle. The data also indicated that the pressure drop characteristics and effects of air are, within experimental error, identical during both modes of condensation and in line with models and theories proposed by previous workers.
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Qur'an, Omar Ali Sammour. "Design criteria and performance of steam turbines in a CPP plant for electrical power generation." Thesis, University of Hertfordshire, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247306.
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Ellakany, Farid. "Enhancing the Thermo-Economic Performance of a Direct Steam Generation Solar Tower Power Plant through the Implementation of Steam Flow Control Strategies for Flexible Operation." Thesis, KTH, Kraft- och värmeteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-150112.
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Above 90% of the current installed concentrating solar power plants are based on conventional steam-turbine cycles. The operation of steam turbines in these plants is distinctive when compared to traditional base-load power plants. The reason goes back to the intermittent nature of solar power which, in the absence of thermal energy storage or a back-up combustion boiler, forces plant operators to shut down the turbines during night time or at times of low solar radiation. Furthermore, such intermittency often leads to undesirable off-design turbine operating circumstances, either by load variations or changes on live-steam conditions.The present study examines the influence of implementing two operating strategies dealing with steam flow control as a function of incoming solar power for enhancing the thermo-economic performance of a direct steam generation solar tower power plant. The first one consists of a simultaneous high pressure turbine stage- and feed-water preheater bypass. This strategy is used during periods in which the solar radiation is higher than nominal. On these occasions, the plant is capable of generating a larger flow of steam, which allows for an increase in the power production when inserting the additional steam in the turbine bypass. On the other hand, the second operating strategy consists of using an additional feed-water preheater when the power from the field is lower than nominal. In this way, the feed water can reach a higher temperature prior entering the boiler, which is not only beneficial during times of cloud-passages, but also during the start-up process.A dynamic model of a direct steam generation solar tower power plant has been developed following design and operation specifications of an existing reference plant. The two proposed strategies were implemented to the reference model, then a whole year worth simulation was performed for both the reference and the modified models. Lastly, the thermodynamic and economic performance of both systems was measured for the purpose of comparison, by means of using KTH in-house tool DYESOPT. Results show that the implementation of the proposed strategies can enhance the economic viability of the systems by yielding a reduction of 8.7% on the levelized cost of electricity, mainly due to allowing achieving a 12% increase in the net electricity production.
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Nolte, Henriette C. "Analysis and Optimisation of a Receiver Tube for Direct Steam Generation in a Solar Parabolic Trough Collector." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/45965.
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This study focused on a numerical second law analysis and optimisation of a receiver tube op-
erating in a parabolic trough solar collector for small-scale application. The receiver functioned
in a Rankine cycle. The focus was on entropy generation minimisation in the receiver due to
the high quality exergy losses in this component. Water functioned as the working
uid and
was heated from ambient conditions (liquid) to a superheated state (vapour), consequently, the
receiver tube was subject to both single phase as well as two-phase
ow.
Entropy generation in the receiver tube was mainly due to nite temperature di erences as well
as
uid friction. The contribution of each of these components was investigated. Geometrical
as well as operating conditions were investigated to obtain good guidelines for receiver tube
and plant design. An operating pressure in the range of 1 MPa (Tsat = 180 C) to 10 MPa
(Tsat = 311 C) was considered. Furthermore a mass
ow range of 0:15 kg=s to 0:4 kg=s was
investigated. Results showed that beyond a diameter of 20 mm, the main contributor to the entropy generation
was the nite temperature di erences for most conditions. Generally, operating pressures below
3 MPa showed bad performance since the
uid friction component was too large for small
operating pressures. This phenomenon was due to long two-phase lengths and high pressure
drops in this region. The nite temperature di erence component increased linearly when the
tube diameter was increased (due to the increase in exposed area) if the focused heat
ux was
kept constant. However, the
uid friction component increased quadratically when the diameter
was reduced.
In general when the concentration ratio was increased, the entropy generation was decreased.
This was due to more focused heat on each section of the receiver pipe and, in general, resulted
in shorter receiver lengths. Unfortunately, there is a limit to the highest concentration ratio
that can be achieved and in this study, it was assumed to be 45 for two-dimensional trough
technology.
A Simulated Annealing (SA) optimisation algorithm was implemented to obtain certain optimum
parameters. The optimisation showed that increasing the diameter could result in a decrease in
entropy generation, provided that the concentration ratio is kept constant. However, beyond a
certain point gains in minimising the entropy generation became negligible. Optimal operating
pressure would generally increase if the mass
ow rate was increased. Finally, it was seen that
the highest operating pressure under consideration (10 MPa) showed the best performance
when considering the minimisation of entropy in conjunction with the maximisation of the
thermodynamic work output.<br>Dissertation (MEng)--University of Pretoria, 2014.<br>tm2015<br>Mechanical and Aeronautical Engineering<br>MEng<br>Unrestricted
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Martin, Stefan [Verfasser], and André [Akademischer Betreuer] Thess. "An investigation of hydrogen generation via steam reforming of liquid fuels / Stefan Martin ; Betreuer: André Thess." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2017. http://d-nb.info/1130656985/34.
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Weerasiri, Udayani Priyadarshana. "A waste heat recovery steam power generation system for ACE Power Embilipitiya (Pvt) Ltd, Sri Lanka." Thesis, KTH, Kraft- och värmeteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-157832.
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In this study, the heat recovery from exhaust gas at the ACE Power Embilipitiya (Pvt) Ltd (APE) in Sri Lanka was conceptually proposed and evaluated. APE has an installed capacity of 100 MW comprising 14 units of 7.5MW medium speed diesel engines fired with heavy fuel oil. There is only a minimum recovery of waste heat in the plant at the moment, only for fuel preheating, whereas waste heat recovery (WHR) boilers of 750kWth are equipped on eight engines. The larger portion of the waste heat is dumped into the environment without being used in any reasonable way. The objective of this work was to design a HRSG system for the remaining six engines to recover maximum possible heat from the exhaust gas and select a suitable steam turbine according to the heat demand capacity of the proposed HRSG, for generating additional power and thus converting the APE plant into a sort of a combined cycle. At the initial stage of the investigation, the amount of recoverable waste heat was estimated by evaluating the known parameters of the engines at fully loaded condition. The maximum theoretical waste heat recovery potential from the exhaust gas stream of one engine was calculated as 9807.87 MJ/h, equivalent to a heat rate of 2724.4 kW. The modelling and optimization of the proposed HRSG was done using the Engineering Equation Solver (EES) software, considering technical and practical limitations such as pinch point temperature difference, approach point temperature difference, terminal temperature difference and sulphur dew point in the stack. A commercially available steam turbine with a power output of 3.579 MW was selected as the optimum steam turbine for the desired conditions, utilising 12884.4 MJ/h of recovered waste energy amounting to 21.89% of the total available energy in the flue gas.
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Buongiorno, Jacopo 1971. "Conceptual design of a lead-bismuth cooled fast reactor with in-vessel direct-contact steam generation." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/32205.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2001.<br>Includes bibliographical references (p. 357-366).<br>The feasibility of a lead-bismuth (Pb-Bi) cooled fast reactor that eliminates the need for steam generators and coolant pumps was explored. The working steam is generated by direct contact vaporization of water and liquid metal in the chimney above the core and then is sent to the turbine. The presence of a lighter fluid in the chimney drives the natural circulation of the Pb- Bi within the reactor pool. Three key technical issues were addressed: 1) the maximum thermal power removable by direct contact heat transfer without violating the fuel, clad and vessel temperature limits, 2) the consequences of Pb-Bi aerosol transport on the design and operation of the turbine and 3) the release of radioactive polonium (a product of coolant activation) to the steam. Modeling of the multi-phase phenomena occurring in the chimney confirmed the effectiveness of the direct contact heat transfer mode within a well-defined design envelope for the reactor power, chimney height and steam superheat. A 1260MWth power is found possible for 10m chimney height and 25°C superheat. The temperature of the low-nickel steel clad is maintained below 600°C, which results in limited corrosion if tight control of the coolant oxygen concentration is adopted.<br>Generation, transport and deposition of Pb-Bi aerosols were also modeled. It was found that the design of a chevron steam separator reduces the heavy liquid metal in the steam lines by about three orders of magnitude. Nevertheless, the residual Pb-Bi is predicted to cause embrittlement of the turbine blades. Four solutions to this problem were assessed: blade coating, employment of alternative materials, electrostatic precipitation and oxidation of the Pb-Bi droplets. An experimental campaign was conducted to investigate the polonium release from a hot Pb- Bi bath to a gas-streamn. Th thermodynamics of the polonium hydride formation reaction (free- energy vs. temperature). as welQ as the vapor pressure of the lead-polonide were measured and then utilized to model the polonium transport in the reactor. It was found that the polonium concentration in the steam and on the surface of the power cycle components is significantly above the acceptable limits, which makes the very concept of a direct contact reactor open to question.<br>by Jacopo Buongiorno.<br>Ph.D.
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Al-Anfaji, Ahmed Suaal Bashar. "The optimization of combined power-power generation cycles." Thesis, University of Hertfordshire, 2015. http://hdl.handle.net/2299/15485.
