우주 비행체 열 제어 시스템을 위한 MEMS 기반 가변 방사율 라디에이터의 설계 및 성능 검증

Abstract

Recently, MEMS-based louver and shutter variable emissivity radiators have been developed to achieve the efficient thermal control by varying their emissivity according to the temperature condition. However, they are still problematic to be applied for space missions because they consume the power continuously to maintain the intended emissivity and their actuating parts are weak in terms of the mechanical strength. In this study, to overcome above drawbacks, we proposed a MEMS-based variable emissivity radiator, which can change the emissivity property according to the polarity change of electrodes by using electric charge of the silicon powder. The radiator was placed in the vacuum chamber to minimize the effect of convection heat transfer. The thermal control performance was evaluated by measuring temperature differences between two modes at the high and low temperatures. The temperature was recorded by an infrared (IR) camera. The IR thermographs at the hot and cold cases. The temperature difference at two cases. When the plate on which the radiator is attached is fixed to 53°C, the temperature at the closed mode was 45.6°C because of the high emissivity. On the other hand, at the open mode, the radiator temperature was 52°C because of the low emissivity. Overall, the radiator temperature at the open mode tended to be higher than that at the closed mode. The temperature difference between two modes at the hot case was 6.4°C. At the cold case where the radiator temperature was 10°C, the radiator temperature at the close mode was 13.1°C, whereas it is 6.2°C at the open mode. Thus, the radiator temperature at the closed mode was higher than that at the open mode. The temperature difference between two modes was 6.9°C. Based on the results, it is suggested that the operating concept and thermal control performance of the MEMS variable emissivity of radiator proposed in the present study was verified at the open and closed modes, respectively. In this study, the effectiveness of the performance tested the MEMS-based variable emissivity radiator.