Fundamentals of Heat and Mass Transfer

Chapter 7

Transient Heat Conduction

7.1 Introduction

In chapter 3, we derived the general differential equation for conduction and then applied it to problems of increasing complexity, e.g. first, we studied heat transfer in simple geometries without heat generation and then we studied heat transfer when there was internal heat generation. In all these problems, steady state heat transfer was assumed, i.e. the temperature within the solid was only a function of position and did not depend on time, i.e. mathematically, T = T(x, y, z). However, all the process equipments used in engineering practice, such as boilers, heat exchangers, regenerators, etc. have to pass through an unsteady state in the beginning when the process is started, and, they ...