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Pradeepkumar, K. N. "Analysis of a 115MW, 3 shaft, helium Brayton cycle." Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/9219.
Full textAbstract:
This research theme is originated from a development project that is going on in
South Africa, for the design and construction of a closed cycle gas turbine plant using
gas-cooled reactor as the heat source to generate 115 MW of electricity. South African
Power utility company, Eskom, promotes this developmental work through its
subsidiary called PBMR (Pebble Bed Modular Reactor). Some of the attractive features
of this plant are the inherent and passive safety features, modular geometry, small
evacuation area, small infrastructure requirements for the installation and running of the
plant, small construction time, quick starting and stopping and also low operational
cost.
This exercise is looking at the operational aspects of a closed cycle gas turbine,
the finding of which will have a direct input towards the successful development and
commissioning of the plant. A thorough understanding of the fluid dynamics in this
three-shaft system and its transient performance analysis were the two main objectives
of this research work. A computer programme called GTSI, developed by a previous
Cranfield University research student, has been used in this as a base programme for the
performance analysis. Some modifications were done on this programme to improve its
control abilities. The areas covered in the performance analysis are Start-up, Shutdown
and Load ramping. A detailed literature survey has been conducted to learn from the
helium Turbo machinery experiences, though it is very limited. A critical analysis on
the design philosophy of the PBMR is also carried out as part of this research work.
The performance analysis has shown the advantage, disadvantage and impact of
various power modulation methods suggested for the PBMR. It has tracked the effect of
the operations of the various valves included in the PBMR design. The start-up using a
hot gas injection has been analysed in detail and a successful start region has been
mapped. A start-up procedure is also written based on this. The analysis on the normal
and emergency load rejection using various power modulation devices has been done
and it stress the importance of more control facilities during full load rejection due to
generator faults.
A computational fluid dynamics (CFD) analysis, using commercial software, has
been carried out on some geometry of the PBMR design to find out whether its flow
characteristic will have any serious impact on the performance on the cycle during the
load control of the plant. The analysis has demonstrated that there will not be much
impact on the performance, during load control using pressure level changes, from this
geometry. However, some locations in the geometry have been identified as areas where
the flow is experiencing comparatively high pressure losses. Recommendations, which
include modification in the physical design, were made to improve this.
The CFD analysis has extended to a cascade to compare the flow behaviour of
Air and Helium with an objective of using air, being inexpensive, to test the helium
flow characteristic in a test rig to simulate the behavioural pattern of helium in the
PBMR pressure vessel. The specification of a hypothetical test rig and the necessary
scaling parameters has been derived from this exercise. This will be useful for designing
test rigs during the developmental and operational stage of the PBMR project.
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Staudt, James E. "Design study of an MGR direct Brayton-cycle power plant." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14864.
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Kleut, Petar. "Recuperation of the exhaust gases energy using a Brayton cycle machine." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/76807.
Full textAbstract:
Lately, car manufacturers have been put to a big challenge to reduce the CO2 emission of their entire fleets. Norms of pollutant emissions limit the ways to achieve the desired CO2 emission goals, as some of the solutions that would lead to lower CO2 emission also lead to higher pollutant emission. Waste Heat Recovery (WHR) could be a good solution to lower the CO2 emission of the Internal Combustion Engine (ICE) without increasing the pollutant emission. In the present thesis different WHR strategies are analysed and the results suggested it would be interesting to further study the Brayton cycle machine.
Air Brayton Cycle (ABC) represents a way to recover a part of the heat energy of the ICE exhaust gases and transform it into mechanical energy. Recovered mechanical energy would then be returned to the crankshaft of the ICE, thereby reducing the amount of energy that has to be liberated by combustion of fuel which lowers the fuel consumption and CO2 emission.
The study of ABC started with an analysis of the ideal cycle in order to obtain the theoretical maximum of the system. The study continued with an analysis of the semi ideal cycle where all losses are taken into account only by two efficiency coefficients. This analysis showed that for the diesel engine efficiency of the ABC is very low because of the low exhaust gas temperature. For the gasoline engine the cycle could be viable when the ICE is working under steady condition and higher load. These conditions could be fulfilled when the vehicle is driven on the highway.
Detailed analysis was aimed at determining the cycle main losses. They were determined to be: pumping losses, losses caused by heat transfer and mechanical losses. Taking into account these main losses along with other direct and indirect losses it was concluded that the cycle is not viable for the types of the WHR machines that were considered in this study.
In order for the cycle to be viable some other either existing or new machine type should be tested, that would lower the main losses and offer good isentropic and mechanical efficiency for desired conditions.Últimamente los fabricantes de automóviles se han puesto el gran reto de reducir la emisión de CO2 en la totalidad de sus flotas. Las nuevas normativas para la reducción de las emisiones contaminantes limitan los medios para lograr los objetivos deseados en la emisión de CO2 porque algunas de las soluciones que llevan a la reducción en la emisión de CO2 también dan lugar a un incremento en la emisión de otros contaminantes. La recuperación de calor residual (WHR) podría ser una buena solución para reducir las emisiones de CO2 del motor de combustión interna (ICE) sin poner en peligro la emisión de contaminantes. En la presente Tesis se analizaron diferentes estrategias de WHR y se concluyó que sería interesante estudiar más a fondo la máquina de ciclo Brayton. El Ciclo Brayton de Aire (ABC) permite recuperar una parte del calor de los gases de escape del ICE y transformar este calor en energía mecánica. La energía mecánica recuperada se devuelve al cigüeñal del ICE, reduciendo de ese modo la cantidad de energía que tiene que ser liberada por la combustión del combustible, lo cual permite reducir el consumo de combustible y las emisiones de CO2. En esta Tesis se estudia el ABC mediante un análisis del ciclo ideal con el fin de obtener el máximo teórico del sistema. El modelo se mejora con un análisis del ciclo semi-ideal donde se tienen en cuenta todas las pérdidas mediante el uso de dos coeficientes generales. Este análisis muestra que para el motor diesel la eficiencia del ciclo ABC es muy baja debido a la baja temperatura del gas de escape. Para el motor de gasolina el ciclo podría ser viable cuando el ICE está trabajando bajo condiciones estacionarias y una carga mayor. Estas condiciones se podrían cumplir cuando el vehículo está circulando en autopista. El análisis detallado de este ciclo tiene como objetivo determinar las pérdidas principales de ciclo. Las pérdidas principales se identificaron como: las pérdidas de bombeo, las pérdidas causadas por la transferencia de calor y las pérdidas mecánicas. Teniendo en cuenta estas pérdidas principales junto con otras pérdidas directas e indirectas, se concluyó que el ciclo no es viable para los tipos de máquinas WHR que fueron considerados en este estudio. Para que el ciclo sea viable se tiene que buscar alguna otra máquina existente o un nuevo tipo de máquina que reduzca las principales pérdidas y ofrezca un buen rendimiento isentrópico y mecánico para las condiciones deseadas.
Últimament els fabricants d'automòbils s'han posat el gran repte de reduir l'emissió de CO2 de la totalitat de les seues flotes. Les noves normatives de reducció de les emissions contaminants limiten els mitjans per assolir els objectius desitjats d'emissió de CO2 perquè algunes de les solucions que porten a la reducció en l'emissió de CO2 també donen lloc a un increment a l'emissió de altres contaminants. La recuperació de calor residual (WHR) podria ser una bona solució per reduir les emissions de CO2 del motor de combustió interna (ICE) sense posar en perill l'emissió de contaminants. En la present Tesi s'han analitzat diferents estratègies WHR i es va concloure que seria interessant estudiar més a fons el cicle Brayton. El Cicle Brayton d'Aire (ABC) representa una manera de recuperar una part de la calor dels gasos d'escapament de l'ICE i transformar calor a l'energia mecànica. L'energia mecànica recuperada es retorna al cigonyal de l'ICE reduint d'aquesta manera la quantitat d'energia que ha de ser alliberada per la combustió del combustible permitint la reducció del consum de combustible i les emissions de CO2. En aquesta Tesi s'ha començat estudiant un ABC amb una anàlisi del cicle ideal per tal d'obtenir el màxim teòric del sistema. Este model es millora amb una anàlisi del cicle semiideal on es tenen en compte totes les pèrdues amb tan sols dos coeficients d'eficiència. Aquesta anàlisi va mostrar que per al motor dièsel l'eficiència del cicle ABC és molt baixa a causa de la baixa temperatura del gas d'escapament. Per al motor de gasolina el cicle podria ser viable quan l'ICE està treballant sota condicions estacionàries i una càrrega més gran. Aquestes condicions es podrien complir quan el vehicle està circulant en autopista. L'anàlisi detallada del cicle va tenir com a objectiu determinar les pèrdues principals de cicle. Les pèrdues principals es van identificar com: les pèrdues de bombament, les pèrdues causades per la transferència de calor i les pèrdues mecàniques. Tenint en compte aquestes pèrdues principals juntament amb altres pèrdues directes i indirectes, es va concloure que el cicle no és viable per als tipus de màquines WHR que van ser considerats en aquest estudi. Perquè el cicle puga ser viable s'ha de buscar alguna altra màquina existent o un nou tipus de màquina que puga reduir les principals pèrdues i puga oferir un bon rendiment isentròpic i mecànic per a les condicions desitjades.
Kleut, P. (2016). Recuperation of the exhaust gases energy using a Brayton cycle machine [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/76807
TESIS
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Persigehl, Bernhard [Verfasser]. "Exergetische Optimierung einfacher Gasturbinenprozesse durch den Inversen Brayton Cycle / Bernhard Persigehl." Aachen : Shaker, 2012. http://d-nb.info/1067736271/34.
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Moxon, Matthew. "Thermodynamic analysis of the Brayton-cycle gas turbine under equilibrium chemistry assumptions." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/9237.
Full textAbstract:
A design-point thermodynamic model of the Brayton-cycle gas-turbine
under assumptions of perfect chemical equilibrium is described.
This approach is novel to the best knowledge of the author.
The model uniquely derives an optimum work balance between power
turbine and nozzle as a function of flight conditions and propulsor
efficiency.
The model may easily be expanded to allow analysis and comparison of
arbitrary cycles using any combination of fuel and oxidizer.
The model allows the consideration of engines under a variety of
conditions, from sea level/static to >20 km altitude and flight Mach
numbers greater than 4.
Isentropic or polytropic turbomachinery component efficiency standards
may be used independently for compressor, gas generator turbine and
power turbine.
