人字形波纹板式换热器性能数值模拟的研究

Hydrodynamics and thermal characteristics of chevron-type plate heat exchangers

基于简化模型的计算结果难以准确描述换热器内完整的流体流动和换热特性。为此,本文建立与人字形波纹板片完全相同的,含分配区和传热区冷热双流道换热的计算模型,用计算流体力学软件Fluent 6.3,数值模拟4组不同名义速度下流体的流动和换热情况。分析流道内速度场和温度场发现,进口分配区对流体流动分布和换热都有显著影响,还将流体在流道内的流动情况详细描述。两侧流体的压降和进出口温差的计算值与实验值的误差小于6%,较准确地反映了换热器内整体的流动和换热特性,可直接用于研究板式换热器的性能,具有一定的工程实际意义。

Simulation results based on the simplified model are difficult to predict hydrodynamics and thermal characteristics of plate heat exchanger accurately. Therefore, a model of the accurate size of actual chevron-type plate heat exchanger geometry is built in this paper, including distribution area and heat exchange area, with two channels for hot and cold water respectively. Using CFD software FLUENT 6. 3, the pressure drop and heat transfer coefficient for cross-corrugated plate heat exchangers at four different inlet velocities were investigated. By analyzing the simulation results of velocity and temperature fields, the structure of distribution area of inlet and outlet has significant influence on overall hydrodynamics and heat transfer performance of PHEs. The flow patterns in two channels were described in detail. The simulation results of pressure drop and temperature difference between the inlet and outlet were compared with the experimental data, which shows a less than 6% error. From the simulation results, the hydrodynamics and thermal characteristics of chevron-type plate heat exchangers was properly reproduced and this method is feasible alternative of physical performance test of PHEs, which is of some practical significance.