Steady-state energy balance for an adiabatic throttle:

\[0= \Delta H\]

where \(\Delta H\) is the change in enthalpy for the fluid from inlet to outlet.

Joule-Thomson coefficient:

\[\mu = \left( \frac{\partial T}{\partial P} \right) _H\]

Note that the same symbol \(\mu\) is used for the J-T coefficient and for chemical potential.