Investigation of Lightweight Space Radiator Design for Low and No Gravity Environments

Abstract

Space heat rejection is heavily relying on radiator subsystem, which is only depended on pure radiation heat transfer and typical convection is not available. Increased efficiency coupled with reduced mass is of strategic importance in space thermal system. This paper reviews the existing individual aspects of lightweight space radiator subsystem designs under low and no gravity environments, i.e. working fluids, fin design, or optimization, based on standard construction materials. In addition, new concept approaches using latest technologies and their challenges are also investigated in this study. Common designs include heat pipe, liquid sheet, and liquid droplet radiators, the latter two being more conceptual than functional. Most technological advances have been made in the materials of construction and optimization areas while using the traditional heat pipe design since 1960s. Carbon composites are the most promising material for construction, as they possess a good heat transfer rate while minimizing the weight of the system. Working fluids selection has more to do with the operational temperature range than the system design, though construction materials must be taken into account when selecting a working fluid. Fin design is the least reported on, but the general consensus is triangular fins are the best option for minimizing weight while increasing surface area for radiation. Based on the review of current research, the most promising design would be a carbon composite heat pipe with a working fluid of liquid water or ammonia and triangular fins.