A system that is used to transfer heat between two or more fluids is known as a heat exchanger. It can be used for cooling as well as heating processes. The fluids may be in direct contact or may be separated by a solid wall to prevent mixing. A prominent example of heat exchanger is present within an internal combustion engine. The circulating fluid in an internal combustion engine is known as engine coolant. It flows through radiator coils and air flows past the coils. This cools the coolant and heats the incoming air. Heat exchangers are widely used in refrigeration, air conditioning, space heating, petrochemical plants and petroleum refineries. The topics included in this book on heat exchangers are of utmost significance and bound to provide incredible insights to readers. Also included herein is a detailed explanation of the various designs and applications of heat exchangers. This book is a complete source of knowledge on the present status of this important field.