Optimization Of A Heat Pump For Satellite Cooling

In recent years the heat fluxes that must be removed from terrestrial electrical systems have been steadily increasing. The same increase in electrical component heat flux can also be seen in satellite and aerospace applications. As a result, it has proven necessary to develop heat pump systems that can operate in low-gravity environments with high reliability and efficiency to cool electrical components in the satellite. It is currently common practice to use heat pipes to conduct the heat generated by the electrical components to the radiators of the satellite, but tomorrow's electrical components will have heat fluxes high enough to make this system no longer feasible. The heat pump system considered here is a conventional four-component heat pump (compressor, condenser, expansion valve, evaporator) that uses an oil-free scroll compressor in place of the oil-lubricated compressor that is more often employed for terrestrial applications. There are a number of other unique features to this system, including the fact that all the heat rejection occurs through radiative heat transfer and the heat load is fixed (rather than being a function of source and sink temperatures). These unique features result in a system behavior that is quite different than conventional air-to-air heat pumps. The first part of this study considers the fluid selection, as choosing the best working fluid is critical for the overall performance and environmental safety of the system. This study then delves into the detailed performance analysis of the oil-free scroll compressors that are envisaged to be used in this system. Finally, the entire operating envelope of the heat pump system is considered, including variations in electrical load and seasonal variations in the radiative environmental temperature.