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Dissertations / Theses on the topic 'Refrigeration'
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Delano, Andrew Douglas. "Analysis of the Einstein refrigeration cycle." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17887.
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Delano, Andrew D. "Design analysis of the Einstein refrigeration cycle." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17578.
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Altenhof, Jeffrey L. "Computer-aided concurrent engineering in refrigeration system design." Master's thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-01262010-020010/.
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Wilson, Kyle B. "The use of Sage simulation software in the design and testing of Sunpower's pulse tube cryocooler." Ohio : Ohio University, 2005. http://www.ohiolink.edu/etd/view.cgi?ohiou1126908659.
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Lough, Benjamin C. C. "Investigations into thermionic cooling for domestic refrigeration." School of Engineering Physics - Faculty of Engineering, 2004. http://ro.uow.edu.au/theses/230.
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Thermionic refrigeration using semiconductor heterostructures is examined theoretically and experimentally. A theory of single-barrier devices is first developed where two classes of single-barrier devices are defined and compared. So-called class 1 devices are found to always perform better. A theory of multiple-barrier devices based on class 1 barriers is then developed using a numerical solution. Experimentally, three generations of 10-barrier devices based on A1(subscript x)Ga(subscript 1-x)As-GaAs heterostructures were made and electrically characterised. This material is by no means ideal (as will be discussed) but was used to availability and because, at the commencement of this work, had never been used for this purpose before. Thermal measurements were made to determine if any cooling occurred at room temperature. No cooling was observed but the electrical characteristics allowed for examination of the models developed. It was found that the earlier models used did not accurately model the I-V characteristics of the devices. This was attributed to the fact that the initial models did not take space-charge into account. A more robust numerical model is developed in which the I-V characteristics of devices are predicted much more accurately. This model is then used to design new generations of devices. The work concludes by recommending a next generation design in which substantially more cooling is expected compared to the samples examined here. The probability of cooling being observed in the future is therefore increased. The types of devices described here will always be hindered because of heat conduction. Other methods incorporating thermionic emission, such as an opto-thermionic system in which removed heat is given off as light, may ultimately prove to be the best solution. This aside, it is hoped that the work presented here will contribute to the understanding of the field.
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Menegay, Peter. "Experimental investigation of an ejector as a refrigerant expansion engine." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10222009-124957/.
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Mirza-Tolouee, Changiz M. "Experimental study of zeotropic refrigerant mixture HFC-407C as a replacement for HCFC-22 in refrigeration and air-conditioning systems." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070416.141307/index.html.
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Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, 2006.A thesis submitted for the degree of Doctor of Philosophy, School of Engineering and Science, Swinburne University of Technology, 2006. Typescript. Includes bibliographical references (p. 123-127).
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Mavalankar, Aquila Mukund. "Thermometry and refrigeration using quantum dots." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708092.
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Yildiz, Seyfettin. "Design And Simulation Of A Vapor Compression Refrigeration Cycle For A Micro Refrigerator." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612133/index.pdf.
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Cooling of electronic equipments has become an important issue as the advances in technology enabled the fabrication of very small devices. The main challenge in cooling is the space limitation. The use of miniature refrigerators seems to be a solution alternative for the cooling problem.
The objective of this study is to design and simulate a vapor compression refrigeration cycle for a micro-scale refrigerator. A MATLAB code is developed for the simulations. The four components of the refrigerator, namely, the condenser,
evaporator, compressor and the capillary tube are designed separately. The cycle is successfully completed nearly at the same point where it begins.
The cold space temperature, ambient air temperature, condensation and evaporation temperatures, and the evaporator heat load are the predetermined parameters. A fan is used to cool the condenser, and the compressor is selected as isentropic.
R-134A is selected as the refrigerant and a simple interpolation code is developed to
obtain the thermophysical properties of R-134A.
The original design is carried out with an isentropic compressor. For the purpose of
comparison, a cycle with a polytropic compressor is also considered. Similarly, two alternative designs for the evaporator are developed and simulated. A second law
analysis is performed at the end of the study.
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Swart, JC. "Solar refrigeration using the Peltier Effect." Thesis, Cape Technikon, 1996. http://hdl.handle.net/20.500.11838/1153.
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Thesis (Master Diploma (Electrical Engineering))--Cape Technikon, Cape Town,1996In order to design a coolerbox, utilising Thermo-electric technology as a heat pump, it was necessary to determine if this type of technology would be suitable for a coolerbox heat pump application. A detailed TEC (Thermo Electric Cooler) sizing estimation was done, using formulas supplied by the manufacturer, and using thermo-electric themy formulas to calculate the absolute theoretical performance parameters for a suitable TEe The correct heat pumping capability is important since.it is possible to obtain TEes with different input currents, voltages and heat pumping capabilities. Using the TEC as a heat pump, it was decided to use water cooling due to the extremely high cost of a suitable air cooled heatsink. It should be noted that to cool the hot side of theTEe a vel}' efficient heat exchanger should be used. A simulator was constructed to simulate, under variable operating temperatures and input powers, the cooling capacity of the TEC heat exchanger. The cooling characteristics were then used to determine if the theol}' and manufacturers claims correspond with the cooling characteristics of the coolerbox. It might be possible that the performance of the TEC would be drastically influenced, since installation con~itions may not be ideal when installed; and, that the manufacturers performance claims are done when the TEC is operated under ideal conditions. This would ensure optimum results because, should an under sized TEC be used, the result would be poor cooling characteristics; or, if the TEC is over sized, the coolerbox would consume too much power, resulting in an inefficient system.
