Abstract

This paper presents a problem undergoing conjugate heat transfer (CHT). Conjugate heat transfer problems are common domestic heating/cooling, industrial heat exchangers, cooling of electronics (e.g. PC fans). It is to be noted that in conjugate heat transfer problems, the convection part of the heat transfer is dominated. In the given study, a hypothetical case is built where a heat source (a burning candle) is placed under a thin aluminium sheet. The aluminium sheet is exposed to wind velocity using a fan (velocity of ~1.75 m/s). The aluminium sheet is coated with acrylic paint to increase the infrared emissivity of the surface. FLIR® T1030sc camera is used to visualise the developed infrared signature. Precautions are taken to ensure the correctness of results. The given problem is simulated using ANSYS® Multiphysics, where fluid mechanics equations; continuity, momentum and energy are coupled with the heat equation. This Multiphysics problem is solved using a finite volume method. Mesh sensitivity analysis is performed to ensure the correctness of results. The results from infrared thermography and the Multiphysics model are compared and found to be in reasonable accuracy.

Highlights

  • Heat transfer has three mechanisms including thermal conduction in solids, thermal convection in fluids and thermal radiation by electromagnetic waves

  • The objective of this study is to demonstrate that a conjugate heat transfer (CHT) problem can be studied by IR thermography

  • The presented results are focused on showing the accuracy of experimental results collected by IR thermography and Multiphysics modelling by ANSYS®

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Summary

Introduction

Heat transfer has three mechanisms including thermal conduction in solids, thermal convection in fluids and thermal radiation by electromagnetic waves. Heat transfer in solids can be described by Fourier’s law as shown in Equation (1). The conductive heat flux, qq (W/m2), has a direct relation with the gradient of TT temperature (K) and thermal conductivity coefficient kk (W/(m.K)) [1, 2]. When the temperature is time-independent, the temperature field in a constant solid can be described as Equation (2). Where ρρ (kg/m3) is density, cc (J/(kg.K)) is heat capacity at constant pressure, QQ (W/m3) is the volumetric energy generation term, TT (K) is temperature field and tt (s) is time. Equation (2) can be written in three spatial dimensions as shown in Equation (3).

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