Full textAbstract:
An investigation into the performance of several combined gas-steam power generating plants’ cycles was undertaken at the School of Engineering and Technology at the University of Hertfordshire and it is predominantly analytical in nature. The investigation covered in principle the aspect of the fundamentals and the performance parameters of the following cycles: gas turbine, steam turbine, ammonia-water, partial oxidation and the absorption chiller. Complete thermal analysis of the individual cycles was undertaken initially. Subsequently, these were linked to generate a comprehensive computer model which was employed to predict the performance and characteristics of the optimized combination. The developed model was run using various input parameters to test the performance of the cycle’s combination with respect to the combined cycle’s efficiency, power output, specific fuel consumption and the temperature of the stack gases. In addition, the impact of the optimized cycles on the generation of CO2 and NOX was also investigated. This research goes over the thermal power stations of which most of the world electrical energy is currently generated by. Through which, to meet the increase in the electricity consumption and the environmental pollution associated with its production as well as the limitation of the natural hydrocarbon resources necessitated. By making use of the progressive increase of high temperature gases in recent decades, the advent of high temperature material and the use of large compression ratios and generating electricity from high temperature of gas turbine discharge, which is otherwise lost to the environment, a better electrical power is generated by such plant, which depends on a variety of influencing factors. This thesis deals with an investigation undertaken to optimize the performance of the combined Brayton-Rankine power cycles' performance. This work includes a comprehensive review of the previous work reported in the literature on the combined cycles is presented. An evaluation of the performance of combined cycle power plant and its enhancements is detailed to provide: A full understanding of the operational behaviour of the combined power plants, and demonstration of the relevance between power generations and environmental impact. A basic analytical model was constructed for the combined gas (Brayton) and the steam (Rankine) and used in a parametric study to reveal the optimization parameters, and its results were discussed. The role of the parameters of each cycle on the overall performance of the combined power cycle is revealed by assessing the effect of the operating parameters in each individual cycle on the performance of the CCPP. P impacts on the environment were assessed through changes in the fuel consumption and the temperature of stack gases. A comprehensive and detailed analytical model was created for the operation of hypothetical combined cycle power and power plant. Details of the operation of each component in the cycle was modelled and integrated in the overall all combined cycle/plant operation. The cycle/plant simulation and matching as well as the modelling results and their analysis were presented. Two advanced configurations of gas turbine cycle for the combined cycle power plants are selected, investigated, modelled and optimized as a part of combined cycle power plant. Both configurations work on fuel rich combustion, therefore, the combustor model for rich fuel atmosphere was established. Additionally, models were created for the other components of the turbine which work on the same gases. Another model was created for the components of two configurations of ammonia water mixture (kalina) cycle. As integrated to the combined cycle power plant, the optimization strategy considered for these configurations is for them to be powered by the exhaust gases from either the gas turbine or the gases leaving the Rankine boiler (HRSG). This included ChGT regarding its performance and its environmental characteristics. The previously considered combined configuration is integrated by as single and double effect configurations of an ammonia water absorption cooling system (AWACS) for compressor inlet air cooling. Both were investigated and designed for optimizing the triple combination power cycle described above. During this research, tens of functions were constructed using VBA to look up tables linked to either estimating fluids' thermodynamic properties, or to determine a number of parameters regarding the performance of several components. New and very interesting results were obtained, which show the impact of the input parameters of the individual cycles on the performance parameters of a certain combined plant’s cycle. The optimized parameters are of a great practical influence on the application and running condition of the real combined plants. Such influence manifested itself in higher rate of heat recovery, higher combined plant thermal efficiency from those of the individual plants, less harmful emission, better fuel economy and higher power output. Lastly, it could be claimed that various concluding remarks drawn from the current study could help to improve the understanding of the behaviour of the combined cycle and help power plant designers to reduce the time, effort and cost of prototyping.
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Desai, Ranjit. "Thermo-Economic Analysis of a Solar Thermal Power Plant with a Central Tower Receiver for Direct Steam Generation." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-131764.
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Min, Zhenhua. "Catalytic steam reforming of biomass tar using iron catalysts." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/184.
Full textAbstract:
Biomass has become an increasingly important renewable source of energy forenhanced energy security and reduced CO[subscript]2 emissions. Gasification is at the core of many biomass utilisation technologies for such purposes as the generation of electricity and the production of hydrogen, liquid fuels and chemicals. However, gasification faces a number of technical challenges to become a commercially feasible renewable energy technology. The most important one is the presence of tar in the gasification product gas. The ultimate purpose of this thesis was to investigate the catalytic reforming of tar using cheap catalysts as an effective means of tar destruction.In this thesis, natural ilmenite ore and novel char-supported catalysts were studied as catalysts for the steam reforming of biomass tar derived from the pyrolysis of mallee biomass in situ in two-stage fluidised-bed/fixed-bed quartz reactors. In addition to the quantification of tar conversion, the residual tar samples were also characterised with UV-fluorescence spectroscopy. Both fresh and spent catalysts were characterised with X-ray diffraction spectroscopy, FT-Raman spectroscopy and thermogravimetric analysis.The results indicate that ilmenite has activity for the reforming of tar due to its highly dispersed iron-containing species. Both the externally added steam and low concentration oxygen affect the tar reforming on ilmenite significantly. The properties of biomass affect the chemical composition of its volatiles and therefore their reforming with the ilmenite catalyst. Compared with sintering, coke deposited on ilmenite is the predominant factor for its deactivation.During the steam reforming process, the char-supported iron/nickel catalysts exhibit very high activity for the reforming of tar. In addition, NO[subscript]x precursors could be decomposed effectively on the char-supported iron catalyst during the steam reforming process. The hydrolysis of HCN and the decomposition of NH[subscript]3 on the catalyst are the key reactions for the catalytic destruction of NO[subscript]x precursors.The kinetic compensation effects demonstrate that the reaction pathways on the char-supported catalysts are similar but different from those on ilmenite. The proprieties of catalyst support could play important roles for the activities of the catalysts and the reaction pathways on the catalysts. The char support as part of the char-supported catalysts can undergo significant structural changes during the catalytic reforming of biomass volatiles.
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Barner, Robert Buckner. "Power conversion unit studies for the next generation nuclear plant coupled to a high-temperature steam electrolysis facility." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4835.
Full textAbstract:
The Department of Energy and the Idaho National Laboratory are developing a
Next Generation Nuclear Plant (NGNP) to serve as a demonstration of state-of-the-art
nuclear technology. The purpose of the demonstration is two fold: 1) efficient low cost
energy generation and 2) hydrogen production. Although a next generation plant could
be developed as a single-purpose facility, early designs are expected to be dual-purpose.
While hydrogen production and advanced energy cycles are still in their early stages of
development, research towards coupling a high temperature reactor, electrical generation
and hydrogen production is under way. Many aspects of the NGNP must be researched
and developed to make recommendations on the final design of the plant. Parameters
such as working conditions, cycle components, working fluids, and power conversion
unit configurations must be understood.
Three configurations of the power conversion unit were modeled using the
process code HYSYS; a three-shaft design with 3 turbines and 4 compressors, a
combined cycle with a Brayton top cycle and a Rankine bottoming cycle, and a reheated
cycle with 3 stages of reheat were investigated. A high temperature steam electrolysis
hydrogen production plant was coupled to the reactor and power conversion unit by
means of an intermediate heat transport loop. Helium, CO2, and an 80% nitrogen, 20%
helium mixture (by weight) were studied to determine the best working fluid in terms
cycle efficiency and development cost. In each of these configurations the relative heat
exchanger size and turbomachinery work were estimated for the different working fluids. Parametric studies away from the baseline values of the three-shaft and combined cycles
were performed to determine the effect of varying conditions in the cycle.
Recommendations on the optimal working fluid for each configuration were made.
The helium working fluid produced the highest overall plant efficiency for the
three-shaft and reheat cycle; however, the nitrogen-helium mixture produced similar
efficiency with smaller component sizes. The CO2 working fluid is recommend in the
combined cycle configuration.
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Wipplinger, Karl Paul Martin. "Utilising a high pressure, cross flow, stainless steel fintube heat exchanger for direct steam generation from recovered waste heat." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50217.
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Thesis (MScEng) -- Stellenbosch University, 2004.<br>ENGLISH ABSTRACT: Around the world the implementation of heat recovery systems is playing an increasingly
important role in the engineering inqustry. The recovered energy is utilised in the plants
and saves companies millions in expenses per year. Not only is this seen on the grand
scale of industry, but also in everyday life, where for instance turbochargers are used to
boost the performance of automobiles by utilising the wasted energy expelled along with
exhaust gasses.
The aim of this project is to investigate a small scale waste heat recovery system, and to
determine the optimum method by which to convert the recovered energy into electrical
energy, which can be used as a secondary energy source.
The research contained in this thesis, centres on the main components and theory needed
for the construction of a small scale waste heat recovery system. Also included, is a
theoretical analysis concerning the design and construction of the system, utilising
researched theory and a simulation program of the recovery system. The simulation is
control volume-based and generates property data on the fluid and exhaust gas throughout
the heat exchanger.
The final design included a finite element stress analysis of certain parts of the system to
ensure safe testing at high pressures and temperatures.
The final design resulted in a high pressure, cross flow, stainless steel fintube heat
exchanger that, by using a continuous combustion unit as energy source and water as the
working fluid, reached efficiencies of up to 74% in direct steam generation testing. The
tube-side of the heat exchanger was designed to withstand pressures of up to 2MPa
(20bar), which is imperative for the implementation of the next phase, where a
turbocharger will be connected to the heat exchanger.
The completion of this part of the project has paved the way for further development and
implementation of the heat recovery system.<br>AFRIKAANSE OPSOMMING: Die herwinning van energie begin 'n toenemend belangrike rol in die ingenieurs industrie
speel. Die herwonne energie word in fabrieke ben ut en spaar maatskappye milj oene aan
uitgawes per jaar. Hierdie beginsel word nie net in die grootskaalse nywerhede toegepas
nie, maar ook in die allerdaagse lewe, soos byvoorbeeld in voertuie waar turbo-aanjaers
gebruik word om die energie-uitset van enjins te verhoog deur bloot gebruik te maak van
die verlore energie wat saam met die uitlaatgasse in die atmosfeer gepomp word.
Die doel van hierdie projek is om 'n kleinskaalse energieherwinningstelsel te ondersoek
en die mees effektiewe metode te vind om die herwinde energie na elektriese energie om
te skakel wat as 'n sekondere energiebron gebruik kan word.
Die navorsing bevat in die tesis, kyk na al die hoofkomponente en teoretiese kennis wat
nodig is vir die konstruksie van 'n kleinskaalse hitteherwinningstelsel. Ook ingesluit is 'n
teoretiese analise ten opsigte van die ontwerp en konstruksie van die sisteem. Dit behels
die gebruik van nagevorsde teorie saam met 'n simulasie program van die herwinnings
stelsel. Die simulasie program is op kontrole volumes gebasseet en genereer uitlaatgas- en
water eienskappe soos dit deur die hitteruiler vloei.
Die finale ontwerp bevat 'n eindige element spannmgs analise van sekere kritiese
komponente in die stelsel om die veilige gebruik van die sisteem by hoe drukke en
temperature te verseker.
Die finale ontwerp was 'n hoedruk, kruisvloei, vlekvrye staal finbuis hitteruiler. Deur 'n
konstante verbrandingseenheid as energiebron te gebruik saam met water as werksvloeier,
het die hitteruiler effektiwiteite van tot 74% in direkte stoomgenerasie-toetse bereik. Die
hitteruiler is ontwerp om hoe drukke van tot 2MPa (20bar) te hanteer wat baie belangrik is
vir die implementasie van die volgende fase van die projek waar 'n turbo-aanjaer aan die
stelsel gekoppel sal.
