超临界二氧化碳在印刷电路板式换热器内的流动换热特性研究

印刷电路板式换热器（PCHE）是一种微通道换热器，具有换热效率高、耐高温、耐高压等优势，可广泛应用于海洋工程、核能、光热发电等领域。本文采用数值模拟的方法，计算了跨拟临界点超临界二氧化碳（SCO₂）在印刷电路板式换热器内的流动换热特性。结果表明：SCO₂流体温度达到拟临界温度时，流通截面内流体温度分布最均匀，因为此时流体的有效导热系数最大；SCO₂侧对流换热热阻在总热阻中占比最大，其次为导热热阻，水侧对流换热热阻最小；采用等效厚度法计算得到的导热热阻偏大；雷诺数越大，在拟临界温度附近换热强化的程度越大。

Flow and Heat Transfer Characteristic Study of Supercritical CO2 in Printed Circuit Heat Exchanger

Printed circuit heat exchanger (PCHE) is a micro-channel heat exchanger with the benefit of high efficiency, and can endure high temperature and pressure. Based on these benefits, PCHE are widely used in marine engineering, nuclear engineering and solar thermal system. The flow and heat transfer characteristic of supercritical CO₂ (SCO₂) near pseudo-critical point in PCHE was numerically studied in this paper. The results show that the temperature distribution is the flattest when the SCO₂ fluid temperature reaches pseudo-critical temperature, because the effective thermal conductivity of the fluid is the largest. The convection thermal resistance of SCO₂ is the largest of the total resistance, and then is the conductive resistance, the smallest is the convection thermal resistance of water. The conductive resistance calculated by equivalent thickness method is larger than simulation.With the increase of Reynolds number, the enhancement of heat transfer near pseudo-critical point is enhanced.