With a methodology based on the paper by M.V. Casey, “Accounting
for losses” (2007), and using Bridgman’s partial differentials , the
model uniquely describes the properties of a gas turbine solely by
reference to the properties of the gas mixture passing through the
engine.
Turbine cooling is modelled using a method put forward by Kurzke.
Turboshaft, turboprop, separate exhaust turbofan and turbojet engines
may be modelled. Where applicable, optimisation of the power turbine
and exhaust nozzle work split for flight conditions and component
performances is automatically undertaken.
The model is implemented via a VB.net code, which calculates
thermodynamic states and controls the NASA CEA code for the
calculation of thermodynamic properties at those states. Microsoft
Excel® is used as a graphical user interface.
It is explained that comprehensive design-point cycle analysis may
allow novel approaches to off-design analysis, including engine health
management, and that further development may allow the automation of
cycle design, possibly leading to the discovery of opportunities for
novel cycles.
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Trinh, Tri Q. (Tri Quang). "Dynamic response of the supercritical C0₂ Brayton recompression cycle to various system transients." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53527.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2009.Page 208 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 159-160).
The supercritical carbon dioxide (SC0₂) power conversion system has been suggested for use with many of the Generation IV nuclear reactors. The SC0₂ cycle is highly attractive because of its low operating temperatures and high efficiency associated with working near the critical point of CO2. Unfortunately, the appealing features of using C0₂ near its critical point create complications in control. The Transient SC0₂ Cycles Code (TSCYCO) has been developed as a transient simulation control design and cycle scoping code for the recompression SC0₂ Brayton cycle. It is based off of the SC0₂ Power Systems (SCPS) code, and incorporates many improvements and modifications. Written in FORTRAN 90, TSCYCO uses a lumped parameter model and a momentum integral model approach. The code uses a semi-implicit solution process and implements Gaussian elimination to solve the system of equations. Transient behavior of the printed circuit heat exchangers is determined via the previously developed code HXMOD. Turbomachinery performance is modeled using the Real Gas Radial Compressor (RGRC) code with a scaling scheme for off-design conditions. Currently, TSCYCO has the capability of modeling several transients, including: loss of external load (LOEL), power load change, and cycle low-temperature change. Simulations show that TSCYCO can be run at quasi-steady state for an indefinite period of time. In the case of a 10% LOEL, the axial turbine experiences choke as a result of shaft overspeed. Turbine choke can be avoided if one bypasses more flow during LOEL.
(cont.) Moreover, one can incorporate more accurate axial turbine performance models to account for shaft speed variation. TSCYCO experiences instabilities when operated too closely to the critical point of C0₂. This could be remedied with a more robust Runge-Kutta solution method.
by Tri Q. Trinh.
S.M.
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Kloppers, Cornelius Petrus. "Thermodynamic cycle design of a Brayton–Rankine combined cycle for a pebble bed modular reactor / Cornelius Petrus Kloppers." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7623.
Full textAbstract:
The rapid development in nuclear technology worldwide has created the need for an efficient power conversion unit to extract the energy from the new generation IV reactors. The generation IV reactor currently under investigation in South Africa is the PBMR–DPP (Pebble Bed Modular Reactor Demonstration Power Plant) based on the High temperature Reactor Modul. This reactor produces 200 MW of thermal energy at inlet/outlet temperatures of 250oC/700oC. Due to the reactor layout and accompanying thermal fluid path design outlet temperatures in the order of 900oC would be possible. This dissertation is aimed at the design and optimisation of a Brayton–Rankine combined cycle for use with a PBMR–DPP. The combination of these two cycles improves the thermal efficiency due to the large difference between the maximum and minimum temperatures. The Brayton and Rankine cycles will be developed independently and optimised to ensure that the best possible efficiency is gained from the combined cycle. The heat energy available in the reactor is the input parameter for the Brayton cycle, After the Brayton cycle's pressure ratio has been optimised the heat rejected to the Rankine cycle will be known. The aim of the design is to determine if 50% combined cycle thermal efficiency is achievable. The initial sizing calculation of the cycle parameters has been done in a software package that has been developed for use in the thermo–hydraulics field. Engineering Equation Solver (EES) makes use of an iterative process to simultaneously solve the set of equations. The results obtained from EES were verified by Microsoft Excel with a specialised macro installed for thermo–hydraulics.
A very specific methodology was used to solve the Brayton cycle. Traditionally the Brayton cycle is optimised for maximum cycle efficiency to ultimately obtain the best combined cycle efficiency. Very complex cycles such as reheat and multi–shaft Brayton cycles were used. The solution methodology used in this dissertation is to optimise the simple Brayton cycle for the maximum specific work produced in the cycle. The large amount of heat at the turbine outlet is then transferred to the Rankine cycle. The results obtained from the calculations preformed were that a combined cycle efficiency of 52.914% has been achieved at optimum operating conditions. The combined cycle has been shown to operate above 50% efficiency in a wide variety of load–following conditions.Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2011.
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Minář, Luděk. "Analýza dvouhřídelové spalovací turbiny se sériově a paralelně řazenými turbinami." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230908.
Full textAbstract:
Master thesis deals with analysis of characteristic points of two-shaft combustion turbine cycle for two different concepts of turbine’s arrangement. Computational model is compiled within the thesis for serial and parallel arrangement. Thermodynamic magnitudes of characteristic points of cycle are calculated with the computational model for designed operating point. Initial values of the computational model are chosen in consideration of reaching compromise between maximal thermal efficiency and maximal specific power.
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Vorster, Christo. "Fault diagnostic system for predictive maintenance on a Brayton cycle power plant / C. Vorster." Thesis, North-West University, 2004. http://hdl.handle.net/10394/254.
Full textAbstract:
Model-based fault detection and diagnostic systems have become an important solution (Munoz &
Sanz-Bobi, 1998:178) in the industry for preventive maintenance. This not only increases plant
safety, but also reduces down time and financial losses. This paper investigates a model-based
fault detection and diagnostic system by using neural networks.
To mimic process models, a normal feed-forward neural network with time delays is implemented
by using the MATLAB@ neural network toolbox. By using these neural network models, residuals
are generated. These residuals are then classified by using other neural networks. The main
process in question is the Brayton cycle thermal process used in the pebble bed modular reactor.
Flownet simulation software is used to generate the data, where practical data is absent.
Various training algorithms were implemented and tested during the investigation of modelling
and classification concepts on two benchmark processes. The training algorithm that performed
best was finally implemented in an integrated conceptThesis (M.Ing. (Electronical Engineering))--North-West University, Potchefstroom Campus, 2004.
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Du, Rand Carel Petrus. "Health monitoring of a Brayton cycle-based power conversion unit / Carel P. du Rand." Thesis, North-West University, 2007. http://hdl.handle.net/10394/2883.
Full textAbstract:
The next generation nuclear power plants like the Pebble Bed Modular Reactor (PBMR) permit for the design of advanced health monitoring (fault diagnosis) systems to improve safety, system reliability and operational performance. Traditionally, fault diagnosis has been performed by applying limit value checking techniques. Although simple, the inability of these techniques to model parameter dependencies and detect incipient fault behaviour renders them unfavourable. More recent approaches to fault diagnosis can be attributed to the advances in computational intelligence. Data driven methods like artificial neural networks are more widely used when modelling complex nonlinear systems, using only historical plant data. These methods are however dependent on the quality and amount of data used for model development.
The key to developing an advanced fault diagnosis system is to adopt an integrated approach for monitoring the different aspects of the total process. Within this context, this goal is realized by presenting a new integrated architecture for sensor fault diagnosis in addition to the enthalpy-entropy graph approach for process fault diagnosis. The integrated architecture for sensor fault diagnosis named SENSE, exploits the strengths of several existing techniques whilst reducing their individual shortcomings. A novel approach for process fault diagnosis is proposed based on the characteristics inherent in the design of the PBMR. Power control by means of an inventory control system and no bypass valve operation facilitates a reference model that remains invariant over the power range. Consequently, the devised reference fault signatures remain static during steady state and transient variations of the normal process.
In the thesis, both single and multiple fault conditions are considered during steady state and transient variations of the normal process. It is demonstrated that by applying SENSE, the fused variable estimates are consistent and more accurate than the individual sensor readings. Test cases corresponding to 32 single and multiple fault conditions confirmed that it is possible to use the enthalpy-entropy graph approach for process fault diagnosis. In addition, the proposed fault diagnosis approach is validated through an application to real data from the prototype Pebble Bed Micro Model (PBMM) plant. This application demonstrated that the proposed approach is ideally suited for early detection of faults and greatly reduces the amount of plant data required for model development.Thesis (Ph.D. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2008.
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THORSSON, BJÖRN J., and HADY R. SOLIMAN. "Supercritical Carbon Dioxide Brayton Cycle for Power Generation : Utilizing Waste Heat in EU Industries." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-282919.
