降膜蒸发式冷却器传热性能模拟分析
Simulation Analysis of Heat Transfer Performance of Falling Film Evaporative Cooler

为研究降膜蒸发式冷却器的传热性能，通过仿真和实验相结合，探究了呈叉排排列的水平管在不同喷淋密度和迎面风速下的降膜流动和热质传递。结果表明：在周向上，液膜厚度先变小后变大，最薄区域位于周向角90？~110？内；迎面风速的增大对水平管下半部分的液膜厚度影响较大。局部传热系数随喷淋密度和迎面风速的增大而增大，在周向角0？~20？内，局部传热系数迅速减小，而在160？~180？范围内，局部传热系数出现回升。迎面风速和喷淋密度的增大，可以提高水平管外液膜的热质传递效果，并存在最佳喷淋密度0.092 kg？m^？1？s^？1。工况范围内汽化换热量占总换热量的比值为0.73~0.79，且随迎面风速的增大而下降。
In order to study the heat transfer performance of falling film evaporative cooler, the falling film flow and heat and mass transfer of horizontal pipe arranged in a fork at different spray density and head-on wind velocity were investigated by combining simulation and experiment. The results show that in the circumferential direction, the thickness of liquid film decreases first and then increases, and the thinnest region is within 90？~110？ of the circumferential Angle. The increase of head-on wind velocity has a great influence on the liquid film thickness of the lower part of the horizontal pipe. The local heat transfer coefficient increases with the increase of spray density and head-on wind velocity, and it decreases rapidly in the circumferential angle of 0°20°, while it rebounds in the range of 160？~180？. The increase of head-on wind velocity and spray density can improve the heat and mass transfer effect of the liquid film outside the horizontal pipe, and there is optimal spray density of 0.092 kg？m^？1？s^？1. The ratio of vaporization heat transfer to total heat transfer is 0.73~0.79, and decreases with the increase of head-on wind velocity.