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Nellis, Gregory F. (Gregory Francis). "Magnetically augmented cryogenic refrigeration." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11482.
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Browne, J. A. "Multiple expansion refrigeration cycles." Master's thesis, University of Cape Town, 1986. http://hdl.handle.net/11427/23793.
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O'Loughlin, R. L. "Optimal design of organic refrigerant reverse cycle absorption air conditioning systems /." Title page, contents and abstract only, 1986. http://web4.library.adelaide.edu.au/theses/09ENS/09enso52.pdf.
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Al-Ansary, Hany A. M. "Investigation and improvement of ejector-driven heating and refrigeration systems." Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-06072004-131032/unrestricted/al-ansary%5Fhany%5Fa%5Fm%5F200405%5Fphd.pdf.
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MARTINEZ, LUIS CARLOS CASTILLO. "OPTIMIZATION THE CIRCUITING REFRIGERATION OF THE HEAT EXCHANGERS IN VAPOR COMPRESSION REFRIGERATION SYSTEMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=31763@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
Em sistemas de refrigeração por compressão de vapor, o projeto adequado dos circuitos para o refrigerante nos trocadores de calor pode ter um impacto significativo no seu coeficiente de performance (COP). O projeto otimizado dos circuitos de refrigerante em sistemas de refrigeração com trocadores de calor do tipo tubo-aletado não é trivial, devido à complexidade de sua representação assim como o elevado número de possíveis combinações, mesmo quando metodologias inteligentes de otimização são empregadas. No presente trabalho propõe-se uma nova metodologia para a otimização simultânea (condensador e evaporador) dos circuitos do refrigerante em sistemas de refrigeração com trocadores de calor de tipo tubo-aletado. Esta metodologia, aqui denominada como GAFIS (Genetic algorithms applied in filtered spaces), mostra-se mais eficiente que as metodologias até então descritas na literatura. Foi aplicado o método GAFIS, em conjunto com um simulador completo para o sistema de refrigeração, Genesym, na otimização de unidades comerciais de condicionamento de ar de alto desempenho. Estudaram-se casos onde o sistema atingiu aumentos de até 15,3 por cento no coeficiente de performance. Em outros estudos, obtiveram-se casos onde o custo de produção foi reduzido em 3,85 por cento (do custo total da unidade), mantendo-se um similar desempenho (capacidade e COP). Testes de otimização, considerando-se diferentes diâmetros dos tubos, na construção dos trocadores de calor, e sistemas com distribuição não uniforme de velocidade de ar, também foram realizados com o GAFIS. Igualmente foram estudados condensadores de microcanais, devido ao interesse atual da indústria com estes trocadores de calor. A otimização do circuito para o refrigerante, neste caso, é relativamente simples, devido ao baixo custo computacional das simulações. Entretanto, modelos de simulação adequados para estes tipos de trocadores de calor só recentemente começaram a surgir, e não têm sido explorados de maneira adequada até a presente data. Explorou-se no presente trabalho, a influência, no desempenho térmico do condensador, dos parâmetros que definem o circuito do refrigerante. Para tal efeito, desenvolveu-se um modelo de simulação baseado em análise local, validado com dados experimentais disponíveis, de condensadores de microcanais de uso automotivo com diâmetro hidráulico (lado do refrigerante) de 0,9 e 1,0mm, para refrigerantes R-134a, Fluid-H e R-1234yf. Foram encontradas relações diretas entre os parâmetros geométricos que definem os circuitos de refrigerante no condensador e seu desempenho térmico. Tal fato pode ser utilizado como orientação expedita para o projeto do circuito ótimo do condensador.
Refrigerant circuiting in condensers and evaporators has a significant effect in the performance of refrigeration systems. The optimized project of the refrigerant circuits in refrigeration systems with plate-fin heat exchangers is not trivial, due to the complexity of their representation as well as the high number of possible combinations, even when methodologies of intelligent optimization are used. The present work proposes a new methodology for the simultaneous optimization of refrigerant circuiting in air-air refrigeration systems with plate-fin heat exchangers. This new methodology, here defined as GAFIS (Genetic algorithms applied in filtered spaces), has proven to be more efficient than traditional methods. The GAFIS method was applied, in conjunction with a full refrigeration system simulator, Genesym, for the optimization of high performance commercial air-conditioning units. Typical cases were studied and a coefficient of performance improvement of up to 15.3 percent has been observed. In other studies, there were cases where the manufacturer s predicted cost was reduced in 3,85 percent (of total cost of the unit), while a similar thermal performance (capacity and COP) was maintained. Optimization tests, considering different diameters of tube, for the construction of heat exchangers, as well as systems with non-uniform air velocity distribution, were also performed with the GAFIS method. Microchannel condensers were also studied, given the current interest of industry on this kind of heat exchanger. The optimization of the refrigerant circuiting, in this case, would not be a major problem, due to the low computational cost of its simulation. However, simulation models appropriate for these types of heat exchangers have only been recently in use, and, to date, have not been adequately explored. In the present work, the influence on condenser performance of parameters that define the refrigerant circuiting has been investigated. For this purpose, a simulation model, based on local analysis, was developed. It was validated against experimental data, available from automotive microchannel condenser tests, with hydraulic diameters (refrigerantside) of 0.9 and 1.0mm for refrigerants R-134a, Fluid-H and R-1234yf. A direct relation was found between the geometric parameters that define the condenser refrigerant circuiting and its thermal performance. This fact can be appropriately used as guidance for expeditious design practices of the optimal refrigerant circuit of the condenser.