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The industrial sector accounts for approximately 30% of the global total energy consumption and up to 50% of it is lost as waste heat. Recovering that waste heat from industries and utilizing it as an energy source is a sustainable way of generating electricity. Supercritical CO2 (sCO2) cycles can be integrated with various heat sources including waste heat. Current literature primarily focuses on the cycle’s performance without investigating the economics of the system. This is mainly due to the lack of reliable cost estimates for the cycle components. Recently developed cost scaling models have enabled performing more accurate techno-economic studies on these systems. This enables a shift in focus from plant efficiency to economics as a driver for commercialization of sCO2 technology. This work aims to develop a techno-economic model for these waste-heat-to-power systems. Based on the literature, waste heat from different industries is calculated, showing that the four industries with the greatest potential for waste heat recovery are cement, iron and steel, aluminum and gas compressor stations. Six different sCO2 cycle configurations were developed and simulated for these four industries. The techno-economic model optimizes for the highest Net Present Value (NPV) using an Artificial Bee Colony algorithm. The optimization variables are the pressure levels, split ratios, recuperators effectiveness, condenser temperature and the turbine inlet temperature limited by the heat source. The results show a vast potential for industries to cut down costs using this system. Out of the four industries modeled, a waste heat recovery system in an iron and steel factory yielded the highest NPV. Results show that the integration of sCO2 cycle in the cement industry could help reduce their waste heat by 60%, whilst simultaneously enabling them to cover up to 56% of their electricity demand. The payback period for the four industries varies between 6 to 9 years. Furthermore, simple recuperated sCO2 cycles with preheating are more economical than recompression cycles. Even though recompression cycles have higher thermal efficiency, they are limited by the temperature glide in the waste heat exchanger. This analysis could help investors and engineers take more informed decisions to increase the efficiency and economic return on investment for sCO2 cycles and heat recovery at industrial sites. To encourage adoption of supercritical CO2 cycles, a demo is needed along with more research for higher temperature applications with special attention to mechanical integrity.Industrisektorn står för cirka 30% av den globala totala energiförbrukningen och upp till 50% av den går förlorad som spillvärme. Återskapa att spillvärme från industrier och använda det som energikälla är ett hållbart sätt att producera el. Superkritiska CO2 (sCO2) cykler kan integreras med olika värmekällor inklusive spillvärme. Nuvarande litteratur fokuserar främst på cykelens prestanda utan att undersöka systemets ekonomi. Detta beror främst på bristen på tillförlitliga kostnadsberäkningar för cykelkomponenterna. Baserat på nyligen utvecklade kostnadsskalningsmodeller är det möjligt att utföra mer exakta teknikekonomiska studier på dessa system. Detta möjliggör en förskjutning i fokus från cykeleffektivitet till ekonomi som drivkraft för kommersialisering av sCO2 teknologi. Detta arbete syftar till att utveckla en teknisk ekonomisk modell för dessa avfall-värme-till-kraftsystem. Baserat på litteraturen beräknas spillvärme från olika industrier, vilket visar att de fyra industrierna med störst potential för återvinning av spillvärme är cement, järn och stål, aluminium och gaskompressorstationer. Sex olika sCO2 konfigurationer utvecklades och simulerades för dessa fyra industrier. Den teknisk-ekonomiska modellen optimerar för det högsta Net Present Value (NPV) med hjälp av en artificiell bi-kolonialgoritm. Optimeringsvariablerna är pressure levels, delade förhållanden, recuperatorseffektivitet, kondensortemperatur och turbininloppstemperaturen begränsad av värmekällan. Resultaten visar en stor potential för industrier att sänka kostnaderna med detta system. Av de fyra modellerna industrin gav ett återvinningssystem i en järn och stålfabrik den högsta NPV. Resultaten visar att integrationen av sCO2 cykeln i cementindustrin kan bidra till att minska deras spillvärme med 60%, samtidigt som de gör det möjligt för dem att täcka upp till 56% av deras elbehov. Återbetalningsperioden för de fyra branscherna varierar mellan 6 till 9 år. Dessutom är simple recuperated sCO2 cykler med förvärmning mer ekonomiska än recompressioncykler. Trots att recompressioncykler har högre termisk effektivitet, begränsas de av temperaturglidningen i spillvärmeväxlaren. Denna analys kan hjälpa investerare och ingenjörer att fatta mer informerade beslut för att öka effektiviteten och ekonomiska avkastningen på investeringar för sCO2 cykler och värmeåtervinning på industriområden. För att uppmuntra antagandet av superkritiska CO2 cykler krävs en demo tillsammans med mer forskning för högre temperaturapplikationer med särskild uppmärksamhet på mekanisk integritet.
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Trtík, Jan. "Uvádění do provozu plynové spalovací turbíny." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219389.
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Master thesis is concerned with gas turbines from Siemens company. The thesis consists of two main parts. In the first part describes the different types of turbines, their characteristics and use in practice. The following is a detailed description of components and systems the biggest industrial gas turbine SGT-800. The second part discusses about the necessary steps for commissioning turbine. These particulars are managing software, testing, commissioning and phasing of the turbine generator to the distribution network. The conclusion is devoted to the example of calculating return investment on the overall gas turbine project.
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Dellar, Kyle Eric. "Clamped plate-style recuperator for a small-scale solar thermal brayton cycle using high-temperature sealant." Thesis, University of Pretoria, 2019. http://hdl.handle.net/2263/73467.
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South Africa is plagued by rolling blackouts, and many citizens do not have access to electricity or clean water. A personalised micro-turbine power generation system presents a solution to this issue and may become as commonplace as a personal computer. With South Africa’s excellent solar direct normal irradiation (DNI) levels, a small-scale recuperated solar thermal Brayton cycle (STBC) shows enormous potential. However, a recuperator comprises up to 30% of the capital cost associated with a micro-turbine package and requires complex and costly manufacturing methods within a South African context. Thus, the objective of this research is to investigate a clamped plate-style recuperator that can be cost-effectively manufactured locally. Literature was consulted and criteria were outlined that a recuperator in a Brayton cycle should adhere to. To uphold these requirements, a counterflow plate-style recuperator is mandatory, and to combat complex manufacturing methods, a gasketed stacked-plate design, which requires a gasket material, was proposed. A sodium silicate-based sealant called Soudal Calofer is available locally and can withstand the operating conditions of an STBC. Experimental testing was carried out successfully on two small-scale versions of the proposed recuperator design. Testing showed that the physical construction was simple and cost-effective and the clamped plate-style high-temperature sealant combination worked well to form the recuperator core, facilitating an easy assembly and disassembly process. The construction sustained an airtight seal (Mark I) for the entire testing period at various pressures and high temperatures. Despite the occurrence of heavy soot-based fouling deposits during Test 1 due to incomplete combustion of the LPG as a result of the very low air mass flow rates, a mathematical model was able to match the values gathered from the testing. The data showed a cold-side effectiveness of 58.6% and a total pressure loss of 17.78%. For Test 2, a cold-side effectiveness of 82.5% and a total pressure loss of 11.48% were found for the recuperator core, which also validated the mathematical model. A case study was performed for the small-scale STBC. The results showed that the combination of a cold-side effectiveness of 84% and a total pressure loss of less than 5% could be attained when implementing the recuperator within the STBC for a channel height of 1 mm and width of 50 mm. Alternatively, if pressure loss is of less concern, a cold-side effectiveness of 89% could be achieved by increasing the total pressure loss to 19 kPa, which equates to an 8.8% pressure loss. It is recommended that a large-scale recuperator be built and tested to confirm the performance characteristics of larger mass flow rates and that the insulation of the unit be varied to determine its effects. Gasket geometry and the assembly method also need to be further researched to develop a uniform and consistent assembly technique that results in an airtight seal for every unit assembled. This may be achieved by regulating the amount of water added to the Soudal Calofer for thinning purposes to achieve a consistency which facilitates uniform application and by extended drying time to allow for the assembly to be completed, while not thinning the sealant so much as to lead to a seal failure. In conjunction, the clamping force distribution is critical to sealing the inner channel division. It is also recommended that the usable lifespan of such a recuperator be determined. Most crucially, thermal and pressure cycling must be investigated, especially where seal integrity is concerned.Dissertation (MSc)--University of Pretoria, 2019.
Mechanical and Aeronautical Engineering
MSc
Unrestricted
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Hadid, Zoheir. "Gazéification du GNL par cycle de Brayton associé à une boucle caloportrice et une pompe à chaleur." Thesis, Paris, ENMP, 2012. http://www.theses.fr/2012ENMP0112/document.
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Le marché du gaz naturel liquéfié (GNL) est en plein essor et présente l'avantage de diversifier les approvisionnements. Le GNL est acheminé à une température de -162 °C et à pression atmosphérique. L'objet principal de la thèse vise à valoriser l'exergie contenue dans le GNL lors de sa gazéification et de son réchauffage avant d'être distribué sur le réseau. La thèse étudie un nouveau concept de gazéification qui se différentie des développements en cours par l'usage de l'air ambiant comme seule source de chaleur et par la valorisation d'une partie de l'exergie du GNL en énergie mécanique.Une analyse énergétique et exergétique a permis de définir des architectures de cycles moteurs utilisant l'énergie calorifique de l'air comme source chaude (récupérée par un fluide intermédiaire qui est le propane) et le GNL comme puits froid.L'usage de l'air ambiant conduit à gérer les cycles de givrage et dégivrage sur les évaporateurs du fluide intermédiaire récupérant les calories de l'air. Ceci nécessite la compréhension des phénomènes couplés de transferts de chaleur et de masse. Pour cela un banc d'essai a été construit afin de caractériser des échangeurs à ailettes rondes discontinues en condition de givrage et de valider un modèle numérique simulant le comportement de ces échangeurs en présence de givre. Cette modélisation a permis de proposer une logique de dimensionnement et d'exploitation des évaporateurs à air en prenant en compte l'effet du givre. Une étude saisonnière a montré que le procédé proposé est énergétiquement excédentaire tout au long de l'annéeThe market of liquefied natural gas (LNG) is growing and presents the advantage of diversifying supplies. The LNG is fed at a temperature of -162°C and at atmospheric pressure. The main objective of the thesis aims at the valorization of the LNG exergy during its gasification and heating before being delivered through the network. The thesis investigates a new concept of gasification that differs from the current developments by the use of ambient air as the only heat source and by partial valorization of the LNG exergy in mechanical energy.An energy and exergy analysis helped to the definition of engine-cycle architectures using the air heating capacity as a heat source (recovered by an intermediate fluid, here propane) and LNG as a cold sink.The use of ambient air led to manage frosting and defrosting cycles on the evaporators of intermediate fluid recovering heat from the air. This requires understanding the coupled heat and mass-transfer phenomena. A test bench was built to characterize Circular Finned-Tube Heat Exchangers in frosting conditions and to validate a numerical model simulating the behavior of such heat exchangers in presence of frost. As a result, a logic for the design and operation of air heat exchangers is proposed taking into account the frosting effect. A seasonal study showed that the output power generated by the new concept of gasification is superior to its energy consumption throughout the year
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Forster, Christopher James. "DEVELOPMENT OF AN AIR‐CYCLE ENVIRONMENTAL CONTROL SYSTEM FOR AUTOMOTIVE APPLICATIONS." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/197.
