Heat Exchangers: Classification, Selection, and Thermal Design, Third Edition discusses heat exchangers and their various applications, such as refrigeration, air conditioning, automobiles, gas turbines, process industries, refineries, and thermal power plants. With a focus on thermal design methods, including rating and sizing, the book covers thermohydraulic fundamentals and thermal effectiveness charts for various flow configurations and shell and tube heat exchangers. It provides construction details, geometrical features and correlations, and thermo-hydraulic details for tube-fin, plate fin, air-cooled, shell and tube, microchannel, and plate heat exchangers and thermal design methods like rating and sizing. The book explores additive manufacturing of heat exchangers, printed circuit heat exchangers, and heat transfer augmentation methods. The book also describes recuperators and regenerators of gas turbine cycles, waste heat recovery devices, and phase change phenomena including boiling, condensation and steam generation. The book serves as a useful reference for researchers, graduate students, and engineers in the field of heat exchanger design, including heat exchanger manufacturers.