Design and performance analysis of converging heat pipe radiator applied for astronautical thermal management

• An innovative converging heat pipe radiator is designed and analyzed. • The maximum capillary pressure demand might decrease compared to the straight pipe. • The power-mass ratio could be improved if the fin efficiency is sufficiently high. With the development of space missions, the demands for heat rejection of spacecrafts keep growing, which makes a high power-mass ratio radiator a critical component. Heat pipe has advantages in light weight and high thermal conduction, hence Heat Pipe Radiator (HPR) is a conventional choice for large-power spacecrafts. In this study, a converging heat pipe radiator is proposed. This type of HPR reduces its radius along the axial direction to decrease mass. The influence of converging on pressure, temperature and power-mass ratio are studied. Computational Fluid Dynamics (CFD) is used to calculate the internal flow field and external radiation power. The results show that the power-mass ratio of high efficiency fin HPR rises monotonously with the decline of the converging ratio, maximum rise of 8.3%, while low efficiency fin HPR drops monotonously, maximum drop 4.7%. For the aspect of losses, slightly converged HPR have even lower pressure loss, while highly converged HPR have higher, the magnitude and direction of change depend on the heat rejection power and converging scale.