TABLE OF CONTENTS Heat conduction is one of the three basic modes of thermal energy transport (convection and radiation being the other two) and is involved in virtually all process heat-transfer operations. In commercial heat exchange equipment, for example, heat is conducted through a solid wall (often a tube wall) that separates two fluids having different temperatures. Furthermore, the concept of thermal resistance, which follows from the fundamental equations of heat conduction, is widely used in the analysis of problems arising in the design and operation of industrial equipment. In addition, many routine process engineering problems can be solved with acceptable accuracy using simple solutions of the heat conduction equation for rectangular, cylindrical, and spherical geometries.
This chapter provides an introduction to the macroscopic theory of heat conduction and its engineering applications. The key concept of thermal resistance, used throughout the text, is developed here, and its utility in analyzing and solving problems of practical interest is illustrated.
The mathematical theory of heat conduction was developed early in the nineteenth century by Joseph Fourier [1]. The theory was based on the results of experiments similar to that illustrated in Figure 1.1 in which one side of a rectangular solid is held at temperature T 1, while the opposite side is held at a lower temperature, T 2. The other four sides are insulated so that heat can flow only in the x-direction. For a given material, it is found that the rate,
