Searching for an analogy concept between heat transfer and pressure drop is anything but new, nevertheless it is still the subject of researches as it enables the prediction of heat transfer from pressure drop data, which helps reducing experimental effort for heat transfer measurements. The Generalized Lévêque Equation (GLE) is a widely-used analogy concept, which allows the prediction of heat transfer from pressure drop data, if hydrodynamic boundary layer is developed or still developing. This analogy concept has been successfully applied to flow situations with practical relevance like chevron-type plate heat exchangers, packed beds and in tube bundles, where the boundary layers are forced to reform continuously. In this contribution, the GLE is applied to flat tube flow without and with passive inserts, investigating the impact of passive inserts, which force the boundary layers to reform continuously, on the application of the GLE.

This paper presents results of an experimental investigation on pressure drop and heat transfer in flat tubes without and with passive inserts, covering a wide range of Prandtl number (8 < Pr < 60) and Reynolds number values (40 < Re < 3500). These parameter ranges and the passive inserts represent the typical conditions and design used for the liquid side of single-phase flat tube heat exchangers used in the automotive industry. 238 experimental data points for heat transfer coefficients are compared to heat transfer coefficients calculated from pressure drop data with the GLE.

The results show that the GLE is not applicable to flat tubes without passive inserts, yet becomes applicable with passive inserts, which are forcing a re-formation of boundary layers in the whole range of investigated Reynolds and Prandtl numbers.

在传热和压降之间寻找类比概念并不是什么新鲜事物，尽管如此，它仍然是研究的主题，因为它可以根据压降数据预测传热，这有助于减少传热测量的实验工作量。广义Lévêque方程（GLE）是一种广泛使用的类比概念，它允许在流体动力学边界层已开发或仍在开发的情况下，根据压降数据预测传热。这种类比概念已成功应用于具有实际意义的流动情况，例如人字形板式换热器，填充床和管束中，其中边界层被迫不断地进行重整。在这一贡献中，GLE适用于不带和带有被动插件的扁管流量，

本文介绍了在不带和带有被动插入件的扁平管中的压降和传热的实验研究结果，涵盖了广泛的Prandtl数（8 < Pr <60）和雷诺数（40 < Re <3500）。这些参数范围和无源插入物代表了用于汽车行业的单相扁平管式热交换器液体侧的典型条件和设计。将238个传热系数的实验数据点与使用GLE从压降数据计算出的传热系数进行比较。

结果表明，GLE不适用于没有无源嵌件的扁管，但对无源嵌件也适用，这迫使在研究的雷诺数和普朗特数的整个范围内重新形成边界层。