Radiators are heat exchanger
Heat exchanger
A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact...

s used to transfer thermal energy
Thermal energy
Thermal energy is the part of the total internal energy of a thermodynamic system or sample of matter that results in the system's temperature....

 from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...

. The radiator is always a source of heat to its environment, although this may be for either the purpose of heating this environment, or for cooling the fluid or coolant
A coolant is a fluid which flows through a device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, and chemically inert, neither causing nor...

 supplied to it, as for engine cooling.

The heating radiator
Radiator (heating)
Radiators and convectors are heat exchangers designed to transfer thermal energy from one medium to another for the purpose of space heating. The heating radiator was invented by Franz San Galli, a Prussian-born Russian businessman living in St. Petersburg, between 1855–1857.- Radiation vs...

 was invented by Franz San Galli
Franz San Galli
Franz San Galli was a Russian businessman who invented the radiator, which significantly contributed to modern central heating systems. Born in Stettin , he was mostly of Italian and German descent. He spent most of his life in St...

, a Polish-born Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

n businessman living in St.