Printed Circuit Heat Exchangers (PCHEs) are applied in processes involving high temperatures and working pressures, such as the supercritical CO Brayton cycle. These devices are typically designed with semi-circular channels and zigzag paths to enhance thermal performance. In recent years, several Nusselt number correlations for zigzag channels have been proposed to estimate the thermal performance. However, under similar operating conditions and zigzag angles, these correlations yield divergent results for supercritical and non-supercritical condition. No study has compared these correlations to identify the most accurate one. Therefore, this research performed a thermal analysis of PCHEs operating with straight and zigzag channels, using fluids in normal and supercritical conditions. Additionally, it was evaluated existing Nusselt number correlations to determine which ones presents the best result. This study examined 37 Nusselt number correlations, analyzed four experimental studies available in the literature and evaluated a total of 374 experimental data. For straight channels, the error ranged from 3% to 27%, whereas for zigzag channels, the error varied between 3% and 84%. This demonstrates how correlations developed for the same application can lead to discrepant results.

中文翻译：

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直通道和锯齿形通道印刷电路热交换器的努塞尔数分析

印刷电路热交换器 (PCHE) 适用于涉及高温和工作压力的过程，例如超临界 CO 布雷顿循环。这些设备通常设计有半圆形通道和锯齿形路径，以增强热性能。近年来，人们提出了几种锯齿形通道的努塞尔数相关性来估计热性能。然而，在相似的操作条件和锯齿角下，这些相关性对于超临界和非超临界条件产生不同的结果。没有研究比较这些相关性以确定最准确的相关性。因此，本研究使用正常和超临界条件下的流体，对直通道和锯齿形通道运行的 PCHE 进行了热分析。此外，还评估了现有的努塞尔数相关性，以确定哪些提供了最佳结果。这项研究检查了 37 个努塞尔数相关性，分析了文献中的四项实验研究，并评估了总共 374 个实验数据。对于直线通道，误差范围为 3% 至 27%，而对于锯齿形通道，误差范围为 3% 至 84%。这表明为同一应用程序开发的相关性如何导致不同的结果。