竖直圆管内R113的降膜换热特性数值模拟

为开发适用于低温热源的高效降膜蒸发换热装置,本研究采用FLUENT软件对低沸点有机工质氟利昂(R113)在竖直管内汽液两相逆流降膜蒸发进行模拟研究。汽液界面捕捉选用VOF模型,并通过udf编程模拟汽液两相蒸发传热,研究了喷淋密度、热流密度及入口温度对R113降膜蒸发换热的影响。结果表明:在一定结构参数下,存在降膜换热最佳喷淋密度;在一定喷淋密度下,热流密度对降膜换热影响显著,且热流密度越高换热效果越好;随着入口温度升高,降膜换热效果削弱,且高于某温度后其对降膜换热几乎没有影响。

Numerical Simulation on Falling Film Heat Transfer Characteristics of R113 inside Vertical Tube

For developing high efficiency falling film evaporation heat exchange device that is suitable for low temperature heat source recovery & power generation,the gas-liquid two-phase countercurrent falling R113 (low-boiling working medium) film evaporation inside vertical tube was numerically studied by FLUENT software.The gas-liquid interface was captured by VOF model,and gas-liquid two-phase evaporation heat and mass transfer was simulated by using UDF programming.The effects of spray density,heat flux and inlet temperature on the heat transfer of falling film evaporation of R113 were studied.The results showed that the falling film heat transfer has the optimal spray density under certain structural parameters.Under a certain spray density,the heat flux has a significant effect on the film heat transfer.And the higher the heat flux,the better the heat transfer effect.With the increase of the inlet temperature,the heat transfer effect of falling film becomes weaker.And it is almost no effect on the falling film heat transfer when the temperature rises to a certain value.