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White, S. D. "Design and modelling of novel absorption refrigeration cycles /." Title page, contents and summary only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phw5878.pdf.
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Tegusi. "Novel materials for magnetic refrigeration." Amsterdam : Amsterdam : [s.n.] ; Universiteit van Amsterdam [Host], 2003. http://dare.uva.nl/document/69615.
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Sawalha, Samer. "Carbon Dioxide in Supermarket Refrigeration." Doctoral thesis, Stockholm : Energiteknik, Energy Technology, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4753.
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PORTILLA, GUSTAVO FERNANDO DORREGARAY. "REFRIGERATION SYSTEMS SIMULATION IN SUPERMARKETS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16197@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICODesenvolveu-se um modelo termodinâmico para cálculo do consumo energético e do impacto ambiental (LCCP e TEWI) em sistemas de refrigeração de supermercados para três diferentes configurações (expansão direta, fluido secundário e em cascata). O modelo termodinâmico trabalha solidário com o pacote de cálculo de propriedades REFPROP e determina diversos parâmetros de funcionamento do ciclo de refrigeração, tais como o COP e a capacidade de refrigeração. O modelo simula sistemas operando com substâncias puras ou misturas delas, podendo estas ser azeotrópicas ou não-azeotrópicas. Procede-se a uma análise do tipo BIN (Intervalo) a partir de informações climatológicas anuais de cada cidade e ao cálculo do consumo anual de energia para cada intervalo considerando-se o consumo do compressor, das bombas, se for o caso específico da utilização de fluido secundário, e também o consumo energético dos expositores frigoríficos. Realizou-se, também, uma análise da carga total (inventário) do refrigerante no supermercado. Finalmente, conhecidos o consumo energético anual, a massa total de refrigerante contido no sistema e estimativa de seu vazamento anual, e outros fatores ambientais, procedeu-se ao cálculo do LCCP (Life cycle climate performance) e do TEWI (Total equivalent warming impact), em quilogramas equivalentes de CO2. Um programa computacional, com interface baseada na plataforma Visual-Basic 6.0, com aplicações para Excel, foi desenvolvido para a solução dos sistemas de equações resultantes do modelo matémático desenvolvido. Os resultados obtidos com o código computacional foram comparados com dados de campo e de outros modelos.
A thermodynamic model was developed for the evaluation of energy consumption and environmental impact (LCCP and TEWI) of supermarket refrigeration systems operating in three different configurations (direct expansion, secondary fluid and cascade). The model simulates refrigeration systems operating with pure substances or a mixture (azeotropic or non-azeotropic) of them. A BIN analysis is carried out taking into account year-round climate data for each city and the annual energy consumption, in each time interval, of each component: compressor, pumps, freezers and coolers. Refrigerant inventory was also calculated. Finally, with the annual energy consumption, total refrigerant charge, annual leakage estimate, environmental impact indicators LCCP (Life cycle climate performance) and TEWI (Total equivalent warming impact), in kilograms equivalent of CO(2), were calculated. A computational code, with interface based on Visual Basic 6.0 platform, was developed for the solution of the resulting systems of equations that form the mathematical model. Predicted results were compared with field data and with data predicted from other models.
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Conrad, Theodore Judson. "Miniaturized pulse tube refrigerators." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41108.
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Pulse tube refrigerators (PTR) are robust, rugged cryocoolers that do not have a moving component at their cold ends. They are often employed for cryogenic cooling of high performance electronics in space applications where reliability is paramount. Miniaturizing these refrigerators has been a subject of intense research interest because of the benefits of minimal size and weight for airborne operation and because miniature coolers would be an enabling technology for other applications. Despite much effort, the extent of possible PTR miniaturization is still uncertain.
To partially remedy this, an investigation of the miniaturization of pulse tube refrigerators has been undertaken using several numerical modeling techniques. In support of these models, experiments were performed to determine directional hydrodynamic parameters characteristic of stacked screens of #635 stainless steel and #325 phosphor bronze wire mesh, two fine-mesh porous materials suitable for use in the regenerator and heat exchanger components of miniature PTRs. Complete system level and pulse tube component level CFD models incorporating these parameters were then employed to quantitatively estimate the effects of several phenomena expected to impact the performance of miniature PTRs. These included the presence of preferential flow paths in an annular region near the regenerator wall and increased viscous and thermal boundary layer thicknesses relative to the pulse tube diameter. The effects of tapering or chamfering the junctions between components of dissimilar diameters were also investigated.
The results of these models were subsequently applied to produce successively smaller micro-scale PTR models having total volumes as small as 0.141 cc for which sufficient net cooling was predicted to make operation at cryogenic temperatures feasible.
The results of this investigation provide design criteria for miniaturized PTRs and establish the feasibility of their operation at frequencies up to 1000 Hz with dimensions roughly an order of magnitude smaller than those that have recently been demonstrated, provided that challenges related to their regenerator fillers and compressors can be addressed.
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Jurns, John M. "Flow of sub-cooled cryogens through a Joule-Thomson device : investigation of metastability conditions." Cleveland, Ohio : Cleveland State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=csu1198954696.
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Thesis (M.S.)--Cleveland State University, 2007.Abstract. Title from PDF t.p. (viewed on May 8, 2008). Includes bibliographical references (p. 80-82). Available online via the OhioLINK ETD Center. Also available in print.
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Herman, David Laurence. "Experimental optimization of cooling tower fan control based on field data." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/16629.
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Weber, Eric Dean. "Modeling and general optimization of commercial building chiller/cooling tower systems." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/16874.
