What is Heat Transfer?
Heat is transferred from one object to another in three possible ways, Conduction, Convection and Radiation.
Conduction occurs when heat energy is passed through a material from one particle to the next. The particles at the warm end move faster and hit the particles next to them causing them to move faster, in this way heat is transferred by the vibrational movement of atoms.
Convection occurs when particles in a gas or liquid (that are free to move) become warm. When particles become warm they expand and become less dense, than the cold particles nearby. The warm particles then rise and the cooler particles fall into the space left behind by the warm particles. When this happen convection current is set up.
Radiation is the method of heat transfer that takes place without the need for a material to pass through (it can happen where there are no particles). It is the way that the Earth receives heat energy from the sun through the vacuum of space. The above mentioned terms are the principals of which heat transfer is based on, the principles have been used to develop devices that can help in production.
Heat exchangers have been developed based on the basic principles of heat transfer. A heat exchanger is a device built for efficient heat transfer from one fluid to another. They are widely used in refrigeration, air conditioning, space heating, electricity generation, and chemical processing. One common example of a heat exchanger is the radiator in a car, in which a hot engine-cooling fluid, like antifreeze, transfers heat to air flowing through the radiator.