Joule-Thomson effect

The Joule-Thomson effect is also known as the Joule-Kelvin effect. This effect is present in non ideal gasses, where a change in temperature occurs upon expansion.

Joule-Thomson coefficient

The Joule-Thomson coefficient is given by

${\mu }_{\mathrm{J}T}={\frac{\partial T}{\partial p}|}_H$

where T is the temperature, p is the pressure and H is the enthalpy.

In terms of heat capacities one has

${\mu }_{\mathrm{J}T}{C}_V=-{\frac{\partial E}{\partial V}|}_T$

and

${\mu }_{\mathrm{J}T}{C}_p=-{\frac{\partial H}{\partial p}|}_T$

In terms of the second virial coefficient at zero pressure one has

${\mu }_{\mathrm{J}T}{|}_{p=0}{=}^0\varphi =B_2(T)-T\frac{d{B}_2(T)}{dT}$

Inversion temperature

<ref>E. Albarran-Zavala, B. A. Espinoza-Elizarraraz, F. Angulo-Brown "Joule Inversion Temperatures for Some Simple Real Gases", The Open Thermodynamics Journal 3 pp. 17-22 (2009)

References

Related reading

• Thomas R. Rybolt "A virial treatment of the Joule and Joule-Thomson coefficients", Journal of Chemical Education 58 pp. 620-624 (1981)