Mechanical and nuclear engineers are currently working on Generation IV concept - a supercritical, water-cooled nuclear reactor. In addition, there are already hundreds of supercritical steam generators operating worldwide in the thermal power industry. Development, design, and successful operation of these power-generating units requires knowledge of heat transfer, pressure drop, and thermal hydraulics at supercritical pressures. Demand for reliable information is high, and until now, no single book related to this topic has been published. This book brings together and integrates the results from over 500 of the latest sources from the global publications devoted to heat transfer and hydraulic resistance of fluids flowing inside channels of various geometries at near-critical and supercritical pressures. This book is a valuable resourse to nuclear and mechanical engineers in both industry and academia, who are concerned with the development and design of next-generation reactors, and engineers and technologists currently working with supercritical steam generators and power systems.