基于有限元方法的溴化锂降膜吸收传热传质的数值研究

吸收器是吸收式制冷系统的重要部件。溴化锂溶液的降膜吸收是吸收器中最常见的传质传热形式之一。通过对溴化锂溶液在降膜吸收过程中传质和传热特性的分析,使用基于有限元法的COMSOL Multiphysics软件,建立了溴化锂溶液和水蒸汽降膜吸收的物理数学模型,计算了液膜内部温度和质量分数的分布、界面处传质通量、界面处传热通量、传质传热速率和液相传质传热系数。根据计算结果分析了喷淋密度对平均传质通量、平均传热通量和平均传质传热系数的影响。结果表明:平均传质系数和平均传热系数均随着喷淋密度的增大而增大;平均传质通量和平均传热通量均随喷淋密度的增大而先增后减。

Numerical study on heat and mass transfer of LiBr falling film absorption based on finite element method

Absorber is an important component of absorption refrigeration system. Falling film absorption is one of the most common forms of mass and heat transfer in absorption system. Based on the numerical simulation software COMSOL Multiphysics, the finite element method is used to establish the physics model of water vapor absorption into lithium bromide solution falling film. The distributions of temperature and concentration inside the liquid film, mass and heat transfer fluxes at the interface, local mass and heat transfer coefficient, mass and heat transfer rates were calculated. The effects of liquid film flow rate on average mass flux, average heat flux, average heat transfer coefficient and average mass transfer coefficient were analyzed. The results show that the average mass transfer coefficient and average heat transfer coefficient increases with the increase of liquid film flow rate. Average mass transfer flux and heat transfer flux will increase first and then decrease as the liquid film flow rate increases.