Abstract

A comprehensive three-dimensional numerical model is developed to evaluate the effects of bending on the performance of both low temperature and high temperature heat pipes. The model solves for wall, wick, and vapor regions and includes the compressibility effects of the vapor. The proposed model can calculate the operating pressure and temperature of the heat pipe based on the operational and physical conditions. The effects of one 90-degree bend (L-Shaped) and two 90-degree bends (U-Shaped) are evaluated based on the hydrodynamics and thermal performance of the cylindrical heat pipes. The effects of bending on the heat pipe wall temperature are more significant for a high temperature heat pipe at a lower operating temperature range compared to a low-temperature heat pipe. The effects of bending on heat pipe is not significant if the wick of the heat pipe is not damaged due to bending and the blockage of liquid flow does not occur. In addition, if the heat pipe is operating in a horizontal plane where the evaporator and condenser are at the same level, the liquid pressure drop in the wick is not affected significantly by bending. Furthermore, the effects of gravity can be important when bending heat pipes and consideration should be given for this factor.

摘要

开发了一个综合的三维数值模型来评估弯曲对低温和高温热管性能的影响。该模型求解壁、灯芯和蒸汽区域，并包括蒸汽的可压缩性效应。所提出的模型可以根据运行和物理条件计算热管的运行压力和温度。基于圆柱形热管的流体动力学和热性能评估一个 90 度弯曲（L 形）和两个 90 度弯曲（U 形）的效果。与低温热管相比，在较低工作温度范围内，高温热管的弯曲对热管壁温的影响更为显着。如果热管的灯芯没有因弯曲而损坏，并且没有发生液体流动的阻塞，那么弯曲对热管的影响并不显着。此外，如果热管在蒸发器和冷凝器处于同一水平面的水平面上运行，则灯芯中的液体压降不会受到弯曲的显着影响。此外，在弯曲热管时重力的影响可能很重要，应该考虑这个因素。