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White, Susan Jennifer. "Bubble pump design and performance." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/16914.
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Norrman, Marcus, and Felix Monthan. "Heat Pump Data Performance Analysis of Large Scale Ground Source Heat Pump Systems." Thesis, KTH, Energiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-276072.
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This study aimed at refining and improving current methodology concerning large-scale heat pump performance. This study was performed on two large-scale ground source heat pumps located in Solna (Stockholm). These were connected to an aquifer thermal energy storage system which provided heating and cooling for two office buildings. The heat pumps had been equipped with preliminary sensors from the BMS (Building management system) and been in operation since 2016. In 2019, additional detailed measurement equipment from ClimaCheck was installed to collect comprehensive data from the heat pumps to allow a more comprehensive performance evaluation. This study was primarily performed by data pre-processing of the BMS-data and the ClimaCheck-data. Once this was done, the ClimaCheck parameters were backtracked and recalculated. Subsequently new models for system evaluation was implemented. The most desired parameter to replace in the ClimaCheck model was the mass flow rate, which they obtain though an energy balance over the compressors. The latter part of the study was to see whether the BMS had sufficient data to provide the same information as ClimaCheck. This was done by implementing a regression of the BMS-data, where the heating and cooling capacities from ClimaCheck were used as targets. The results from the study showed that implementing a mass flow rate based upon compressor efficiency instead of an assumed heat loss was difficult and only reliable for higher loads. When evaluating the ClimaCheck parameters, interesting results were found concerning their calculations for the heating capacity, which might not be calculated the way they express in their formulas. The regression from the BMS-data was proven difficult because of the insufficient and lacking data for some instances. Five different models were produced and compared, some models showed accuracy up to 95% depending on the desired metric. It can be concluded that it is possible to estimate the key performance indicators using the BMS-data. It yields good results for the COP’s and very accurate results for the SPF’s over a year. This makes it possible to evaluate the heat pump performance for years prior to the installation of the ClimaCheck system.<br>I den här studien analyseras metodiken för att bestämma prestandan hos industriella värmepumpar. Studien utfördes i Solna utanför Stockholm på ett värmepumpsystem som är kopplat till en grundvattenkälla. Systemet tillförde uppvärmning och kylning till tv˚a kontorsbyggnader. Systemet har varit i drift sedan 2016 och i samband med installation s˚a sattes sensorer upp f¨or att kontrollera systemet. Dessa sensorer ¨ar kopplade till bygnadernas BMS, som är utvecklat av Siemens. I början av 2019 anlitades företaget ClimaCheck för att installera ytterligare ett mätsystem, så att värmepumparnas prestanda kunde analyseras. Denna studie utfördes endast på värmepumparna som bara utgjorde en liten del av hela systemet. Till en början fokuserade studien på analys och databehandling av all data, både på datan från Siemens och ClimaCheck. Med hjålp av den uppmätta ClimaCheck-datan verifierades sedan ClimaChecks metod, genom att implementera ClimaChecks beräkningar i python. Detta gjordes primärt för att både kunna verifiera och sedan kunna implementera en möjlig förbättring i massflödet som ClimaCheck använder i sin modell. Sedan gjordes flera regressionsmodeller med BMS variabler, där targetvariablen sattes till antingen ClimaChecks beräknade värmeeffekt eller kyleffekt, beroende på vilken av dem som analyserades. Anledningen till detta var att BMS-datan inte innehåller de mätpunkter som krävs för att teoretiskt bestämma kapaciteterna. När det nya mass flödet introducerades blev resultatet inte önskvärt och den nya modellen var bara tillämpbar då värmepumparna gick på max effekt. När ClimaChecks beräkningar och parametrar återskapades hittades intressanta resultat angående värmekapaciteten. Den gick inte att återskapa med deras enthalpiberäkningar, utan den hittades istället med en annan metod. Regressionen som gjordes gav goda resultat om man bortser från vissa antaganden som gjorts. Regressionen kunde beroende på vilken parameter som efterfrågades ha en noggrannhet på upp till 95%. Studien visar att ClimaCheck har en bra och fungerande modell men den kan förbättras. Den tar även upp hur viktigt det är med data för att ordentligt och effektivt kunna utvärdera system. Slutligen kommer studien åskådliggöra en god metodik för hur data kan hanteras och tillämpas. Systemutvärdering är av yttersta vikt för att reducera energikostnader och många system skulle behöva utvärderas.
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Headley, F. Anthony Jr. "Performance limitations of an ejector heat pump." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/20290.
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Engin, Ertan. "Design, Construction And Performance Evaluation Of A Submersible Pump With Numerical Experimentation." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/12606532/index.pdf.
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Due to the increasing demand, nonclog type sewage pumps are designed and manufactured in large amounts all over the world. However, a methodology on the design of these special duty pumps is not encountered in the literature. Therefore, the manufacturers tend to develop their own empirical methodologies.
In this thesis, a nonclog pump is designed and constructed on the basis of suitable approaches of known centrifugal pump design methods. In this frame, a nonclog type submersible pump that is capable of handling solids, up to a diameter of 80 mm is aimed to be designed. The designed pump delivers 100 l/s flow rate against a head of 24 m. The rotational speed of the pump is 1000 rpm. Design procedure and the important points that differ nonclog pump design from standard centrifugal pump designs are given.
In addition, hydraulic characteristics of two nonclog pumps, one of which is the pump designed in this study, are investigated by means of computational fluid dynamics (CFD) code.
The designed pump is manufactured and tested in Layne Bowler Pump Company Inc. The test result indicates that design point is reached with a deviation in the limits of the related standard. Wire to water total best efficiency obtained by the test is 60%.
Close agreement between results of actual test and numerical experimentation performed by CFD code shows that CFD analysis is a quite useful tool in predicting the hydraulic characteristics of nonclog pumps.
Moreover, the pump is tested at 750 rpm and the test results are found to be in good agreement with the similitude anaysis results.
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Wong, Yuen-wah, and 黃婉華. "Performance prediction model for a solar water pump." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31223722.
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Walmsley, Nigel. "The numerical representation of pump-turbine performance characteristics." Thesis, University of Warwick, 1986. http://wrap.warwick.ac.uk/36663/.
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This thesis investigates the hydraulic transient analysis of hydro-power plants with particular emphasis being placed on the turbine and pump-turbine boundary conditions. A lack of suitable data, in the form of the machine performance characteristics, during the early stages of a hydro-power station's development led to the investigation of alternative sources of performance characteristics, not based on the testing of a hydraulically similar model turbine. Two methods of obtaining turbine performance characteristics were developed, one based on the published performance characteristics of typical reaction turbines and the second based on performance characteristics from a turbine of similar specific speed. The problems particular to the unit parameter representation of four quadrant reversible pump-turbine performance characteristics for use in hydraulic transient analyses were investigated. A review of alternative forms of representation led to the solution of the pump-turbine boundary based on a modified unit parameter representation. The method reduces the multi-variable problem of the pump-turbine boundary condition to that of a single variable. The solution algorithm is equally successful for use with standard turbines. A computer program for the analysis of hydraulic transients in hydro-power plants was developed and comparisons with site recordings, taken during a full load rejection at a typical pumped storage scheme, made in order to verify the operation of the computer program. Further simulations demonstrate the combined boundary condition of turbine and relief valve.
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Wong, Yuen-wah. "Performance prediction model for a solar water pump /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21607424.
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Homer, C. J. "The modelling of pump performance in two-phase flow." Thesis, Open University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377706.
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This work firstly reviews the experimental data for centrifugal pumps operating in steady-state and transient two-phase flow. The pump head and torque become degraded in two-phase pumping operation. This degradation becomes increasingly severe and abrupt as pump specific speed falls, and is chiefly due to the reduced impeller performance. Degradation depends primarily on specific speed and pump geometry, void fraction and flow coefficient. Degradation also depends on flow regime, fluid viscosity, flow rate and system pressure. The evidence suggests that transient pump performance can be accurately predicted by steady-state tests.A pseudo-two-dimensional analysis is then presented of two-phase flow through a centrifugal pump to predict the head and torque performance over the full range of operating conditions. The loss of performance in the impeller in pumping operation is caused by the large slip that develops between the two phases as the gas slows dramatically compared to the liquid, particularly in stratified flow. In these conditions there is little or no pressure recovery by diffusion in the pump casing, with further energy losses at the impeller exit due to flow impact against the casing.The head and torque performance predicted by the model compared favourably with the results from the single-phase and two-phase experimental pump tests. The comparisons cover all 4 quadrants of pump operation over the whole voidage range for a comprehensive range of pump designs and fluid mixtures. A number of recommendations are made to improve two-phase pump performance for industrial applications.
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Downham, S. E. "Modelling the two-phase performance of a centrifugal pump." Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/11005.
