Simulation of the Vapor-Liquid Two-Phase Flow of Evaporation and Condensation

The heat pipe receiver with integrated high temperature latent thermal energy storage is one of the key components of Solar Dynamic Space Power System (SDPSS), among which the evaporation and condensation is the main heat transfer mode, a very complicated two-phase flow. However, research on the two-phase flow and heat transfer characteristics is an effective way to improve the system efficiency and reduce the system mass. So a two-dimensional physical model was built and the volume of fluid (VOF) technique was used to model the interaction between the two phases. The UDF (Users Define Function) was introduced to handle the mass source terms. In the study, the relationship between superheat, subcooling and wall heat flux were investigated. In addition, the flow pattern of bubbles in the tube was analyzed. Compared with the churn bubbles flow, the heat transfer coefficient of the bubbles flow was much higher. Bubble departure diameter increased as surface subcooling increased. The work in this paper lays a good foundation for the further research on the heat transfer characteristics of heat pipe receiver with integrated high temperature latent thermal energy storage.