ABSTRACT
This chapter focuses on different mechanisms of heat transfer, namely conduction, convection and radiation, involving solid, liquid and gases. It discusses the main attributes in heat flow are the thermal properties of the materials. The chapter explores steady-state heat transfer first and unsteady-state heat conduction in solid. It also discusses the design criteria for tubular heat exchanger and plate heat exchanger. Heat transfer is a basic engineering science in understanding for several food processing operations. The heat transfer in practice involves both steady- and unsteady-state systems. Steady-state heat transfer involves conduction, convection and radiation. Besides steady-state heat transfer, unsteady-state heat transfer concerning time and position is a common phenomenon in various food processing operations involving solid foods and composite systems which appear to be the solid system. Thermal sterilization of packaged foods and freezing of foods are practical examples of unsteady-state heat transfer.
