Definition - What does Adiabatic Expansion mean?
Adiabatic expansion is a situation whereby an external work acts upon a system at the expense of utilizing internal energy of the gas and results in lowering the temperature of the molecules of gas. It is related to principles of thermodynamics. The terms adiabatic refers to the process in which heat energy is neither gained nor lost by a system.
Petropedia explains Adiabatic Expansion
When gas is compressed, its temperature increases and is said to be in adiabatic compression, however, when the temperature of the same gas drops while keeping pressure constant, it is said to be in adiabatic expansion phase. A free expansion of gas only happens when it is in isothermal process phase. In an adiabatic expansion phase, neither heat is gained nor lost, i.e., “Q” remains zero. Also the adiabatic process happens very quickly so there is no time to exchange heat, i.e., the system is well insulated. Thus, the ideal gas equation from first law of thermodynamics in adiabatic process can be written as:
n.Cv.dT = - P.dV
P.dV + V.dP = n.R.dT