Here's a reduction-valve with an adiabatic expansion feature, to supply extra air to your heat-suit.
"Sand Doom"
William Fitzgerald Jenkins
A curve in which the combined effects of volume and resulting temperatures is represented is called the adiabatic curve, or curve of no transmission; since, if no heat is transmitted to or from the fluid during change of volume, its sensible temperature will change according to a fixed ratio, which will be the same for the same fluid in all cases.
"Modern Machine-Shop Practice, Volumes I and II"
Joshua Rose
If the radioactive heating was strictly adiabatic-that is, if all the heat was conserved and none entered from without-the time required for the attainment of the equilibrium radioactive temperature would be just about six million years.
"The Birth-Time of the World and Other Scientific Essays"
J. (John) Joly