Joule-Thomas Coefficient

Name:
Joule-Thomas Coefficient
Detailed information:
The change in temperature per atmosphere change of pressure on a gas or other fluid when the enthalpy remains constant. It is found by measuring the temperature change from T′ to T when the pressure p′ of a gas on one side of a porous plug changes to Phosphorus on the other side. The change of temperature (T′ – T) and of (p′ – p) are measured under conditions such that no heat is gained or lost, and the pressure of the plug is great enough to insure a nearly constant pressure in the incoming and outgoing gas. The ratio of (T′ – T)/(p′ – p) at several pressure ranges is extrapolated to the limiting case as (p′ – p) approaches zero. This limiting value is the Joule-Thomson coefficient, µ. Thus,μ=(αTαP)H