Die suksesvolle voltooiing van hierdie fase van die projek het die weg gebaan vir die
verdere ontwikkeling en implimentasie van die energieherwinningsstelsel.
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Swanepoel, Jonathan Kyle. "Helically coiled cavity receiver for a micro-scale direct generation steam Rankine cycle using a novel solar dish design." Diss., University of Pretoria, 2019. http://hdl.handle.net/2263/73460.
Full textAbstract:
Sub-Saharan Africa has an underutilised solar resource that is available to provide distributed-scale power to rural communities that are not reached by the current grid systems that are in place. Renewable power generation systems are typically infeasible for this purpose due to their high manufacturing and maintenance costs. This research proposes to address this by experimentally investigating the performance of a micro-scale, solar thermal Rankine cycle with direct steam generation using an affordable solar collector design. The intended power generation range is between 0.1 and 1 kW, which can be used for the direct mechanical pumping of rural irrigation systems or municipal water supplies. The study focuses on the performance of the solar collector (the solar reflector and the solar receiver) under realistic solar thermal conditions in sub-Saharan Africa, as it is considered to be one of the most important components in the solar thermal Rankine cycle. The performance of the solar collector was first characterised in an optical analysis of the new faceted dish reflector design, which comprised six Mylar membranes stretched over the elliptical rims of television satellite dishes. The optical analysis was conducted with the main goal of determining how much concentrated solar radiation would intercept the experimental receiver aperture during solar testing. This was determined by measuring the reflectivity of the reflector facets through ultraviolet and visible light (UV-VIS) spectroscopy and producing an intercept factor trend as a function of receiver aperture size through photographic lunar flux mapping. Based on the spectroscopy analysis, the spectral reflectivity of the clean Mylar facets was determined to be 97% for the visible light spectrum. The intercept factor was determined to be 87% for the designed receiver aperture diameter of 135 mm. The thermal testing took place on a clear, sunny day with low wind velocities. The solar collector followed the arc of the sun throughout the day with a 1° tracking error. During the testing, municipal water was passed through the receiver at 0.284 g/s and the temperature and pressure within the receiver were recorded. A 91-minute testing period occurred, where the inlet and outlet process flows obtained relatively constant operating temperatures with the inlet temperature at 54 °C and the outlet temperature at 343 °C. The total solar irradiance dropped from 801 to 705 W/m2 during this testing period. Using a reflector with a total incident area of 2.73 m2, the total radiation intercepted at the aperture dropped from 1 845 to 1 625 W during this period. The total power capture by the working fluid averaged at approximately 861 W and the total rate of heat loss was determined to be between 1 000 and 750 W. An average collector efficiency of 42% and an average receiver efficiency of 49% were determined for the testing period. An analysis of the heat loss showed that approximately 84% of the heat was lost through the aperture, of which, 31% was from reflected radiation. The second-law analysis showed that most of the irreversibility in the solar collector was caused by absorption of the concentrated radiation at the coil surface. This was because of the large temperature difference between the sun and the receiver coils. The experimental thermal analysis highlighted the design challenges of the micro-scale thermal Rankine cycle. However, the analysis showed that a solar collector can be constructed using locally sourced, affordable materials and can be used to produce power at a micro-scale. With appropriate attention given to optimising the collector design and determining the optimum operating conditions of the solar receiver, the power cycle would be able to compete with current technologies to provide decentralised power to communities in need.<br>Dissertation (MEng)--University of Pretoria, 2019.<br>Technology Innovation Agency (TIA); National Research Foundation (NRF); Department of Science and Innovation (DSI)<br>Mechanical and Aeronautical Engineering<br>MEng (Mechanical)<br>Unrestricted
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Charlesworth, Chris. "Ultrasonic phased array testing in the power generation industry : novel wedge development for the inspection of steam turbine blades roots." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/49401/.
Full textAbstract:
The thesis presented herein comprises of the work undertaken to research novel methods of Phased array ultrasonic inspection of complex steam turbine blade roots as found in the power generation industry. The research was conducted as part of the Engineering Doctorate scheme, administered by the Research Centre for Non-Destructive Evaluation (RCNDE), in conjunction with RWE npower and the University of Warwick. Steam turbine blades, and in particularly last stage blades of low pressure steam turbines, are amongst the most highly stressed components on a power generating plant. Two of the most common blade root fixing types include ‘curved axial entry fir tree roots’ (CAEFTR), and axial pinned roots, both of which are prone to cracking due to the high stresses to which they are subjected under operating conditions. Failure of the blade root fixings of such components, leading to the release of the blades, has historically led to the catastrophic failure and destruction of the whole turbine; the cost of collateral damage to plant components and the loss in generating income are seconded only by the risk these failures pose to life. Due to the high price of failure, NDT plays a critical part in the support and management of engineering maintenance, offering insight into the condition and integrity of turbine components through regular planned inspection regimes. It will be shown in this thesis how the invention of a novel continuous wedge, used to refract ultrasound into the critical regions of the blade roots, has significantly improved the ability to detect defects. Combined with the development of bespoke scanning frames these wedges facilitate the efficient and accurate acquisition of scanned data to assess the integrity of the component. By combining the latest reverse engineering, modelling and simulation tools with novel application of rapid prototyping, the author has been able to demonstrate significant reduction in design cycles whilst improving accuracy, sensitivity and repeatability of the applied inspections. Furthermore, application of this design philosophy has led to the development of inspection techniques which have facilitated the inspection of remote regions of the blade roots where manual access is limited or impossible. The developments and techniques invented during this research have been successfully deployed across numerous RWE npower and customer projects, leading to estimated savings in excess of £1m.
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de, Santos López Guillermo. "Techno-economic Analysis and Market Potential Study of Solar Heat in Industrial Processes : A Fresnel Direct Steam Generation case study." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293918.
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The industrial sector not only has a big contribution to global emissions but also a low share of renewable energy for heat demand. Knowing that most of the energy consumption in industry is heat and that half of it is at medium-low temperature (below 400 ºC), it is a great market for the integration of solar thermal technologies. Following the criteria of high heat demand and low-temperature requirements, five promising industrial sectors and their processes have been analysed: food and beverage, paper and pulp, chemical, textile and mining. Steam generation at supply level has been considered one of the most promising systems considering its integration advantages and the potential of direct steam generation plants. The market potential study has been geographically determined performing an MCA; countries all over the world have been assessed considering their heat consumption in the promising sectors and other conditions that enhance the SHIP feasibility such as solar radiation levels, favourable energy policies, previous experience in SHIP plants, ease of doing business, etc. The price of natural gas has been also considered after selecting Europe as a suitable market. The potential heat demand that this technology could cover has been estimated considering limitations as the competitiveness with other renewable heat sources, the expected heat recovery potential for some sectors, the solar fraction of the region and roof space of the factories. The results show that the five countries with bigger potential are Germany, France, Netherlands, Italy, and Spain, while the sectors with the most suitable market are food and beverage, and chemical. A case study has been selected based on the previous conclusions: a Fresnel direct steam generation plant in Sevilla (Spain) characterized thanks to the data provided by the company Solatom. The plant has been modelled using the software TRNSYS, taking special consideration in the Fresnel performance, the dynamic steam drum behaviour and its influence on the start-up time of the plant. The results achieved through the techno-economic analysis show that parameters such as solar radiation, conventional fuel prices and EU ETS prices have a major impact on the economic indicators. A sensitivity analysis shows that locations with radiation levels above 1750 kWh/m2 have positive values for NPV, and above 2250 kWh/m2 the cost of generating solar heating (LCOH) is under European natural gas prices. In addition to this, fuel prices above 50 €/MWh, which are common for SMEs, results in payback periods under 10 years. Future trends depict favourable scenarios as current European policies are causing a rapid growth of the ETS. Therefore, solar heat in industrial processes can be a feasible alternative, or work as a complement, to conventional systems. Its deployment is driven by supportive policies, high radiation levels, costly fuels prices (such as the ones for SMEs) and the necessity of reducing GHG emissions and decrease the independence on fossil energies.<br>Industrisektorn har inte bara ett stort bidrag till globala utsläpp utan också en låg andel förnybar energi för värmebehov. Att veta att det mesta av energiförbrukningen i industrin är värme och att hälften av den är vid medelhög låg temperatur (under 400ºC), är det en fantastisk marknad för integration av solvärmeteknik. Enligt kriterierna för högt värmebehov och lågtemperaturkrav har fem lovande industrisektorer och deras processer analyserats: mat och dryck, papper och massa, kemikalier, textil och gruvdrift. Ånggenerering på leveransnivå har ansetts vara ett av de mest lovande systemen med tanke på dess integrationsfördelar och potentialen hos direkta ånggenereringsanläggningar. Marknadspotentialstudien har fastställts geografiskt med en MCA; länder över hela världen har bedömts med tanke på deras värmeförbrukning i de lovande sektorerna och andra förhållanden som förbättrar SHIP-genomförbarheten, såsom solstrålningsnivåer, gynnsam energipolitik, tidigare erfarenhet av SHIP-anläggningar, lätt att göra affärer etc. Priset på naturgas har också övervägs efter valet av Europa som en lämplig marknad. Det potentiella värmebehovet som denna teknik kan täcka har uppskattats med tanke på begränsningar som konkurrenskraft med andra förnybara värmekällor, den förväntade värmeåtervinningspotentialen för vissa sektorer, solfraktionen i regionen och fabrikernas takutrymme. Resultaten visar att de fem länderna med större potential är Tyskland, Frankrike, Nederländerna, Italien och Spanien, medan de sektorer som har den mest lämpliga marknaden är mat och dryck samt kemikalier. En fallstudie har valts utifrån de tidigare slutsatserna: en Fresnel-ångproduktionsanläggning i Sevilla (Spanien) som kännetecknas av uppgifterna från företaget. Anläggningen har modellerats med hjälp av programvaran TRNSYS, med särskild hänsyn till Fresnel-prestanda, det dynamiska ångtrummans beteende och dess inflytande på anläggningens starttid. De resultat som uppnåtts genom den tekno-ekonomiska analysen visar att parametrar som solstrålning, konventionella bränslepriser och EU: s ETS-priser har stor inverkan på de ekonomiska indikatorerna. En känslighetsanalys visar att platser med strålningsvärden över 1750 kWh/m2 har positiva värden för NPV och över 2250 kWh/m2 är kostnaden för att generera solvärme (LCOH) under europeiska naturgaspriser. Utöver detta leder bränslepriser över 50 €/MWh, som är vanliga för små och medelstora företag, till återbetalningsperioder under tio år. Framtida trender visar gynnsamma scenarier eftersom europeisk politik orsakar en snabb tillväxt på ETS. Därför kan solvärme i industriella processer vara ett genomförbart alternativ eller fungera som ett komplement till konventionella system. Dess utplacering drivs av stödjande politik, höga strålningsnivåer, dyra bränslepriser (som de för små och medelstora företag) och behovet av att minska växthusgasutsläppen och minska självständigheten för fossila energier.
