Development of Loop Heat Pipe Steady-State Model and its Application
Date Issued
2007
Date
2007
Author(s)
Yao, Ta-Chung
DOI
zh-TW
Abstract
Loop heat pipe (LHP) is a passive two-phase thermal transport device with high heat transfer capacity and long transport distance, and is widely used for aeronautics and electronic cooling. A mathematical model to simulate the thermohydraulic performance of LHPs is required for a design of such a thermal device. This study focuses on the development and application of LHP 1-D steady-state model. Mathematical model is based on the steady-state energy balance equations at each component of the LHP. The heat transfer, pressure drop and heat exchange with ambient between each component are also taken into account. Loop operating temperature is calculated as a function of the heat load, and the maximum heat transfer capacity is also predicted. Predicted result with reference data is within 10.2%. Dissimilarities between two-phase pressure drop correlation and heat transfer correlation are the main sources of error margin.
In considering the pressure drop and steady-state temperature, relative parameters are divided into two parts. The primary parameters are as follows: (1)wick effective pore radius;(2)wick porosity;(3)wick thickness. Secondary parameters include the working fluid, the tube material, and the size of evaporator, condenser, transport region, and compensation chamber. In this study we present a methodology to assistant and improve the design of a LHP. According to the requirements for heat dissipation and the consideration for manufacture, the fine primary parameters can be determined by steady-state model.
In the aspects of experiment, two correlations between the effective pore radius and the porosity, the effective pore radius and the permeability of the wick, are established and used for the steady-state model calculations for the predictions of better wick parameters. A wick with fine design parameters is chosen and tested for the heat transfer performance. The comparison between the predicted results and experimental data shows a good agreement (within 11%). To summarize, the development of a LHP steady-state model is proved to be a useful tool for the study and prediction in LHP performance characteristics.
Subjects
迴路式熱管
二相流
毛細結構
Loop heat pipe
two-phase flow
wick
Type
thesis
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