溴化锂溶液竖管内降膜蒸发传热性能分析

Heat transfer performance analysis of lithium bromide solution falling film evaporation in vertical tube

为了直接高效利用低温烟气余热驱动制冷,对不同热流密度、不同浓度溴化锂水溶液竖管内层流降膜蒸发的传热性能进行了实验研究。结果表明,降膜传热系数随溶液进口浓度升高而减小,随热流密度增加而显著增大。对实验数据进行多元线性回归计算,得到实验范围内降膜传热系数关联式。用该关联式设计降膜蒸发传热的降膜式发生器,并对相同传热量的沉浸式发生器进行设计,性能对比表明,降膜式发生器在传热系数、换热组件重量和体积上有十分显著的优势。

For making the refrigeration system directly driven by low temperature waste flue gas heat more efficiently,an experimental research on the heat transfer of vertical in-tube laminar falling film with different heat fluxes and different concentrations of lithium bromide solution is conducted.The outcome of falling film evaporation experiments show that the heat transfer coefficient increases with the decrease ofinlet concentration of lithium bromide solution and significantly increases with the increase of heat flux.Based on multiple linear regression calculation of experimental data,an experimental correlation of falling film heat transfer coefficient is obtained.A falling film generator of lithium bromide absorption chiller is designed from the correlation,and the immersed generator whose heat load is equal to the falling film generator is designed.The comparison of the two generators on heat transfer coefficient,weight and volume of heat transfer components shows that the falling film generator has great advantages.