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Mokhtar, Marwan M. [Verfasser], and R. [Akademischer Betreuer] Stieglitz. "Control of Solar Thermal Linear Fresnel Collector Plants in Single Phase and Direct Steam Generation Modes / Marwan M. Mokhtar ; Betreuer: R. Stieglitz." Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1177147130/34.
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HIPOLITO, FABIO C. "Avaliação das metodologias de análise de sistemas de tubulações de vapor sujeitas a carregamentos do tipo Steam Hammer." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26938.
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Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2016-12-21T18:18:35Z
No. of bitstreams: 0<br>Made available in DSpace on 2016-12-21T18:18:35Z (GMT). No. of bitstreams: 0<br>Carregamentos transientes termo hidráulicos do tipo Steam Hammer são eventos comuns em sistemas de tubulações de vapor com grandes potenciais de catástrofes em plantas de geração de energia. Uma vez iniciado o evento, ondas de pressões são geradas com amplitudes, geralmente, de grande magnitude ocasionando altas pressões no sistema, ruídos, deformações, fadiga, com possibilidade de danos materiais e econômicos e em casos extremos fatalidades. Os procedimentos da indústria para análise deste tipo de sistema consistem realização de análises estáticas equivalentes ou análise de espectro de resposta com carregamentos caracterizados por meio de métodos analíticos baseados em hipóteses simplificadoras do fluido e fluxo. Neste trabalho é proposta a analise de sistema de tubulações por meio do método de integração numérica com superposição modal e carregamento caracterizado por método numérico com base no método das características. Comparações foram efetuadas entre os resultados obtidos pela metodologia proposta e os procedimentos da indústria, demonstrando que, dado ao alto grau de conservadorismo, os procedimentos da indústria acarretam em superdimensionamento de estruturas e tubulações ocasionando custos adicionais de projeto, sendo a otimização do projeto obtida aplicando-se a metodologia proposta no trabalho.<br>Dissertação (Mestrado em Tecnologia Nuclear)<br>IPEN/D<br>Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Payne, Nathaniel M. "Development of a Combined Thermal Management and Power Generation System using a Multi-Mode Rankine Cycle." Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright1622657194320193.
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Hoffmann, Alexander [Verfasser], Robert [Akademischer Betreuer] Pitz-Paal, and Uwe [Akademischer Betreuer] Hampel. "Numerical and Experimental Investigation of Transient Two-phase Flow Phenomena in Concentrated Solar Power Plants with Direct Steam Generation / Alexander Hoffmann ; Robert Pitz-Paal, Uwe Hampel." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1162063718/34.
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Miranda, André Navarro de. "Síntese e caracterização de óxidos mistos de cobalto, manganês e alumínio para decomposição catalítica de H2O2 70% e geração de vapor." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/97/97134/tde-13092016-110132/.
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Este trabalho teve como objetivo o desenvolvimento de catalisadores mássicos à base de óxidos mistos de cobalto, manganês e alumínio, para a decomposição de peróxido de hidrogênio comercial, 70% em massa, e consequente geração de vapor d\'água. A síntese dos materiais foi realizada por coprecipitação em meio básico. Durante a reação foram sistematicamente estudados o pH do meio, a concentração inicial de carbonato, a velocidade de agitação, o tempo de envelhecimento, a influência da lavagem do precitado, o diâmetro médio das partículas e a temperatura e tempo de tratamento térmico. Os materiais foram caracterizados quanto as fases presentes, porcentagem mássica, massa específica, área específica, resistência mecânica e atividade catalítica, visando correlacionar suas propriedades físico-químicas com sua atividade na decomposição catalítica do peróxido de hidrogênio. Finalmente, os materiais que apresentaram melhor resistência mecânica e atividade catalítica foram testados em um sistema gerador de vapor. O melhor catalisador apresentou alta resistência mecânica, baixo tempo de indução e se mostrou ativo em testes de longa duração, possibilitando ao sistema alcançar temperaturas próximas à de decomposição adiabática do H2O2 70% em massa.<br>This work aimed to develop catalysts based on mixed oxides of cobalt, manganese and aluminum for the decomposition of commercial hydrogen peroxide, 70% p, inducing steam generation. The materials were synthesized by coprecipitation under alkaline condition. During reaction, were systematically studied the pH of the solution, the initial concentration of carbonate, the stirring speed, the aging time, the precipitate washing, the average particle diameter, the temperature and time of thermal treatment. The materials were characterized to determine the present phases, mass concentration, density, surface area, mechanical strength and catalytic activity, aiming to correlate their physicochemical properties with its activity on hydrogen peroxide catalytic decomposition. Once the best parameters were set, the best catalysts were tested in a steam generating system. The best catalyst have presented high mechanical strength, low induction time and proved to be active in long-term tests, enabling the system to reach temperatures close to the adiabatic decomposition of the H2O2 70% wt.
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Mathias, Rodrigo Escada [UNESP]. "Redução do consumo de energia fóssil na geração de vapor utilizado em restaurante industrial de empresa automotiva." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/144534.
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Previous issue date: 2016-09-01<br>No atual contexto energético mundial, a busca pela mitigação e, sempre que possível, a substituição de combustíveis fósseis por fontes renováveis, são a pauta de diversas instituições e empresas, pois a disponibilidade de recursos não é proporcional ao crescimento do consumo. Este trabalho tem por objetivo a redução do uso de gás natural para geração de vapor nos processos de cocção de cozinha industrial. Foi realizado a caracterização do processo e dos equipamentos, identificando o fluxo de vapor ao longo de todo o processo. De modo comparativo, desenvolveu-se propostas utilizando energia renovável para redução do uso de combustível fóssil. Para suportar essa atividade foram realizadas modelagens termodinâmica do sistema atual comparando-a aos sistemas propostos, mostrando o comportamento e definindo qual proposta teria a maior colaboração na redução do consumo de combustível. Por fim, foi estudado a viabilidade financeira de cada proposta através do método do VPL e payback. O presente trabalho gerou oito propostas, entre energia solar, produção de biogás a partir de resíduos orgânicos e efluentes de estação de tratamento de esgoto, geração de energia elétrica por meio de microturbina a gás e motor de combustão interna. Conclui-se que das oito propostas, três apresentaram potencial energético capaz de substituir em 100 % a vazão mássica de gás natural demandada na cozinha industrial, além de obterem viabilidade financeira satisfatória para seguir em frente com implementação do projeto. A substituição do gás natural pelo biogás gerado a partir de efluentes da estação de tratamento foi a proposta que apresentou o melhor desempenho, a mesma foi capaz de substituir 100 % da vazão mássica de gás natural utilizado para gerar vapor aos vasos de pressão da cozinha industrial, sendo 199.741 kWh de potencial energético e um VPL positivo de R$ 2.473.966,15, com retorno dos investimentos em menos de um ano.<br>In the current global energy context of mitigation of non-renewable fuels and whenever it is possible, replacing fossil fuels by renewable sources are the agenda of the most of institutions and companies, because the availability of resources is not proportional to the growth of consumption. This work has as target to reduce the use of natural gas for steam generation in the cooking process of industrial kitchen. It was performed a process and equipment characterization, identifying the steam flow along the whole process. In a comparative way, it has developed proposals using renewable energy for reducing the use of fossil fuel. To support that, it was done a thermodynamic modeling of the current system compared with the proposed ones, showing the behavior and defining which proposal had the larger collaboration in terms of fuel consumption reduction. Finally, it was analyzed the financial feasibility of each alternatives by NPV and payback method. The present work has created eight proposals, such as solar energy, biogas production from organic waste and from wastewater of sewage treatment station, electric energy from gas micro turbine and internal combustion engine. Concludes that from eight proposals, three presented energetic potential able to replace in 100 % the natural gas mass flow demanded in the industrial kitchen, beyond to get satisfactory financial viability to move forwards with the project implementation. The replacement of natural gas by generated biogas from wastewater of sewage treatment station was the proposal that presented the best performance, this ones was able to replace 100 % of the natural gas mass flow used to generate steam to the pressure vessel of industrial kitchen, where 199.741 kWh of energetic potential and a NPV of R$ 2.473.966,15, with an investment return less than one year.
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Kiriarachchi, Hiran D. "Nanostructured Materials for Photocatalysis, Water Treatment and Solar Desalination." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5886.
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Maintaining a constant supply of clean drinking water is among the most pressing global challenges in our time. About one-third of the population is affected by the water scarcity and it can only get worse with climate change, rapid industrialization, and the population growth. Even though nearly 70 percent of the planet is covered by water, the consumable freshwater content is only 2.5 percent of it. Unfortunately, the accessible portion of it is only 1 percent. Even so, most of the freshwater bodies are choked with pollution. Considering the vast availability of saline water on the planet and the increasing wastewater generation, seawater desalination, and wastewater treatment and recycling seem to have the potential to address current water-related issues. Therefore, it is necessary to find efficient techniques for seawater desalination and wastewater treatment. The use of nanostructured materials for these applications is becoming a popular approach due to the unique chemical and physical properties they possess compared to bulk materials
Solar energy is the cleanest and most abundant renewable natural resource available. Materials for solar photothermal energy conversion are highly sought after for their cost savings, clean environment, and broad utility in providing water heating and/or steam for many applications including domestic water heating and solar-driven desalination. Extensive research efforts have been made to develop efficient solar absorbers with characteristics such as low weight, low thermal conductivity, broad solar absorption and porosity to be able to float on water to provide more efficient and cost-effective solar steam generation systems. Metal NPs have been proposed to take advantage of the high efficiency of the photothermal energy conversion associated with surface plasmon resonance absorption. Nanostructured carbon-based materials such as graphene oxide, carbon nanotubes, carbonized biomass are also in use due to their excellent photothermal energy conversion ability over the range of the visible and near infra-red region of the electromagnetic spectrum.
