地铁站板式蒸发冷却器叉流条件下传热传质特性

Subway Station Plate Evaporative Cooler Heat and Mass Transfer of Falling Film under Gas-liquid Cross-flow Condition

在气液叉流条件下,采用非接触式红外热成像测温方法,就不同气相雷诺数和液膜雷诺数对地铁站板式蒸发冷却器液膜传热传质特性影响进行了实验研究,结果表明:对于确定的被冷却水温,在液膜雷诺数增加的过程中,液膜厚度逐渐增加,进出口温差逐渐减小,削弱液膜换热,但雷诺数上升使得液膜湍动强度增强,强化了液膜换热,在这2个因素的协同作用下,存在最佳液膜流动雷诺数,使得液膜的换热热阻最小,传质最强,换热系数最大。

With the influence of the different gas Reynolds number and liquid Reynolds number on falling film heat and mass transfer of subway station plate evaporative cooler,the experiment was carried out by non-contact infrared thermal imaging technology under gas-liquid cross-flow condition.The results indicated that during the increasing of liquid Reynolds number the thickness of liquid film increased and the temperature difference between liquid film inlet and outlet decreased in determined heating water temperature which weakened the heat transfer of liquid film.However,the increase of liquid Reynolds number strengthened the liquid film turbulence that enhanced heat transfer.Under the synergistic effect of these two factors,there was an optimal liquid Reynolds number which minimize thermal resistance and maximize heat and mass transfer coefficient of liquid film.