The second edition of Thermal Engineering (new name Mechanical Engineering) has been published with the hope that this edition too, would be received with the same zeal and enthusiasm as the first edition was privileged to receive earlier. In the new edition four chapters on Manufacturing Processes and chapter on Refrigeration and Air Conditioning have been added. Needless to emphasise, this new edition has been designed as a self-learning capsule. With this aim in view the material has been organised in a logical order and lots of illustrative examples have been incorporated to enable students to thoroughly master the subject. It is believed that this book, mainly meant for under-graduate students, will captivate the attention of senior students as well as teachers.