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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 14 of 14 for “"vapor compression cycle"”.
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A thermodynamics based analysis of exergy destruction in vapor compression cycle systems
In the last few decades, vapor-compression cycle systems (VCSs) have undergone many advances in actuation, allowing for variable aperture valves, variable speed compressors, and variable speed heat exchanger fans. Numerous efforts have been undertaken to quantify the energy efficiency of these …
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Analysis and optimization of a dual-load vapor compression cycle using non-azeotropic refrigerant mixtures
… characteristics which could improve cycle efficiency. A NARM experiences a variable temperature glide during a constant-pressure phase change process, making it a logical candidate for the two-temperature level cooling found in refrigerators. There are two fundamental thermodynamic …
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Design of an ultraviolet absorption spectroscopy oil concentration sensor for online HVAC measurements
… advances in the modeling and control of the vapor compression cycle has developed the need for a real time oil concentration rate (OCR) sensor. Because of its ability to give the most accurate online measurements of OCR, ultraviolet absorption spectroscopy has been selected as the measurement …
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Experimental investigation of vortex tube and vortex nozzle for applications in air-conditioning, refrigeration, and heat pump systems
… through vortex tube in heating and cooling cycles has been examined. Vortex tube thermal separation performance for air, R134a and carbon dioxide is provided. It has been found that when using single-phase vapor as the working fluid the vortex tube cold end temperature can always be lower …
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A Computational Model for Two-Phase Ejector Flow
… to develop the ejector expansion refrigeration cycle, a device which increases performance of a standard vapor compression cycle by replacing the throttling valve with a work-producing ejector. Experimental results have confirmed the performance benefit of the ejector cycle, but significant …
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Testing and modeling of a two-phase ejector
The ejector expansion refrigeration cycle is a modified vapor compression cycle in which a two phase ejector is used to recover a portion of the work otherwise lost in the expansion valve. The ejector improves cycle performance by increasing compressor inlet pressure and by lowering the quality of …
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Experimental study of reversible AC/HP system for electric vehicles
… range reduction of EVs caused by cabin heating. Vapor compression cycle is commonly used for automotive air conditioning. By moderate modification of the air conditioning system, heat pump function can be obtained. A heat pump test setup has been built in the lab based on the heat pump system …
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TRANSIENT PERFORMANCE EVALUATION OF AUTOMOTIVE SECONDARY LOOP SYSTEMS
… a wide range of pull down conditions and drive cycles using a passenger cabin model and associated controls. It was shown that R290 is a viable alternative in secondary loop systems and system performance may be on par or better compared to R134a direct expansion systems. The preservation of …
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Optimal energy use in mobile applications with storage
… system. The refrigerated delivery truck uses a vapor compression cycle system that has been augmented with thermal storage to maintain a desired box temperature while maximizing operational efficiency. These case studies employ different architectures, different energy domains, and different …
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Thermodynamics-based optimization and control of integrated energy systems
… derived for the refrigerant-side dynamics of a vapor-compression cycle system and then used in formulating an exergy destruction minimization (EDM) optimal control problem for the system with full actuation capabilities. The results highlighted how time-varying control decisions can affect the …
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Scuffing and wear of engineering materials under different lubrication regimes in the presence of environmentally friendly refrigerants
… of CO2 with commonly used lubricants in the vapor compression cycle affects the way the lubricant is transported out of the refrigeration circuit. Also, when miscibility and solubility is incomplete, the lubricant accumulates in the system causing pressure drops (especially in the …
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Heat transfer performance and prediction of low global warming potential R134a refrigerant alternatives
… five studies) and R450A (i.e., one study). A vapor compression cycle experimental setup was designed and built to measure heat transfer performance of R134a alternative refrigerants. Experimental heat transfer coefficient data for R513A and R450A in a 0.95 mm diameter, multiport, mini-channel …
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Modeling and design of a power boosted turbo-compression cooling system
… modeling and design of a volume optimized turbo-compression cooling system (TCCS). The TCCS is driven by low-grade waste heat in the shipboard diesel generator set jacket water and lubrication oil and was designed to be a drop-in replacement of electric chiller systems. A case study of a marine …
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Experimental and numerical investigation of the design and control of vapor-compression systems with integration of two-phase ejectors for performance enhancement through expansion work recovery
… to improve the efficiency and capacity of vapor-compression refrigeration cycles by means of expansion work recovery has received significant attention in the past decade. Research has focused primarily on the design and performance of the ejector and the effect the ejector has on cycle …