ABSTRACT
A heat exchanger is a device to provide for the transfer of internal thermal energy (enthalpy) between two or more fluids, between a solid surface and a fluid, or between solid particulates and a fluid, in thermal contact without external heat interactions. The fluids may be single components or mixtures, and they may be single phase or multiphase. Typical applications involve heating or cooling of a fluid stream of concern, vaporization or condensation of a single- or multicomponent fluid stream, or heat recovery or rejection from a system. In other cases, the objective may be to sterilize, pasteurize, distill, fractionate, concentrate, or crystallize the process fluid. Some heat exchangers use internal mechanical devices such as rotating blades to enhance the heat-transfer process.