Full textAbstract:
An air‐cycle air conditioning system, using a typical automotive turbocharger as the core of the system, was designed and tested. Effects on engine performance were kept to a minimum while providing the maximum amount of cooling possible and minimizing weight and space requirements. A test stand utilizing shop compressed air was developed to measure component performance. An unmodified automotive turbocharger was tested initially as a baseline in a Reversed‐Brayton Cycle air cooling system. Once the baseline was established, another aircycle machine, assembled from commercial turbocharger components chosen individually to optimize their performance for cooling purposes, was tested to improve the overall cycle efficiency. Finally, once the air‐cycle air conditioning system was optimized, it was tested on an engine to simulate more realistic operating conditions and performance. The shop‐air test stand experiments showed a peak dry‐air‐rated (DAR) coefficient of performance (COP) of 0.38 and a DAR cooling capacity of 0.45 tons for the baseline turbocharger, and a peak DAR COP of 0.73 and DAR cooling capacity of 1.5 tons for the optimized system with a modified turbocharger. The on‐engine testing was limited due to a thrust bearing failure in the ACM. However, the data collected at lower engine load and speed indicates a DAR COP of 0.56 and a DAR cooling capacity of 0.72 tons. On‐engine testing was planned to include operating points where the stock turbocharger was utilizing turbine‐bypass to limit boost pressure. While it wasn't possible to continue testing, it is expected that DAR COP and cooling capacity would have increased at higher engine load and speed, where turbine‐bypass operation typically occurs.
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Zhao, Qiao. "Conception and optimization of supercritical CO2 Brayton cycles for coal-fired power plant application." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0080/document.
Full textAbstract:
L'amélioration des systèmes énergétiques est considérée comme un levier technologique pour répondre aux défis liés à la croissance de la demande d’électricité et des émissions des gaz à effet de serre. Les futures centrales devraient présenter une intégration thermique plus flexible et des sources de chaleur mixtes possibles. Une des solutions fiables consiste à utiliser un cycle de Brayton au CO2 supercritique (CO2-SC), un tel cycle à haut rendement est théoriquement prometteur pour les applications nucléaires, fossiles et solaires thermiques. Un des principaux obstacles au déploiement du cycle de Brayton au CO2-SC est de justifier sa faisabilité, sa viabilité et son potentiel à l’échelle industrielle. Dans ce contexte deux axes de recherche ont été identifiées : • Une sélection rigoureuse de l’équation d’état qui permet de représenter les propriétés d’intérêt du CO2-SC. • Une nouvelle méthodologie pour l’optimisation des centrales électriques, permettant de sélectionner automatiquement le procédé optimal parmi une grande quantité de configurations possibles (dénomme superstructure). Les résultats de la première partie de cette thèse mettent en lumière que l’équation de SW est pertinente pour limiter l’impact de l’imprécision de l’équation d’état sur le dimensionnement du procédé. Dans cette thèse, un simulateur de procédé commercial, ProSimPlus a été combiné avec un solveur type évolutionnaire (MIDACO) afin d’effectuer des optimisations superstructure. Premièrement, le critère d’optimisation est de maximiser le rendement énergétique du procédé. Dans un deuxième temps, on cherche simultanément à minimiser les coûts du procédé. Pour ce faire, des fonctions de coût internes à EDF ont été utilisées afin de permettre l’estimation des coûts d'investissement (CAPEX), des dépenses opérationnelles (OPEX) et du coût actualisé de l'électricité (LCOE)Efficiency enhancement in power plant can be seen as a key lever in front of increasing energy demand. Nowadays, both the attention and the emphasis are directed to reliable alternatives, i.e., enhancing the energy conversion systems. The supercritical CO2 (SC-CO2) Brayton cycle has recently emerged as a promising solution for high efficiency power production in nuclear, fossil-thermal and solar-thermal applications. Currently, studies on such a thermodynamic power cycle are directed towards the demonstration of its reliability and viability before the possible building of an industrial-scale unit. The objectives of this PhD can be divided in two main parts: • A rigorous selection procedure of an equation of state (EoS) for SC-CO2 which permits to assess influences of thermodynamic model on the performance and design of a SC-CO2 Brayton cycle. • A framework of optimization-based synthesis of energy systems which enables optimizing both system structure and the process parameters. The performed investigations demonstrate that the Span-Wagner EoS is recommended for evaluating the performances of a SC-CO2 Brayton cycle in order to avoid inaccurate predictions in terms of equipment sizing and optimization. By combining a commercial process simulator and an evolutionary algorithm (MIDACO), this dissertation has identified a global feasible optimum design –or at least competitive solutions– for a given process superstructure under different industrial constraints. The carried out optimization firstly base on cycle energy aspects, but the decision making for practical systems necessitates techno-economic optimizations. The establishment of associated techno-economic cost functions in the last part of this dissertation enables to assess the levelized cost of electricity (LCOE). The carried out multi-objective optimization reflects the trade-off between economic and energy criteria, but also reveal the potential of this technology in economic performance
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Uren, Kenneth Richard. "Optimal power control of a three-shaft Brayton cycle based power conversion unit / by Kenneth R. Uren." Thesis, North-West University, 2005. http://hdl.handle.net/10394/733.
Full textAbstract:
The aim of this study is to develop a control system that optimally controls the power
output of a Brayton cycle based power plant. The original design of the PBMR power
plant is considered. It uses helium gas as working fluid. The power output of the
system can be manipulated by changing the helium inventory to the gas cycle.
A linear model of the power plant is derived and modelled in Simulink®. This linear
model is used as an evaluation platform for different control strategies. Four actuators
are identified that are responsible for manipulating the helium inventory. They are:
A booster tank
A gas cycle bypass control valve
Low-pressure injection at the low-pressure side of the system
High-pressure extraction at the high-pressure side of the system
The control system has to intelligently generate set point values for each of these
actuators to eventually control the power output. Two control strategies namely PID
control and Fuzzy control are investigated in this study.
An optimisation technique called Genetic Algorithms is used to adapt the gain constants
of the Fuzzy control strategy. This resulted in an optimal power control system for the
Brayton cycle based power plant.Thesis (M.Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2005.
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Wilhite, Jarred M. "Investigation of Various Novel Air-Breathing Propulsion Systems." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin147981623341895.
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Voseček, Petr. "Optimalizace tepelných oběhů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229061.
Full textAbstract:
The main goal of the thesis was a selection of appropriate thermal cycles for the considerated nuclear power stations with the Generation IV reactors. Characterization and specification of the parametres of the Brayton and the Rankine-Clausi thermodynamic cycle, their optimalization with regard to the parametres of the first cycle was made, than analysis of cycles´properties, mostly efficiency, output and process layout.
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White, Thomas J. "Development of a parametric analysis microcomputer model for evaluating the thermodynamic performance of a reciprocating Brayton cycle engine." PDXScholar, 1987. https://pdxscholar.library.pdx.edu/open_access_etds/3794.
Full textAbstract:
In this thesis, applicable data from research on IC engines have been adapted to PACE engine designs. Data from studies on heat transfer, friction, and pressure losses, in particular, have been used. Certain parameters which define operation and design characteristics appear to influence PACE engine performance very strongly. Some of the more critical parameters, notably friction and heat transfer coefficients, must be determined experimentally if accurate model results are to be expected. Pressure ratio, compressor RPM, and maximum combustor temperature, the independent operating parameters, also have a dramatic effect on engine performance. Other design or operating characteristics and working fluid properties are not controlled independently. These are dictated by the engine physical design configuration and operation, ambient conditions, and choice of fuel.
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Laubscher, Stefan Andries. "Start-up and shutdown control of a three-shaft Brayton cycle based power conversion unit / by Stefan A. Laubscher." Thesis, North-West University, 2005. http://hdl.handle.net/10394/724.
Full textAbstract:
The Pebble Bed Modular Reactor (PBMR) is a graphite-moderated, helium-cooled reactor that uses
the Brayton direct gas cycle to convert the heat, which is generated in the core by nuclear fission.
The heat is transferred to the coolant gas (helium), and converted into electrical energy by means of
a gas turbo-generator.
The Pebble Bed Micro Model (PBMM) is a model that was developed to demonstrate the operation
of the closed, recuperative three-shaft Brayton cycle in order to gain a better understanding of its
dynamic behaviour and to demonstrate the control strategies that will eventually be used in the
PBMR. It is also used to demonstrate the ability of Flownex to simulate the integrated performance
of the cycle.
Flownex is a general-purpose thermal-fluid network analysis code. It solves the flow, pressure and
temperature distribution in large unstructured thermal-fluid networks and provides the engineer or
designer with essential information about the interaction between network components. Flownex
can handle a wide variety of network components such as pipes, pumps, orifices, heat exchangers,
compressors, turbines, controllers and valves. A complete Flownex model of the PBMM exists and
will be used throughout the entire project.
The start-up and shutdown sequences of the Pebble Bed Modular Reactor (PBMR) is characterised
by numerous checks and control actions that occur in a very specific order. This order of events and
continuous checking of important system parameters are intuitively based on rules that inherently
describe the safe and preferred operating region of the plant.
Presently most of the sequences and actions are performed by an expert who knows the system very
well. Some of the sequences and actions are controlled by simple controllers and are only activated
by the operator.
A need therefore exists to capture the different control events of the start-up and shutdown
sequences in a control model or method. A control model or method was developed to control the
start-up and shutdown sequence of the PBMM model in Flownex. The control method was
implemented in SIMULINK® as there is an existing interface between Flownex and SIMULINK®.
The control method directly controls the procedures of start-up and shutdown through the Flownex/
SIMULINK® interface. The most important system parameters are monitored and adjustments are
automatically made by the control method in response to system changes. A graphical user interface
allows a user to manually activate start-up and shutdown.
The aim of the project is to develop a controller that can control the PBMM through start-up as
well as shutdown. Special emphasis is placed on critical transitions and pressure considerations due
to the control of the start-up blower system rotational speed. The project establishes expertise in the
control of the start-up and shutdown sequence of the PBMM in Flownex.
Flownex was successfully used as a modelling platform to simulate the normal and dynamic
operation of the PBMM. Identification of start-up and shutdown was a result of investigating the
start-up and shutdown checklist documents as well as a detailed consideration of data captured by
the PBMM. A control method was implemented in SIMULINK® and controls start-up and
shutdown through the Flownex/SIMULINK® interface. A graphical user interface allows in time
system changes by a user. Data captured by the simulation model was evaluated against data
captured from the real system.Thesis (M. Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2005.
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Meas, Matthew Robert. "Thermodynamic design optimisation of an open recuperative twin-shaft solar thermal Brayton cycle with combined or exclusive reheating and intercooling." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25450.
