板式换热器触点分布对换热阻力性能的影响

为进一步提升人字形板式换热器的综合性能,对其触点分布进行研究,得到触点分布与下层波峰线到板换长度方向对称轴的距离L的关系式。通过数值模拟,分析人字形板式换热器单流道模型L改变时,换热和阻力的变化情况。随着L的变化,第一层触点位置周期性变化,压降与Nu数均呈现周期性变化,在半周期位置获得最小值;面积质量因子j／f的变化也呈现周期性,趋势和压降、Nu数变化相反,由于流场分布的均匀程度不同,j／f在半周期位置获得最大值。触点分布对换热阻力的影响,随着Re的增大而逐渐增大。结果表明:选择L为半周期时,可以在板式换热器的3个基本参数不变的情况下,进一步提高板换的综合性能。

Effects of the contact points distribution on heat transfer and resistance performances of plate heat exchangers

In order to improve comprehensive performance of plate heat exchanger, the distribution of contact points was investigated. The correlations between the distribution and L were obtained. The L was the distance between lower crest line and symmetry axis of plate heat exchanger. Numerical simulation was conducted to investigate the influence of distribution of contact points to the performances of plate heat exchanger. Heat transfer performance and pressure drop characteristics of the chevron plate heat exchanger were got. The results showed that positions of first row contact points, pressure drop and Nu changed periodically, which could get their minimum at half of the cycle. The comprehensive factor j／f had the same cycle and the opposite trend with Nu and pressure drop, which could obtain its maximum at half of the cycle. The influence of the distribution of contact points to the performances of plate heat exchangers increased with the increasing of Re number. The comprehensive performance of plate heat exchanger could improve at half of the cycle.