Abstract: Aiming at the problem that the radiator of manned space thermal control system is designed according to the maximum heat load and is difficult to adapt to the low temperature condition, a technology of variable-emittance radiator based on near-field thermal radiation regulation is proposed. An effective emittance model of a radiator involved in near-field thermal radiation is developed, and the dependences of near-field radiative heat flux and effective emittance on voltage are solved by using fluctuational electrodynamics and semiconductor carrier transport theory. The coupled heat transfer model of variable-emittance radiator and single-phase fluid loop is established, and the performance of the scheme for temperature control of working medium is simulated and analyzed. The results show that the emittance can be varied up to 0.62 in the voltage range of -5 V to 20 V, and the lowest emittance can be reduced to less than 0.2 under heat preservation condition. Used in conjunction with single-phase fluid loop, the perfluorotriethylamine (PFTA) working medium can be maintained in the normal operating temperature range (-100-50℃) under various internal thermal loads and external thermal environments by tuning the control voltage, thus improving the adaptability of the thermal control system. Although it’s currently difficult and costly to fabricate, with the development of nano-processing technology, the technology has the potential to serve space missions with more complex and variable thermal environments, such as manned deep space exploration.

Key words: spacecraft thermal control, radiator, variable emittance, single-phase fluid loop, electrically tunable near-field thermal radiation