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Li, Yong, and 李勇. "Performance prediction model for a rotary multi-bed adsorption coolingsystem." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31245742.
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Kharazi, Amir Ahmadzadeh. "Study of a novel R718 turbocompression cycle." Diss., Connect to online resource - MSU authorized users, 2006.
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Thesis (Ph. D.)--Michigan State University. Dept. of Mechanical Engineering, 2006.Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographic references (p. 84-89). Also issued in print.
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Schneider, Thomas. "An experimental investigation of the finite time efficiency of a Peltier refrigeration device." PDXScholar, 1991. https://pdxscholar.library.pdx.edu/open_access_etds/4261.
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Since the need of energy conservation has become more and more urgent in the past decades, there has been an increased interest in the study and development of more efficient energy conversion systems. One of the fields that have arisen from that endeavor is a branch of physics called Finite Time Thermodynamics (FIT). It may be said that FIT was initiated through the famous paper by Curzon and Ahlborn (1975) that established new bounds on the efficiency of a finite time Carnot heat engine. Before, the traditional treatments gave a fundamental upper limit on the efficiency of any heat engine. However, this figure, the well-known Carnot efficiency, is far too optimistic in comparison to real heat engines. The reason lies in the fact that the traditional Carnot engine is operating infinitely slowly, thus having zero power output. Curzon and Ahlborn were able to improve upon this treatment and to set an upper limit on engines producing finite power.
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Belaid, Ashur Belaid. "A six-chamber medium-to-high temperature refrigeration system for laboratory purposes." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2522.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017.Food and water fuel and sustain life on earth. Since ancient times, their sourcing and preservation have been very important issues to humanity. In modern times, experimentation is a major step in analysing how cold storage problems in the medical and food science technology fields can be addressed. For investigating spoilage of new products and/or growth of pathogens in such cases, it is necessary to do experiments at different low temperatures for prolonged periods and check the effects. While this can be undertaken in a conventional two chambers fridge, it takes a long time to investigate a whole range of feasible storage temperatures. This dissertation describes work intended to treble the samples in such investigations and, therefore, significantly reduce the times. Six well- insulated chambers were constructed from plastic and wood and set at different temperatures. An ordinary deep freezer was used as the main heat sink for the chambers. Experiments were done with different methods to get the best result for the cold air flow into the chambers over period of eight months. The chambers temperatures were set between 0 and 15°C. It was finally established that a properly-designed six-chamber system could successfully be added to an ordinary freezer to provide different medium-to-high refrigeration temperatures without the use of a multi-pressure refrigeration cycle.
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Moorehead, Lynnette Ann. "Design optimization of cooling tower systems for dual-stage absorption chillers." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/16360.
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Gowreesan, Vamadevan. "Process-structure-property relationship of micro-channel tube for CO₂ climate control systems." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1107891543.
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Walters, Joseph D. "Optimization and Thermodynamic Performance Measures of a Class of Finite Time Thermodynamic Cycles." PDXScholar, 1990. https://pdxscholar.library.pdx.edu/open_access_etds/1186.
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Modifications to the quasistatic Carnot cycle are developed in order to formulate improved theoretical bounds on the thermal efficiency of certain refrigeration cycles that produce finite cooling power. The modified refrigeration cycle is based on the idealized endoreversible finite time cycle. Two of the four cycle branches are reversible adiabats, and the other two are the high and low temperature branches along which finite heat fluxes couple the refrigeration cycle with external heat reservoirs.
This finite time model has been used to obtain the following results: First, the performance of a finite time Carnot refrigeration cycle (FTCRC) is examined. In the special case of equal heat transfer coefficients along heat transfer branches, it is found that by optimizing the FTCRC to maximize thermal efficiency and then evaluating the efficiency at peak cooling power, a new bound on the thermal efficiency of certain refrigeration cycles is given by $\epsilon\sb{m} = (\tilde\tau\sp2\sb{m}\ (T\sb{H}/T\sb{L}) - 1)\sp{-1},$ where $T\sb{H}$ and $T\sb{L}$ are the absolute high and low temperatures of the heat reservoirs, respectively, and $\tilde\tau\sb{m}=\sqrt{2}$ + 1 $\simeq$ 2.41 is the dimensionless cycle period at maximum cooling power.
Second, a finite time refrigeration cycle (FTRC) is optimized to obtain four distinct optimal cycling modes that maximize efficiency and cooling power, and minimize power consumption and irreversible entropy production. It is found that to first order in cycling frequency and in the special symmetric case, the maximum efficiency and minimum irreversible entropy production modes are equally efficient. Additionally, simple analytic expressions are obtained for efficiencies at maximum cooling power within each optimal mode. Under certain limiting conditions the bounding efficiency at maximum cooling power shown above is obtained.
Third, the problem of imperfect heat switches linking the working fluid of an FTRC to external heat reservoirs is studied. The maximum efficiency cycling mode is obtained by numerically optimizing the FTRC. Two distinct optimum cycling conditions exist: (1) operation at the global maximum in efficiency, and (2) operation at the frequency of maximum cooling power. The efficiency evaluated at maximum cooling power, and the global maximum efficiency may provide improved bench-mark bounds on thermal efficiencies of certain real irreversible refrigeration cycles.
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Taylor, Robert A. "Comprehensive optimization for thermoelectric refrigeration devices." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4247.
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Thesis (M.S.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (December 20, 2006) Includes bibliographical references.
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NGUYEN, TUYET. "Carbon dioxide in ice rink refrigeration." Thesis, KTH, Tillämpad termodynamik och kylteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118099.
