竖管内溴化锂溶液降膜发生实验研究

Experiment Research on Lithium Bromide Solution Falling Film Generation in Vertical Tube

针对气体类低品位热源驱动的溴化锂溶液吸收式制冷而提出采用竖管内降膜的发生器,其特点是溴化锂溶液薄液膜在竖管内由上而下流动,气体热源在管外部加热。通过实验得到降膜发生传热系数、放气范围、冷剂蒸汽产量与流量、热流密度的变化特性。实验结果表明:层流降膜时(Re<500),传热系数随Re增大而减小,随热流密度增加而显著增大。回归分析得到层流降膜的传热系数关系式:h=14009.87qw 0.0764 Re-0.5391。

A falling film style generator in the lithium bromide absorption refrigeration system was proposed, in which the solution film flows down in vertical tubes and is heated by a low-class exhausted gas. The changes of heat transfer coefficient, deflation ratio and the steam mass flow rate in different solution volume flow and heat flux were obtained by the experiment. The experiment results show that the heat transfer coefficient decreases with the increase of Re number in film laminar flow （Re〈500） and increases significantly with the increase of the heat flux. The heat transfer coefficient in film laminar flow was deduced by analysis and polynomial regression, i.e., h= 14009.87qw^0.0764Re^-0.539.