2019 Volume 27 Issue 1 Pages 43-52
In order to realize a liquid droplet radiator (LDR), which is an equipment used for waste heat rejection in large space structures, the exhaust heat characteristics of a single liquid droplet stream in vacuum are required. In this study, these characteristics were obtained by a combination of experiments and numerical analyses. Experiments were conducted for measuring the amount of waste heat coming from a single liquid droplet stream of silicone oil as the working fluid, using a radiant flux sensor (RFS). The emissivity of the RFS at low temperature was measured, using a black radiation ball with known emissivity at 26°C. Numerical analyses were also performed to separate the radiation from the background of the experimental apparatus included in the radiation measured by the RFS. It was determined that at approximately -180°C, the emissivity of the RFS falls from the catalog value of 0.8 to 0.5. Moreover, the emissivity of the liquid droplet was found to be approximately in the range 0.42–0.51 and the effective emissivity of the single droplet stream was approximately 0.10. The application of these results can improve the feasibility of LDRs.