Full textAbstract:
The Gouy-Stodola Theorem implies that the net power output of a system can be maximised by synchronously sizing the components, thus minimising the cumulative entropy generation rate. The resulting optimal design is related to, and therefore characteristic of, the cycle configuration, since the entropy generation rates in the individual components are interdependent. In this work, optimal design of three common open solar thermal Brayton cycle variants is investigated and compared using principles of the second law of thermodynamics and the method of entropy generation minimisation. The basic cycle, modified accordingly to construct the reheated, intercooled and combined cases, comprises a modified cavity receiver, a counter-flow plate-type recuperator, and a pair of proprietary automotive turbochargers configured to operate as micro-turbines. An additional modified cavity receiver and cross-flow plate heat exchanger constitute the reheater and intercooler, respectively. Net power output is expressed in terms of the temperature and pressure fields in each case, defined in terms of geometric variables characteristic of the components. Heat addition is calculated using the receiver sizing algorithm developed by Stine and Harrigan. Maximum constraints are applied to the recuperator and intercooler lengths and to the surface temperatures of the receiver and reheater absorber tubes. The dynamic-trajectory method is implemented to optimise the variables such that the net power output is maximised. An array of inputs are considered and compared, including 22 micro-turbine models, eight concentrator diameters ranging from six to 20 meters, and both circular and rectangular absorber tube profiles. The influence of receiver inclination, concentrator optics, environmental conditions and design constraints are investigated and the optimisation subroutines validated in the Flownex simulation environment. Results show the optimised power output, operating conditions and design parameters. The intercooled case demonstrates both the highest ratio of total irreversibility to heat input and the highest power output per unit collector surface area. The combined and reheated cases follow. Temperature differences across the components are identified as the primary cause of entropy generation. The optimised heat exchanger lengths are shown to lie on their maximum constraints, and the channel cross-sections found to decrease in size with increasing mass flow rate such that the heat transfer area is maximised and the heat transfer effectiveness improved. As such, plate counts in the optimised heat exchangers are found to be relatively high, and investigation of various compact heat exchanger designs, and regenerative- as opposed to recuperative heat exchangers, is recommended for future work on this topic. The receiver and reheater geometric parameters are found to change such that the absorber tube surface temperatures are kept below the maximum constraint. Trends in the data obtained for circular section absorber tubes are found to be less smooth than the trends in the data obtained for absorber tubes of rectangular section, indicating that the geometric constraints required to maintain the receiver shape offer greater design flexibility for rectangular section absorber tubes than for absorber tubes of circular section. It is concluded that the increases in the compressor and turbine outlet temperatures with mass flow rate and compressor pressure ratio drive the changes in the temperature differences across the heat exchangers, and thus the component entropy generation rates. The entropy generation rates must in turn be distributed during the optimisation procedure such that the cumulative rate is less than the power output, and all of the constraints are met.
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Grange, Avent. "Méthode d'optimisation multiobjectif de la conduite d'un réacteur nucléaire : application à un RNR-Na fonctionnant avec un cycle de Brayton." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0500.
Full textAbstract:
La définition de la conduite d’un réacteur nucléaire permet à ce dernier d’atteindre des objectifs de performance thermodynamique et de répondre à des exigences de sûreté. La méthode développée, lors de ces travaux, définit la conduite par la résolution d’un problème d’optimisation multiobjectif et contraint. Les variables de décision retenues sont les actionneurs et les paramètres descriptifs des régulations intervenant au cours de la conduite. Le nombre de variables de décision étant potentiellement élevé, la résolution d'un problème d'optimisation requiert un grand nombre de calculs. Or, la conduite d’un réacteur est modélisée par l’Outil de Calcul Scientifique (OCS) de thermohydraulique système CATHARE2, caractérisé par de longues durées d’exécution, qui rendent impossible la résolution du problème d’optimisation. Pour résoudre ce problème, la méthode développée réduit la dimension de l’espace de recherche et construit des modèles de substitution (métamodèles) à l’OCS CATHARE2 pour reproduire les objectifs et les contraintes en fonction des variables de décision. Ces métamodèles utilisent la structure de processus gaussiens conditionnés sur une base d’apprentissage de la variable à reproduire. Un couplage de ces modèles de substitution à un algorithme génétique permet de définir un ensemble de conduites réparties de manière homogène dans les zones optimales de l’espace des solutions. Les faibles erreurs de prédiction des métamodèles permettent alors d’approcher efficacement le front de Pareto. La méthode est utilisée pour optimiser la conduite du réacteur ASTRID au cours des transitoires de manque de tension externe et de réglage de fréquenceDefining the reactor operation allows the nuclear power plant to achieve objectives in terms of thermodynamic performance and to meet safety requirements. This work develops a method to define the reactor operation as the solution to a multiobjective optimization and constrained problem. The decision variables selected to solve this kind of problems are the actuators and the descriptive parameters related to regulations implemented in the reactor operation. The decision variables number is potentially high and induced a high number of simulations to solve the multiobjective problem. The reactor operation is modeled using the CATHARE2 code and is characterized by a long computation runtime, which makes the multiobjective problem resolve impossible. To overstep this problem, the developed method reduces the dimension size of the research space and builds surrogate models (metamodels) to replace CATHARE2 code simulations in order to mimic objectives and constraints depending on the decision variables. These metamodels use the conditioned Gaussian processes structure on a learning base of the variable to mimic. A coupling of these substitution models to a genetic algorithm enables the definition of a set of reactor optimal operations homogeneously spread in the solutions space. The low prediction errors of the metamodels provide an accurate estimate of the Pareto Front. The method is used to optimize the ASTRID operation for the loss of off-site power and the frequency setting transients
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Tauveron, Nicolas. "Simulation numérique et analyse du déclenchement et du développement des instabilités axiales dans les turbomachines : Application à un transitoire de brèche dans un réacteur nucléaire à hélium." Ecully, Ecole centrale de Lyon, 2006. http://bibli.ec-lyon.fr/exl-doc/ntauveron.pdf.
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Le travail a porté sur le développement de modèles pour la simulation numérique des instabilités axiales dans les turbomachines multiétagées. L'élaboration d'un modèle monodimensionnel axisymétrique instationnaire de l'écoulement à l'intérieur d'une turbomachine (à l'échelle de la roue), a consisté en : la génération de corrélations ; la construction d'un modèle valable en régime transitoire ; la validation par rapport à des données expérimentales. Des modèles théoriques élémentaires, basés sur la généralisation de la théorie de Greitzer, ont également été élaborés. Ils ont renforcé la compréhension des phénomènes physiques régissant l'apparition et le développement des instabilités en quantifiant différents effets (inerties, compressibilité, seuils de performance) et en mettant en relief les phénomènes majeurs. Les modèles ont été appliqués à des configurations académiques, puis à un projet industriel innovant : un réacteur nucléaire rapide à caloporteur hélium et à cycle de BraytonThe subject of the present work was to develop models able to simulate axial instabilities occurrence and development in multistage turbomachines. The construction of a onedimensional unsteady axisymmetric model of internal flow in a turbomachine (at the scale of the row) has followed different steps : generation of steady correlations ; building of a model able to describe transient behaviour ; validation of the model in comparison of experimental results. An elementary theory has also been developed, based on a generalisation of Greitzer's model. These models have also allowed a more comprehensive description of physical phenomena at stake in instability occurence and development by quantifying various effects (inertia, compressibility, performance levels) and underlying the main phenomena. The models were applied to academic configurations, and then to an innovative industrial project : a helium cooled fast nuclear reactor with a Brayton cycle
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Walter, Ayelet [Verfasser]. "Simulation of operational and accidental behaviour of modular high temperature reactors with Brayton cycle power conversion unit / vorgelegt von Ayelet Walter." Stuttgart : IKE, 2010. http://d-nb.info/1009699253/34.
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Freas, Rosemarv M. "Analysis of required supporting systems for the Supercritical CO2 power conversion system." Thesis, Cambridge Massachusetts Institute of Technology, 2007. http://hdl.handle.net/10945/2992.
Full textAbstract:
Recently, attention has been drawn to the viability of using S-CO(2) as a working fluid in modern reactor designs. Near the critical point, CO2 has a rapid rise in density allowing a significant reduction in the compressor work of a closed Brayton Cycle. Therefore, 45% efficiency can be achieved at much more moderate temperatures than is optimal for the helium Brayton cycles. An additional benefit of the S-CO2 system is its universal applicability as an indirect secondary Power Conversion System (PCS) coupled to most GEN-IV concept reactors, as well as fusion reactors. The United States DOE's GNEP is now focusing on the liquid Na cooled primary as an alternative to conventional Rankine steam cycles. This primary would also benefit from being coupled to an S-CO2 PCS. Despite current progress on designing the S-CO2 PCS, little work has focused on the principal supporting systems required. Many of the required auxiliary systems are similar to those used in other nuclear or fossil-fired units; others have specialized requirements when CO2 is used as the working fluid, and are therefore given attention in this thesis. Auxiliary systems analyzed within this thesis are restricted to those specific to using CO2 as the working fluid. Particular systems discussed include Coolant Make-up and Storage, Coolant Purification, and Coolant Leak Detection.Contract number: N62271-97-G-0026.
US Navy (USN) author
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Ranc, Pierre. "Contribution au développement d'un Moteur à Apport de Chaleur Externe à soufflets métalliques. Étude théorique, conception, réalisation et caractérisation expérimentale." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD045.
