Many heat transfer problems are time dependent. Such unsteady or transient problems typically
arise when the boundary conditions of a system are changed. For example if the surface
temperature of a system is altered the temperature at each point in the system will also begin
to change. The changes will continue to occur until a steady state temperature distribution is
reached. Consider a hot metal billet that is removed from a furnace and exposed to a cool air
stream. Energy is transferred by convection and radiation from its surface to the surroundings.
Energy transfer by conduction also occurs from the interior of the metal to the surface and
the temperature at each point in the billet decreases until a steady state condition is
reached. The final properties of the metal will depend significantly on the time - temperature
history that results from heat transfer. Controlling the heat transfer is one key to
fabricating new materials with enhanced properties. The author's objective in this textbook is
to develop procedures for determining the time dependence of the temperature distribution
within a solid during a transient process as well as for determining heat transfer between the
solid and its surroundings. The nature of the procedure depends on assumptions that may be made
for the process. If for example temperature gradients within the solid may be neglected a
comparatively simple approach termed the lumped capacitance method or negligible internal
resistance theory may be used to determine the variation of temperature with time. The entire
book has been thoroughly revised and a large number of solved examples and additional unsolved
problems have been added. This book contains comprehensive treatment of the subject matter in
simple and direct language. The book comprises eight chapters. All chapters are saturated with
much needed text supported and by simple and self-explanatory examples.
