Heat exchange is the process of thermal energy transfer between two or more systems. The systems may be in contact with each other, or they may be separated by a vacuum or an intervening medium. In most cases, heat exchange involves the transfer of thermal energy from a hotter system to a cooler system.
The rate of heat exchange depends on the temperature difference between the two systems and the properties of the intervening medium. The higher the temperature difference, the greater the heat transfer rate. The properties of the intervening medium affect both its ability to conduct heat and its resistance to convection.
Convection is another mode of heat transfer that can occur between two systems that are in contact with each other. Convective heat transfer occurs when there is a fluid flow between the two systems and results in mixing of hot and cold fluid streams. The rate of convective heat transfer depends on the properties of the fluid, the temperature difference between the two fluids, and the speed of fluid flow.
Conduction is yet another mode of heat transfer that can occur between two solids that are in contact with each other. Conduction occurs as thermal energy is transferred through direct atomic-level collisions from hotter atoms to colder atoms. The rate of conduction heat transfer depends onthe material propertiesof both solid surfaces (e.g.,thermal conductivity), as well as