Heat is defined in physics as the transfer of thermal energy across a well-defined boundary around a thermodynamic system. The transfer of heat is normally from a high temperature object to a lower temperature object. Heat transfer changes the internal energy of both systems involved according to the First Law of Thermodynamics. Heat transfer is the exchange of thermal energy between physical systems. The rate of heat transfer is dependent on the temperatures of the systems and the properties of the intervening medium through which the heat is transferred. The direction of heat transfer is from a region of high temperature to another region of lower temperature, and is governed by the Second Law of Thermodynamics. Heat transfer changes the internal energy of the systems from which and to which the energy is transferred. Heat transfer will occur in a direction that increases the entropy of the collection of systems. The heat transfer and analysis on heat pipe and exchanger, and thermal stress are significant issues in a design of wide range of industrial processes and devices. This book covers mainly thermodynamic effects and thermal stress, heat pipe and exchanger, gas flow and oxidation, and heat analysis. The advanced concepts and information described in this book will be fruitful for the readers to find a sustainable solution in an industrialised society.