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A review was carried out which revealed that no simple mathematical model was available which could be used to predict the performance of a centrifugal pump when it is operating under two phase flow conditions. Experimental analyses were carried out to aid the development of such a model. A rotating channel test rig was designed to study the structure of airwater flow through an impeller passageway. The observations generated a large amount of qualitative data. A full scale centrifugal pump was also tested which provided data that allowed the results of the rotating channel experiments to be considered in more quantitative terms. These two sets of experimental work allowed a conceptual model of the two phase flow through a centrifugal pump to be constructed. The model assumes that forces act on the bubbles as they pass through the impeller passageway because of the rotation and the curvature of the impeller passageway. These forces cause the bubbles to decelerate and coalesce creating a stationary air void which leads to a partial blockage of the channel. This causes the velocity of the fluid passing through the pump to be modified. The model uses a onedimensional velocity vector approach adjusted for hydraulic losses to calculate the head raised by the pump under such conditions. The model presented provides the basis upon which a predictive tool could be developed and used in the development engineering environment. Currently operational problems that arise because of two phase flow are often quantified using scaled hydraulic models, which are expensive, or within the actual application where costly engineering solutions may be required to give acceptable performance. A mathematical model is a much more cost effective tool and its application allows the engineer to decide whether system performance would be compromised by the two phase conditions encountered and propose possible solutions. In recommending the development of such a model it is necessary to consider where and how in the project cycle it should be used. A number of companies were canvassed and it was concluded that in many cases such models are used too late in the project cycle to provide maximum return. In the case of projects which include participants from a number of companies it is suggested that an inter-company team should be constructed if development models are to be widely used. This team should be used to plan and implement the use of development models efficiently and ensure that the data produced is communicated effectively and is of the maximum value to the participants.
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Semenzin, Clayton S. "Determination of Centrifugal Blood Pump Characteristics using CFD and Experimental Analysis." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/401348.
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Background
Cardiovascular diseases are the leading cause of death throughout the developed world, attributed to approximately 17.8 million deaths worldwide in 2017 with increasing prevalence due to the aging population. Cardiovascular diseases generally result in heart failure. While the best treatment option for heart failure patients is heart transplantation, there is a severe deficiency in the availability of donor hearts. Rotary Blood Pumps (RBPs) utilised as Ventricular Assist Devices (VADs) provide an alternative treatment option. These devices are small implantable pumps that support the failing heart by providing power to augment circulation. The development of RBPs generally begins with initial designs obtained using traditional pump design methods (such as that developed by Stepanoff). However, studies have shown that this approach produces RBP prototypes far from optimal in design. Traditional theory relies on design constants derived empirically for large industrial pumps and these do not scale down well when applied to the much smaller RBPs. The initial designs are therefore generally quite poor and require an iterative build-and-test approach to obtain suitable pump prototypes – a process that is expensive and time consuming. Therefore, by improving the methodology for obtaining initial designs to better reflect the final product, development time can be greatly reduced. A popular avenue for analysing the effect of design variations and to further develop early prototypes of RBPs is to employ Computational Fluid Dynamics (CFD) simulations. These numerical simulations provide detailed data regarding the flow fields within these devices. However, a range of simulation options is available, leading to a wide range of potential predictions. In an attempt to provide a benchmark case, the FDA presented a challenge in which a pump design and test conditions were defined, allowing for direct comparison amongst different simulation approaches from a number of labs/RBP developers.
The purpose of this thesis was to produce a gross design tool to provide a good starting point in RBP prototyping and a CFD simulation approach for verification that can also be used as a design refinement tool.
Methods
Formulating a design method for pumps requires the generation of empirical data. A number of pump design variables was identified as having an impact on pump performance, and a large number of experimental tests would have been needed to test the influence of each. Instead, a Design of Experiments (DOE) was utilised to streamline the process. The DOE outputs a relatively small number of tests required to fit a statistical model. Each design specified by the DOE was examined experimentally using a custom-built automated pump test platform to generate a number of performance measures. The obtained results were used to formulate a Response Surface Method (RSM) statistical model that showed acceptable fit to the input data. Coupled with desirability functions, the RSM model allowed for design optimisation. This tool essentially replaces Stepanoff’s traditional design methodology. The RSM model provides a robust tool that allows the user flexibility in design optimisation goals.
The FDA pump was investigated in this thesis and a wide variety of simulation approaches was examined to determine which was most accurate. A range of factors were considered which included: mesh density, interface position between the rotating and stationary zones, steady vs. transient simulations, discretisation schemes, time step size and choice of turbulence model. The most appropriate option from each investigative study was selected to determine a recommended simulation approach. Final simulations were performed using these recommendations and were compared to the FDA experimental results to confirm the suitability of the suggested settings.
Determination of Centrifugal Blood Pump Characteristics using CFD and Experimental Analysis iii
The statistical model developed was used to design two different impellers as validation test cases. The first impeller was designed to optimise the maximum efficiency, P – Q curve slope and efficiency consistency. The second impeller was designed to mimic the approach used in traditional design methods for RBPs in setting a target design point as the primary objective and the aforementioned factors (from the first impeller) as secondary objectives. These two case studies underwent statistical performance predictions, CFD simulations, PIV analysis and experimental hydraulic testing to validate the statistical and CFD models.
Results
From the initial CFD study, a hybrid SBES turbulence model with full transient simulation on a fine grid with small time steps proved to be the most suitable both in terms of pressure rise generated by the FDA pump and resulting velocity fields when compared to published experimental results. From these findings the CFD modelling strategy was established. CFD results for the two validation pumps showed pressure rises matching the experimental data (8% and 1% difference for each impeller) within an acceptable range (<10% from the mean). The simulated velocity fields also closely replicated the PIV data for the majority of the flow domain.
The statistical performance predictions well reflected those measured experimentally with the majority of data points falling within its confidence intervals. The hydraulic results also supported the main goal of this thesis, whereby an impeller generated using the statistical model, operated far closer to the target design point than that of a blood pump designed following Stepanoff’s methodology. Overall, both the statistical model and CFD approach provided accurate predictions and the purpose of the thesis was achieved.
Final Remarks
The statistical and CFD models developed in this thesis yield an effective design tool and verification methodology and show improvement over the current traditional design methods and accuracy in simulated results. Ultimately, the utilisation of these tools will lead to a reduction in the development time for new RBPs and provide a good understanding of the flow dynamics within these pumps, leading to improved pump designs reaching patients sooner. These tools are readily generalizable and could be adopted as design tools now.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>School of Eng & Built Env<br>Science, Environment, Engineering and Technology<br>Full Text
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Weimer, Richard George Jr. "Centrifugal pump performance prediction using quasi-three-dimensional flow analysis." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/17693.
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Aknouche, Sebastien 1979. "Impact of tip clearance flow on centrifugal pump impeller performance." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/82254.
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Kouhestani, Mohammad Salehi. "Experimental investigation on a rotary compressor-expander heat pump performance." Thesis, Ulster University, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.698802.
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This research investigates the performance and impacts of integration of an internal expander within a typical heat pump system for the UK climate. In this novel system, the expansion process takes place within an expander rather than a traditional expansion valve, and it is expected that recovered work by the expander could provide a portion of the required power to drive the compressor. This project comprises a literature review, test rig design and fabrication, control system design instrument selection and calibration, data-logging system setup and installation, implementation of the BS standard for heat pumps performance testing, implementation of tests, and data collection according to relevant standards and data analysis. A test rig is developed and improved throughout this research. More than 20 sets of tests have been carried out between 2011 and 2014, and the most appropriate of them are presented and discussed. To determine the impact of expander integration, the rotary compressor-expander unit was tested with and without an expander, and the system COP, capacity, and isentropic efficiency are discussed. This thesis commences by introducing key drivers of this research, the energy crisis, global warming issues, and the contribution of the domestic sector to energy consumption in the UK. Then it continues by classifying heat pumps according to their energy sources. A detailed review and evaluation of major advanced heat pumps and refrigeration technologies then follows. Test rig design and development (according to the BS EN14511-2:2011) are discussed and outlined comprehensively. The test scenarios are presented, obtained data are discussed, test outcomes are evaluated, and the issues and their causes are addressed in detail. To address the issues and interpret the achieved results, theoretical analysis is carried out as well, then actual outcomes are compared with theoretical anticipated results and the differences are addressed. Results of compressor tests and system integration are presented separately and discussed comprehensively. The last chapter outlines conclusions and recommends further possible work on this research topic and offers practical suggestions to improve the performance of this developed system. However, this research reveals that such integration of an expander and compressor is not suitable in practice for typical UK winter conditions, though it may offer some benefits for extreme winter conditions where the ambient temperature drops to -10°C or below. In addition, it reveals that the designed compressor is not able to overcome a significant temperature increase (which is the case for medium-temperature heating applications and retrofit applications) due to internal refrigerant leakage.
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Davoodi, Mehdi. "High performance repair materials in hydraulic structures and machines." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285358.
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Opperman, Adriaan Jacobus. "Analysis of factors influencing the performance of a hydrokinetic coil pump." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1021041.
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A hydrokinetic coil pump (HCP) is described by its name. It is a coil pump driven by the kinetic energy in flowing water. The hydrokinetic energy is converted into mechanical energy by means of a paddle-wheel. The coil pump makes up part of the paddle-wheel and together is called a HCP. The HCP floats in a stream of flowing water while tethered to the bank. The focus of the study was to identify and analyse the factors influencing the HCP. The HCP was then optimized for rural application. Data acquisition took place through experimentation on a full scale experimental platform according to a central composite experimental design. Variables used for the experimentation included; Stream Velocity, Delivery Head, Number of Coils, Discharge, Number of Paddles, Paddle-Wheel rotational speed Overall HCP efficiencies of up to 22 percent were obtained. The efficiency would drop as the stream velocity increased. Stream velocity has been identified as the most influential factor with regards to the variables analysed by this study. The HCP is ideal for rural application. The simplicity of the design ensures reliability as well as an effective water supply solution. The HCP is ideal for slow flowing rivers and can deliver up to 1190ℓ/h to a delivery head of 5m with a stream velocity of 1.2m/s. This is sufficient to supply a small rural community with running water.