In this dissertation, five projects based on the utility of nanostructured materials for desalination, photocatalysis and water treatment will be discussed. The first three projects involve the fabrication and design of plasmonic and carbon-based photothermal materials for applications in solar steam generation, water desalination, and wastewater treatment. In the fourth project, a unique shape of ZnO nanostructure was synthesized for photodegradation of organic dyes in industrial wastewater. The final project demonstrates the shape-controlled synthesis of iron carbide nanostructures and composite materials of aminated graphene oxide for the removal of Cr(VI) from wastewater.
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Horký, Jiljí. "Analýza stavu potrubí odvodnění parní turbíny K 220-44 a návrh korektivních opatření." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443203.
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This diploma thesis deals with the analysis of the drainage pipeline of the Škoda K 220-44 steam turbine. This turbine is operated in Dukovany Nuclear Power Plant. One part of this work is proposal of corrective measures. The aims of this work include the creation of a search for drainage, steam, erosion corrosion and mapping of defects in long-term operated drainage system. Work also includes the evaluation of measured values of the pipe wall thickness measured by ultrasonic analyzer. In addition, the work contains images created from 3D model, on which the location of defects and measurements are displayed.
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Bowers, Lindsay Jeanine. "Cooked yields, cooked color, tenderness, and sensory traits of beef roasts differing in connective tissue content cooked in an oven with steam generation versus a commercial convection oven to different endpoint temperatures." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/9211.
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Master of Science<br>Department of Animal Sciences and Industry<br>Michael E. Dikeman<br>The CVap steam generation oven was compared to a Blodgett forced-air, convection oven to examine effects of cooking method on yields, cooked color, tenderness, and sensory traits of beef Longissimus lumborum (LL), Deep pectoralis (DP), and Biceps femoris (BF) muscles cooked to three endpoint temperatures (65.6, 71.1, and 76.7°C). For each cooking treatment, four roasts were cooked in the CVap oven for a pre-determined, average amount of time, and two roasts were cooked in the Blodgett oven until they reached desired internal endpoint temperature. Cooking yields were higher (P ≤ 0.05) for BF and LL roasts cooked in the CVap. Slice shear force (SSF) for BF roasts cooked in the CVap were lower (P ≤ 0.05), whereas, SSF values for DP roasts cooked in the Blodgett were lower (P ≤ 0.05). No oven difference (P > 0.05) was found for LL roasts. Sensory tenderness scores for BF roasts cooked in the CVap were slightly higher (P ≤ 0.05) than roasts cooked in the Blodgett. Sensory scores for LL roasts cooked in the CVap were slightly higher but were also drier (both P ≤ 0.05). The CVap oven offers tenderization and cooking yield advantages for certain muscles.
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Marchetti, Francesca. "Carbon – based nanofluids and hybrid natural polymers for enhanced solar-driven evaporation of water: synthesis and characterization." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/260374.
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The scarcity of freshwater is becoming a global challenge worldwide due to limited resources availability and increasing demand both for manufacturing and household use. For this reason, there is an important need to develop efficient, economic and sustainable desalination technologies able to take advantage of unconventional sources of water (seawater, brackish groundwater and wastewater) in order to produce freshwater.
Sun is considered as the most promising abundant renewable (and free) energy source that can be employed in steam and vapor generation processes, which has a great importance in many applications such as: water desalination, domestic water heating, and power generation.
This doctoral dissertation presents a study on the efficiency of different carbon based systems - nanofluids and hybrid natural composites - for the improvement of direct-solar evaporation systems, for the production of freshwater. The two main goals of this work consist of: (i) the synthesis and characterization of stable carbon-based nanofluids in water and of re-usable, economical and ecological hybrid composite materials, and (ii) the comparison of such carbon-based systems applied to water evaporation, understanding mechanisms, advantages and limitations.
Carbon based materials (carbon black, graphene and multi-walled carbon nanotubes) were chosen because of their high sunlight absorption ability, unique thermal properties, as well as low cost and abundant availability. However, the hydrophobic character of such materials makes necessary to find efficient strategies to overcome this problem when dealing with water.
In this work, the suspension stability of graphene-based nanofluids in water - a key parameter for the application of nanofluids in any field - was effectively improved by combining physical (by RF Sputtering coating) or chemical (by NaClO-NaBr solution) graphene surface modification treatments, and the use of common additives (Triton X-114, SDBS and gum arabic) showing different stabilization mechanisms. The best strategy to obtain long-time graphene suspension stability in water (both deionized water and saline solution with 3.5 wt% NaCl) turned out to be the combination of the easy chemical treatment with the electro-steric stabilization effect of gum arabic.
In addition to nanofluids, a re-usable devices based on gum arabic cross-linked gelatin hydrogel were synthesized and characterized. Hydrophobic carbon-based materials were easily and uniformly embedded into the porous hydrogel matrix, thanks to the amphiphilic character of both gelatin and gum arabic. The effect of carbon-nanoparticles nature, morphology and concentration on the measured effective thermal conductivity of the composite material was studied and the thermal conductivity of the nanoparticles was evaluated applying several models based on the effective medium approach. The values obtained for the nanoparticles were far from the tabulated thermal conductivity values because of the combination of the composite features (such as nanoparticles concentration, Kapitza resistance) and the particles characteristics (such as aspect ratio, crystalline structure).
The performance of carbon-based nanofluids and hybrid hydrogels on direct-solar evaporation of water was tested and compared to that of carbon-wood bilayer composite (which presents both hydrophilic character and natural channels for water transportation) under solar simulator. The effect of surface temperature, light-to-heat conversion efficiency of carbon-based materials, heat losses, water transport through a porous medium and suspension stability (in the case of nanofluids) were investigated in order to understand the advantages and limitations of such systems.
All the tested systems were able to improve water evaporation rate and evaporation efficiency up to 70% and 82% under 1 sun and 2 suns respectively using a small amount of nanoparticles: the same amount of particles dispersed in nanofluid (0.01 wt%) was embedded into hydrogels or deposited onto wood. The high sunlight absorption ability of carbon-based nanoparticles appeared as a dominant parameter for the improvement of water evaporation rate. In fact, enhanced light absorption was directly related to a high photothermal conversion efficiency, which caused an improvement in the surface temperature, leading to a consequent enhancement in evaporation rate. It has been found that an adequate supply of water to the evaporation surface represents a fundamental parameter as well considering floating systems.
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Marchetti, Francesca. "Carbon – based nanofluids and hybrid natural polymers for enhanced solar-driven evaporation of water: synthesis and characterization." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/260374.
Full textAbstract:
The scarcity of freshwater is becoming a global challenge worldwide due to limited resources availability and increasing demand both for manufacturing and household use. For this reason, there is an important need to develop efficient, economic and sustainable desalination technologies able to take advantage of unconventional sources of water (seawater, brackish groundwater and wastewater) in order to produce freshwater.
Sun is considered as the most promising abundant renewable (and free) energy source that can be employed in steam and vapor generation processes, which has a great importance in many applications such as: water desalination, domestic water heating, and power generation.
This doctoral dissertation presents a study on the efficiency of different carbon based systems - nanofluids and hybrid natural composites - for the improvement of direct-solar evaporation systems, for the production of freshwater. The two main goals of this work consist of: (i) the synthesis and characterization of stable carbon-based nanofluids in water and of re-usable, economical and ecological hybrid composite materials, and (ii) the comparison of such carbon-based systems applied to water evaporation, understanding mechanisms, advantages and limitations.
Carbon based materials (carbon black, graphene and multi-walled carbon nanotubes) were chosen because of their high sunlight absorption ability, unique thermal properties, as well as low cost and abundant availability. However, the hydrophobic character of such materials makes necessary to find efficient strategies to overcome this problem when dealing with water.
In this work, the suspension stability of graphene-based nanofluids in water - a key parameter for the application of nanofluids in any field - was effectively improved by combining physical (by RF Sputtering coating) or chemical (by NaClO-NaBr solution) graphene surface modification treatments, and the use of common additives (Triton X-114, SDBS and gum arabic) showing different stabilization mechanisms. The best strategy to obtain long-time graphene suspension stability in water (both deionized water and saline solution with 3.5 wt% NaCl) turned out to be the combination of the easy chemical treatment with the electro-steric stabilization effect of gum arabic.
In addition to nanofluids, a re-usable devices based on gum arabic cross-linked gelatin hydrogel were synthesized and characterized. Hydrophobic carbon-based materials were easily and uniformly embedded into the porous hydrogel matrix, thanks to the amphiphilic character of both gelatin and gum arabic. The effect of carbon-nanoparticles nature, morphology and concentration on the measured effective thermal conductivity of the composite material was studied and the thermal conductivity of the nanoparticles was evaluated applying several models based on the effective medium approach. The values obtained for the nanoparticles were far from the tabulated thermal conductivity values because of the combination of the composite features (such as nanoparticles concentration, Kapitza resistance) and the particles characteristics (such as aspect ratio, crystalline structure).
The performance of carbon-based nanofluids and hybrid hydrogels on direct-solar evaporation of water was tested and compared to that of carbon-wood bilayer composite (which presents both hydrophilic character and natural channels for water transportation) under solar simulator. The effect of surface temperature, light-to-heat conversion efficiency of carbon-based materials, heat losses, water transport through a porous medium and suspension stability (in the case of nanofluids) were investigated in order to understand the advantages and limitations of such systems.
All the tested systems were able to improve water evaporation rate and evaporation efficiency up to 70% and 82% under 1 sun and 2 suns respectively using a small amount of nanoparticles: the same amount of particles dispersed in nanofluid (0.01 wt%) was embedded into hydrogels or deposited onto wood. The high sunlight absorption ability of carbon-based nanoparticles appeared as a dominant parameter for the improvement of water evaporation rate. In fact, enhanced light absorption was directly related to a high photothermal conversion efficiency, which caused an improvement in the surface temperature, leading to a consequent enhancement in evaporation rate. It has been found that an adequate supply of water to the evaporation surface represents a fundamental parameter as well considering floating systems.
