Abstract:

An experimental investigation of falling-film generation outside vertical tube with lithium chloride aqueous solution was conducted.For the purpose of the development of a high performance of heat and mass transfer utilizing a lithium chloride aqueous solution as the working pair in solar absorption refrigeration system which use the low grade source, an experimental apparatus is set up to study the process of heat and mass transfer in generator using low temperature source.The experiments show that how the operation conditions such as the flow rate of hot water and the solution, the temperature of the heat source, the concentration of the solution and the system pressure influent the generation process.Some contrast experiments at the same condition with lithium bromide are carried on.The variation trend of the vertical falling film generation with lithium chloride aqueous solution is similar with that with lithium bromide aqueous solution.Although the mass rate of falling film generation with lithium chloride aqueous solution is slightly lower than that using lithium bromide aqueous solution, it has little difference in the effect of heat and mass transfer, and it is good for the performance of the system cycle which using the two working pairs becoming higher at the same condition because of the low operation concentration of lithium chloride aqueous solution.

Key words: experimental validation, vertical tube, falling-film, mass transfer, lithium chloride aqueous solution, laminar flow

摘要：

为了探究LiCl水溶液在低位太阳能吸收式制冷系统中的发生过程中的传热传质效果，在降膜发生实验装置基础上研究了LiCl水溶液在垂直管外降膜发生的传热传质过程。阐述了不同运行工况如不同的热水和溶液的流量、热源的温度、溶液的浓度和系统压力对LiCl水溶液发生过程传热传质效果的影响。同时也进行了相同工况下LiBr水溶液的对比实验。结果表明相同运行工况下LiCl水溶液降膜发生过程和LiBr水溶液的降膜发生过程有着相似的变化规律。虽然LiCl水溶液的垂直降膜发生速率略低于LiBr水溶液，但传质效果相差不大，LiCl溶液的低运行浓度有利于循环热力性能的提升。

关键词: 实验验证, 垂直管, 降膜, 传质过程, LiCl水溶液, 层流