ABSTRACT
The mechanism by which heat is transferred in a heat exchange or an energy conversion system is, in fact, quite complex. There appear to be three rather basic and distinct modes of heat transfer: conduction, radiation, and convection. The chapter reviews some definitions and concepts of thermodynamics needed for the study of heat conduction. A physical law is referred to as a general law if its application is independent of the nature of the medium under consideration. Otherwise, it is called a particular law. There are, in fact, four general laws, on which almost all the analyses concerning heat transfer, depend: the law of conservation of mass, Newton's second law of motion, the first law of thermodynamics, and the second law of thermodynamics. Thermal conductivity is a thermophysical property and has the units W/(m•K) in the SI system. The unit of heat flux is watts per square meter (W/m2) in the SI system.
