Abstract In this paper new improved models for heat transfer calculation in inclined and vertical tubes with viscous-gravitational effects are presented. Three models, two for vertical tubes with upward and downward flow and one for inclined tubes were developed. For the validation of the models, available data of 14 different fluids, including water and organic liquids were used. The first model is valid when forced and natural convection have the same direction, obtaining a correlation adjustment with an average error of 11.6% for 77.8% of the data. The second model is valid when forced and natural convection are in opposite directions and provides a good correlation with an average error of 12.8% for 74.4% of the available experimental data. The third model is valid for inclined tubes with an angle of inclination with respect to the horizontal line between 1∘ ≤ θ ≤ 88∘, and provides a good correlation adjustment with an average error of 15.9% for 75.0% of the available experimental data. A new procedure of analysis to consider the influence of the viscous-gravitational effect on the non-isothermal laminar flow was developed, with the purpose of obtaining a better adjustment index from the experimental available data and to increase the validity range.

中文翻译：

---

具有粘性重力效应的斜管和垂直管传热计算的新改进模型

摘要 本文提出了具有粘性重力效应的斜管和垂直管传热计算的新改进模型。开发了三种型号，两种用于向上和向下流动的垂直管，一种用于斜管。为了验证模型，使用了 14 种不同流体的可用数据，包括水和有机液体。第一个模型在强制对流和自然对流具有相同方向时有效，对77.8%的数据进行了平均误差为11.6%的相关调整。当强制对流和自然对流方向相反时，第二个模型是有效的，并且提供了良好的相关性，对于 74.4% 的可用实验数据，平均误差为 12.8%。第三个模型对于相对于水平线的倾斜角在 1∘ ≤ θ ≤ 88∘ 之间的倾斜管是有效的，并且提供了良好的相关性调整，对于 75.0% 的可用实验数据，平均误差为 15.9%。开发了一种新的分析程序来考虑粘性重力效应对非等温层流的影响，目的是从实验可用数据中获得更好的调整指标并增加有效范围。