Effect of liquid-vapor interaction on the thermal performance of a flat grooved heat pipe

Flat grooved heat pipes (FGHP) are predominantly used in electronics cooling due to their ability to transfer high heat loads with small temperature differences and superior reliability. Modeling the underlying physics is challenging due to the presence of multiple simultaneous physical phenomena, including phase change, free surface, two-phase flow and heat transfer. In this study, a recently developed modeling tool H-PAT [1] is extended by including the interaction at the interface between the two phases of the FGHP's working fluid. The vapor phase is assumed to be saturated, eliminating the need to solve the energy equation for the vapor. Analytical solutions of liquid and vapor flows are used, and the steady-state energy equation is solved via a thermal resistance network to get the temperature distribution. Interface heat transfer is modeled using the fundamental findings of kinetic theory. The model is exercised to quantify the effect of vapor spacing on the thermal performance of a flat grooved heat pipe. The results show that liquid-vapor interaction on the interface enhances the evaporation performance in the micro-region, resulting in a more uniform temperature distribution.