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Naicker, Selvaraj Soosaiappa. "Performance analysis of a large-scale ground source heat pump system." Thesis, De Montfort University, 2015. http://hdl.handle.net/2086/12265.
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The UK government’s Carbon Plan-2011 aims for 80% carbon emission reduction by 2050, and the 2009 UK National Renewable Energy Action Plan has set a target of delivering 15% of total energy demand by renewable energy sources by 2020. Ground Source Heat Pump (GSHP) systems can play a critical role in reaching these goals within the building sector. Achieving such benefits relies on proper design, integration, installation, commissioning, and operation of these systems. This work seeks to provide evidence to improve the practices in design, installation and operations of large GSHP systems. This evidence has been based on collection and analysis of data from an operational large-scale GSHP system providing heating and cooling to a university building. The data set is of significance in that it is collected from a large-scale system incorporating fifty-six borehole heat exchangers and four heat pumps. The data has been collected at high frequency since the start of operation and for a period of three years. The borehole heat exchanger data is intended to form a reference data set for use by other workers in model validation studies. The ground thermal properties at the site have been estimated using a novel combination of numerical model and parameter estimation methods. The utility of the reference data set has been demonstrated through application in a validation study of a numerical borehole heat exchanger model. The system heat balances and power consumption data have firstly been analysed to derive a range of performance metrics such as Seasonal Performance Factors. Analysis has been carried out at the system and individual heat pump level. Annual performance has been found satisfactory overall. A series of analyses have been carried out to investigate the roles of circulating pump energy, control system operation and dynamic behaviour. Monitoring data from one of the heat pumps has also been analysed in further detail to make comparisons with manufacturer’s steady-state performance data and with consideration to variations in fluid properties. Some modest degradation from stated performance has been identified. The most significant operational factors accounting for degradation of overall system performance have been excessive pump energy demands and short cycling behaviour. Some faults in operation of the system during the monitoring period have also been identified. A series of recommendations are made as to ways to improve the design and operation of large-scale GSHP systems based on this evidence. These recommendations are chiefly concerned with better design for part-load operation, reduction in pump energy demands and more robust control systems.
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Caglar, Ahmet. "Theoretical And Experimental Performance Analysis Of A Solar Assisted Heat Pump." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607898/index.pdf.
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In this thesis, performance of a heat pump aided by solar heating system with an evacuated tubular collector has been analyzed theoretically and experimentally. For this purpose, a domestic hot water heating system has been designed, constructed and tested. The evacuated tubular solar collector has been used to achieve higher collector efficiency in winter. The fraction of the solar energy utilized has been measured experimentally and estimated theoretically. Effects of various parameters have been investigated on the performance of the proposed system.
A mathematical model was developed to investigate the effects of different environmental, design and operational parameters on the solar heating system. In order to compare the obtained theoretical results with experimental ones, an experimental study has been carried out. For that, a number of experiments have been made at the solar house of the Mechanical Engineering Department of METU. An air-to-air heat pump was integrated with an evacuated tubular solar water heater unit (closed water circulation) and the performance of it has been studied experimentally. As a result of the experimental study, the maximum value of the coefficient of performance of the solar assisted heat pump used in this study was obtained as 4.85. The second law efficiency of the system was between 4.8-27.4 %.
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Gokce, Gokay. "Performance Evaluation And Cfd Analysis Of A Positive Displacement Diaphragm Pump." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613799/index.pdf.
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In order to understand flow characteristics inside a positive displacement pump, every point in the flow field must be carefully observed. Such observations are difficult, expensive and usually time consuming to achieve with physical testing. During tests one can observe flow characteristics only at the locations where the instrument device is attached, not the whole flow domain.
This thesis mainly focuses on the evaluation of design and performance characteristics of a positive displacement triplex diaphragm pump. For this purpose not only numerical investigations but also experimental studies were conducted
using a positive displacement pump which is supplied by the pump manufacturer and is available in the fluid mechanics laboratory of Middle East Technical University.
The effect of valve characteristics on the pump efficiency such as valve spring stiffness, valve displacement, mass of the check valves, and diaphragm shape are investigated in this thesis by using CFD (Computational Fluid Dynamics) technique. The pump performance is analyzed in terms of its volumetric and hydraulic efficiencies. The effect of the valve closure delay is also discussed.
After the CFD and experimental results of the current pump model are compared and it is seen that they are in close agreement with each other, parametric studies are performed in computer environment. From analysis results it is observed that
using stiffer springs reduces valve closing time and tend to decrease flow reversal effects. Secondly, using heavier check valves increases valve closing and opening times and also increases the stresses on the components of the pump with the
increased pressure drop through discharge valve. As a result of this condition, hydraulic and volumetric efficiency reduce. Thirdly, with the longer valve displacement arrangement, more time is required for opening and closing of the check valves therefore efficiency of the pump reduces.
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Kabamba, Batthe Matanda. "Evaluation of centrifugal pump performance derating procedures for non-Newtonian slurries." Thesis, Cape Peninsula University of Technology, 2006. http://hdl.handle.net/20.500.11838/2170.
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Thesis (MTech(Civil Engineering))--Cape Peninsula University of Technology, 2006.<br>The performance of a centrifugal pump is altered for slurry or viscous materials (Stepanoff,
1969) and this needs to be accounted for. Usually, the suitable selection and evaluation of
centrifugal pumps is based only on water pump performance curves supplied by the pump
manufacturer (Wilson, Addie, Sellgren & Clift, 1997). In 1984 Walker and Goulas
conducted a number of pump performance tests with kaolin clay slurries and coal slurries on
a Warman 4/3 AH horizontal slurry pump and a Hazleton 3-inch B CTL horizontal pump
(Walker and Goulas, 1984).
Walker and Goulas have analysed the test data and correlated the performance derating both
at the best efficiency flow rate (BEP) and at 10% of the best efficiency flow rate (0.1 BEP)
to the modified pump Reynolds number (NRep). They have noticed that the head and the
efficiency reduction ratio decreased for the pump Reynolds number less then 10⁶.
Furthermore, Walker and Goulas obtained a reasonably good agreement (± 5%) between
pump test data for non-Newtonian materials and pump performance prediction using the
Hydraulics Institute chart. Sery and Slatter (2002) have investigated pump deration for non-Newtonian yield pseudoplastic materials. The NRep was calculated using the Bingham
plastic viscosity (µp). Results have shown good agreement with regard to head and efficiency
reduction ratios in comparison with previous work. However, Sery and Slatter's pump
performance correlation using the HI chart did not reach the same conclusion. Error margin
of ± 20% and ± 10% were found for head and efficiency respectively. This study is an attempt to reconcile the differences between Walker and Goulas (1984) and
Sery and Slatter (2002) and extend the evaluation of these derating methods to pseudoplastic
materials. The test work was conducted in the Flow Process Research Centre laboratory of
the Cape Peninsula University of Technology using two centrifugal pumps; a Warman 6/4
and a GrW 4/3. The materials used were water, CMC solution bentonite and kaolin
suspension at different concentrations (7% and 9% by weight for bentonite; 5%, 6% and 7%
by weight for CMC; 17%, 19% and 21% by volume for kaolin).
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BÖRJESSON, MARCUS. "Performance evaluation of ground source heat pump heating systems in Stockholm." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286000.
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GSHP systems are common in Sweden but there are few evaluations quantifying the performance of the systems and highlighting problem that occurs during operations. The research project Annex 52 Long-term performance measurement of GSHP systems serving commercial, institutional and multifamily building part of IEA HPT TCP proves the need to systematically be able to evaluate GSHP systems. This thesis aims to expand the knowledge of how to evaluate GSHP systems and provide case studies for Annex 52. Three residential ground source heating systems used for heating has been evaluated and analyzed in this study. The evaluation has consisted of three parts. The first part analyzes the operation and stability of the GSHP systems. The second part consist of a detailed study of the performance of the GSHP systems. The seasonal performance factor has been calculated for different system boundaries based on the work done by SEPEMO. In addition, a method on how to evaluate the efficiency of the heat pumps based on the two temperature levels, source side temperature and the heat sink temperature, that the heat pump is operating at throughout a year has been developed within this thesis. This has included a method on how to normalize the temperatures based on the operation of the heat pump in order to quantify one temperature for each the two temperature levels. The third part consist of a comparison of the mean secondary fluid temperature between the calculated temperature using the software EED and the measured temperatures. This includes a comparison evaluation and sensitivity analysis on input parameters during the design of the borehole heat exchanger fields. This study has expanded the available reference cases of GSHP systems in Sweden. It also can be used as a guideline for those who will evaluate future GSHP systems. Designers of GSHP system will also benefit from the recommendations listed in this thesis regarding instrumentation and possible problems that may occur. The results show that the evaluation successfully managed to quantify the performance and operational issues that have occurred for each system. The method developed in this study was able to quantify the operation of the different systems based on the temperature levels and can be used for future GSHP evaluations of similar system type.<br>Bergvärmesystem är vanligt förekommande i Sverige men trots detta finns det få studier där prestandan har utvärderats och de vanligt förekommande problemen under drift har belysts. Forskningsprojektet Annex 52 Annex 52 Long-term performance measurement of GSHP systems serving commercial, institutional and multi-family building som är en del av IEA HPT TCP visar på behovet av att systematisk utvärdera bergvärmesystem. Detta examensarbete syftar till att utveckla och bidra till kunskap om hur bergvärmesystem kan utvärderas och att bidra med exempelstudier till Annex 52. Inom detta examensarbete har tre bergvärmesystem som betjänar flerbostadshus utvärderats och analyserats. Utvärderingen bestod av tre analyser. I den första analyserades driften av bergvärmesystemen och hur stabilt systemet har varit historiskt. Detta följdes av en detaljerad analys av olika nyckeltal för bergvärmesystemen. Årsverkningsgraden har beräknats för olika gränsdragningar vilka baseras på det tidigare arbetet utfört av SEPEMO. Inom detta examensarbete har även en metod tagits fram för att utvärdera verkningsgraderna för en värmepump baserat på de två temperaturnivåerna, köldbärarsidan och värmebärarsidan, som värmepumpen arbetar med under ett år. Till detta har en metod tagits fram om hur temperaturen kan normaliserats baserat på driften av värmepumparna för att kvantifiera en temperatur vardera för de två temperaturnivåerna. I den tredje utvärderingen jämfördes den beräknade medelfluidtemperaturen av köldbäraren i borrhålen med den uppmätta temperaturen. Till detta utfördes en känslighetsanalys av hur indata av dessa beräkningar påverkar resultaten.
