Performance evaluation for a combined power generation system of closed-Brayton-cycle and thermoelectric generator with finite cold source at room temperature on hypersonic vehicles

Closed-Brayton-cycle (CBC) power generation system is a potential high-power electricity generation scheme for hypersonic vehicles, but finite cold source onboard limits its power level. One of power enhancement approaches is building a combined closed-Brayton-cycle and thermoelectric generator (TEG) power generation system, aimed to extend the available temperature range of cold source. In this study, a combined power generation system based on supercritical carbon dioxide closed-Brayton-cycle in combination with multi-stage thermoelectric generator is advanced on hypersonic vehicles to promote electric power, in which the cold source is hydrocarbon fuel at room temperature. Analysis results indicate that the electric power rise percentage realized by TEG is as high as 68.3%. At the maximum CBC power, the TEG power and according total electric power increase with the highest temperature of TEG coolant, but the increasing rate of electric power becomes lower due to the decrease of conversion efficiency. In addition, although the simple recuperated CBC has advantage on power output with finite cold source, the total power of combined system with recompressing layout is always higher, due to a larger heat absorption capacity of fuel for the thermoelectric conversion of TEG.