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Ces travaux concernent l'étude d'un Moteur à Apport de Chaleur Externe (M.A.C.E.) de type Ericsson. Un état de l'art des études théoriques et expérimentales antérieures est présenté. Nous avons développé un modèle numérique basé sur le couplage des équations de la thermodynamique et de la mécanique. La modélisation des écoulements au travers des soupapes et des clapets repose sur l'équation de Barré-de-Saint-Venant. Ce modèle permet de simuler le comportement dynamique du moteur pour une large gamme de fonctionnement. La variation des paramètres de simulation comme le taux de compression, la charge mécanique, la température ou le coefficient polytropique permet d'analyser leur influence sur les performances du moteur. Nous avons construit un banc d'essais de M.A.C.E. à enceintes déformables constitué par des soufflets métalliques. Le compresseur, relié au détendeur par l'intermédiaire d'un bras de levier permet de diminuer l'effort de compression lors de la phase de détente. Ce système autorise également la variation de cylindrée entre les enceintes. Le prototype est instrumenté avec des capteurs de pression, de force, de débit, de déplacement et des microthermocouples afin de mesurer les variations temporelles des signaux au cours des essais. Le moteur a été testé avec une admission d'air comprimé à température ambiante afin de caractériser son fonctionnement. Des réchauffeurs électriques permettent de tester l'influence de la température à l'admission avec une valeur maximale en entrée de 450°C. La quantité de chaleur transmise à la culasse réduit alors la température effective dans l'enceinte à seulement 160°C au mieux. La comparaison des résultats théoriques et expérimentaux présente un très bon accord en termes de dynamique de fonctionnement du moteur (pression, déplacement, volume). Un système de refroidissement de la compression par injection d'eau est ajouté au banc d'essais afin de diminuer l'énergie de compression. La température de compression est alors toujours inférieure au cas sans injection. Enfin, le couplage fluidique des enceintes donne une estimation des pertes de charge de l'ensemble du banc d'essais et des niveaux de température. La technologie étudiée est prometteuse en particulier grâce à la capacité des soufflets à échanger de la chaleur avec le fluide de travail et par l'absence de fuite et de frottement liés à la segmentationThis thesis covers the theoretical and experimental study of the Ericsson Externally Heated Valve Engine (E.H.V.E.).Specifically, it focuses on the development of a dedicated dynamic model in order to predict a wide range of the engine's capabilities.This mathematical model is made up of thermodynamical and mechanical equations. The flow which passes through the compressor valves and expander valves is modelled on the Barré-de-Saint-Venant equation. A parametric analysis of the compressor ratio, mechanical load, temperature or polytropic coefficient is done in order to assess their effects on the engine's kinematics. Furthermore, the conception and the build of a test bench is made. It consists of metal bellows that aim to replace the traditional cylinder and piston. The compressor is linked to the expander from a lever which allows the reduction of the pressure force during the expansion stroke. It also gives the possibility to alter the working volume. Pressure, force, flow and temperature sensors are placed on the engine at strategic points in order to study it. A microthermocouple is used to monitor the temperature signal in the compression and expansion phase. Initially, the engine is tested at ambient temperature to give a point of reference. Electrical heaters are used to increase the expansion temperature starting point above 450°C. It appears that a heat flow in the cylinder head, cools down the warm airflow coming from the heater to 160°C in the best case scenario. The experimental results show a really good agreement with the model, particularly if we consider the engine dynamic in terms of pressure, displacement or volume. A compression cooling system is also added to the test bench in order to reduce energy needs. In all cases, the temperature during the compression is always lower with the injection of water mist. And finally, intake expander pipes and discharge compressor pipes are connected to measure the pressure loose and temperature fluctuations of the airflow between the bellows. The studied technology is promising particularly thanks to the use of bellows that allow a superior exchange of heat, as well as avoiding leaks and friction
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Briggs, Maxwell H. "High Pressure Performance of Foil Journal Bearings in Various Gases." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1344447241.
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Fornazari, Filho Ricieri. "Otimização de um ciclo Brayton irreversível com regeneração, inter-resfriamento e reaquecimento através de uma função objetivo termoeconômica." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/154747.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Desenvolver e projetar plantas de potência otimizadas é uma constante e antiga busca da engenharia de energia. Para tal, os modelos de ciclos foram constantemente aprimorados ao longo do tempo. Através de estudos que procuram incorporar funções que descrevam a realidade mais precisamente, o equacionamento de irreversibilidades presentes nos processos e dispositivos reais de interações de trabalho e calor é vasto na literatura. Uma modelagem matemática foi desenvolvida para um ciclo Brayton irreversível com inter-resfriamento, regeneração e reaquecimento. As irreversibilidades consideradas são provenientes das resistências térmicas nos trocadores de calor do ciclo, do comportamento não isentrópicos dos elementos de expansão e compressão, da perda de calor para o reservatório frio e das perdas de carga nas tubulações ao longo do escoamento do fluido de trabalho. O método de otimização escolhido foi uma função termoeconômica a qual relaciona potência líquida com diversos tipos de custos de uma planta de potência, tais como custos de investimentos, de combustíveis, ambientais e de operação e manutenção. A modelagem matemática consistiu em determinar todas as temperaturas e parâmetros de interesse do ciclo através do conhecimento de apenas uma temperatura, denominada temperatura de controle. A partir de variações nesta temperatura foi possível estabelecer o comportamento dos demais parâmetros do ciclo e relacioná-los com irreversibilidades e parâmetros construtivos. O presente trabalho apresentou um modelo de ciclo Brayton não encontrado na literatura, acopladas diversas fontes de irreversibilidades sob a ótica de uma função de custos de quatro termos. Os resultados obtidos demonstram que a faixa ótima para operação em máxima potência difere da faixa ótima para operação sob máxima eficiência, sendo que a operação termoeconômica maximizada se aproxima mais da última do que da primeira. Foi observado também que as perdas de carga e as resistências dos trocadores de calor são irreversibilidades significativas no ciclo de potência.
Developing and designing optimized power plants is a constant and ancient search for energy engineering. For this, cycles models have been constantly improved over time. Through studies that seek to incorporate functions that describe the reality more precisely, the equating of irreversibility present in real processes and devices of work and heat transfer interactions is vast in the literature. A mathematical modeling has been developed for an irreversible Brayton cycle with inter-cooling, regeneration and reheating. The irreversibility considered are due to thermal resistances in the heat exchangers of the cycle, to the non-isentropic behavior of the elements for expansion and compression, to the heat loss to the could reservoir and to the head loss on the pipes along the working fluid flow. The optimization method chosen was a thermoeconomic function that relates the net power to various types of costs of a power plant, such as investment costs, fuel costs, environmental costs and operation and maintenance costs. The mathematical modeling consisted on determining all the cycle temperatures and parameters of interest through the knowledge of only one temperature, called control temperature. From variations in this temperature, it was possible to establish the behavior of the other parameters of the cycle and relate them to irreversibility and constructive parameters. The present work presented a model of Brayton cycle not found in the literature, coupled several sources of irreversibility under the optics of a four terms cost function. The results obtained demonstrate that the optimal operational range under maximum power differs from the optimal operational range under maximum efficiency, and the maximized thermoeconomic operation is closer to the latter than the first. It has also been observed that the head losses and the resistances in the heat exchangers are significant irreversibility in the power cycle.
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Polák, Luboš. "Zvýšení výkonu mikroturbíny pracující v nepřímém oběhu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230159.
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Turbogenerator unit 100B TGU, produced in the First Brno Engineering Velká Bíteš a.s., works in Brayton indirect circulation. The aim of this work is the proposal to increase performance levels of technological unit in which the micro-turbine is applied. The work presents various ways to increase performance and efficiency of circulation. The possible options are compared with each of the technological and economic terms. Based on these criteria was selected variant feeding additional water into the circulation. For this design was the work of a mathematical model based on, which was established as the economic balance of the selected variants. The thesis also proposes a technological scheme, which is already incorporated the selected variant and an outline of the verification tests.
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Börner, Reina. "Modélisation d'échangeur de chaleur : analyse théorique et expérimentale du comportement en régime transitoire : particularisation aux capteurs solaires et optimisation des systèmes moteurs associés." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL011N.
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La filière solaire des centrales actuellement existantes se base essentiellement sur des cycles classiques à vapeur. Mais il est aussi possible de développer une filière gaz en utilisant des turbines à gaz avec des cycles ouverts ou fermés. Dans cette optique a été développée une méthode générale d'optimisation du rendement d'un système capteur solaire à air - moteur thermique, en s'appuyant sur un fonctionnement en cycle de CARNOT puis en cycle de BRAYTON avec ou sans régénération. Les écarts de température à la source et au puits, les pertes thermiques directes entre source et puits sont pris en compte, ainsi que le rendement de régénération pour le cycle de Brayton. L’étude de la sensibilité paramétrique est faite en prenant la température du puits ou la température de stagnation comme référence. Cette première partie se termine par la présentation de quelques résultats significatifs, permettant de situer l'importance de ces paramètres dans la conception des moteurs thermiques de ce type. Dans la deuxième partie, l'étude en régime de relaxation de flux radiatif de ces capteurs solaires comportant des matrices poreuses mène à l'écriture des équations de bilan d'énergie pour les phases solide et fluide. Leur résolution analytique simplifiée en négligeant les termes de diffusion dispersion et le terme d'inertie du fluide aboutit à des valeurs du coefficient volumique de transfert h qui s'accordent avec ceux du régime stationnaire. Le modèle numérique développe ensuite pour la résolution des équations complètes est basé sur la méthode des volumes finis et permet l'identification de h par comparaison des profils de température calculés et expérimentaux. Le présent travail se limite aux milieux poreux suivants: les copeaux de duralumin, la laine de cuivre, la mousse de polyuréthane et les grains de liège. Les valeurs de h déduites du modèle numérique transitoire restent très supérieures à celles déduites du modèle analytique correspondant, mais restent cohérents par rapport aux quelques corrélations de la littérature
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PEREIRA, SERGIO A. "Conceito alternativo de um reator hibrido (conjunto sub-critico acoplado com acelerador)." reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10991.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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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.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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Alabdoadaim, Mohamed Abualkasem. "A thermodynamic study of Brayton, inverse Brayton and Absorption cycles for sustainable power production and cooling." Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413037.
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Netopilová, Petra. "Systémy přeměn energie pro jaderné elektrárny se sodíkem chlazeným reaktorem (SFR)." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229737.
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The aim of the dissertation is proposing and solving energy convection systems for nuc-lear power plants with a sodium fast reactor of the 4th generation. The first part of the dissertation deals with collection and evaluation of information available about nuclear power plants with sodium fast reactor which use nuclear or non-nuclear reheating to increase thermal efficiency. On the basis of the acquired information, thermal schemes are developed and thermal effi-ciency is determined for the systems working in both Rankine thermal cycle and Brayton thermal cycle. In the further part of the dissertation thermal calculation of the reheater for nuclear and non-nuclear reheating is made for the systems working in Rankine thermal cycle. At the end of this dissertation, an apparatus suitable for these systems is suggested and the systems are evaluated in terms of technical implementation and nuclear safety.
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Nkoi, Barinyima. "Techno-economic studies of environmentally friendly Brayton cycles in the petrochemical industry." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/9260.
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Brayton cycles are open gas turbine cycles extensively used in aviation and
industrial applications because of their advantageous volume and weight
characteristics. With the bulk of waste exhaust heat and engine emissions
associated, there is need to be mindful of environmentally-friendliness of these
engine cycles, not compromising good technical performance, and economic
viability.