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Charoenvisal, Kongkun. "Energy Performance and Economic Evaluations of the Geothermal Heat Pump System used in the KnowledgeWorks I and II Buildings, Blacksburg, Virginia." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/33942.
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Heating, Ventilating and Air Conditioning Systems (HVAC) are not only one of the most energy consuming components in buildings but also contribute to green house gas emissions. As a result often environmental design strategies are focused on the performance of these systems. New HVAC technologies such as Geothermal Heat Pump systems have relatively high performance efficiencies when compared to typical systems and therefore could be part of whole-building performance design strategies.<P>In collaboration with the Virginia Tech Corporate Research Center, Inc., this research studies the energy consumption and cost benefits of the Geothermal Heat Pump System that has been integrated and operated in the KnowledgeWorks I and II buildings located on the Virginia Tech campus.<P>The purpose of this thesis is to understand the energy and cost benefits of the Geothermal Heat Pumps System when compared to the conventional package variable air volume (VAV) with hot water coil heating and air-source heat pump systems using computer simulation and statistical models. The quantitative methods of building energy performance and life-cycle cost analyses are applied to evaluate the results of simulation models, the in-situ monitoring data, and the associated documents. This understanding can be expanded to the higher level of architectural systems integration.<br>Master of Science
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Palleda, Siva Prakash. "Mathematical model for optimising the performance of a ground source heat pump." Thesis, Sheffield Hallam University, 2009. http://shura.shu.ac.uk/20159/.
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Energy demand for the twenty first century is expected to increase many fold along with corresponding diversification of energy sources and generation methods. Of the many energy sources available, use of Ground Source Heat Pump (GSHP) system is the focus of the analysis in this research. This work is carried out to identify the key parameters which affect the performance of the GSHP system. A mathematical model has been developed to understand the complex operation of the heat pump under typical working conditions. Individual sub-systems, such as Ground Heat Exchanger (GHE), evaporator, condenser, compressor and radiator are modelled in MathCAD and coupled together and solved simultaneously. The performance of the system is predicted while varying air temperature, power input to the compressor and the ground temperature beneath the earth's surface. In addition a special sub-model was developed for the single vertical U-tube GHE in FLUENT, a Computational Fluid Dynamics (CFD) software, to calculate the overall heat transfer coefficient for varying outer surface temperature of the borehole. The overall system results are validated against the published results with the system operating range of 18°C to 33°C with around 10 percent deviations. It is determined that the COP of the system increases with surface area and overall heat transfer coefficient (OHTC) of the heat exchanger. An increase in up to 500 m2 surface area, steep raise of COP from 10.05 to 10.3 is observed. Similarly increase of 10 W/m2K of OHTC has steep COP rise from 10.05 to 10.28. The temperature gradient across the system also has influence on its operating performance, where a 15°C increase in the ground temperature for cooling mode reduces the COP by around 5%. Finally the degree of refrigerant sub-cooling has a positive effect, for every 5°C temperature drop the COP improves by 0.5 similarly for degree of super-heating, COP improves by 0.25. Scope for performance enhancement for GSHP is investigated by tuning operating conditions. The effect of operating variables to the sensitivity of performance of heat pump is also determined.
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Tan, Honghui. "Performance Modeling and Efficiency Analysis for a Piezohydraulic Pump with Active Valves." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/36223.
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Piezoelectric actuation is an expanding field that makes use of piezoelectric materials that have high power density as actuators. These actuation systems have the potential higher power density than the traditional servo motor technology.
However, due to tiny strain of the piezoelectric materials, displacement amplification mechanism should be incorporated into design for most commercial applications. Piezohydraulic actuation provides an ideal amplification that can achieve any combination of stroke and force, which is superior than most other amplification technologies. The concept of piezohydraulic actuation takes advantage of the high force capabilities that piezoceramics have and combines it with the operation at high frequencies, in order to achieve the hydraulic actuation of a system under a specified stroke and force.
In this research, a compact piezohydraulic pump with active valves has been developed, tested and characterized. Furthermore, theoretical models are developed based on different levels of approximation of the hydraulic fluid. The first model, which assumes an incompressible and inviscid fluid, provides us views of the basic features of piezohydraulic actuation. The second model which takes into account the viscosity of the fluid and the third model which takes into account both viscosity and compressibility of the fluid are then presented. Then, their simulation results are compared with experimental data, which shows the compressibility of the fluid is important to system performance. At last, a power and efficiency analysis based on experimental results is presented.<br>Master of Science
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Excoffon, Tony. "3-D flow and performance of a tandem-bladed rocket pump inducer." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-05042010-020152/.
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Fernandez, Nicholas Edward Peter. "Performance and oil retention characteristics of a CO2 heat pump water heater." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/9008.
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Thesis (M.S.) -- University of Maryland, College Park, 2008.<br>Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Coronado, Pons Mar. "Modelling the performance of heat pump systems for single-family house applications." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-261601.
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Ground source heat pumps (GSHP) extracting the heat through borehole heat exchangers (BHEs) are an extremely efficient way to provide heating. Their performance is affected by the temperature of the thermal source: the ground; the higher it is the temperature of the ground, the higher their performance. As the demand of this heating technology increases, the amount of GSHP in densely populated areas is at risk of escalating notably. Consequently the study of thermal influence between neighbouring GSHPs is of paramount importance to properly design these systems in such areas. A comparison is made between the performance of an isolated house, and the same house as part of an area with high density of houses using identical GSHPs. The aim of the project is to study the long term consequences of exploiting the ground thermal source in an extensive manner, to analyse how the GSHP operation is affected in this specific case study, and present a methodology general enough to be implemented for different conditions. It is presented a methodology based on a parameter calibration model for the HP to analyse the performance along the years of a ground source heat pump system located in an area where there is a high density of identical installations. The model was tested to verify its accuracy when simulating the performance of the HP and was implemented for two case studies that emulate the conditions found in Sweden for residential heating. For the first case study, where a 6kW HP unit is simulated, the COP of the system decreased around 15% for the 25 studied years. In good agreement with this decline of the COP, an electricity consumption increase above 10% is faced. For the second case study, a heat pump unit double the size of the one employed for the first case is modelled. In this case, the drop for the COP is 16% and the electricity consumption growth is above 20%.<br>Markvärmepumpar (GSHP) som utvinner värmen genom borrhålvärmeväxlare (BHE) är ett extremt effektivt sätt att tillhandahålla värme. Deras prestanda påverkas av temperaturen på den termiska källan: marken; ju högre det är temperaturen på marken, desto högre är deras prestanda. När efterfrågan på denna uppvärmningsteknologi ökar riskerar mängden GSHP i tätbefolkade områden att öka särskilt. Följaktligen är studien av termiskt inflytande mellan angränsande GSHP: er av yttersta vikt för att korrekt utforma dessa system i sådana områden. En jämförelse görs mellan prestanda för ett isolerat hus, och samma hus som en del av ett område med hög täthet av hus med identiska GSHP. Syftet med projektet är att studera de långsiktiga konsekvenserna av att utnyttja den termiska jordkällan på ett omfattande sätt, analysera hur GSHP-operationen påverkas i denna specifika fallstudie och presentera en metod som är tillräckligt generell för att kunna implementeras för olika förhållanden. Det presenteras en metodik baserad på en parameterkalibreringsmodell för HP för att analysera prestandan under åren för ett jordvärmepumpsystem som ligger i ett område där det finns en hög densitet av identiska installationer. Modellen testades för att verifiera dess noggrannhet vid simulering av HP: s prestanda och implementerades för två fallstudier som emulerar de förhållanden som finns i Sverige för uppvärmning av bostäder. För den första fallstudien, där en 6kW HP-enhet simuleras, minskade systemets COP cirka 15% under de 25 studerade åren. I god överensstämmelse med denna nedgång i COP står en ökad elförbrukning över 10% inför. För den andra fallstudien modelleras en värmepumpsenhet som är dubbelt så stor som den som används för det första fallet. I detta fall är fallet för COP 16% och elförbrukningstillväxten över 20%.
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Gleeson, C. P. "Understanding the field performance of domestic heat pumps : an analysis of recent residential heat pump field trials and training needs." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1431425/.
