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ACRC Technical Report 130PDF


Title:Feasibility Study of a Pressure Exchanger in an Air-Cycle Air Conditioner
Author(s):Herbst, G.W.; Newell, T.A.; Korst, H.H.
Subject(s):pressure exchanger
air-cycle air conditioner
Abstract:The use of a pressure exchanger, or wave rotor, in an air-cycle air conditioner is examined as an alternative to vapor-compression cycles which use chloroflourocarbons (CFC's), hydrochlorofluorocarbons (HCFC's) and hydrofluorocarbons (HFC's). In a pressure exchanger, expansion and normal shock waves are the mechanisms which transfer energy from a high pressure gas, by expanding it, to a low pressure gas, by compressing it. The device consists of a rotor which is divided into cells and a stator end-plate which controls inflow and outflow. A one-dimensional, homentropic unsteady numerical model was developed using the method of characteristics to simulate the flow through one cell. By entering the inlet and outlet pressures, the locations of the high pressure inlet and outlet ports and the low pressure inlet and outlet ports are calculated based on flow conditions. The mass flow rate through the system and the size of the rotor are also determined. Besides the pressure exchanger, an air-to-air heat exchanger and air compressor are necessary to develop an air conditioning cycle. These components can be arranged into six configurations of which two are superior to the rest. One configuration consists of the pressure exchanger and compressor working in parallel to raise room air to a higher pressure and temperature so that the heat can be transferred outside. In the other configuration, room air is compressed in stages, first by the pressure exchanger and then by the compressor with heat exchangers located after each compression stage. Six configurations of these components can provide cooling. Three involve expanding outside air below atmospheric pressure to absorb heat from the cooled space. These are not practical because of variability due to outside ambient humidity, high outlet temperatures for cool air to prevent frosting, and high volumetric flow rates of air. Of the three systems which compress room air to extract energy, the configuration with the pressure exchanger and compressor operating in parallel exhibited slightly better performance than the two configurations where the pressure exchanger and compressor compress the air in series.
Issue Date:1997-08
Publisher:Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Air Conditioning and Refrigeration Center TR-130
Genre:Technical Report
Date Available in IDEALS:2009-04-29
Identifier in Online Catalog:4214818

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