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The average energy consumption of one ice rink is around 1000MWh/year, which approximately69% is occupied by the refrigeration unit and heating demand. With the aim of decreasing theenergy consumption, a new concept of refrigeration system with CO2 as a refrigerant has beendeveloped and it is promising to become a high potential next generation for refrigeration systemin ice rink.This thesis is to evaluate a new refrigerant application in ice rink refrigeration system underthree different aspects; energy performance, heat recovery potential and economic efficiency. Inorder to make this evaluation, three main tasks are executed. Firstly, literature review and marketstatistic are processed to give a general picture of the CO2 development as a refrigerant. Secondly, asoftware Pack Calculation II is used for the simulations of CO2 refrigeration system and traditionalice rink refrigeration system. Älta ice rink located in Sweden, is chosen as a reference case forsimulation’s input data. The simulation results is to compare these system in terms of energyperformance and heat recovery potential. Finally, life cycle cost of these systems is calculated toinvestigate the economic benefits from this new application.Results from this study show good benefits of the new CO2 application in ice rink. Fromthe market statistics, CO2 has become a successful refrigerant in supermarket food and beverageindustry with 1331 CO2 refrigeration system installed until 2011 in Europe (Shecco2012). In icerink industry, 24 ice rinks have been applied CO2 in the second cycle of refrigeration system; oneice rink in Canada applied a refrigeration system with only CO2 in the first cycle and the distributionsystem.From the simulation’s result, CO2 full system has been proven as the most efficiency sys-tem with the lowest energy consumption (30% lower than NH3/Brine system and 46% lower thanCO2/Brine system) and the highest COP (6.4 in comparison with 4.9 of NH3/Brine system and4.37 of CO2/Brine system). Regarding heat recovery potential, CO2 full system has highest energysaving in comparison with the other two systems.Due to lower energy cost and service cost, the life cycle cost of CO2 full system is loweraround 13% than the traditional NH3/Brine system, furthermore, the component cost of CO2 sys-tem is promising to decrease in the next years thanks to the rapid development of this market insupermarket industry.To conclude, CO2 full system has high potential to become a next generation of refrigerationsystem in ice rink, however, because of its transcritical working, this application can be restrictedin the regions of warm climate.
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Marhoon, Fatema Salman. "Heat Exchangers Used in Refrigeration Circuits." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502999.
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Ma, Xiaoli. "Investigation of novel thermoelectric refrigeration systems." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/12377/.
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Concern over global warming and depletion of the ozone layer has stimulated research to develop cooling methods that do not employ environmentally damaging working fluids such as CFCs and HCFCs. Two methods that have been considered are absorption and thermoelectric `Peltier' cooling systems. Absorption systems, using H20/LiBr have the advantage of being able to use low-grade waste heat. However, the large volume, high capital cost and low performance of these systems have inhibited their widespread application. Thermoelectric systems were developed in the 1950s and use of this technology for air-conditioning applications was investigated as early as the 1960s. However, the continued development of thermoelectric systems was slow owing to technical difficulties and the superior performance of vapour-compression systems in terms of coefficient of performance (COP). It is known however that most working fluids employed in vapour-compression systems are damaging to the environment, and as vapour-compression systems contain moving parts, they have the further disadvantage of being noisy and requiring regular maintenance. In recent years therefore, there has been stimulated interest in using thermoelectric "Peltier" cooling systems for domestic refrigerators and air conditioning. Investigation of novel thermoelectric refrigeration systems was carried out in this research. The systems use thermoelectric "peltier" coolers (thermoelectric modules) to produce cooling or heating. Thermoelectric modules are solid state heat pump, which have the advantage of being environmentally friendly, being quiet, have no moving parts and can operate using direct current supplied from photovoltaic solar cells (PVs). This work mainly investigated a passive technology based on integration of a thermal diode and thermoelectric modules for building integrated heat pump. The heat pump uses thermoelectric modules to produce cooling or heating, and the thermal diode to transfer heat in or out of the building, and prevent reverse heat flow in the event of power failure. The heat pump was designed to have the following features: • Very compact and suitable for incorporation within the building structure; • Does not require a plant room and simple to construct; • Easily switched between cooling and heating modes; • Can prevent reverse heat flow in the event of power failure; • Low manufacturing cost; • Environmentally friendly; • Can be driven by solar photovoltaic panels. This work also investigated the potential application of phase change materials (PCMs) in the thermoelectric refrigeration system. The system employs phase change material to improve the performance of a thermoelectric refrigerator as well as the cooling storage capability. The refrigerator employing phase change material was designed to have following features: • Be able to overcome the peak loads and losses during door openings and power-off periods. • Prevent reverse heat flow via thermoelectric modules in the event of the power being turned off by integrating the thermosyphon with the phase change material. • Low manufacturing cost. • Environmentally friendly. • Can be driven by solar photovoltaic panels The research initially involved the investigation of the performance of the components of the thermoelectric refrigeration systems, including thermoelectric modules, heat pipes and heat sinks. The analytical models were developed to evaluate the heat transfer and optimise the design of these components. Correlations between heat transfer and fluid flow inside the heat pipes were explored by computer modelling. The research work further involved the design, modelling, construction and tests of a thermoelectric heat pump prototype. A computer model was developed to evaluate the performance of the heat pump system for two different modes, i. e., cooling and heating, under various operating and ambient temperatures. Laboratory tests were carried out to validate the modelling predictions and experimentally examine the thermal performance of the heat pump. Comparison was made between the modelling and testing results, and the reasons for error formation were analysed and correction was given. Further experimental investigation showed that reducing the temperature of the condenser of the thermal diode could provide a significant improvement of the efficiency of the coefficient of performance (COP) of the system in cooling mode. This can be achieved by using the evaporation of water on the heat sink attached to the condenser. The research work also involved the design, construction and tests of a thermoelectric refrigerator employing phase change material. The work intended to investigate the potential application of phase change materials (PCMs) in the thermoelectric refrigeration system. The system was first fabricated and tested using a conventional heat sink system as the cold heat sink. In order to improve the performance and the storage capability, the system was reconstructed and tested using an encapsulated PCM as a cold heat sink. Results of tests of the latter system showed an improved performance compared with the former system. However, to improve the storage capability, in particular during off-power periods, it was found necessary to integrate the PCM with a thermosyphons, which would allow heat flow in one direction only. Results of tests carried out on the system employing phase change material integrated with thermosyphons showed considerable improvement in the storage capability of the thermoelectric refrigeration system compared with the previous ones. On the basis of the above investigation the further work for improving the performance of the thermoelectric refrigeration system was suggested, which is illustrated in Chapter 7, and its key technical issues are discussed.
