Closed Brayton Cycles for Power Generation in Space: Modeling, simulation and exergy analysis

Abstract

The opportunity of producing power in space seems to be attractive considering the exponential growth of the human population and the renewed interest in space missions. Space Solar Dynamic Systems promise to be a better alternative to PVs by eliminating the need for batteries, offering lower drag problems and high efficiencies taking advantage of the lower temperature of space. In this paper the modeling, simulation and exergy analysis of a Closed Brayton Cycle (CBC) for power generation in space driven by a solar parabolic collector is presented. The main objective has been the investigation of a “reduced weight” configuration, to reduce the launch costs, one of the most critical issues for the system feasibility. The investigation of a “reduced weight” configuration has been performed identifying the key process parameters: the compressor inlet temperature and its pressure ratio and the receiver diameter. Starting from the NASA Freedom data, the results have shown a weight reduction of 21% and an exergy efficiency increase of 7.4%. A comparison with a CBC driven by nuclear power has been then performed, showing the thermodynamic conditions for which the solar dynamic systems could get the recommended specific weight of 30 kg/kW.