换热器板管间隙对流动与传热的影响研究

Study of influence of baffle-tube clearance of heat exchanger on fluid flow and heat transfer

折流板换热器中,由板壳间隙引起的漏流和由板管间隙引起的漏流均不利于壳程侧的传热。为此,通过数值模拟,以GB151—1999推荐尺寸为基准,对管壳式折流板换热器壳程内板管间隙对压降、传热系数以及综合性能的影响进行了研究与分析。计算中采用标准κ-ε方程,SIMPLE算法,压力方程为标准格式。分析结果表明,当换热器壳程流体流量较小,板管间隙在小于等于国家一级管束基准间隙时,可以取得较好的传热效果,但较小的间隙使得压降增大,综合性能指标较差;当换热器壳程流体流量较大时,可以在充分考虑制造安装精度的前提下,适当减小板管间隙,以取得较好的传热效果。

The characteristics of fluid flow and heat transfer in the shellside of tubular heat exchanger are studied with different clearance between tube and tube hole in baffle under directions of GB151-1999, in which tube outer diameter is selected as 19 mm. The numerical simulations are carried out by using the CFD code FLUENT, and the pressure drop, heat transfer coefficient and comprehensive characteristics of shellside in the tubular heat exchanger are studied and analyzed. It can be concluded that for the condition of small flow rate, the comprehensive characteristics of tubular heat exchangers would be improved by enlarging the clearance between the tube and tube hole in baffle appropriately based on recommended values of GB151-1999, and for the condition of high flow rate, the heat transfer will be enhanced but with little negative influences to the comprehensive characteristics by reducing the clearance between the tube and baffle hole appropriately based on recommended values of GB151-1999.