Study On Heat And Mass Transfer Of The Evaporating Meniscus Based On Surface Evolver

Heat and mass transfer capability of evaporating capillary meniscus in a porous structure is crucially important for the operation of capillary pumped heat transfer devices. In this thesis, the calculation principles of mass flow rate of the evaporation on capillary meniscus is studied. Microstructure geometry model of capillary meniscus is built using an open program-Surface Evolver, and is imported into FLUENT to establish numerical simulation model to simulate, heat and mass transfer of capillary meniscus is analyzed. Based on the microstructure geometry model of capillary meniscus,a mathematical model of macroscopic three-dimensional loop heat pipe(LHP) disc evaporator is coupled and numerically solved, the influence of the geometry and the thermal load on the heat transfer and flow of the evaporator is analyzed.The research results indicate that,when solid-liquid contact angle increases, the degree of curvature of the capillary meniscus becomes small,capillary meniscus spreads out to smaller surface area,heat transfer of the evaporation is reduced; change of the surface tension has no effect on the geometry of the capillary meniscus in Surface Evolver. For the microstructure geometry model of capillary meniscus, the temperature of the liquid is higher when closer to the solid skeleton; Along the x-axis direction, the temperature of the evaporation interface decreases, the mass flow rate is evaporation reduced, the velocity on the evaporation interface is larger when the degree of curvature is higher, Marangoni effect is formed due to the non-isothermal evaporation of the interface which facilitates the flow of heat transfer. For the model of three-dimensional disc LHP evaporator, the wick structure and steam channel structure have great influence on the temperature distribution inside the evaporator; the flow and heat transfer characteristics of the liquid in the compensation chamber exhibit a large difference under different heat loads, the internal heat exchange has a significant difference. Under high heat loads, reverse thermal and sidewall heat leakage form a local hot spots in the compensation chamber.