印刷电路板换热器中S-CO_(2)换热特性数值分析

Numerical analysis of S-CO_(2) heat transfer characteristics in a printed circuit heat exchanger

为了探究超临界二氧化碳(S-CO_(2))在直通道印刷电路板换热器(PCHE)中换热特性,本文采用数值模拟方法对此问题进行了研究。计算分析了S-CO_(2)在印刷电路板换热器中的换热特性,并对比了在单独改变一侧通道入口温度、工作压力及工质流量时对流换热系数和壁面努塞尔数的变化趋势。研究结果表明:由于工作压力不同,超临界二氧化碳工质存在从类液区向类气区过渡的情况,导致印刷电路板换热器换热通道入口温度或流量变化相同时对流换热系数和壁面努塞尔数呈现出不同的变化趋势。保持超临界二氧化碳工作压力和流量一定时改变冷侧入口温度比改变热侧入口温度对印刷电路板换热器热功率的影响更大;改变热通道的压力或流量要比改变冷通道的压力或流量对PCHE热功率的影响更大。

In this study,numerical calculation methods are used to conduct in-depth research to analyze the heat transfer characteristics of supercritical carbon dioxide(S-CO_(2))in a printed circuit heat exchanger(PCHE).The heat transfer characteristics of S-CO_(2) in PCHE are calculated and analyzed,and the change trends of the convective heat transfer coefficient(h)and Nusselt number(Nu)are compared when the inlet temperature,working pressure,and working fluid flow rate of one side channel are individually changed.The research results show that because of different working pressures,when the PCHE side channel inlet temperature or flow rate is changed,h and Nu on the wall exhibit different trends.Changing the inlet temperature of the cold side has a more considerable effect on the thermal power of the PCHE than changing the inlet temperature of the hot side.When the working pressure and flow rate of S-CO_(2) are kept constant,changing the pressure or flow rate of the hot aisle affects the thermal power of the PCHE more considerably than changing the pressure or flow rate of the cold aisle.