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International Heat Transfer Conference 15

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

Thermal Radiation Characteristics in Sub-Micron Region for MEMS Space Radiator

Ai Ueno
The University of Tokyo

Yuji Suzuki
Department of Mechanical Engineering, The University of Tokyo Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

DOI: 10.1615/IHTC15.rad.009636
pages 7127-7134


KEY WORDS: Radiation, NEMS/MEMS, Radiation and MEMS

Abstract

Thermal management is crucial for high-functional spacecrafts operated in significant fluctuations of thermal environment. Previously, bulky heat exchangers such as heat pipe or thermal louvers/shutters with a low fill factor are proposed, but they are not suitable for next-generation small satellites. We have proposed an electrostatically-driven MEMS active radiator that enables higher fill factor. The operation principle is based on the near-field radiation effect, by which the radiation heat flux between a substrate and a movable diaphragm can exceed that for the black body when the gap is reduced smaller than the wavelength. In the present MEMS radiator, a diaphragm with a plane electrode is suspended with four polymer tethers, which is snapped down when the voltage is applied to the top electrode. In this report, we investigate the near-field radiation effect in the MEMS radiator with a preliminary experiment and thermal analysis. A measurement setup for the surface temperature of the diaphragm and the radiation heat flux in vacuum environment is developed, and the thermal contact resistance between the diaphragm and the substrate is investigated. The contact resistance of the present device is measured to be 5.5×106 K/W, which leads to 40 % increase in the radiation heat quantity. On the other hand, the thermal resistance of the near-field effect is estimated to be 4.7×105 K/W. Thus, when a MEMS radiator can utilize the near field effect, the total heat quantity can be increased by 12 times.

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