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Eltom, Osman Mirghani Mohamed. "Solar refrigeration applications in the Sudan." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332819.
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Zeiny, Aimen Rashad Noor. "Nanofluids for solar absorption refrigeration systems." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/22416/.
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Vapour absorption refrigeration systems (VARSs), which utilise eco-friendly refrigerants (water), can work based on low-grade thermal energy, such as the solar energy. Using solar energy can relief the high electrical load on many national grids around the world as the peak load almost coincides with the high solar intensities time during summer. However, high initial cost, big specific size and low coefficient of performance are the main challenges that face the VARSs. Therefore, improving the efficiencies of the components of a solar refrigeration system, such as the solar collector, generator and absorber, is crucial to improve the overall efficiency of that system and to reduce its size and the cost. To improve the efficiency of a solar VARS, nanofluids are proposed in this work through direct and indirect ways. The direct way is seeding functional nanoparticles in the aqueous solution of a VARS. The expectations are that refrigerant (steam) can be generated efficiently via direct volumetric absorption of the solar energy at the generator and can be absorbed effectively via the Brownian motion of the nanoparticles at the absorber. While, the indirect way is; using aqueous nanofluids in direct solar collectors can harvest the solar energy in an efficient way, saving it in a storage tank. This stored energy is used later to generate the steam in the generator of the VARS. This work aims to investigate fundamentally the applicability of utilising nanofluids for solar absorption refrigeration systems through performing three main studies: Firstly, a comparative study of gold, copper oxide, gold and copper oxide hybrids, and carbon black nanofluids has been conducted to investigate the photo-thermal conversion efficiency. The results have shown that gold nanofluids are not feasible for solar application due to the high cost and low performance comparing to the carbon black nanofluids. Moreover, this study has demonstrated that blending different nanofluids of different narrow spectral absorption peaks can really broaden the effective spectral absorption peak but reduces its value due to the accompanied dilution of the blended nanofluids as the overall volume unavoidably increases. Secondly, a comparative study of solar steam generation among gold nanofluids, carbon black nanofluids and a thin carbon-based porous medium has been conducted. The results have also shown the infeasibility of using gold nanofluids comparing with the carbon black nanofluids due to the high cost and low absorptivity. Furthermore, this study has shown the superiority of using a thin, carbon-based porous medium in producing steam due to its capability to absorb most the solar energy in micro-sized thickness. While, very high nanoparticles concentration is required to trap and absorb the solar energy in such a thin layer, which consequently leads to an instability, high viscosity and high-cost issues. Finally, a study of the steam absorption by and generation from aqueous lithium bromide solutions seeded with carbon black and carbon nanotubes has been conducted. The results have demonstrated that a very low concentration of carbon black nanoparticles can reduce the transparency of the solutions to zero. However, seeding nanoparticles in the solutions has shown the negligible effect on the steam absorption rate, which demonstrated that the Brownian motion of the nanoparticles has a negligible effect on the steam absorption. Although the experiments conducted in this project showed negligible enhancement in the steam absorption, obvious enhancements in the photo-thermal conversion efficiency and steam generation were achieved by using nanofluids. Recommendations are suggested for future work to study other affecting aspects of seeding nanoparticles in aqueous solutions.
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Al, Juma Marwan. "Solar absorption cycle for cooling/refrigeration." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/67695/.
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The purpose of this thesis is to critically highlight the development of solar absorption refrigeration technologies through time. The factors that have prompted the urgent need to reconsider this area of engineering will also be analyzed in depth. The relevant research in the area of solar absorption to date will be shown with specific emphasis on its contribution to industrial and domestic cooling systems. The Middle East may be awash with oil in the present circumstances with 48% of the known oil reserves in the world but challenges exist owing to fossil fuel being a finite resource and its exploitation fraught with environmental problems. Therefore developing solar cooling systems appears to be an essential and inevitable requisite for harnessing solar energy in order to make a lasting contribution to the development of the region, as well as the world Targeting the coefficient of performance (COP) of the solar absorption refrigeration systems was considered to be the fundamental part of this research. By investigating the absorber chamber in an absorption refrigeration system, it was found that enhancing the quality of the spray of the absorber fluid could raise the COP. Using a Phase Doppler Anemometry (PDA), a detailed analysis of the spray characteristics was achievable; this helped in targeting parameters which will have influence on the spray characteristics. These include the nozzle geometry, for instance, the size of orifice, as well as the internal forces of the liquid such as viscosity and surface tension. Operating parameters were also considered to influence the spray quality. The main operating parameter is to create a partial vacuum to simulate the absorber chamber working condition. Results revealed that high viscosity of the fluid and the vacuum had negative effects towards spray quality. But when combining these with a surfactant such as 2-ethyl-1-hexanol, the spray quality increases in terms of droplet diameter, which in turn decreases and thereby causes an increase in the surface area to volume ratio, resulting in the enhancement of COP.