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This thesis explores heat pump performance. Renewable technology, based on ambient conditions, is at a distinct thermodynamic disadvantage when compared with such technologies as gas condensing boilers since the temperature gradients in which they work are so much smaller. This disadvantage makes renewable technologies, and specifically heat pumps, sensitive to design and installation practice. A mixed methods approach of quantitative and qualitative investigation is applied, principally through the analysis of heat pump field trial performance; a meta-analysis of eight European field trials of over 600 heat pump installations in terms of historical and contemporary system boundaries, and a taxonomical analysis of the UK Energy Saving Trust field trial. The trials are placed in context through the analysis of UK central heating practice, UK and EU policy, thermodynamics, manufacturers’ test regimes and a pilot field trial. From this analysis it is apparent that a wide range of performance is exhibited by residential heat pump installations. This potential to underperform, or ‘sensitivity to context’, is explored through its plausible link to vocational education and training (VET). The process of re-aligning EU VET for heat pumps is underway, driven in the UK by the Microgeneration Scheme’s design literature and training requirements. However, doubts remain as to the abilities of current UK contractors to synthesise the technical design requirements given the relatively low educational demands made on residential heating occupations when compared with EUCERT heat pump requirements, more closely aligned with the Continental concept of savoir-faire, 'know-how' or berufliche Handlungsfähigkeit, a multidimensional 'occupational capacity'.
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Ozdemir, Sahika. "Design Considerations And Performance Evaluation Of A Surge Tank For Diaphragm Pump Operation." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612662/index.pdf.
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This thesis is performed to evaluate the design consideration and performance characteristics of a surge tank for a diaphragm pump operation and to evaluate the proper volume and inlet area of surge tank in order to reduce the pulsations of the discharge pressure.
An experimental set up is constructed for a three diaphragm positive displacement pump and the experiments are conducted afterwards. The surge tanks having different volumes and the surge tank inlet area configurations are tested in order to achieve the minimum peak to peak pulsations.
Experiments showed that among the different sizes of the surge tanks, the minimum peak to peak pulsations are achieved with the largest volume which is the original surge tank of the test pump used by the pump manufacturer. This result is supported by the literature which states that with greater surge tank size the magnitude of pulsations can be diminished more.
Regarding the surge tank inlet area design<br>among the eight different adaptors a proper inlet area value is concluded having the minimum peak to peak pulsations also smaller than the original configuration.
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Yildiz, Mehmet. "Design And Performance Analysis Of A Pump-turbine System Using Computational Fluid Dynamics." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613761/index.pdf.
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In this thesis, a parametric methodology is investigated to design a Pump-Turbine system using Computational Fluid Dynamics ( CFD ). The parts of Pump-Turbine are created parametrically according to the experience curves and theoretical design methods. Then, these parts are modified to obtain 500 kW turbine working as a pump with 28.15 meters head. The final design of Pump-Turbine parts are obtained by adjusting parameters according to the results of the CFD simulations. The designed parts of the Pump-Turbine are spiral case, stay vanes, guide vanes, runner and draft tube. These parts are designed to obtain not only turbine mode properties but also pump mode properties.
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Cordova, Cordova. "Investigation of new heat exchanger design performance for solar thermal chemical heat pump." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-127039.
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The emergence of Thermally Driven Cooling system has received more attention recently due to its ability to utilize low grade heat from engine, incinerator or simple flat plate solar collector which are considered as renewable energy sources. ClimateWell AB located in Stockholm has been developing this cooling system based on its patented chemical heat pump technology. The heat pump with its tube shape is put under the absorber as in simple flat plate solar collector making it possible be directly attached on the roof without any additional solar collector. A high performance heat exchanger is needed by its reactor to absorb the energy efficiently during the desorption process as well as to recover heat during the absorption process. Current heat exchanger design has direct contact with the tube’s surface, yet air gaps between the tube and heat exchanger result in alower amount of heat transferred and non-uniform heat distribution across this surface. Moreover, a special treatment which cannot be done by machinery has to be performed in attaching the tube with this heat exchanger. It becomes a problem during mass production since a lot of man power is needed. A new heat exchanger design was proposed to overcome those limitations. This design has annulus which is filled with thermal fluid inside. This fluid will make perfect contact to the heat pump tube’s surface and eliminate the air gap. Furthermore, the need of man power in its production can be minimized. Even though perfect contact can be achieved, the fluid in this new design will increase thermal resistance in the radial direction. Therefore, an investigation has to be conducted to evaluate the performance of this new heat exchanger design based on heat transfer coefficient under steady state condition. The performance investigation also included the influence of various thermal fluids which will be used for this new heat exchanger. The work performed by doing simulation in COMSOL continued with validation of the result with experiment in laboratory. New heat exchanger design efficiency was only 50% while the current one was 82% during the desorption process. In this process, the fluid’s thermal conductivity was the most influencing fluid property. During absorption process, two heat recovery methods are used. First is by flowing the fluid inside the annulus and second is by using additional heat recovery pipe that is attached outside the heat exchanger surface. The first method gave the highest UA value around 34 W/K while the second one gave almost the same value as the current design which is around 11 W/K. In the first method, the thermal fluid’s viscosity strongly influenced its UA value while the second method is greatly influenced by fluid’s heat conductivity.
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Fratarcangeli, Catherine Eileen. "A study of fuel pump performance testing and its implications on product acceptability." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37737.
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Carter, Casey Joseph. "Aerodynamic Performance of a Flow Controlled Compressor Stator Using an Imbedded Ejector Pump." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/31297.
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A high-turning compressor stator with a unique flow control design was developed and tested. Both boundary layer suction and trailing edge blowing developed from a single supplied motive pressure source are employed on the stator. Massflow removed through boundary layer suction is added to the motive massflow, and the resulting combined flow is used for trailing edge blowing to reduce the total pressure deficit generated by the stator wake. The effectiveness of the flow control design was investigated experimentally by measuring the reduction in the total pressure loss coefficient. The experiment was conducted in a linear transonic blowdown cascade wind tunnel. The inlet Mach number for all tests was 0.79, with a Reynolds number based on stator chordlength of 2,000,000. A range of inlet cascade angles was tested to identify the useful range of the flow control design. The effect of different supply massflows represented as a percentage of the passage throughflow was also documented. Significant reductions in the total pressure loss coefficient were accomplished with flow control at low cascade angles. A maximum reduction of 65% in the baseline (no flow control) loss coefficient was achieved by using a motive massflow of 1.6% of the passage throughflow, at cascade angle of 0°. The corresponding suction and blowing massflow ratio was approximately 1:3.6. Cascade angle results near 0° showed significant reductions in the loss coefficient, while increases in the cascade angle diminished the effects of flow control. Considerable suction side separation and the presence of a leading edge shock are noticeable as the cascade angle is increased, and contribute to the losses across the stator surface. Also identified was the estimated increase in wake turning due to flow control of up to 4.5°.<br>Master of Science
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Wang, Xudong. "Performance investigation of two-stage heat pump system with vapor-injected scroll compressor." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/7863.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.<br>Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Dongellini, Matteo <1988>. "Dynamic Modeling and Seasonal Performance Evaluation of Air-to-Water Heat Pump Systems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/7901/1/Dynamic%20modeling%20and%20seasonal%20performance%20evaluation%20of%20air-to-water%20heat%20pump%20systems.pdf.
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In this Thesis a series of numerical models for the evaluation of the seasonal performance of reversible air-to-water heat pump systems coupled to residential and non-residential buildings are presented. The exploitation of the energy saving potential linked to the adoption of heat pumps is a hard task for designers due to the influence on their energy performance of several factors, like the external climate variability, the heat pump modulation capacity, the system control strategy and the hydronic loop configuration. The aim of this work is to study in detail all these aspects.
In the first part of this Thesis a series of models which use a temperature class approach for the prediction of the seasonal performance of reversible air source heat pumps are shown. An innovative methodology for the calculation of the seasonal performance of an air-to-water heat pump has been proposed as an extension of the procedure reported by the European standard EN 14825. This methodology can be applied not only to air-to-water single-stage heat pumps (On-off HPs) but also to multi-stage (MSHPs) and inverter-driven units (IDHPs).
In the second part, dynamic simulation has been used with the aim to optimize the control systems of the heat pump and of the HVAC plant. A series of dynamic models, developed by means of TRNSYS, are presented to study the behavior of On-off HPs, MSHPs and IDHPs. The main goal of these dynamic simulations is to show the influence of the heat pump control strategies and of the lay-out of the hydronic loop used to couple the heat pump to the emitters on the seasonal performance of the system. A particular focus is given to the modeling of the energy losses linked to on-off cycling.<br>Questa Tesi presenta una serie di modelli numerici sviluppati per la valutazione delle prestazioni stagionali di sistemi basati su pompe di calore reversibili di tipo aria-acqua accoppiate a edifici residenziali e non residenziali.
Lo sfruttamento del potenziale risparmio energetico legato all'adozione di pompe di calore èun compito difficile per i progettisti, in quanto diversi fattori come la variabilità delle condizioni climatiche esterne, la capacità delle pompe di calore di modulare la potenza termica/frigorifera erogata, la logica di controllo del sistema e la configurazione impiantistica utilizzata influiscono sulle prestazioni energetiche ottenibili. Lo scopo di questo lavoro è quello di studiare in dettaglio tutti questi aspetti.
