Convective heat transfer is the result of fluid flowing between objects of different temperatures. Thus it may be the objective of a process (as in refrigeration) or it may be an incidental aspect of other processes. Intended for graduate students and for researchers entering the field, this text reviews in a concise and unified manner recent contributions to the principles of convective heat transfer for single and multi-phase systems: It summarizes the role of the fundamental mechanism and the governing differential equations, describes approximation schemes and phenomenological models, and examines their solutions and applications. After a review of the basic physics and thermodynamics, the book divides the subject into three parts. Part 1 deals with single-medium transfers, specifically with intraphase transfers in single-phase flows and with intramedium transfers in two-phase flows. Part 2 deals with fluid-solid transfer processes, both in cases where the interface is small and in cases where it is large, as well as liquid-liquid transfer processes. Part 3 considers three media, addressing both liquid-solid-solid and gas-liquid-solid systems. The emphasis on the presence multiple phases and on energy-conversion mechanisms, such as phase changes or chemical reactions, will make this text a valuable reference for practicing engineers. This new edition has been updated throughout and contains new examples and problems.