This book describes the importance of heat transfer in heat exchangers, and fluids properties play a vital role to increase heat transfer rate translating the size of the equipment and cuts in the capital and running cost in the long term. Nanofluids applications in heat exchangers will help to improve the thermophysical properties of the fluid and therefore heat transfer. And, this book explains the enhancing mechanisms of heat transfer by employing nanofluids in heat exchangers. A critical discussion will enable to estimate the pros and cons of such fluids in different types of heat exchangers. Prevailing working conditions for short- and long-term implementation of various types of nanofluids will be discussed and introduced to the readers.