Nella prima parte della Tesi viene presentata una serie di modelli basati su un approccio di tipo "temperature class" per la previsione delle prestazioni stagionali di una pompa di calore reversibile aria-acqua. Viene proposta un'innovativa procedura di calcolo per la determinazione dell'efficienza stagionale della pompa di calore costruita come un'estensione della metodologia riportata dalla norma europea EN 14825. Tale procedura può essere applicata non solo per lo studio di pompe di calore mono-compressore (On-off HPs), ma anche di pompe di calore multi-compressore (MSHPs) ed a velocità variabile (IDHPs).
Nella seconda parte della Tesi la simulazione dinamica è stata utilizzata allo scopo di ottimizzare il sistema di controllo della pompa di calore e dell’impianto. I modelli dinamici sono stati realizzati utilizzando il software TRNSYS e permettono di simulare il comportamento dinamico di On-off HPs, MSHPs e IDHPs. Lo scopo principale dei modelli dinamici presentati è quello di evidenziare l'influenza dei sistemi di regolazione della pompa di calore e della configurazione del circuito idronico utilizzato per accoppiare la pompa di calore ai terminali sulle prestazioni stagionali dell'impianto. Particolare attenzione è stata rivolta alla modellazione delle perdite energetiche legate ai cicli di on-off della pompa di calore.
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Poppi, Stefano. "Solar heat pump systems for heating applications : Analysis of system performance and possible solutions for improving system performance." Doctoral thesis, KTH, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214552.
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Solar heat pump systems (SHPs) are systems that combine solar energy and heat pumps. SHPs have been investigated for several decades and have been proven to increase the share of renewable energy and reduce electric energy demand in residential heating applications. Many solar thermal heat pump systems have become market-available in recent years; however these systems are still not widely employed in the residential sector. This is due mainly to the high initial costs (investment and installation costs) of solar thermal heat pump systems, which limits their cost-effectiveness. Enhancing cost-effectiveness of solar thermal heat pump systems is necessary for a more effective and broader market penetration. In this thesis, solar thermal and photovoltaic systems combined with heat pumps for heating applications are treated. The overall aims of the thesis are to: 1) investigate techno-economics of SHPs and 2) investigate possible solutions for improving system performance of a reference solar thermal and heat pump system for residential heating applications. In the first part of the thesis, the influence of climatic boundary conditions on economic performance of SHPs has been investigated by means of: a) an economic comparison of SHPs found in the relevant literature and b) system simulations of the reference solar thermal heat pump system. In the second part of the thesis, potential solutions for improving system performance of the reference solar thermal heat pump system with limited change in system’ costs are investigated. A systematic approach was used for investigating cost-effectiveness of the system improvements in the reference system. Based on results of the cost-effectiveness analysis, some of the investigated system improvements were chosen for being included in the design of a novel solar thermal and air source heat pump system concept. The novel system was designed for a house standard with relatively high operating temperatures (55°C/45°C) in the space heating distribution system and for high space heating demand (123 kWh/m2·year). Finally, the thesis ends with a cost-effectiveness analysis of the novel system.<br><p>QC 20170918</p><br>MacSheep<br>iNSPiRe
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Meng, Xiaona. "The performance implications of pump laser instability due to optical reflection in an EDFA." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0014/MQ31232.pdf.
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Pursch, Lindsay Jane. "The short-term effects of off-pump cardiopulmonary bypass graft surgery on cognitive performance." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/10772.
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Includes bibliographical references (leaves 56-67).<br>Postoperative neurocognitive impairment has been associated with coronary artery bypass graft surgery (CABG). This study investigates the short-term effects of off-pump cardiopulmonary bypass graft surgery (OPCAB) on cognitive performance, as a possible safer alternative in the treatment of coronary artery disease. This research forms part of a larger study in which, in addition to the OPCAB procedure, the cognitive effects of CABG surgery and percutaneous transluminal coronary angioplasty with intra-coronary stenting are assessed. 36 participants undergoing OPCAB surgery were included in the study, with a further 36 participants included as an age- and education- matched non-surgical control group. A standardized battery of neuropsychological tests, designed to assess seven cognitive domains, was administered on two occasions, preoperatively at 1-2 days prior to surgery, and postoperatively at 1 month after surgery, with control participant assessments at the same intervals. Emotional state scales assessing depression and anxiety levels were administered at each assessment. Data analysis included a two-way mixed analysis of variance conducted on each measure of cognitive function, and on the indicators of emotional state. In addition, standard multiple regression was conducted to assess whether change in emotional state is able to predict change in any of the cognitive domains. Results indicated no evidence of short-term cognitive decline, and highlighted an improvement in cognitive performance in both surgical and control groups in the domain of language, psychomotor speed, executive function and visual memory, with the control group demonstrating a consistently superior performance. This counter-intuitive finding could not be attributed to practice effects.
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Spetsotaki, Konstantina [Verfasser], Rüdiger [Akademischer Betreuer] Autschbach, and Thomas [Akademischer Betreuer] Breuer. "Evaluation of left ventricular myocardial wrk performance in patients undergoing on-pump and off-pump coronary artery bypass surgery / Konstantina Spetsotaki ; Rüdiger Autschbach, Thomas Breuer." Aachen : Universitätsbibliothek der RWTH Aachen, 2021. http://d-nb.info/1240615671/34.
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MARTORANA, Francesca. "INNOVATIVE PHOTOVOLTAIC-THERMAL HEAT PUMP SOLUTIONS FOR DOMESTIC HOT WATER PRODUCTION." Doctoral thesis, Università degli Studi di Palermo, 2022. http://hdl.handle.net/10447/533576.
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With the rapid growth of energy consumption in the building sector and the consequent necessity to develop energy efficiency strategies, the application of heat pump systems seems to be a competitive solution to improve energy efficiency. In particular, air-source heat pump (ASHP) systems assisted by solar energy have drawn great attention, owing to their great feasibility in buildings for space heating/cooling and hot ater
production purposes. The complementation system between solar and air energy can solve the poor performance of the air source heat pump under low-temperature conditions and can also make up for the shortcoming of the solar collector as an unstable energy source. Both solar energy technologies and air source heat pumps (ASHP) are widely used renewable energy sources at the moment. The former has the advantages of low utilization cost, simple technology, easy access, and no pollution, while the latter has the advantages of high efficiency,
energy-saving, and good environmental benefits. Among emerging technologies coupled to heat pump systems, PV/T hybrid solar collectors are estimated to have a high potential and a fast-growing market. The PV performance of PV/T collectors increases slightly compared with a panel with PV cells since the operating temperatures of the PV cells are reduced due to the cooling effect of the heat extraction. Solar-assisted heat pump systems for DHW and space heating purposes have been studied by several researchers. Both experimental investigations and numerical studies aimed to assess the potential and performance of various system designs under different climatic boundaries. The aim of the present thesis is the investigation of the energy performance of systems based on the coupling of air to water heat pumps with PV/T hybrid solar collectors for producing domestic hot water (DHW). The gains from using these two currently promising technologies and the benefits of
their integration are investigated by analising different configurations of these integrated systems. Comparisons with more traditional technologies were performed both in terms of thermal and electrical power production and energy savings. In particular, investigations were performed in order to identify the optimal number of modules that make up the solar plant and the most performing technology with the purpose of this thesis among PV, PV/T, and ST collectors. Furthermore, two different integration configurations were analysed depending on the different functions of the thermal contribution of the PV/T string within the entire system. The simulations were performed both for the context of the mainland, considering the climate of Palermo (Italy), both for the context of the minor Mediterranean islands, with particular reference to Lampedusa (Italy). For the latter case, in particular, the impact of the substitution of existing fuel-based technologies with heat pump systems eventually coupled to a photovoltaic (PV), solar thermal plant (ST), and hybrid photovoltaic-thermal (PV/T) systems was analysed.
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Oelofse, Stephanus Phillipus. "An investigation into the performance of a Rankine-heat pump combined cycle / Stephanus Phillipus Oelofse." Thesis, North-West University, 2012. http://hdl.handle.net/10394/9185.
Full textAbstract:
The global growth in electricity consumption and the shortcomings of renewable electricity generation technologies are some of the reasons why it is still relevant to evaluate the performance of power conversion technologies that are used in fossil fuel power stations.
The power conversion technology that is widely used in fossil fuel power stations is the Rankine cycle. The goal of this study was to determine if the efficiency of a typical Rankine cycle can be improved by adding a heat pump as a bottoming cycle. Three simulation models were developed to perform this evaluation.
The first is a simulation model of a Rankine cycle. A quite detailed Rankine cycle configuration was evaluated. The simulation model was used to determine the heating requirements of the heat pump cycle as well as its operating temperature ranges. The efficiency of this Rankine cycle was calculated as 43.05 %.
A basic vapour compression cycle configuration was selected as the heat pump of the combined cycle. A simulation model of the vapour compression cycle and the interfaces with the Rankine cycle was developed as the second simulation model.
Working fluids that are typically used in vapour compression cycles cannot be used for this application, due to temperature limitations. The vapour compression cycle’s simulation model was therefore also used to calculate the coefficient of performance (COP) for various working fluids in order to select a suitable working fluid. The best cycle COP (3.015 heating) was obtained with ethanol as working fluid.
These simulation models were combined to form the simulation model of the Rankine-heat pump combined cycle. This model was used to evaluate the performance of the combined cycle for two different compressor power sources.
This study showed that the concept of using steam turbine or electrical power to drive a compressor driven vapour compression cycle in the configuration proposed here does not improve the overall efficiency of the cycle.
The reasons for this were discovered and warrant future investigation.<br>Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013.
