Experimental Observation of Natural Convection Heat Transfer Performance of a Rectangular Thermosyphon

C S Huang,R H Chen,Chia-Wang Yu,Chi-Ming Lai,Chun-Ta Tzeng

doi:10.3390/en12091702

C S Huang, R H Chen + Show 3 more

Open Access

https://doi.org/10.3390/en12091702

Copy DOI

Abstract

This study experimentally investigates the natural convection heat transfer performance of a rectangular thermosyphon with an aspect ratio of 3.5. The experimental model is divided into a loop body, a heating section, a cooling section, and two adiabatic sections. The heating section and the cooling section are located in the vertical legs of the rectangular loop. The length of the vertical heating section and the length of the upper and lower horizontal insulation sections are 700 mm and 200 mm, respectively, and the inner diameter of the loop is 11 mm. The relevant parameters and their ranges are as follows: the input thermal power is 30–60 W (with a heat flux in the range of 60–3800 W/m2); the temperature in the cooling section is 30, 40, or 50 °C; and the potential difference between the hot and cold sections is 5, 11, or 18 for the cooling section lengths of 60, 45, and 30 cm, respectively. The results indicate that the value of the dimensionless heat transfer coefficient, the Nusselt number, is generally between 5 and 10. The heating power is the main factor affecting the natural convection intensity of the thermosyphon.

Highlights

A thermosyphon is a type of natural convection loop
Because the literature on heating and cooling sections positioned in the two vertical sections of a rectangular thermosyphon is quite limited, despite the high potential of this application, this paper explores the natural convection heat transfer phenomenon of a rectangular thermosyphon with a geometric aspect ratio of 3.5
This experiment mainly discusses the effects of the heating power, cooling section temperature

Summary

Introduction

By proper arrangement of the heating zone and the cooling zone, the fluid in the loop changes in density, and the resulting thermal buoyancy drives the heat transfer of the working fluid. Heating of the working fluid produces a lower density, which generates thermal buoyancy and upward flow, and the heat is radiated toward the cooling section. There are many considerations when designing a thermosyphon with good thermal efficiency, such as the choice of working fluid, the choice of wall material, the location of the heating and cooling sections, and the geometry of the loop [1,2,3,4,5,6,7,8,9,10]

Objectives

Methods

Results

Conclusion