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Lindeman, Lukas. "Refrigeration system performance using alternative refrigerants." Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-188606.
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When running a refrigeration system, the refrigerant will always leak into the atmosphere in various ways. The leakage of currently used refrigerants have a non-negligible impact on the global warming. The European Commission recently approved the Regulation No 517/2014 on fluorinated greenhouse gases (FGR). This regulation implies, among other, that refrigerants with GWP of 2500 or more will be restricted from being used in stationary refrigeration equipment being placed on European refrigeration market. In this study a number of new refrigerants are analysed and evaluated as potential replacements for R404A which is a popular commercially used refrigerant with high global warming potential. A few refrigerants from different manufacturers have been evaluated using a computer model of a basic vapour-compression system, as well as analysed from the position of refrigerant safety. It was found that the best short term replacement for R404A are two refrigerants called R448A and R449A and the best long term replacement is DR7.I ett kylsystem kommer köldmediet alltid att, på ett eller annat sätt, läcka ut i atmosfären. Läckage av all världens köldmedium har en icke försumbar inverkan på den globala uppvärmningen. Den europeiska kommissionen nyligen godkänt en förordning kallad Regulation No 517/2014 on fluorinated greenhouse gases (FGR). Denna förordning innebär, bland flera saker, att kommersiella köldmedium med en global uppvärmningspotential på 2500 eller mer kommer att förbjudas för användning i stationära kylsystem. I denna studie har ett antal nya köldmedier analyserats och utvärderats i syfte att hitta ersättare till R404A vilket är ett populär kommersiellt köldmedium med en hög global uppvärmningspotential. Jämfört med R404A har nya köldmedier from olika producenter utvärderas i en databaserad modell av ett enkelt kylsystem för att utvärdera deras effektivitet. Studien fokuserar också på säkerhet kring köldmedier och tillsammans med resultaten från modellen framkom det att på kort sikt är det bästa alternativet för att ersätta R404A är två köldmedium kallat R448A R449A och på lång sikt ett köldmedium kallat DR7.
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Eriksson, Peter. "Refrigeration system performance using alternative refrigerants." Thesis, KTH, Energiteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175160.
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The European Parliament has shown its legislative capabilities by adopting a tough approach on the reduction of fluorinated gases (F-gases). The EU Regulation No 517/2014, will phase out F-gases with high global warming potential (GWP) within a well-defined step down time schedule. This will affect refrigerants which are commonly used in commercial cooling applications. While the time schedule implies existence of replace- ment refrigerants, the market continues to develop alternatives for the refrigerants already in deployment. Though the R404A,which is a commonly used refrigerant in station- ary cooling applications, will be prohibited of use 1 January 2020. In this paper, the two alternatives R448A from Honeywell and R449A from DuPont were compared to the R404A baseline, within a theoretical model with empirical compressor and system input data. The key points of comparison were cooling capacity, compressor discharge temperature, coefficient of performance (COP) and total equivalent warming impact (TEWI). The outcome of the model showed a decrease in cooling capacity for both alternatives, as well as an overall increase in compressor discharge temperature. For low evaporator temperatures, a decrease in COP was present and vice versa for high evaporator temperatures, both for medium and high condenser temperature. However, the TEWI for the both refrigerants, showed a decrease in carbon dioxide (CO2) equivalent emissions during the refrigerant system lifespan, running on both R448A and R449A, regardless of which European country the electricity was produced in.Det Europeiska Parlamentet har visat sin lagstiftande förmåga i och med antagandet av en tuff förordning om reducering av F-gaser. EU Förordningen Nr 517/2014 kommer att fasa ut flourinerade gaser med högt GWP värde och det med en väl definierad nedtrappningsperiod. Detta kommer bland annat att påverka köldmedier som ofta förekommer i kommersiella kylapplikationer. Medan tidsschemat förutsätter redan existerande ersättare fortsätter marknaden att utveckla alternativ för de köldmedier som idag är i bruk, samtidigt som användandet av det vanligt förekommande kylmediet R404A kommer att förbjudas i och med 1 januari 2020. I den här rapporten jämförs de två alternativa kylmedierna R448A från Honeywell och R449A från DuPont i en teoretiskt modell, med empiriska data för kompressor- och systemvariabler, där kylmediet R404A används som referens. Huvudsakligen jämfördes kyleffekt, kompressorns utströmningstemperatur, COP och TEWI. Resultaten från modellen visade en minskad kyleffekt för båda de båda alternativen, såväl som en ökad utströmningstemperatur för kompressorn. Låga evaporatortemperaturer resulterade i en minskning av COP och vice versa för höga evaporatortemperaturer, både för mellan och hög kondensortemperatur. Dock konstaterades för TEWI, en minskning av de sammanlagda CO2 ekvivalenta utsläpp under kylsystemets livslängd, under drift på både R448A och R449A oavsett i vilket Europeiskt land elektriciteten producerats i.
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Soares, Darrow P. "Curriculum in mathematics for air conditioning and refrigeration." CSUSB ScholarWorks, 1996. https://scholarworks.lib.csusb.edu/etd-project/1239.
