This book is intended for engineering students and design engineers working on thermal systems. The objective is to produce a book which will enable the students to apply principles to applications. Topics such as modelling and analysis and experimental heat transfer have been included and there is an emphasis on including data pertaining to system design. This will help students to develop their own experimental procedure to test thermal systems and also to simulate the heat transfer using computer codes and software. Simple computer programs have been developed using 'C' language for a problem in each chapter, to guide the students so that they can develop their own code when they attempt to design thermal systems.