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Aurousseau, Antoine. "Modélisation dynamique et régulation des centrales solaires thermodynamiques linéaires à génération directe de vapeur." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2016. http://www.theses.fr/2016EMAC0003/document.
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Les Centrales Solaires Thermodynamiques à génération directe de vapeur utilisent la concentration optique du rayonnement solaire direct pour produire de la vapeur d'eau à haute pression et haute température. La vapeur d'eau est ensuite utilisée directement comme fluide de travail d'un cycle thermodynamique type Rankine, pour la propulsion d'un couple turbine-génératrice et assurer ainsi une production électrique. La conjonction de la variabilité naturelle de l'ensoleillement, qu'elle soit lente et déterministe (cycle jour/nuit, cycle saisonnier, dégradation des performances optiques), ou rapide et non déterministe (passages nuageux), et de la présence d'un écoulement diphasique eau/vapeur dans les tubes horizontaux, provoque un comportement fortement dynamique du système de génération de vapeur. Par ailleurs, les turbines à vapeur étant très sensibles aux fluctuations de la température d'admission de vapeur, il convient donc de réguler le plus efficacement possible la production de vapeur. Les temps de séjour de fluide dans les champs solaires linéaires pouvant être relativement longs, les stratégies de contrôle conventionnelles se révèlent moins adaptées et peu efficaces. L'objectif de ce travail est d'étudier, par la réalisation de modèles et de leur utilisation en simulation, le fonctionnement dynamique du système de génération de vapeur. Des modèles dynamiques de centrales linéaires de Fresnel et cylindro-parabolique sont réalisés, et des données expérimentales issues d'un prototype cylindro-parabolique sont utilisées pour la validation. Les modèles permettent ensuite l'étude de stratégies de régulation, permettant un contrôle de la vapeur sortant du champ solaire soumis à des transitoires. L'étude de l'utilisation de méthodes de prédiction de l'ensoleillement direct à court terme est abordée à la fin de ce travail, afin d'évaluer la possibilité d'intégrer ces méthodes dans les stratégies de régulation<br>Direct steam generation concentrated solar power plants use the optical concentration of solar direct irradiation to generate high pressure and high temperature steam in the absorber tubes. Steam is used as the working fluid of a Rankine-type thermodynamic cycle for the propelling of a steam turbine and an electric generator. The conjunction of the natural transient condition of solar irradiation and the presence of a two-phase flow inside the absorber tubes leads to a strong dynamic behavior of the steam generation system. Moreover, steam turbines being very sensitive to inlet temperature transients, the control of steam generation has to be achieved with the best possible efficiency. Because of the large time constants of the flow in the solar field (among other reasons), basic control strategies are poorly efficient and not well suited. The aim of this thesis work is the study, through modeling and simulation, of the dynamic behavior of the steam generation system. Dynamic modeling of linear Fresnel and parabolic-trough solar plants is carried out, and experimental data from a parabolic-trough prototype are used for validation. The models are used for the study of advanced control strategies, for a better control of steam conditions at the solar field outlet, under irradiation transients. Short-term irradiation prediction methods are evaluated for a use in the control strategies
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de, Leng Daniel. "Spatio-Temporal Stream Reasoning with Adaptive State Stream Generation." Licentiate thesis, Linköpings universitet, Artificiell intelligens och integrerade datorsystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-138645.
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A lot of today's data is generated incrementally over time by a large variety of producers. This data ranges from quantitative sensor observations produced by robot systems to complex unstructured human-generated texts on social media. With data being so abundant, making sense of these streams of data through reasoning is challenging. Reasoning over streams is particularly relevant for autonomous robotic systems that operate in a physical environment. They commonly observe this environment through incremental observations, gradually refining information about their surroundings. This makes robust management of streaming data and its refinement an important problem. Many contemporary approaches to stream reasoning focus on the issue of querying data streams in order to generate higher-level information by relying on well-known database approaches. Other approaches apply logic-based reasoning techniques, which rarely consider the provenance of their symbolic interpretations. In this thesis, we integrate techniques for logic-based spatio-temporal stream reasoning with the adaptive generation of the state streams needed to do the reasoning over. This combination deals with both the challenge of reasoning over streaming data and the problem of robustly managing streaming data and its refinement. The main contributions of this thesis are (1) a logic-based spatio-temporal reasoning technique that combines temporal reasoning with qualitative spatial reasoning; (2) an adaptive reconfiguration procedure for generating and maintaining a data stream required to perform spatio-temporal stream reasoning over; and (3) integration of these two techniques into a stream reasoning framework. The proposed spatio-temporal stream reasoning technique is able to reason with intertemporal spatial relations by leveraging landmarks. Adaptive state stream generation allows the framework to adapt in situations in which the set of available streaming resources changes. Management of streaming resources is formalised in the DyKnow model, which introduces a configuration life-cycle to adaptively generate state streams. The DyKnow-ROS stream reasoning framework is a concrete realisation of this model that extends the Robot Operating System (ROS). DyKnow-ROS has been deployed on the SoftBank Robotics NAO platform to demonstrate the system's capabilities in the context of a case study on run-time adaptive reconfiguration. The results show that the proposed system – by combining reasoning over and reasoning about streams – can robustly perform spatio-temporal stream reasoning, even when the availability of streaming resources changes.<br><p>The series name <em>Linköping Studies in Science and Technology Licentiate Thesis</em> is inocorrect. The correct series name is <em>Linköping Studies in Science and Technology Thesis</em>.</p><br>NFFP6<br>CENIIT
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Fernandes, Ademir Edson. "Estudo de caso de um sistema de cogeração em uma indústria farmacêutica." Universidade de Taubaté, 2011. http://www.bdtd.unitau.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=271.
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No atual período de incertezas na geração e transmissão de energia elétrica no Brasil, a utilização dos sistemas de cogeração com uso de gás natural, tornou-se uma grande oportunidade econômica, estratégica e tecnológica, para as pequenas e médias empresas, considerando a extensão e perspectivas de expansão da rede de distribuição de gás natural. Uma empresa farmacêutica para se manter competitiva e reduzir o impacto dos custos indiretos em seus produtos, necessitava aumentar sua linha de injetáveis, produzindo no Brasil alguns medicamentos que até então eram importados de filiais em outros países e para que isto fosse possível, teria de investir na construção de novos laboratórios, compra de equipamentos, aumento de utilidades para sua fabricação como vapor de água para injetáveis, sistema de HVAC para salas limpas, o que levaria a um aumento de consumo de energia, vapor, água de refrigeração. Este investimento inviabilizaria a produção desta nova linha de produtos, pois tanto o custo do investimento em novas centrais de utilidades, quanto mais o custo desta geração e sua manutenção, decretariam um fim para a esta empreita. Neste trabalho, apresentou-se uma alternativa como solução para viabilizar esta instalação, trocando-se os chillers convencionais por um chiller de absorção, que alem de consumir pouca energia elétrica utilizando a troca térmica entre brometo de lítio e vapor para gerar água de resfriamento para o sistema de ar condicionado, o sistema proposto proporcionou um aumento de fornecimento de vapor não só para alimentar o sistema de HVAC como para a produção da fabrica, anexo a esta caldeira de recuperação é proposto a instalação de uma turbina á gás com condições suficientes de gerar energia elétrica para todo o site e ainda ter condições de negociar o excedente de energia para ser vendido para a concessionária. O resultado deste sistema proposto demonstrou uma excelente eficiência, frente ao sistema convencional, o que tecnicamente se apresentou como muito viável.<br>In the current period of uncertainty in the generation and transmission of electric energy in Brazil, the use of cogeneration systems using natural gas, has become a great economic opportunity, strategic and technology for small and medium enterprises, considering the extent and prospects for expansion of the distribution of natural gas. A pharmaceutical company to remain competitive and reduce the impact of indirect costs in their products, needed to increase its line of injectables, producing here in Brazil some drugs that were previously imported from subsidiaries in other countries and to make this possible, would invest in building new laboratories, purchase equipment, increase of utilities for its manufacture steam as water for injection, the HVAC system for clean rooms, leading to an increased consumption of energy, steam, cooling water. This investment would make impracticable the production of this new line of products, therefore not only the cost of the investment in new central offices of utilities, the more the cost of this generation of utilities and its maintenance, would decree an end for the this take over on a contract basis. In this work, presented as an alternative solution to enable this facility, exchanging conventional chillers for an absorption chiller, which besides consume little electricity using the heat exchange between lithium bromide to generate steam and cooling water for the air conditioning system, the proposed system provided an increased supply of steam to feed not only the HVAC system for the production of manufactures, attached to this recovery boiler is proposed to install a gas turbine with sufficient conditions generate electricity for the entire site and still be able to trade the surplus energy to be sold to the utility. The result of this proposed system showed an excellent efficiency, compared to the conventional system, which technically is presented as very viable.
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Bouvier, Jean-Louis. "Étude expérimentale d'une installation de micro-cogénération solaire couplant un concentrateur cylindro-parabolique et un moteur à cycle de Hirn." Thesis, La Rochelle, 2014. http://www.theses.fr/2014LAROS031/document.
