Numerical study of two-phase hydrodynamics for boiling heat transfer in bi-porous evaporator

Bi-porous evaporator for heat pipes has been studied to replace conventional mono-porous evaporators with lower thermal capacity. The thermal superiority of bi-porous evaporator is a direct function of phase separation phenomenon in small and large-pore zones. However, due to the microscale nature of the system the hidden microscopic phenomenon associated with thermal superiority has not been well established experimentally. In addition, only a few numerical studies have addressed this phenomenon using limited information. In this paper, a two-dimensional numerical simulation is conducted which accurately predicts the thermal performance of a bi-porous evaporator. Additionally, for the first time, several microscopic phenomena such as phase separation, vapor blanket formation, and liquid film formation are numerically reproduced. Thus, the thermal performance of bi-porous evaporator is successfully quantified. The effects of various design parameters are also studied and their effect on thermal performance is also quantified. For comparison, a mono-porous evaporator is also simulated.