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Chen, Chung-Kang. "Applications of substructuring methods to the dynamic finite element analysis of a container refrigeration unit frame structure /." Online version of thesis, 1992. http://hdl.handle.net/1850/11688.
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Golden, James Hollis. "Ammonia - water desorption in flooded columns." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44884.
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Refrigeration systems employing the NH3-H2O absorption cycle provide cooling using a thermal energy input. This cycle relies on the zeotropic nature of the refrigerant - absorbent pair: because of the difference in boiling temperatures between NH3 and H2O, they can be separated through selective boiling in the desorber. Desorbers with counter-current flow of the solution and generated vapor enable efficient heat and mass transfer between the two phases, reducing the absorbent content in the generated vapor.
Flow visualization experiments at temperatures, concentrations and pressures representative of operating conditions are necessary to understand the heat and mass transfer processes and flow regime characteristics within the component. In this study, a Flooded Column desorber, which accomplishes desorption of the refrigerant vapor through a combination of falling-film and pool boiling, was fabricated and tested. Refrigerant-rich solution enters the top of the component and fills a column, which is heated by an adjacent heated microchannel array. The vapor generated within the component is removed from the top of the component, while the dilute solution drains from the bottom.
Flow visualization experiments showed that the Flooded Column desorber operated most stably in a partially flooded condition, with a pool-boiling region below a falling-film region. It was found that the liquid column level was dependent on operating conditions, and that the pool-boiling region exhibits aggressive mixing between the vapor and solution phases.
Heat transfer coefficients were calculated from the data for the pool-boiling region, and were compared with the predictions of several mixture pool-boiling correlations from the literature. The correlations from the literature were in general unable to predict the data from this study adequately. It was found that the Flooded Column desorber yielded higher heat transfer coefficients within the pool-boiling region than those predicted by these correlations. Therefore, modifications to existing mixture boiling correlations are suggested based on the findings of this study. The resulting modified correlation predicts 33 of the 35 data points from this study within ±40%, with an average absolute error of 19%.
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Riley, Caryn M. "Current-based sensorless vibration monitoring of small ac machines." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13741.
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Hill, John Michael. "Simulation of a variable speed air conditioner as a multiple loop thermal system." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/16754.
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Joyce, Charles Thane. "Optimized design of a commercial building chiller/cooking tower system." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/24115.
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Nascimento, Ubiraci Silva. "Carvão de babaçu como fonte termica para sistema de refrigeração por absorção no estado do Maranhão." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265326.
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Orientador: Jorge Isaias Llagostera BeltranDissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-04T02:56:29Z (GMT). No. of bitstreams: 1 Nascimento_UbiraciSilva_M.pdf: 4551351 bytes, checksum: d36f11b4eb3e73786c0d3e1a3785be33 (MD5) Previous issue date: 2004
Resumo: Neste trabalho procurou desenvolver-se uma análise teórica da utilização integral do babaçu como fonte energética, procurando da ênfase às potencialidades agregadas ao carvão. Foi realizado um estudo de caso em municípios maranhenses, visando diagnosticar aspectos que relacionam o homem do campo a essa importante fonte de biomassa. Um forno foi projetado para a produção do carvão do babaçu com melhores índices de qualidade e quantidade. O sistema de refrigeração consta de um acoplamento do forno acionado com carvão de babaçu uma geladeira de absorção tipo Platen-Munters, através de um termosifão bifásico fechado. Os resultados obtidos decorreram de uma análise comparativa a um experimento já realizado com um sistema similar, movido a um fogão à lenha, onde percebe-se claramente uma melhoria significativa da eficiência do sistema proposto
Abstract: In this work a theoretical analysis of the integral use of Babaçu looked for to develop itself as energy source, looking for to give emphasis to the aggregate potentialities to the coal. A study of case in maranhenses cities was carried through, aiming at to diagnosis aspects that relate the man of the field to this important source of biomass. The refrigeration system consists of a coupling of the oven a set in motion with coal of Babassu na absorption refrigerator Platen-Munters type, through a closed two-phase thermosiphon. The gotten results had a similar system, moved to a stove to the firewood, where a significant improvement of the efficiency of the considered system is perceived clearly
Mestrado
Refrigeração de Condicionamento Ambiental
Mestre Profissional em Engenharia Mecanica
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Celik, Aydin. "Performance of two-stage CO₂ refrigeration cycles." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1857.
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Thesis (M.S.) -- University of Maryland, College Park, 2004.Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Carbon dioxide appears on title page as CO₂. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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McLaughlin, Shannon. "An Alternative Refrigeration System For Automotive Applications." MSSTATE, 2005. http://sun.library.msstate.edu/ETD-db/theses/available/etd-05242005-115750/.
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The air conditioning systems currently utilized in automobiles are the vapor compression systems. This type of system has many disadvantages: the refrigerant used is not environmentally friendly, the compressor is in competition with the engine coolant system, and the compressor uses a significant portion of the engine power. A waste heat driven absorption refrigeration system is one alternative to the current systems that could address these problems. The absorption refrigeration system uses solutions for the absorbent-refrigerant pair that do not harm the environment. This investigation includes a theoretical analysis of the feasibility of absorption air conditioning system in automotive applications. Also, a comparison of the power requirements of the proposed system and the vapor compression system is performed.
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Klingshirn, Astrid. "Innovative storage concepts in private home refrigeration." Aachen Shaker, 2007. http://d-nb.info/98776120X/04.
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Wu, Guodong. "Design and retrofit of integrated refrigeration systems." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506289.
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