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L’objectif de cette thèse est d’étudier expérimentalement les performances énergétiques d'une installation de micro-cogénération solaire. Le prototype réalisé est constitué d'un concentrateur cylindro-parabolique associé à un moteur à vapeur fonctionnant suivant un cycle de Hirn (Rankine avec surchauffe). Les originalités de ce projet sont l’utilisation de l’énergie solaire, renouvelable et inépuisable mais intermittente, la génération directe de vapeur au sein d'un concentrateur de taille réduite (46,5 m²), le système de suivi solaire sur deux axes et le couplage à un moteur à piston non lubrifié. La première partie de l'étude porte sur le concentrateur seul. Son fonctionnement est étudié sur deux journées types (ensoleillée et nuageuse) et son rendement thermique est évalué. La dynamique du système est également abordée notamment par l'étude de sa réponse à des perturbations. Une régulation de type boucle ouverte a été mise en place et validée. La seconde partie concerne la caractérisation du moteur seul. Des essais ont été menés avec une puissance de source chaude stable puis variable. À partir des résultats obtenus, un modèle empirique est développé, puis exploité dans le cadre d'une étude paramétrique du moteur. Cette étude montre l'influence importante du ratio de pression et de la vitesse de rotation sur le rendement. Dans la dernière partie, les performances globales (rendement, puissances électrique et thermique produites) du micro-cogénérateur sont évaluées. Des essais à pression et à vitesse régulées sont présentés. A partir de cartographies de fonctionnement réalisées à l’aide d’un modèle empirique, une régulation basée sur l'utilisation d'un by-pass est alors mise en place, puis testée<br>The objective of this thesis is the experimental study of the energy performances of a micro combined solar heat and power (micro-CHP) unit. The prototype is composed of a solar parabolic trough collector coupled to a Hirn (superheated Rankine) cycle engine. The originalities of this project are the use of solar energy which is renewable and inexhaustible but intermittent, the direct steam generation with a reduced size parabolic trough collector (46.5 m²), the two axis tracking system and the coupling with an oil-free reciprocating steam engine. The first part of this study is focussed on the solar collector. Thermal performances under sunny and cloudy conditions are presented and the thermal efficiency is evaluated. The system dynamic is also investigated through the characterization of the inertia as well as a study of its response to perturbations. Then a control strategy is set up and validated. The second part deals with the characterization of the engine. Tests have been performed with a stable and variable heat source power. From these tests, an empirical model has been developed and used in a parametrical study. This study shows the significant influence of the pressure ratio and of the rotational speed on the efficiency of the engine. In the last part, global performances (efficiency, output thermal and electrical powers) of the entire micro-CHP unit are evaluated. Tests with controlled pressure and speed are presented. From operating maps established from an empirical model, a control strategy based on the use of a by-pass is set up and tested
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Sartori, Chiara. "Generation of ovine induced pluripotent stem cells." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6491.
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Embryonic stem cells (ESCs) are pluripotent cells derived from the early embryo and are able to differentiate into cells belonging to the three germ layers. They are a valuable tool in research and for clinical use, but their applications are limited by ethical and technical issues. In 2006 a breakthrough report described the generation of induced pluripotent stem cells (iPSCs). IPSCs are ESC-like cells generated from somatic cells by forcing the ectopic expression of specific transcription factors. This circumvents the ethical issues about the use of embryos in research and provides multiple opportunities to understand the mechanisms behind pluripotency. The aim of this project was to generate sheep iPSCs and characterise them. In order to learn the technique I initially repeated the original iPSC methodology: the putative mouse iPSCs I have generated display a morphology typical of ESCs, characterised by a high nuclear to cytoplasmic ratio, and form colonies with neat edges and smooth domes. These cells are positive to Nanog, a marker of pluripotency, and can give rise to cells belonging to the mesodermal and the ectodermal lineages when differentiated in vitro. Since the main aim of the thesis was the derivation of sheep pluripotent cells, once established the protocol in mouse, I then moved to the generation of ovine iPSC colonies. The cells I have generated have a morphology similar to that of mouse ESCs, express markers of pluripotency such as alkaline phosphatase and Nanog and can differentiate in vitro and in vivo into cells belonging to the three germ layers. Additionally, these ovine iPSCs can contribute to live born chimeric lambs, although at low level.
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Laberge, Sebastien. "DC voltage generation using periodic bit-stream modulation." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33976.
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In recent years, the trend for continuous down-scaling of CMOS device dimension has made analog design much more challenging. This trend has been a major driving force in trying to find new approaches for designing common analog building blocks. One such block is the bandgap voltage reference. This common circuit serves the purpose of generating a fixed DC voltage reference and has uses in a wide variety of applications.<br>This thesis introduces a new way of generating a programmable DC voltage reference with similar performance to the traditional means. This voltage reference generator is based on periodic bit-stream modulation and relies on simple digital logic combined with a low pass filter (LPF) to demodulate the DC reference level. The advantage of the proposed DC voltage reference lies in its immunity to technology scaling as it is mostly digital. The programmability of the proposed circuit also makes it usable as a digital to analog converter (DAC).<br>Through simulation and experimental results obtained using a set of integrated circuits implemented in 0.35 mum, 0.25 mum and 0.18 mum CMOS technologies a number of conclusions are reached. The tradeoffs between the two different bit-stream modulation scheme, pulse width modulation (PWM) and pulse density modulation (PDM), are compared yielding PDM as the best approach. The analysis and simulation of a new synthesis method will demonstrate that high-order passive RC filters yield the most attractive realization of the LPF. Experimental results will also demonstrate that performance due to temperature variations comparable to bandgap references can be achieved. A set of experiments will also demonstrate the excellent performance of this voltage reference when used as a DAC. Lastly, the use of asynchronous logic for generating periodic bit-streams will be shown to yield promising results.
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Gao, Lan. "A Dual Approach For Water Purification Based On Solar Energy." Thesis, Université Gustave Eiffel, 2022. https://these.univ-paris-est.fr/intranet/2022/TH2022UEFL2002.
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Dans le contexte de la réduction de la ressource en eau potable à échelle mondiale, un intérêt croissant est porté au développement de technologies efficaces de purification de l'eau. Dans les travaux de cette thèse de doctorat, nous avons exploré le potentiel des micro- et nanotechnologies afin de proposer et évaluer deux méthodes de purification de l'eau, toutes deux entièrement autonomes en énergie et n'utilisant que l'énergie solaire pour leur mise en œuvre. La première méthode consiste en la génération de vapeur d'eau de façon accélérée grâce à la mise en œuvre d'une méta-mousse que nous avons conçus, dont nous avons modélisé et simulé le fonctionnement, puis optimisé pour la rendre la plus efficace en terme de quantité de vapeur générée par unité de temps et par unité de surface. En exploitant le silicium noir nanostructuré et en y rajoutant une micro-structuration bidimensionnelle contrôlée, unesérie de méta-mousses ont été réalisées et évaluées et les résultats ont montré une efficacité de conversion de 89% et une vitesse d'évaporation de 1,34 kg/(h·m2), ce qui représente une performance au-delà de l'état de l'art et proche de la limite théorique. La deuxième méthode est basée sur la photocatalyse. Elle se veut complémentaire de la première car elle permet de purifier les polluants résiduels volatils qui persistent après la mise en œuvre de la première méthode basée sur l'évaporation (et la condensation). Pour répondre aux exigences du traitement de l'eau à grande échelle, il y a deux points importants : L'un est la durabilité incluant la stabilité chimique du matériau photocatalyseur, en particulier dans des conditions extrêmes de pH de l'eau. L'autre est la facilité de synthèse de tels photocatalyseurs avec unenano-structure spécifiques. Sur la base de l'expérience du laboratoire en matière de croissance de nanofils (NWs) de ZnO, connu pour ses excellentes propriétés photocatalytiques, notre principale contribution dans cette thèse a consisté à le rendre plus durable et robuste aux environnements chimiques agressifs. A cet effet, nous avons proposé et évalué une combinaison de ZnO et de TiO 2 , tous deux ayant de hautes performances de dépollution. Cette combinaison a pour objectif de tirer profit des avantages respectifs des deux matériaux: la très bonne robustesse chimique du TiO 2 d'une part et la possibilité de synthétiser du ZnO sous forme de nanofils, donc avec une très grande surface spécifique. Il nous a semblé donc avantageux d'effectuer un revêtement de TiO 2 d'une épaisseur nanométrique sur des nanofils de ZnO (NW) après qu'un réseau homogène de ZnO NW ait été synthétisé. Cet assemblage original du tandem TiO 2 /ZnO nanostructuré a été caractérisé puis nous avons évalué sa durabilité et sa fonctionnalité de purification de l'eau. Notre solution s'est avérée efficace aussi bien dans dessolutions aqueuses fortement acides et fortement basiques. De plus, l'expérience de purification photocatalytique de l'eau des colorants organiques a été démontrée avec succès. Les résultats engrangés dans cette thèse offrent la perspective de valorisation en vue de la réalisation de systèmes de purification d'eau complètement autonomes et à bas coût<br>In the context of increasing global water scarcity, many efforts have been devoted to developing efficient water purification technologies. In this thesis work, two eco-friendly and promising approaches water purification approaches, surface-enhanced solar steam generation and photocatalysis, are studied to come out with a nano-enabled, fully self-consistent device that operates solely based on sunlight for delivering high-quality water.Surface-enhanced solar steam generation can be applied to purify insoluble and soluble water pollutants. It requires proper active photothermal material surface and optimized porosity to achieve high evaporation efficiency by localizing the heat at the water-air interface during solar steam generation. Herein, Taking the advantage of the characteristics of silicon that can be tailored to the target shape in the nanofabrication process and the high absorptivity of the black silicon, we report a bilayer black absorber sheet consisting of black silicon and commercial foam, being capable of providing superior performance in photothermal conversion, thermal insulation, and water imbibition simultaneously. The porosity of the foam is theoretically optimized by numerical modeling. Subsequent scanning electron microscopy and Fourier-transform infrared spectroscopy characterization and validated experiments revealed that the solar steam generation efficiency was increased to above 88% with the evaporation rate of 1.34 kg/(h·m2) under 1 sun illumination, a pioneering value compared with the state-of-the-art. In addition to insoluble and soluble water pollutants, there are some volatile organic water pollutants that cannot be eliminated by enhanced steam generation. Therefore, the photocatalysis water purification method is also studied, which proved to be effective in degrading organic water pollutants. To meet the requirement of large-scale water treatment, there are two important points: One is the lifetime and chemical stability of the photocatalyst material, especially in complex and harsh aqueous conditions. The other is the ease of synthesis of such photocatalysts with specific nano-morphology. In this thesis work, ZnO and TiO2 these two common photocatalysts are selected due to their high performance in degradation by producing the oxidative free radical after being illuminated by UV light. This involves the combination of both TiO2 and ZnO in a two-step si mple synthesis method. It appears advantageous to exploit the conformal deposition of atomic layer deposition (ALD) to achieve nanometer-thick TiO2 coating on ZnO nanowires (NWs) after a homogeneous ZnO NW array successfully grown using hydrothermal synthesis method with a high aspect ratio, which is firmly anchored to a substrate and exhibit a large specific surface area. After being characterized by energy-dispersive X-ray analysis via high resolution- scanning electron microscopy measurements, the high chemical stability of the ALD TiO2 coating has been investigated in detail and proven to be effective under both strong acid and strong alkaline aqueous solutions. In addition, the photocatalysis for water purification experiments with organic dyes shows that via this simple two-step synthesis method. Finally, it’s proved that the produced ZnO/TiO2 tandem does indeed exhibit improved chemical stability in a harsh environment while allowing efficient photodegradation
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Nauditt, Alexandra. "Understanding stream flow generation in sparsely monitored montane catchments." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=233935.