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Rodrigues, Arnaldo. "Computational investigation of flow regimes and performance characteristics of a pump operating as a turbine." Thesis, Nottingham Trent University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442089.
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Hincapie, Paula Andrea Ruiz. "Performance characteristics of centrifugal pump impeller for heart failure therapy : numerical and in-vitro approach." Thesis, Queen Mary, University of London, 2016. http://qmro.qmul.ac.uk/xmlui/handle/123456789/23884.
Full textAbstract:
Heart failure (HF) is a common cause of hospitalisation and mortality across industrialised countries. The number of hospitalisations and deaths attributed to heart failure is increasing, and this trend is predicted to continue. Numerical and in-vitro simulations of the human cardiovascular system constitute the basic tools for enhancing diagnostic and therapeutic technologies for HF and this would in turn, have significant effects on morbidity,mortality, and healthcare expenditure. Mechanical Circulatory Support (MCS) as a destination therapy for HF is rising significantly as it provides a cost-effective alternative to long-term treatment and cardiac transplantation. However, long-term versatility is far from ideal and incidence of transient and permanent neurological events is still high. To this end, evolution of MCS devices calls for more sophisticated design and evaluation methods. The purpose of this work is to develop a numerical model and to implemented a novel in-vitro model of the cardiovascular system with the intention of evaluating the performance characteristics of a purposely selected centrifugal pump impeller for the treatment of both Class III and IV HF conditions when placed in series with the heart at two different anatomic locations: Ascending Aorta and Descending Aorta. An existing lumped-parameter model of the CV system, that included models for the heart, the pulmonary and the systemic circulatory loops by adapting a modified version of the fourth-element Windkessel model was enhanced by dividing the systemic circulation into six parallel vascular beds, and by including an autoregulatory system to control both pressures and volumes throughout the system. As part of the novelty of the present work, a volume reflex loop was included with the purpose of simulating volume overload conditions, as commonly found in HF conditions, and obtaining a more realistic analysis of volume displacement, while using a MCS device. The in-vitro model implemented in this work adopted most of the features included in the mathematical counterpart with the purpose of validating the numerical results. As a result of the combination of models and proper optimisation of the system parameters, predictions of pathophysiological trends and MCS usage are satisfactorily obtained. The models implemented in this work offer a valuable tool for the selection and performance evaluation of MCS devices for the treatment of HF conditions.
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Yu, Chung-Kai, and 游仲凱. "Design and Performance Analysis of Plunger pump." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/54201639575091944793.
Full textAbstract:
碩士<br>南開科技大學<br>車輛與機電產業研究所<br>99<br>The design and manufacturing of a piston pump is conducted in the present paper. Researches are focused on two mechanical key points used for the development of plunger pump, i.e.,(1) the contact mechanism of the driving swash-plate and the cylinder block, (2) the fine tolerance necessary for efficient operation of the reciprocating piston-cylinder assembly.
The integrated units completed in the present program are replaced with the corresponding parts of the original purchased piston pump in the performance tests. One part of this program is to design and manufacturing of a swashplate. The properly designed contact geometry of the plate is produced based on the principle of optimum lubricating and minimum contact stress with the cylinder block. The wear mechanisms are inspected during the running tests. The second part of this program is to design and manufacturing of a piston/cylinder assembly based on the design philosophy applicable for plunger pump. The completed mechanical units are assembled on the testing-piston-pump and put on an oil test apparatus for the performance and temperature measurements.
The expected problems during the developing process will be the development of the precision manufacturing technique used for piston/cylinder assembly with the fitting tolerance within a few 0.01mm, and also the taper angle of the slender plunger less than 1°. However, with high precision machines and strong machining skill, the manufacturing difficult points are solved accordingly.
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Chen, Hsueh-Hsuan, and 陳雪瑄. "Performance Analysis of Claw Type Vacuum Pump." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/99359108414712691919.
Full textAbstract:
碩士<br>國立中興大學<br>機械工程學系所<br>100<br>A new type of mechanical vacuum pump is introduced in this paper. It is composed of two conjugated rotors spinning in opposite directions. The shape of rotor looks like a claw, and it is called a claw vacuum pump.
Two ways to predict the performance of the claw type pump were implemented in this paper. The first one was air standard cycle model. The whole cycle was decomposed into 14 ideal thermodynamic processes, including isentropic compression, isentropic expansion, constant volume mixing, constant pressure separation, and constant pressure expelling.
The pressure variation and the temperature variation as well as the work required to complete the whole cycle was calculated with this model. It was found that as the pressure of vacuum chamber is reduced, the air removed by the rotor decreases, but the work to drive the rotor increases. The exhaust temperature is raised as the inlet pressure becomes lower, and as the inlet pressure is lower than 30 kPa, the exhaust temperature would be affected by the volume of exhaust port. Smaller size of exhaust port requires less work. In the limiting case of zero exhaust port volume, the work is the minimum theoretically.
In the second method, a zero dimensional model was used in this paper to analyze the performance of this vacuum pump. The whole system was decomposed into five subsystems. Each subsystem has its own values in temperature, pressure and mass. The pressure variations and the temperature variations as well as the work required to complete the whole cycle were calculated with this model. It was found that the major leakage route is from exit port to chamber. The averaged outlet temperature may reach 483K. However, inner leakage may ease the problem of high temperature flow.
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Chen, Huan-Wen, and 陳煥文. "Performance Analysis of Heat Pump Sludge Drying." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3sz63c.
Full textAbstract:
碩士<br>國立勤益科技大學<br>冷凍空調系<br>106<br>This study proposes an improved design of the existing air source heat pump for sludge drying based on the real cases in two factories in the central region of Taiwan. This study also introduces a heat recovery technology for the air circulation to improve the system's operational performance. In this study, the continuous feeding process of the sludge was designed, so that the heat transfer efficiency between the sludge on the conveyor belt and the hot air sent through the condenser in the drying chamber can be enhanced. The experimental results show that the operation control of the system with smaller capacity is relatively stable during the drying process. However, due to the small system cavity, the treated sludge cannot be fed in large quantities during the drying process. In the restricted temperature and system pressure, excessive start and stop cause energy losses. In case 1, the total 12 tons capacity of sludge drying heat pump system was used, and the drying amount consumed by one degree of electricity was 1.466 kg. And in case 2, the total 500 kg capacity of sludge drying heat pump system was used, and the drying amount consumed by one degree of electricity was 0.45 kg. In case 1, the average cost per ton of treated sludge is 698.3 NTD, and the average cost per ton of treated sludge in case 2 is 1090 NTD.
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Wu, Chi-Hao, and 吳繼浩. "Design of High Performance Regulated Charge Pump Circuit." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/16165785946692108906.
Full textAbstract:
博士<br>臺灣大學<br>電子工程學研究所<br>98<br>Motivated by emerging portable applications that demand ultra-low-power hardware to maximize battery run-time, and high-efficiency low-voltage DC-DC conversion is presented as a key electrical device.
Charge pump circuit has been shown to be a critical DC-DC converter for low-battery voltage technology in mobile equipments with color displays.
This thesis introduces and demonstrates an array of regulated charge pump design techniques which make the power system of display high efficiency, high performance, and compact. The primary design challenges to high-efficiency high-performance regulated charge pump are summarized. Design techniques at the power delivery system, individual control system, and circuit levels are described which help meet the stringent requirements imposed by the portable environment.
The research is focused on portable display-driving applications, where small size, low cost, and high energy efficiency and performance are the primary design objectives.
The design and measured results are reported on three regulated charge pumps which include voltage and current regulations, and successfully demonstrate the design techniques of this thesis. Description as follows:
1. High-voltage positive and negative charge pump as ± 6×VDD with voltage regulated to powering gate drivers of TFT-LCD drivers for their individual loads, can provide up to 17.5V and -14.5V in overall input voltage range of mobile equipments. Nine-phase clocks pumping is proposed to reduce one external flying capacitor for cost-efficient. Special design for the negative regulated scheme using differential difference comparator has been introduced, which increases accuracy of the negative regulated voltage, and reduces power consumption and chip area.
2. The lowest voltage-ripple design applied to a regulated voltage doubler is used to reduce the output ripple voltage for powering source drivers of TFT-LCD drivers. Multi-phase operation is proposed to minimize the output voltage-ripple, and this is with a 28 mV output voltage-ripple by up to 20mA load current. It delivers a regulated voltage from 4.5V to 5V with 1μF flying and load capacitors. Design equations and closed-form expressions for low ripple regulated charge pump are presented.
3. The high power-efficiency current-regulated charge pump is proposed to drive WLED for extension at low battery voltage and decreasing chip area.
As the result, the approach presented in this thesis is evidently viable for realizing compact and highly efficient DC-DC converters for used as low battery-voltage power systems to powering display drivers in portable electronic applications.
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Chen, Min-Yen, and 陳民彥. "Performance and fabricabation analyses of the electroosmotic pump." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/91949045163921960245.
Full textAbstract:
碩士<br>國立中央大學<br>機械工程研究所<br>93<br>We have fabricated an electroosmotic (EO) micropump and test its pressure and flowrate performance. Such no-moving part pump can be used as the transporting flow device in the microelectronic cooler. The EO pump uses the sintered-silica as the porous media and the pump overall geometry is 80×80×50 mm3. The platinum electrode provides voltage and using the borate (N2B4O7) and KCl solutions as the working fluid. Various range of concentrations (C=0.1-4 mM) and applied voltages (100-300 V) are tested to measure the performance of the EO pump.
