Radiative and evaporative characteristics analysis of a liquid droplet layer for space applications

Abstract

Liquid droplet radiator is promised to be used for waste heat dissipation of the large power space nuclear reactor. This paper analyzes the radiative heat transfer and evaporative characteristics by treating the droplet layer as a participating medium. The silicon oil is adopted as the working fluid. The mathematical models are established. The effects of the optical thickness κD, initial temperature, and flight time on the droplet radiation and evaporation are investigated. The main works are listed as follows: Firstly, the grid independence analysis of the temperature calculation is conducted, and the grid number on the thickness direction is suggested to be 100 times of κD. Secondly, the calculation results obtained from the one dimensional (1-D) simplified formula and the two dimensional (2-D) simulation have been compared, proving that it is acceptable to obtain the average temperature by 1-D simulation for droplet layers with any κD. Thirdly, detailed temperature distribution is calculated for both thin and thick droplet layers, and higher initial temperature and longer flight time can enhance the radiative heat transfer. Finally, the evaporative loss rate of the working fluid is found to be nearly constant with κD larger than 4. This paper may contribute to the thermal design and optimization of the liquid droplet radiator for space applications.