Why Does Compressed Air Get Cold When Released

The reason the can gets cold after being used is due to a process known as adiabatic cooling a property of thermodynamics.

Why does compressed air get cold when released.

The cold temperature profile sneaks back towards the can because the air is such a lousy conductor of heat so the heat is all coming from the can. Then the gas is released through a nozzle the gas expands again and cools. Metal however feels cold to touch even when at environment temperature due to the high thermal conductivity. This is the principle operation of air conditioners refrigerators and other heat pumps.

The process involved is the expansion of the gas. Eventually your hand gets cold. Cans of compressed air get cold while they re discharging because of a thermodynamic principle known as the adiabatic effect. A gas initially at high pressure cools significantly when that pressure is released.

Travelling along this pressure gradient the gas expands and does work and this removes energy from the gas. When you pressurize a gas by compressing it into a container you re putting all those molecules into a smaller volume of space and you re adding potential energy by the compression. Minutephysics knows the actual reason why compressed air cans become so cold and will explain it. When air or other gas is compressed work is done and the gas heats up.

There is no reason that the compressed air tank should have a lower temperature in the compressed state when the pressure was not changed for a couple hours.