不同流道结构的印刷电路板烟气换热器性能对比研究

Comparative study on performance of printed circuit exhaust heat exchanger with different flow channel structures

内燃机余热回收技术对节能减排具有重要意义,其中超临界二氧化碳(S-CO2)动力循环系统因成本低、环境友好等优点,受到越来越多的关注。烟气换热器作为S-CO2动力循环系统的关键部件,其换热性能直接影响循环整体效率。印刷电路板换热器具有换热效率高、结构紧凑的特点,但目前鲜有在内燃机余热回收上的应用。因此,本文开展印刷电路板烟气换热器的结构设计及优化工作。设计了3种S-CO2侧流道结构的烟气换热器,并通过数值模拟,对比了不同流道结构对换热器内部流动及换热性能的影响。结果表明,镂空流道烟气换热器的单位质量换热量与Kv值远高于直角流道换热器和圆角流道换热器,说明镂空流道印刷电路板换热器可以更好地满足小型化、紧凑化的要求。

Waste heat recovery technology of internal combustion engine is of great significance to energy conservation and emission reduction.Among them,supercritical carbon dioxide(S-CO2)power cycle system has received more and more attention due to its low cost and friendly to environment.As a key component of the S-CO2 power circulation system,the heat transfer performance of exhaust heat exchanger directly affects the overall efficiency of the circulation.Printed circuit heat exchanger has the characteristics of high heat transfer efficiency and compact structure,but it is seldom used in waste heat recovery of internal combustion engine.Therefore,this paper carries out the structural design and optimization for printed circuit type exhaust heat exchanger.Three kinds of exhaust heat exchangers with different flow channel structures at S-CO2 side were designed,and the effects of different flow channel structures on the internal flow and heat transfer performance of the heat exchanger were compared through numerical simulation.The results show that,the heat exchange per unit weight and Kv value of exhaust heat exchanger with hollow channel are much higher than that of the heat exchanger with right angle channel and rounded corner channel,indicating that the printed circuit heat exchanger with hollow channel can satisfy the volume requirement of small and compact.