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.

Nine pages of Addenda and eight pages of Errata in back pocket. / Includes bibliographical references. / vii, 192, [78] : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1994

No description available.

No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 117-119). Also available via the Internet.

Thesis (M.S>)--Rochester Institute of Technology, 1992. / Typescript. Includes bibliographical references (leaves 87-88).

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 164-173). Also available on the World Wide Web.

Thesis (Master Diploma (Electrical Engineering))--Cape Technikon, Cape Town,1996 / In 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.

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.

Orientador: Jorge Isaias Llagostera Beltran / Dissertação (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