竖管内溴化锂溶液降膜蒸发数值研究

NUMBERICAL RESEARCH OF FALLING FILM EVAPORATION OF LITHIUM BROMIDE SOLUTION IN VERTICAL TUBE

研究以太阳集热板制取的高温空气为热源,直接驱动竖管内溴化锂溶液降膜蒸发的传热性能。提出适用于竖管内溴化锂溶液降膜蒸发传热传质耦合的数学模型,根据合理的数值解法,运用MATLAB软件编程,计算出降膜区域内温度场和浓度场,入口Re数越大,换热效果相对降低,而传质效果增强,并得到量纲为1的降膜换热准则式。通过与经验公式对比发现,溴化锂溶液中传质对传热有抑制作用,且其影响不可忽略。

The heat transfer performance of falling film evaporating LiBr solution in-vertical tube was investigated, which was directly driven by hot air from solar collector. Based on the coupled models of heat transfer and mass transfer, the numerical method of falling film evaporation of lithium bromide solution in vertical tube was presented Using reasonable mathematical solution and MATLAB, the concentration and temperature distributions were calcu- lated, the heat transfer coefficient was weaken with the increasing of inlet Re number, but the mass transfer coefficient was enhanced, and dimensionless relation of falling film evaporation was obtained. The compared results show that mass transfer will restrain heat transfer in falling film, and the affection can＇ t be neglected.