Theoretical and Experimental Study on Heat Transfer Characteristics of Water Heat Pipe

TL;DR

This paper combines theoretical analysis and experimental testing to investigate the heat transfer limits and thermal conductance of water heat pipes, highlighting the dominant heat transfer limits at different temperatures.

Contribution

It provides detailed calculation methods and experimental validation for heat transfer limits and thermal conductance of water heat pipes, especially in nuclear engineering applications.

Findings

Capillary limit dominates at low temperatures.

Boiling limit dominates at high temperatures.

Experimental thermal conductance matches theoretical calculations.

Abstract

Heat pipe is an efficient heat transfer element based on two-phase natural circulation, which has advantages of simple structure, strong heat transfer ability, and good isothermal performance. Heat pipes are widely used in heat transfer and other fields, and especially have important applications in nuclear engineering. One of its most important characteristics is the heat transfer limit. In this work, heat transfer limits are first reviewed, and the detailed calculation equations are presented. Then, a Matlab code to calculate heat transfer limits as well as the thermal conductance are provided. Second, an experimental setup for testing the heat transfer characteristics of heat pipes was developed, which could be used to measure the thermal conductance as well as the heat transfer limits. The calculated results show that, for water heat pipes, the capillary limit mainly affects heat transfer in low temperature conditions, while in high temperature conditions, boiling limit dominates. In addition, the experiment results show that the thermal conductance of the measured heat pipe is 7267 W/(m^2*K), which agrees with the calculation result.