Simulation and Experimental Study of Two-Phase Gas–Liquid Behavior in Two-Dimensional Porous Medium Based on Lattice Boltzmann Method

Abstract Loop heat pipe is a passive two-phase heat transfer device. The key component of the loop heat pipe is the evaporator. In this study, the gas–liquid two-phase behavior inside a two-dimensional porous medium with a single-pore size and multi-pore size distributions was comparatively studied, both experimentally and numerically by the lattice Boltzmann method. With a constant heat flux applied to the evaporator's shell, the wick initially fills with saturated liquid, then undergoes evaporation with vapor invasion, and partially dries out with a gas–liquid interface. Due to the multi-pore size distribution in porous medium, vapor is more easily expelled from the wick. There is a significant difference gas–liquid interface inside the wick between the single-pore size wick and the multi-pore size wick, and the temperature of the evaporator's shell of the multi-pore size wick is 27.6% lower than that of the single-pore size wick. To validate the numerical results, two loop heat pipes were built, including monoporous wick and biporous wick, respectively. The experiment found that under high power, the performance of loop heat pipe with biporous wick is significantly better than that of loop heat pipe with monoporous wick. The temperature of the biporous wick is 9.79 K lower than that of the monoporous wick at 230 W. Experiments and simulations show that the porous medium with multi-pore has better performance.