will provide both the photovoltaic and solar dynamic power generation systems. The Solar Dynamic Power Module (Fig. 8), consists of the solar energy concentrator, the radiator assembly, the power generation subassembly (PGS), and the necessary system structure and controls. As a subcontractor to Rocketdyne, Fluid Systems is developing the closed Brayton cycle PGS (Fig. 9), which is comprised of the receiver, turboalternator compressor (TAC), recuperator, cooler, and required controls and power conditioning. In order to provide the desired 25.0 kW net power to the station from each power unit, the PGS must produce a gross electrical power at the alternator terminal of 31.6 kW. However, changes in both insolation and sink temperature resulting from variations in orbital attitude, position in orbit and seasonal changes in solar insolation cause a significant difference in the energy input to the system between the most favourable and least favourable cases. In order to provide the desired output power at the least favourable condition, the PGS must be capable of producing 38.0 kW at the best condition (maximum insolation orbit at sunrise, when the station is leaving the eclipse period). The system operating parameters for this condition are shown in Fig. 10. Control of the system over the range of user demand and orbital conditions is accomplished by both load dissipation through a parasitic load radiator and by changing the operating fluid inventory (cycle pressure level). The heat source for the system consists of a concentrator and a receiver. The offset parabolic concentrator captures the solar rays and focuses this concentrated energy into the receiver. Since the power unit must function during the entire orbit, thermal energy storage in the form of molten salt is incorporated. The cylindrical receiver consists of 82 tubes carrying the He-Xe working fluid that absorbs the solar energy. These tubes are surrounded by canisters containing the salt, a eutectic mixture of LiF-CaF2, that operates through the orbit as a phase-change material. The latent heat of fusion of this salt provides thermal energy storage to provide heat to the engine while the Space Station is in the eclipse or shadow portion of the orbit. This heat
RkJQdWJsaXNoZXIy MTU5NjU0Mg==