This research considers assessment of power plants in helicopters, and aeroderivative
industrial gas turbines combined-heat-and-power (ADIGT-CHP) in the
petrochemical industry. Thus, it consists of two parts: part A focuses on
performance analysis of helicopter gas turbines, while part B entails technoeconomic
and environmental risk assessment of ADIGT-CHP in the
petrochemical industry. The investigation encompasses comparative
assessment of simple cycle (SC) and advanced gas turbine cycle options
including the component behaviours and the environmental and economic
analysis of the systems. The advanced cycles considered include: recuperated
(RC), intercooled (IC), intercooled-recuperated (ICR), and low pressure
compressor zero-staged (LPC-ZS), cycles.
The helicopter engines are analysed and subsequently converted to small-scale
ADIGT engines. Also, modelling combined-heat-and-power (CHP)
performances of small-scale (SS), and large-scale (LS) ADIGT engines is
implemented. More importantly, a large part of the research is devoted to
developing a techno-economic model for assessing, predicting, and comparing
viability of simple and advanced cycle ADIGT-CHP in the petrochemical
industry in terms of net present value (NPV), internal rate of return (IRR), and
simple payback period (SPBP). The techno-economic performances of the
ADIGT-CHP cycles are measured against the conventional case of grid power
plus on-site boiler. Besides, risk and sensitivity of NPV with respect to uncertain
changes in grid electricity cost, gas fuel cost, emission cost, and electricity
export tariff, are investigated. Two case studies underlie the development of the
techno-economic model. One case study demonstrates the application of the
model for large-scale (LS) ADIGT-CHP, and the other for small-scale (SS)
ADIGT-CHP, all in the petrochemical industry. By so doing, techno-economic
and environmental risk analysis framework (a multi-disciplinary preliminary
design assessment tool comprising performance, emissions, economic, and risk
modules) is adapted to ADIGT-CHP in the petrochemical industry, which is the
aim of this research.
The investigation and results led to the conclusions that advanced cycle
helicopter and ADIGT engines exhibit higher thermal efficiencies than simple
cycle, and that savings exist in operational costs of ADIGT-CHP above the
conventional case. Thus, for both SS ADIGT-CHP, and LS ADIGT-CHP cases,
all ADIGT-CHP cycles are profitable than the conventional case. For LS ADIGT-
CHP category, the IC ADIGT-CHP is the most profitable, whereas for SS
ADIGT-CHP category, the RC ADIGT-CHP is the most profitable. The
contribution to knowledge of this research is the development of a technoeconomic
model for assessing, predicting, and comparing viability of simple and
advanced cycle ADIGT-CHP in the petrochemical industry in terms of NPV,
SPBP, and IRR over the conventional case of grid power plus on-site boiler. A
second contribution is the derivation of simple and advanced cycle small-scale
ADIGT and ADIGT-CHP from helicopter engines.
Cont/D.
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Périlhon, Christelle. "Analyses théorique et expérimentale des cycles Joule-Brayton direct et inversé modifiés par l'utilisation de l'air humide." Orléans, 1992. http://www.theses.fr/1992ORLE2031.
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Des procedes fonctionnant suivant le cycle de joule-brayton inverse furent utilises il y a pres d'un siecle pour produire du froid. Tombe en desuetude, ce cycle revient aujourd'hui a l'etude du fait des problemes de pollution. Or l'air ambiant utilise comme fluide frigorigene n'est jamais sec. Les modifications du cycle dues a l'influence de l'humidite sur les caracteristiques de fonctionnement sont mises en evidence. L'humidite influe sur les performances du cycle en les ameliorant. D'autre part, il est possible de concevoir un procede de dessalement fonctionnant suivant le cycle de joule-brayton utilisant l'air humide comme fluide de travail. Sous certaines conditions qui sont precisees, il est possible grace a ce procede de produire de l'eau douce accompagnee d'une faible production d'energie noble
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Riotto, Antonio. "Analisi termodinamica di cicli di potenza complessi a CO2 supercritica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22430/.
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La finalità di questo lavoro di tesi è la valutazione quantitativa delle prestazioni dei cicli Brayton a CO2 supercritica. Per dare fondamento alle motivazioni che spingono ad un tale studio, il punto di partenza è stato analizzare la statistica riguardante le potenzialità del calore di scarto. Un passo ulteriore è stato non solo quantificare l’energia recuperabile, ma anche avere tabulati con le temperature alle quali tali energie sono disponibili in un panorama industriale che coinvolge diversi settori produttivi. Per ogni settore produttivo è stato possibile anche associare, ad un suo j-esimo processo, una fascia di temperatura alla quale il fluido viene scartato, come liquido o come gas. Successivamente, è stato necessario mettere in luce le proprietà della CO2 . Esso si mostra infatti compatibile con un utilizzo all’interno di un ciclo Brayton, e può anche presentare dei vantaggi rispetto ai fluidi dei cicli tradizionali: la sua densità è grande a tal punto da ottenere impianti con potenze in uscita elevate e ingombri particolarmente ridotti. Si è passati poi ad una rassegna di tre layout, uno semplice e due più complessi, studiati da più autori, con conclusioni complementari. Il capitolo successivo, quello della simulazione dei cicli di potenza in ambiente Aspen Hysys, è stato suddiviso in due parti. Nella prima parte sono presenti istruzioni più di carattere operativo per l’utilizzo del software. Nella seconda parte vengono invece mostrati i risultati delle simulazioni, con l’obiettivo di massimizzare il rendimento totale di recupero termico ηtot . Tale obiettivo è stato conseguito al variare di alcuni parametri, come temperatura di ingresso dei fumi nello scambiatore principale (Tfumi), temperatura di ingresso in turbina ( TIT ), pressione massima di ciclo (pmax), e potenza netta erogata dall’impianto ( Pnet ).
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Hodás, Ladislav. "Konstrukce kompresní části Brayssonova motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-374733.
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This master thesis deals with design of compression part of Braysson engine which is instrumental to energy producing. The first part addresses generally the problem of Braysson cycle and briefly sums the knowledge about compressors. The next part focuses on the projection of design itself. It contains proposals of various possibilities of solutions, choice of optimal variants. Individual parts of the machine are described and design and control computations are provided. The final part contains evaluation.
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Venker, Jeanne [Verfasser], and Jörg [Akademischer Betreuer] Starflinger. "Development and validation of models for simulation of supercritical carbon dioxide Brayton cycles and application to self-propelling heat removal systems in boiling water reactors / Jeanne Venker. Betreuer: Jörg Starflinger." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2015. http://d-nb.info/1074871154/34.
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Kantor, Radek. "Aplikační případy využití zkapalněného zemního plynu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401563.
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Lin, Yu-Chao, and 林裕超. "Ecological Optimization Analysis of Irreversible Brayton Cycle." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/09114531554260018004.
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碩士國立成功大學
機械工程學系
86
The model of gas turbine is the air standard Brayton cycle.An" ecological" criterion is used for optimizing the operation of this heat engine.It consists in maximizing an ecological criterion function which represents the best compromise between the power generation and the entropy production.The thermodynamic performance of endoreversible and irreversible Brayton cycles are analyzed in this thesis byusing ecological criterion.The irreversibilities considered include:heat transfer between external heat source and combustion chamber,exhaust working fluid to atmosphere, exhaust heat to the atmosphere, irreversibilities of compressor and turbine.The pressure ratio, compressor efficiency, and turbine efficiency are the important factors considered in analyzing the cycle efficiency.We hope the individal efficiency of compressor and turbine as high as possible, increase turbine inlet temperature anddecrease compressor inlet temperature to improve the cycle efficiency.
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CHIOU, FENG REN, and 邱豐壬. "Supercritical CO2 Brayton Cycle Turbine Blade Analysis." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/45712932760899143164.
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碩士國立清華大學
動力機械工程學系
103
As the fossil fuel consumption is increasing, the energy shortage has gradually become a big problem nowadays. However, the industrial energy utilization is less than 50%, which means almost half of the precious energy is discharged into the air as waste heat or other forms that cannot be further used. The environment is deteriorating, so people are more concerned about the waste heat recovery and the uses of renewable energies (such as geothermal energy). Our laboratory has focused on researches about waste heat recovery system for plants for many years. From subcritical cycle systems (Organic Rankine Cycle, ORC) to supercritical cycle systems (Supercritical CO2 Brayton Cycle), the latter is our main research at present. The reasons for choosing CO2 as working fluid are because of its stability, low critical point conditions, wide range of applications and greenhouse gas reduction. The Turbine-Alternator-Compressor (TAC) component is a very important part in supercritical Brayton cycle system, especially the designs of rotors in compressor and expander, which are extremely difficult. The radial type of rotor is used both in compressor and turbine, and to reduce difficulties, I used the rotor of P-15 jet engine as basic model, but its blade shape still need to be modified corresponding to design points. Then CFD simulation is applied to improve rotor efficiency by repeatedly correct errors. At last, semi-closed system is used to reduce the difficulties of initial test and also for the safety issues.
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Lin, Bo Hung, and 林柏宏. "Supercritical CO2 Brayton Cycle Turbine Blade Analysis." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/88439005217672493410.
Full textAbstract:
碩士國立清華大學
動力機械工程學系
104
There is a lot of electricity power used for production by industry. degree of electricity produced would consume a pound of coal and release lots of CO2 and wasted heat which cause the global warming、air pollution、acid rain、ozone hole etc. It’s necessary to find the substitute and recycle energy. For recycle energy, many researches changed the direction to supercritical cycle recently. According to the report from Sandia, the America National lab, supercritical Brayton cycle’s heat efficiency can be over 50% which is about 1.25~1.5 times compare to the traditional Rankine cycle. The reason choosing CO2 as working fluid is based on its stability , low critical point condition, wide range of applications and greenhouse gas reduction in the atmosphere. However the compressor and turbine of the system need to be designed precisely. To meet the work conditions of supercritical system, we choose the radial rotor as interior component. Utilize the design procedure built with ANSYS software by the lab graduated student Mr. Chiu to redesign a rotor which could take the high temperature and high pressure (12~18MPa、500~700K) design point. First using the software Aspen Plus to simulate the cycle stations and analyze the workout and efficiency. The design point of the rotor is 1kg/s of mass flowrate and 30000RPM of the rotor velocity to make 14MPa working fluid decrease to about 8MPa and keep the rotor efficiency over 75%. After the theory analysis and design procedure there are two rotor models derived. Although the pressure drop conforms to the design point but the inducer’s effect doesn’t answer to the anticipation and also influence the rotor efficiency to be only 60%. The flaw will be corrected to improve the rotor efficiency and meet the design point.
