In physics, an adiabatic process is a Thermodynamic process in which there is no heat or matter transfer into or out of a system and is generally obtained by surrounding the entire system with a strongly insulating material or by carrying out the process so quickly that there is no time for a significant heat or matter transfer to take place.
On applying the first law of thermodynamics to the adiabatic process, we get:
Delta U = -W,
Delta U is the change in internal energy and W is work done by the system. We get following results from above relation:
- A system expanding under adiabatic conditions does positive work; hence its internal energy is decreased.
- A system contracting under adiabatic conditions does negative work; hence its internal energy is increased.
A common example of an adiabatic process is the compression and expansion stroke in an internal combustion engine. A negligible amount of heat is transferred outside of the system in an internal combustion engine; therefore it follows adiabatic compression and expansion.