A heat exchanger is a device that allows heat to be transferred from one fluid to another, with conduction, convection, and radiation as the three acknowledged ways of heat transfer. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact. Few examples of Heat exchangers are Air preheaters, economizers, evaporators, superheaters, condensers, and cooling towers.