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Churilov, Vitaliy. "Hybrid Brayton Cycle model and facility commissioning." 2014. http://hdl.handle.net/1993/23292.
Full textAbstract:
There is a lack of available technology to make small-scale power from biomass cost effectively. The proposed Hybrid Brayton cycle is an indirectly heated Brayton cycle with evaporative cooling for combined heat and power generation. It converts a direct fired microturbine to an indirectly heated power system. The Hybrid Brayton cycle offers a flexible biomass power generation platform in the 30 to 250 kWe range, achieving competitive efficiencies and advantages compared to other systems of similar power level. This cycle is designed to be implemented in remote and off-grids communities, small industries and net-zero communities, where local biomass feedstock is sustainably available. This proposed platform keeps operator qualifications to a minimum. In an effort to validate this new power cycle, a 30 kWe experimental facility was developed and initial commission phases performed. This facility purpose is to validate numerical model predictions and is used for optimization. The facility is described and results of the commissioning tests are reported with various problems encountered, solutions implemented and recommendations proposed. The thermodynamic model of the Hybrid Brayton cycle is also implemented in the MatLAB environment, incorporating experimental findings and new properties for humidified air at high temperatures. The MatLAB model confirms that an indirect fired Brayton cycle with evaporative cooling could be a viable approach for small scale distributed power generation using biomass. Additional experimental data of humidified air at elevated temperatures would provide more certainty in property predictions. The MatLAB model provides a modeling tool to allow resolving the issues identified during the commissioning of the test facility and offers alternatives to optimize various design configurations, implementing the most up to date property correlations for humidified air at elevated temperatures.
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Shen, Kuo-Hao, and 沈國豪. "Total Useful Energy Analysis of Brayton Cogeneration Cycle." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/91102467735480400097.
Full textAbstract:
碩士國立高雄海洋科技大學
輪機工程研究所
99
In this paper, the method of finite time thermodynamics was adopted on the investigations for the irreversible open-Brayton cogeneration cycles. Two kinds of irreversible cycle are studied including the simple gas-turbine cogeneration cycle, and the conventional regenerative cycle with cogeneration. The analysis of the objective function for optimization is achieved in the total useful energy rate and the thermal efficiency. Furthermore, a new performance coefficient concerning in the heat recovery is proposed by the assistance of the availability analysis. In order to analyze the thermodynamic cycle system, the effects of various influential parameters including the pressure ratio, the ratio of power-to-heat, the maximum cycle temperature ratio, and the user’s demand thermal energy ratio on the total useful energy rate and the thermal efficiency are numerically assessed by using the EES software. Variations of the dimensionless total useful-energy rate with to the thermal efficiency have also been studied. It is observed that the new performance coefficient based on the availability of the recovery heat may guide towards a more realistic criterion for actual cogeneration cycles.
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Liu, Kai-Wen, and 劉凱文. "Supercritical CO2 Brayton Cycle Compressor Blade Design and Analysis." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/ma3872.
Full textAbstract:
碩士國立清華大學
動力機械工程學系
105
Accompanied by the prosperity of technology, the electricity needed for production is increasing year to year. However, the overall efficiency is not above 50%, and thus it will produce large amount of carbon dioxide and waste heat. It will give rise to the global warming aggravation and the air pollution, sour rain, ozonosphere holes and the destruction of forest…etc. So this paper intend to find an solution to finding alternative energy and recovery of waste heat, with the increasing literatures focusing on the super critical cycle in the energy recovery field. This paper put aim on the super critical Brayton cycle to make the first compressor design. According to the Sandia Laboratory’ reports, the overall efficiency of the combined cycle can be high above 50%. The reason to use carbon dioxide to be the working fluid is due to its stability, low critical condition, large range of application and capable of reducing the global warming. This paper design the prototype of the blades and rotors of the compressor. And then, by using ANSYS this paper propose a layout of the rotor and blade which can bear high temperature and pressure(7.8~15 MPa, 300~500K). And this model has been verified by comparing the simulation results with the paper [35]. The results are quite similar where the errors are below 6%. The efficiency of the impeller is about 50.1%, compared with the 25% efficiency of the impeller by using Air Ideal Gas as working fluid. It has been proven that the SCO2 compressor impeller is the best choice over the conventional Rankine cycle and the Brayton cycle by Air Ideal Gas. With the advantages of high rotating speed and the low volume, the pressure ratio of this compressor is about 1.85; the efficiency is about 50%.
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Wen, Meng-Yang, and 溫孟揚. "Design, Analysis, and Simulation of a Turbine for Supercritical CO2 Brayton Cycle." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/x4838c.
Full textAbstract:
碩士國立清華大學
動力機械工程學系
105
The research of Supercritical CO2 (sCO2) Brayton Cycle has been popular over the past decade, due to its higher efficiency and smaller component size compared with those of steam Rankine cycle and air Brayton Cycle. Studies showed that SCO2 Brayton Cycle can accommodate a wide range of temperature as the heat source, starting from 260°C to 1200 °C. Thus, various research had been investigated to apply sCO2 Brayton Cycle into fields such as concentrated solar power, nuclear power, geothermal power, and waste heat recovery, making it a viable option for renewable energy. This study is a subproject of SCO2 Brayton Cycle power generation system, a project under the National Energy Program-Phase II in Taiwan, with the objective of designing a power generation system using waste heat as heat source. The temperature of the waste heat is set to be 450°C, conforming to mid-range waste heat. The aim of this subproject is to design a turbine with the inlet total pressure of 14.1 MPa and total temperature of 573K, respectively, and outlet pressure of 8.5 MPa, corresponding to an expansion ratio of 1.658. Due to its small size and low mass flow rate, radial inflow turbine is selected instead of the axial flow turbine. Some efforts were made by previous member of this lab to modify the existing turbine model to avoid the complexity of designing a turbine model from scratch. The efficiency, however, turned out to be lower the expectation. Therefore, in this study, the previously modified turbine model would be discarded and the new turbine would be built from square one. This study tried to use Meanline Analysis from the literature as a preliminary design tool. Although most studies devoting to the design of radial inflow turbine were developed for turbine using air as working fluid, recent studies about the design of SCO2 turbine indicated that Meanline Analysis is qualified to be a preliminary design tool. The simulation result of the Meanline Analysis was shown to be deviate from the design point, as expected. Fortunately, with the aid of CFD, the problem predicted by the simulation could be corrected and the model could be adjusted accordingly. At the end, with some bold assumption, the turbine model close to the expected pressure ratio and power output was devised.
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Khivsara, Sagar D. "A Design Concept of a Volumetric Solar Receiver for Supercritical CO2 Brayton Cycle." Thesis, 2014. http://hdl.handle.net/2005/2996.
Full textAbstract:
Recently, the supercritical carbon dioxide (s-CO2) Brayton cycle has been identified as a promising candidate for solar-thermal energy conversion due to its potentially high thermal efficiency (50%, for turbine inlet temperatures of ~ 1000 K). Realization of such a system requires development of solar receivers which can raise the temperature of s-CO2 by over 200 K, to a receiver outlet
temperature of 1000 K. Volumetric receivers are an attractive alternative to tubular receivers due to their geometry, functionality and reduced thermal losses. A concept of a ceramic pressurized volumetric receiver for s-CO2 has been developed in this work. Computational Fluid Dynamics (CFD) analysis along with a Discrete Ordinate method (DOM) radiation heat transfer model has been carried out, and the results for temperature distribution in the receiver and
the resulting thermal efficiency are presented. Issues regarding material
selection for the absorber structure, window, coating, receiver body and
insulation are also addressed. A modular small scale prototype with 0.5 kWth
solar heat input has been designed. The design of a small scale s-CO2 loop for
testing this receiver module is also presented in this work.
There is a lot of ongoing investigation for design and simulation of different
configurations of heat exchangers and solar receivers using s-CO2 as the working fluid, in which wall temperatures up to 1000 K are encountered. While CO2 is considered to be transparent as far as solar radiation spectrum is concerned, there may be considerable absorption of radiation in the longer wavelength range associated with radiation emission from the heated cavity
walls and tubes inside the receivers. An attempt has been made, in this study, to
include radiation modelling to capture the effect of absorption bands of s-CO2
and the radiative heat transfer among the equipment surfaces. As a case study, a
numerical study has been performed to evaluate the contribution of radiative
heat transfer as compared to convection and conduction, for s-CO2 flow through
a circular pipe. The intent is to provide a guideline for future research to
determine the conditions for which radiation heat transfer modelling inside the
pipe can be significant, and what errors can be expected otherwise. The effect of
parameters such as Reynolds number, pipe diameter, length to diameter ratio,
wall emissivity and total wall heat flux has been studied. The effect of radiation
modelling on wall temperatures attained for certain amount of heat flux to be
transferred to s-CO2 is also studied. The resulting temperature distribution, in
turn, affects the estimation of heat loss to the environment
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Lusanga, Peter Kabanda. "Model predictive control of a Brayton cycle based power plant / Peter Kabanda Lusanga." Thesis, 2012. http://hdl.handle.net/10394/11090.
Full textAbstract:
The aim of this study is to implement the model predictive control in order to optimally
control the power output of a Brayton cycle based power plant. Other control strategies
have been tried but there still exists the need for better performance. In real systems, a
number of constraints exist. Incorporating these into the control design is no trivial task.
Unlike in most control strategies, model predictive control allows the designer to explicitly
incorporate constraints in its formulation. The original design of the PBMR power plant is
considered. It uses helium gas as the working fluid. The power output of the system can be
controlled by manipulating the helium inventory to the gas cycle.
A linear model of the power plant, modelled in Simulink® is used. This linear model is used
as an evaluation platform for the control strategy. The helium inventory is manipulated by
means of actuators which use values generated by the controller. The controller computes
these values by minimizing the cost of future outputs over a finite horizon in the presence of
constraints.
The dynamic response of the system is used to tune the controller. The power output
performance at different configurations of the controller under perfect conditions and with
disturbances is examined. The best configuration is used resulting in an optimal power
control system for the Brayton cycle based power plant.
Results showed that the method employed can be used to implement the control strategy.
Furthermore, better performance can be realised with model predictive control.Thesis (M.Ing. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2012