Under the conditions of same working fluid and concentration the flowrate and pressure magnify as the applied voltage increases. For the same working fluid and apply voltage, those solutions with higher concentration result in higher flowrate and lower pressure. The borate solution performs better than the KCl solution for its relation between the flowrate and applied voltage is linear while the latter has abnormal fluctuation; moreover, its flowrate is higher. The present EO pump achieves a maximum flowrate and pressure of Qmax=19.7 ml/min and Pmax =124 kPa, respectively
The operating condition of present EO pump has high concentration and voltage which generate high current and thus prompt significant Joule heating effect. The Joule heating effect actually heats the solution inside the EO pump and even result in boiling of the KCl solution in the chamber of EO pump. The flowrate of the EO pump is enhanced by the Joule heating effect since the solution viscosity is reduced.
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Verma, Ravi. "Development of Cryocooler Based High Performance Cryosorption Pump." Thesis, 2018. https://etd.iisc.ac.in/handle/2005/5262.
Full textAbstract:
The aim of this work is to develop high performance cryosorption (or cryoadsorption) pumps specifically for fusion applications. An actual cryopump for the above application will use the supercritical liquid helium flow through the channels embedded in the large scale cryopanels. In this case, the liquid helium requirement (both as normal and as supercritical fluids) will be large, depending on the size of the cryosorption pump. However, in a research laboratory wherein such large quantities of liquid helium are not available, an alternate arrangement of cooling the cryopanels has to be considered.
One of the possible options can then be as follows. A scaled-down version of the cryopanel can be used and cooled by a two stage cryo-refrigerator system with adequate cooling power. This system is known as cryocooler based cryosorption pump. Due to the availability of a two stage GM cryocooler with a refrigeration power of ~ 1.5 W at 4.2 K in our laboratory, which can be used for the above purpose, the main objective of this work is the “development of a cryocooler based high performance cryosorption pump”.
The cryopanel which is mounted on the second stage cold head of the cryocooler is not necessarily a single panel, but is usually a set of panels (stacked one over the other) and consists of mainly three components and they are: (a) the metallic panel made of copper and cooled by the cryocooler (b) the adhesive to bind the adsorbent onto the metallic panel and (c) the adsorbent (in the present case, activated carbon (AC)) which is used to adsorb the gas molecules. By this arrangement, the adsorbent gets cooled to the lowest possible temperature to enable cryopumping.
To develop the cryocooler based high performance cryosorption pump, we need to select: (a) the best adsorbent (with large adsorption surface area) and adhere it on a cryopanel to evaluate its performance as a cryopump and (b) the best adhesive with high thermal conductivity, high bonding strength and ability to withstand several thermal cycles.
The surface area of an adsorbent in the range of temperatures range from 4.5 K to 77 K can be arrived at by a micropore analyser ( Model: ASIQ, Quantachrome, USA) integrated with a two stage GM cryocooler (Janis: SRDK415D), with helium as adsorbate gas at 4.5 K and nitrogen as adsorbate gas at 77 K. Based on the above studies, we can choose the best activated carbon with high surface area.
Next, the best adhesive which is used for binding the adsorbent onto the panel is chosen on the basis of its high thermal conductivity. The thermal conductivity of the adhesive has been measured using two dedicated thermal conductivity measurement systems namely: (a) liquid helium based Janis SuperVariTemp (SVT) cryostat and (b) two-stage GM cryocooler based experimental setup developed in our laboratory in the temperature range from 4.5 K to 300 K.
In order to make comparative studies of cryosorption of different activated carbons, a standard cryopanel, such as the one used in the commercial cryopump (Make: Varian, Model Ebara SP8) has been chosen in our studies. (Henceforth, this will be designated as “Commercial cryopanel”). In other words, the physical dimensions of all the cryopanels fabricated with indigenous activated carbons are exactly the same as that of the commercial cryopanel. By this, the experimental results of pumping speeds of different indigenous AC cryopanels can be benchmarked against the commercial cryopanel and the best performing activated carbon cryopanel can be arrived at.
In the following, we discuss the works carried out for the development of the cryocooler based high performance cryosorption pump.
a) A specially prepared indigenously developed Knitted Carbon Cloth (KCC/IIS01) is found to have a larger surface area for adsorption compared to the other adsorbents. This adsorbent has a surface area of ~ 3000 m2/g for helium adsorption at 4.5 K, which is significantly higher than those of granular charcoals which are in the range of ~ 1600 m2/g for similar experimental conditions. This AC cloth has been used for the development of our cryosorption pump.
b) A special epoxy based adhesive (SEBA/IIS01) with higher thermal conductivity, (measured using the experimental setups mentioned earlier) in the temperature range from 4.5 K to 7 K (which is generally the operating temperature range of a cryosorption pump for efficient pumping of helium gas) compared to the commercially available epoxy adhesives such as STYCAST 2850 FT and G10 Cryocomp has been developed indigenously and used.
c) Using the above Knitted Carbon Cloth KCC/IIS01 and the epoxy adhesive SEBA/IIS01, cryopanel has been prepared and studied for its performance. The pumping speeds of the developed cryopanel are improved on an average by factors of 1.55 and 1.54 when compared with those of commercial panel for gases such as hydrogen (H2) and helium (He) respectively in the specific pressure range.
To enhance the thermal conductivity of SEBA/IIS01, fine powders of metallic fillers (such as aluminium, silver etc.) can be added to the pure epoxy adhesive. However it is also essential that the epoxy-aluminium composite adhesive should withstand the thermal cycling from 4.5 K to 300 K during its functioning as a cryosorption pump.
d) Now the thermal conductivities of epoxy-aluminium composites in the temperature range from 4.5 K to 300 K has been measured using the dedicated experimental setups for measurements of thermal conductivity (developed in-house). The measurements of thermal conductivity using the above experimental setups are based on one-dimensional Fourier heat conduction with longitudinal steady state heat flow method. Detailed experimental studies on thermal conductivity of epoxy and epoxy-aluminium composites have been carried out by the above experimental setups.
e) Further the thermal conductivities of the epoxy-aluminium composites have been theoretically predicted by analytical heat conduction models. Here, the epoxy forms the base matrix and aluminium powder forms the filler. Appropriate models have been developed both for the low and high volume fractions of the filler in the epoxy base matrix. The thermal conductivity values predicted by the models match quite well with the experimentally measured values of the epoxy-aluminium composite samples. Also the developed models are able to predict the thermal conductivity values of the published data.
f) By the addition of metallic (aluminium) filler particles to the epoxy adhesive, the thermal conductivity of the epoxy adhesive is increased. However, the downside of adding aluminium fine powder is the reduction of the bonding strength of the epoxy onto the cryopanel. An experimental setup has been developed to measure the strength of epoxy- aluminium composite adhesive. Based on the experimental studies, an optimum composition of the aluminium powder filler in the epoxy adhesive has been estimated as ~ 35 % by volume fraction. This epoxy-aluminium composite adhesive is designated henceforth as “EAL35”.
g) A new cryopanel has been fabricated wherein the activated carbon cloth KCC/IIS01 is bonded using EAL35. The pumping speeds of the newly developed cryopanel are improved on an average by factors of 3.63 and 3.60 when compared with those of commercial panel for gases such as hydrogen and helium respectively in the pressure range from 5E-6 to 4E-5 mbar.
Our studies have led to the development of a cryocooler based cryosorption pump with higher pumping speeds for gases such as H2 and He compared to the commercial cryopumps. Hence the present studies will be quite useful to the development of the appropriate cryosorption pumps for the Tokamak related applications.
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Narayanan, Shankar Bhaskaran. "Fluid Dynamic and Performance Behavior of Multiphase Progressive Cavity Pumps." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-9693.
Full textAbstract:
It is common for an oil well to produce a mixture of hydrocarbons that flash when exposed to atmospheric pressure. The separation of oil and gas mixtures on site may prove expensive and lead to higher infrastructure and maintenance costs as well. A multiphase pump offers a good alternative with a lower capital cost and increased overall production.
A Progressive Cavity Pump (PCP) is a positive displacement pump type that can be used to pump a wide range of multiphase mixtures, including high viscosity fluids with entrained gas and solid particles in suspension. Despite its advantages, a PCP has a reduced ability to handle high gas-liquid ratios due to limitations of its elastomeric stator material required to overcome thermo and mechanical effects. Also the efficiency decreases significantly with increases in gas volume fractions and reduced differential pressures.
The current study focuses on studying the behavior of this unique pump in a wide range of GVFs and studying the effect of this ratio on overall efficiency, temperature and pressure distribution on the stator. The pump exhibits vibration issues at specific differential pressures and they have been studied in this work. This can be of critical value as severe vibration issues can damage the pump components such as couplings and bearings leading to high maintenance costs.
Another important issue addressed by this research is the behavior of this pump in transient conditions. Oil well production is highly unpredictable with unexpected rises and drops in GVFs. These transient conditions have been simulated by varying the GVF over wide ranges and studying the pump's behavior in terms of load, temperature rises and instantaneous pressure profiles on the pump stator.
This thesis provides a comprehensive study of this pump, its operating ranges and behavior in off-design conditions to assist oil and gas exploration ventures in making an informed choice in pump selection for their applications based on field conditions.
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Tsai, Fu-Kang, and 蔡阜剛. "Performance improvement of a four-bed adsorption heat pump." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/v7c5da.
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