Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 45 for “"Refrigeration systems"”.
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Refrigerant charge reduction in small commercial refrigeration systems
This paper presents analysis of location of refrigerant inventory and numerical results of charge reduction in a typical bottle cooler. The original unit was first characterized by determining its capacity, the coefficient of performance (COP), pull-down characteristics, and total charge using …
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Investigation of miniature lithium-bromide/water absorption refrigeration systems
… which are associated with vapour compression refrigeration systems, alternative cooling means, like the Lithium-Bromide/Water (LiBr/H2O) absorption refrigeration system, are being investigated and produced in developed countries. However, the majority of these LiBr/H2O absorption refrigeration …
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Modelling the performance and dynamics of vapour compression refrigeration systems
The impact of refrigeration systems on the environment can be reduced by the use of alternative reffigerants which are less harmful to the atmosphere and the optimisation of systems and control strategies to deliver increased levels of energy efficiency. Mathematical modelling offers the …
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On the behavior of contaminants in cryogenic helium refrigeration systems
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1988.
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Dynamic Modeling and Advanced Control of Air Conditioning and Refrigeration Systems
… control strategies for vapor compression systems is presented. These results demonstrate that while linear control techniques offer significant advantages versus traditional a/c control systems over small ranges, the gain-scheduled approach extends these advantages over the entire …
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Superheat control for air conditioning and refrigeration systems: Simulation and experiments
Ever since the invention of air conditioning and refrigeration in the late nineteenth century, there has been tremendous interest in increasing system efficiency to reduce the impact these systems have on global energy consumption. Efficiency improvements have been accomplished through component …
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Investigating the Generation and Reaction of Organoaluminiums in Marine Container Refrigeration Systems
… presence of chloromethane in marine container refrigeration systems has led to multiple explosions reported around the world. This is thought to occur due to the generation of methylaluminium chlorides, from the reaction of aluminium with chloromethane, which can then react with the …
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Dynamic modeling and simulation of frost and defrost conditions for refrigeration systems
Heating and cooling systems are widely used throughout the world in an array of applications as a means of providing thermal energy transfer. Recent decades have seen economic and environmental awareness come to a forefront and innovation resultingly being pushed toward a standard of greater …
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A Combined Energy–Exergy Approach for Improving Refrigeration Systems in Deep-Level Gold Mines: Method Development and Case Study Validation
… energy consumers on deep-level mines is the refrigeration system, which supplies chilled water for cooling the underground working environment. Due to the outdated nature of these systems, and their fixed supply capacities, they are prone to energy wastage through inefficient operation. …
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Nonlinear observer design using contraction theory with application to heat exchangers having varying phase transition
Thermo-fluid systems such as air conditioning and refrigeration systems are widely used in residential, commercial, and industrial applications. By the end of the 20th century, nearly 70 percent of U.S. households had air conditioning, and 99.5 percent had at least one refrigerator. Advanced …
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Flow modelling of scroll compressors and expanders
The use of scroll compressors in refrigeration systems is becoming increasing popular. However the development and use of a scroll machine as an expander to replace a throttle valve has never been reported. This thesis describes the work carried out to develop a two phase scroll expander for use in …
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Fluidodinamica bifase in condotti elicoidali per applicazioni nucleari
… in heat exchangers for air conditioning and refrigeration systems, chemical reactors, and nuclear power plants is due to their heat transfer high efficiency and their compactness. Depending on specific applications of these components, for adequate design purposes, it is important to have a …
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Modeling of Air-Assisted and Flash Boiling Sprays in Gasoline Direct Injection Engines
… ranging from nuclear reactor coolant safety to refrigeration systems.
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Theoretical and experimental analysis of the thermoacoustic refrigeration
… is studied in detail and its application to refrigeration is analyzed. This new refrigerator which uses resonant high amplitude sound in inert gases to pump heat will be described. It will be seen that without any moving parts, except the driver (speaker diaphragm), this refrigerator is as …
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Enhanced condensation with active methods
… in liquefied natural gas processing and refrigeration systems. Current state of the art low surface energy low hysteresis coatings are not able to achieve dropwise condensation below 10 mN/m. Surface acoustic waves are proposed as an active method to shed thin condensate films to reduce …
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Oil Retention and Pressure Drop in Horizontal and Vertical Suction Lines with R410A / POE ISO 32
In refrigeration systems a small amount of compressor lubricant is entrained in the refrigerant and circulated through the system, where some is retained in each component. The suction line to the compressor has the largest potential for oil retention. This paper presents results from an …
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Motor vehicle air-conditioning : utilising the exhaust gas energy to power an absorption refrigeration cycle
… by replacing the traditional compression refrigeration system, used for air-conditioning a motor car, with an absorption unit. The thesis deals with some theoretical aspects of the absorption refrigeration cycle as well as practical aspects of motor car air-conditioning. A fair amount of …
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Modelling and prediction of flashing flow in short tubes
… extrapolated to other refrigerants and to other refrigeration systems. Most of the existing methods of predicting flowrates are achieved by doing a lot of experimental work and developing empirical or semi-empirical relations; because of the high degree of empiricism they are only valid for the …
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Subambient Passive Cooling Enabled by Polyethylene Aerogels
… consumption, straining existing electrical systems and contributing to 3% of global CO2 emissions. With growing space cooling demand stemming from economic and population growth in hot and developing parts of the world, more efficient air-conditioning and refrigeration systems are urgently …
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