加导流条的间接蒸发冷却器性能实验研究

Experimental study on performance of indirect evaporative cooler with stream guiders

通过正交实验方法,对一台加有正弦型波纹导流条的板式换热器性能进行了研究。实验发现,阻力的实验结果大于层流的理论计算结果;随着二次空气与一次空气流量比的增加,干工况的换热器效能降低,湿工况的换热器效能增加。导流条的应用增加了流动阻力,对换热的作用具有两面性:一方面因扰动而强化换热,另一方面也可能因导流条波谷处的固定漩涡而阻碍换热。由于壁面非均匀润湿的原因,湿工况的换热器效能不增反降,因此提高换热器润湿率是提高间接蒸发冷却换热器性能的重要措施。

The performances of a plate-type indirect evaporative cooler with sinusoidal stream guiders were investigated through the orthogonal experiment.It shows that the experimental values of flow pressure drop are greater than those calculated according to the theoretical equation for fully-developed rectangular laminar flow.With the increasing of the mass ratio of the secondary air flow to the primary air flow,the effective value decreases in dry conditions,but increases in wet conditions.Compared with the ordinary plate type heat exchanger,the flow pressure drop increases with the sinusoidal inserts.However,the influence of which on the heat transfer performance is two-fold： while the disturbance caused by the inserts may help to enhance the heat transfer,the flow vortices in the troughs of the inserts deteriorates the performance.Because the water film on the wall is not well-distributed,the efficiency drops in wet conditions.So,increasing the surface wettability is an important measure to improve the heat transfer performance of the indirect evaporative cooler.