Joule-Thomson Effect
The temperature change experienced by a real gas when throttled through an insulated porous plug or valve at constant enthalpy.
Governing formula
μ_JT = (∂T / ∂P)_H
SI unit
K/Pa
In depth
If initial temperature is below the inversion temperature ($T < T_{inv}$), throttling expansion causes cooling ($μ_{JT} > 0$). Used extensively for gas liquefaction.
Examples in the real world
Cooling compressed air via throttling expansion to liquefy nitrogen and oxygen industrially.