水平管外降膜蒸发传热性能实验研究

Experimental research on heat transfer performance of falling film evaporation on horizontal tubes

建立了降膜蒸发实验台,研究了在低压状态下水平管喷淋降膜蒸发的传热性能.实验蒸发管分别使用光管和某种型号强化管.实验测试了管子结构、喷淋流量以及在喷淋液中加入添加剂对换热的影响.结果表明,喷淋流量增大,管外换热系数和总传热系数都会有一定的增加,当增大到一定程度会出现换热效果变差的情况.强化管的总传热系数比普通光管高62%.本次实验使用的质量分数为4.15%的添加剂对于换热无强化效果.

A falling film evaporator test-rig was designed and established to study the heat transfer performance of spray falling film evaporation on horizontal tubes at low pressure. Smooth tubes and some kinds of enhanced tubes were taken as test objects. The impacts of tube structure, spray flow, and additives in spray solution on the heat transfer performance were studied experimentally. By analyzing the experimental results it is shown that with the increase of flow rate of spray liquid, the evaporative heat transfer coefficient and the overall heat transfer coefficient have a certain degree of increase. However, when the flow increases to a certain extent, there may appear an instance at that the effects of heat transfer become worse. The heat transfer coefficient of enhanced tubes is higher by 62% than that of smooth tubes. In this experiment,4.15% mass fraction of the additive has no enhancing effect on falling film evaporation heat transfer.