Effects of refrigeration in a transportable cryogenic aerospace application

Preliminary feasibility studies, based on refrigeration thermodynamics, have been conducted for candidate power conditioning components in a 1MWe terrestrial/transportable cryogenic power system. The cryogenic power system being considered has a super conducting generator for high power applications such as the power source for a Ground Based Radar (GBR) System. While the superconducting generator operates at 77K or lower, the present analysis indicates that significant benefits cannot be derived by cooling the various components of the power conditioning system to such low temperatures. It was found that, by operating the power conditioning component at 150K instead of at 77K the overall system efficiency was not jeopardized by way of large input power requirements to dissipate small refrigerator loads. This is an acute problem as current cryogenic refrigeration systems allow for very low levels of energy dissipation while performing at about 7 to 10% of the Carnot coefficients of performance (COP) between 300K and 77K