We feel satisfied in presenting the new edition of this standard treatise. this book have enjoyed all over India and abroad, is a matter of greatsatisfaction for us.The present multicolour edition has been thoroughly revised and brought up-to-date. In a chapter of refrigerants, a new article on Substitutes for Chloro-Fluoro- Carbon (CFC) refrigerant has been added, for which we are highly thankful to Mr. Sanjiv Kumar Gupta, B. Tech. (Mechanical Engineering), M.S. (Manufactur-ing Management). We wish to express our sincere thanks to numerous professors and students, both at home and abroad, for sending their valuable suggestions and recommending the book to their students and friends. We hope, that they will continue to patronise this book in the future also.We also like to express our sincere thanks to Mr. Navin Joshi, Vice-President (Publishing) for his personal interest taken in printing this book. Our grateful thanks are due to the Editorial Staff of S. Chand & Company Ltd., especially Mr.Shishir Bhatnagar, Manager (Pre-press), Mr. Rupesh Gupta, Subject Editor for their help in conversion of the book into multicolour edition and Mr. Dhan Singh Karki for designing and layouting of this book.Any errors, omissions and suggestions, for the improvement of this volume brought to our notice, will be thankfully acknowledged and incorporated in the next edition.