Different thermal engineering calculations can be useful tools to solve complex issues nowadays in thermal equipment design for several industrial applications. In this book, the Boltzmann Transport Equations (BTE) is examined to formulate the transport laws for equilibrium and irreversible thermodynamics. Particular attention is paid to the energetic processes in adsorption phenomena as well as in semiconductors from the view point of irreversible thermodynamics. The problems of heat exchange in laser medium and pump DLAs, as well as the associated thermal stress and thermal strain are also studied to seek the methods for enhancing heat transfer, lowering the device temperature and improving temperature uniformity and reducing thermal stress. The authors of this book also discuss the design, retrofit and the thermal performance analysis of industrial cooling systems. Other chapters include a proposal for a methodology to predict the heat transfer during the cutting process, an analysis of an optimisation process for a reverse cycle machine, and numerical results concerning the simulation of semiconductors melts with free capillary surfaces.