This second volume of the textbook Hydraulic and Thermal Machines focuses on thermal machines. It covers the fundamentals of heat transfer and thermodynamics for reacting and non-reacting mixtures, and compressible fluids, followed by the principles of design, control and operation of thermal machines. With an uncomplicated yet rigorous approach, and using numerous examples, the book gradually guides readers through different kind of fluid machines/systems such as compressors, turbines, vapor and gas turbine power plants, internal combustion engines, and hybrid systems, discussing important issues for their application in propulsion. Furthermore, the book covers reversed cycle systems, with a special attention to air conditioning.