1995-07-01

A Parametric Study of Parabolic Radiator Shades for Lunar Base Thermal Control Systems 951525

When permanent bases are established on the moon, various methods may be employed to reject the heat generated by the base. One proposed concept is the use of a vertical thermal radiator operating with a parabolic shade. The shade reduces background environmental heating by several means, thereby, increasing the performance of the radiator. Specifically, the shade focuses the incoming solar radiation in a line above the radiator and through the use of thermal control coatings substantially reduces infrared radiation originating from the lunar surface. To further enhance the performance of the radiator, it is aligned with the moon's equator.Several different parabolic shade geometries were evaluated using the Thermal Synthesizer System (TSS) which allows the full spectrum of specular surfaces to be included in the modeling process. This modeling system uses a Monte-Carlo, ray tracing technique to determine the infrared radiation conductors between the model nodes and the environmental (solar) heating. The modeling system also allows for a variety of orbital parameters, such the beta angle or surface alignment, to be considered.For the current study, two different focal length parabolic shades were examined under a variety of operating conditions and thermal control coatings. The shade's infrared and solar specularity as well as its emissivity and absorptivity were varied. In addition, the radiator misalignment and off equator performance were examined. The results of the study showed that both the shade's solar and infrared specularity have a significant impact of the heat rejection capability of the radiator. Shade absorptivity and emissivity are also important parameters governing the heat transfer process. Also, radiator misalignment plays an important role in the performance of the radiator.

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