以工业广泛使用的板式换热器为研究对象，模拟了人字型波纹板片和凹坑型板片内的流动和换热，得到了平均努塞尔数Nu、阻力系数和综合传热性能因子随雷诺数Re的变化，分析了凹坑深度对换热性能的影响。相同工况下，人字比凹坑型板片的换热效果好但阻力大，故后者综合性能更优。相同来流速度下，凹坑深度越小，综合传热性能越优。同时，对凹坑板式换热器的热阻分析表明，换热温差给定时，热阻越小，换热量越大，因此热阻也可以评价板式换热器的性能。
The plate heat exchangers have been widely used in industry. This paper presents a numerical simulation of the fluid flow and heat transfer characteristics in cross-corrugated chevron-type plate heat exchangers and dimpled ones. The variations of the overall Nusselt number, resistance coefficient and integrated heat transfer performance factor with the Reynolds number and the dimple depth are obtained. The results show that under the same conditions, both the Nusselt number and the resistance coefficient of the cross-corrugated chevron-type plate are higher than that of the dimpled one. Thus, from the view of the integrated heat transfer performance, the dimpled plate is better. Furthermore, the integrated factor increases as the dimple depth decreases for the studied seven different dimple depths with the same inlet fluid velocity. It is found that the heat transfer processes in plate heat exchangers can be well described by the concept of generalized thermal resistance. Under prescribed temperature boundary conditions, the heat transfer increases with the decrease of the thermal resistance. Therefore, the generalized thermal resistance can be taken as an evaluation standard for the heat transfer performance of a plate heat exchanger.
参考文献
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