This book a complete textbook for undergraduate students in mechanical engineering and will serve as a reference for postgraduate students and practicing engineers. The subject material covered in this book contains new topics revelant to the undergraduate curriculams of most universities. It is student-friendly, concise, with good illustrations and problem solving hints. The author has used his experience of teaching this subject in India and the US universities in designing this book. He has also made full use of his industrial consulting experience in the field of Registration and Air Conditioning in making this textbook up-to-date with the current scenario in the field of RAC.