Heating or cooling of processes, equipment, or enclosed environments are within the purview of thermal engineering.

One or more of the following disciplines may be involved in solving a particular thermal engineering problem:

Thermodynamics
Fluid mechanics
Heat transfer
Mass transfer
Thermal engineering may be practiced by mechanical engineers and chemical engineers.

One branch of knowledge used frequently in thermal engineering is that of thermofluids.

Applications
Engineering : HVAC
Cooling of computer chips
Boiler design
Solar heating
In design of combustion engines
Thermal power plants
Commercial cooling system