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Hwang, Yeonsang. "Impact of input uncertainty in ensemble stream flow generation." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/dissertations/fullcit/3178345.
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Beliakova, Natalia Yurievna 1967. "Generation and maintenance of recirculations by Gulf Stream instabilities." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/58539.
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Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), February 1999.<br>Includes bibliographical references (leaves 220-224).<br>This thesis studies the problems of generation and maintenance of recirculations by Gulf Stream instabilities. Observations show that the horizontal structure of the jet and its recirculations suffer significant changes in time. Here, the role of internal dynamics of the jet is isolated as one of the possible sources of such variability, and the differences between barotropic and baroclinic instabilities are investigated. The problem of recirculation development is considered in a framework of a free spin down of the 2-layer and the lI-layer, zonally symmetric, quasi-geostrophic jets. Linear stability analysis shows that in strongly baroclinic basic flows, eddies are capable of driving recirculations in the lower layer through the residual meridional circulation. In strongly barotropic jets, the linearly most unstable wave simply diffuses the jet. Nonlinear stability analysis indicates that recirculations are robust features of the 2-layer model. The strength of recirculations is a function of the model's parameters. It increases with a decrease in the value of the nondimensional # due to potential vorticity homogenization constrained by enstrophy conservation. The recirculation strength is a non-monotonic function of the baroclinic velocity parameter; it is the strongest for strongly baroclinic basic flows, weakest for flows with intermediate baroclinic structure and of medium strength for strongly barotropic basic flows. Such non-monotonic behavior is the result of two different processes responsible for the recirculation development: linear eddy-mean flow interactions for strongly baroclinic basic flows and strongly nonlinear eddy-eddy and eddy-mean flow interaction for strongly barotropic flows. In the case of the reduced-gravity model, recirculations develop only for infinite deformation raduis. Basic flows with finite deformation radius are only weakly supercritical and therefore produced negligible recirculations after equilibration. The problem of maintenance of the recirculations is coupled to the questions of existence of low frequency variability and of multiple dynamical regimes of a system consisting of a quasi-geostrophic jet and its recirculations. The problem is studied in a framework of a 2-layer or a reduced-gravity colliding jets model which has no windforcing. Instead, it is forced by inflows and outflows through the open boundaries. Only the western boundary of the domain is closed, and a free slip boundary condition is used there. The results of the numerical experiments show that when only the mechanism of barotropic instability is present, the model has two energy states for a wide range of interfacial friction coefficients. The high energy state is characterized by well-developed recirculations and displays strong variability associated with either large recirculating gyres and a weak eddy field or small recirculations and a strong eddy field. The low energy state is characterized by large meridional excursions in the separation point and large amplitude, westward propagating meanders that produce strong rings after interacting with the western wall. For physically relevant bottom friction values, the presence of baroclinic instability in the recirculation regions of the 2-layer model allows for a unique dynamical regime characterized by well-developed recirculations in both layers. The low-frequency variability associated with the regime is weak and is related to meridional shifts in the position of the jet, to wrapping of the recirculations around each other, and to pulsations in their zonal extent.<br>by Natalia Yurievna Beliakova.<br>Ph.D.
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Wu, Hao, and Zhangdui Zhong. "A SECURE MEDIA STREAM COMMUNICATION FOR NEXT GENERATION NETWORK." International Foundation for Telemetering, 2005. http://hdl.handle.net/10150/604879.
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ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada<br>In NGN, the open interfaces and the IP protocol make the hazard of security aspect increased
accordingly. Thereby, it is a very important premise for NGN network operation to afford a good
secure media stream communication. In this paper, we will present a secure media stream
communication for NGN. Then we will discuss the three parts of the media stream secure
communication——media stream source authentication, secret key negotiation and distribution;
media stream encryption/decryption in detail. It can effectively realize media stream end-to-end
secure communication. Meanwhile, it also makes use of the expanding of former protocol during
the secret key negotiation process.
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Cresswell, Nicholas William. "The generation potential of diffuser augmented tidal stream turbines." Thesis, Durham University, 2015. http://etheses.dur.ac.uk/10980/.
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This thesis investigates the power generation potential of diffuser augmented horizontal axis tidal stream turbines. The use of diffuser augmentation for such devices is not a new concept, though many questions remained unanswered regarding the device performance and economics. This work highlighted a number of limitations within the literature on such devices and aimed to clarify the main factors which affect their performance and economics in tidal stream flows. Extant numerical modelling methods for diffuser augmented turbines were shown to produce inaccurate power prediction results due to modelling simplifications. The accurate numerical modelling of diffuser augmented turbines was made possible by the derivation of an extended blade element momentum turbine model within computational fluid dynamics. This model was verified experimentally and found to reproduce the experimental data accurately, matching both power outputs and diffuser surface pressures. The investigation was undertaken using a combination of numerical modelling and wind tunnel experimentation. It was found that effective diffuser augmentation requires a rotor with a thrust of approximately 1/2 that of a bare rotor. The rotor geometry was found to have a significant impact upon the boundary layer flows and therefore the diffusion and power output. The impact of the hub and the component geometry interactions were also highlighted. It was also found that diffuser augmentation allows sustained performance under yawed flows and potential for improvement in highly turbulent flow. It was shown that diffuser augmented devices with lower area ratios are more efficient at power capture. An economic analysis was performed, combining a derived cost model and an annual energy production analysis using real tidal stream data, incorporating flow yaw and turbulence effects. It was shown that using current technology, bare rotor type devices are the more economically viable means of power generation.
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Montanet, Edouard. "Modélisation et optimisation des centrales solaires linéaires Fresnel à génération directe de vapeur." Electronic Thesis or Diss., Perpignan, 2024. http://www.theses.fr/2024PERP0010.
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Ce manuscrit aborde la modélisation numérique d’une installation commerciale utilisant la technologie de concentration solaire linéaire Fresnel pour la production directe de vapeur d’eau à haute pression (70 bars) qui sera valorisée en énergie électrique grâce à un groupe turbo-alternateur de 10 MW. Cette installation nommée centrale solaire eLLO, située sur le plateau Cerdan dans les Pyrénées-Orientales, France, fait suite à l’expérience positive de SUNCNIM sur la conception et la réalisation d’un prototype de concentrateur linéaire Fresnel à génération directe de vapeur à La Seyne-sur-Mer, Var, France. Néanmoins, le changement d’échelle et les premières années d’exploitation révèlent le besoin de redéfinir les sousmodèles utilisés pour le dimensionnement du projet eLLO.Ainsi, le projet de recherche présenté dans ce document a pour objectif de développer un modèle global de la centrale pour étudier ses performances et proposer des pistes d’optimisations de l’installation et des stratégies opératoires. Un modèle optique, développé sur la base de la méthode de lancer de rayons, permet de définir le comportement optique des concentrateurs solaires pour toutes les positions solaires et d’étudier les particularités des champs solaires de la centrale eLLO comme l’orientation et l’inclinaison des concentrateurs, la non-coplanarité des récepteurs solaires ou encore la distribution asymétrique des rayons de cintrage des miroirs. Une étude thermique expérimentale et un modèle numérique permettent de redéfinir la caractérisation des pertes thermiques des récepteurs solaires. La validation de ces études est effectuée en comparant les résultats aux performances optiques et thermiques d’autres concentrateurs solaires linéaires Fresnel développés par des industriels ou des laboratoires. Finalement, ces résultats sont utilisés comme donnée d’entrée du modèle global qui est constitué de l’ensemble des composants et des régulations, du récepteur solaire au groupe turbo-alternateur du cycle thermodynamique de Hirn mis en oeuvre à la centrale. Validé en comparant les résultats numériques aux données expérimentales, le modèle global permet de décrire le comportement dynamique de l’installation industrielle et ainsi de mettre en évidence des pistes d’améliorations du procédé. Les connaissances apportées par le modèle optique et l’étude des pertes thermiques permettent de proposer une stratégie de régulation de la recirculation de l’eau dans les champs solaires ayant pour objectif 80 % de vapeur à la sortie des lignes solaires. Ce document se termine par une analyse des données expérimentales issues de la centrale et la caractérisation de certains indicateurs de performance qui sont, à notre connaissance, une première dans la littérature scientifique pour une installation commerciale<br>This manuscript presents the numerical modelling of a commercial plant using Fresnel linear solar concentrator technology for the direct production of high-pressure (70 bar) steam, which will be converted into electrical energy using a 10 MW turbine-generator set. This installation, known as the eLLO solar power plant, located on the Cerdan plateau in the Pyrénées-Orientales, France, follows SUNCNIM's positive experience in designing and building a linear Fresnel concentrator prototype for direct steam generation in La Seyne-sur-Mer, Var, France.Nevertheless, the change of scale and the first years of operation revealed the need to redefine the sub-models used for sizing the eLLO project. The aim of the research project presented in this document is therefore to develop a global model of the power plant in order to study these performances and propose ways of optimizing the installation and the operating strategies. An optical model, developed on the basis of the ray-tracing method, is used to define the optical behaviour of the solarconcentrators for all solar positions, and to study the particularities of the eLLO power plant's solar fields, such as the orientation and inclination of the concentrators, the non-coplanarity of the solar receivers and the asymmetric distribution of the mirrors bending radius. An experimental thermal study and a numerical model are used to redefine the characterizationof solar receiver heat losses. These studies are validated by comparing the results with the optical and thermal performance of other Fresnel linear solar concentrators developed by industries or laboratories.Finally, these results are used as input data for the global model, which comprises all components and controls, from the solar receivers to the turbo-alternator unit of the Hirn thermodynamic cycle implemented at the plant. Validated by comparing numerical results with experimental data, the global model can be used to describe the dynamic behaviour of the industrial plant, and thus highlights potential areas of process improvement. The knowledge provided by the optical model and the heat loss study enables to come up with a strategy for regulating water recirculation in the solar fields, with a target of 80% steam at the outlet of the solar lines. The manuscript concludes with an analysis of experimental data and the characterization of performance indicators which, to our knowledge, is a first achievement in the scientific literature for a commercial installation
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Yanna, Marc-Gabriel. "An investigation of flow-induced vibrations of a steam-generator tube." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07212009-040348/.
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