The need for a textbook in the field of “Refrigeration and air conditioning” for the present generation of students admitting in engineering courses of various national & international Universities has been felt since a long time. It should also serve as a useful reference for practicing engineers. A few texts follow the extremely rigorous approach, whereas others are restricted to merely the elementary and empirical form. In this text a conscious effort has been made to maintain a reasonable level of rigour, but at the same time to employ simple techniques for solving fairly complex problems. Throughout the book, emphasis has been laid on physical understanding while at the same time relying on simple analytical treatment. A sound physical basis has also been laid for obtaining fairly precise estimates of refrigeration and air conditioning equipment. It is hoped that it will also prove of equal interest to the candidates preparing for other professional examination. While writing this book the author has all along tried his best to make the language as simple as possible. The subject matter has been given in a very systematic manner.