This paper shows a theoretical prediction of the final temperature T(a
) which can be obtained using the Joule-Thomson (J-T) effect by expand
ing nitrogen gas across a throttling valve to 0.101 M Pa. An iteration
method using the J-T coefficient mu is first used to predict T(a). Th
e Benedict-Webb-Rubin (BWR) and Redlich-Kwong (RK) equations are used
to determine the specific volume and the derivatives of properties, re
spectively. Values of T(a) can be well predicted by a five-step expans
ion simulation, except for cases where the isenthalpic lines to 0.101
MPa cross a region around T = 120-160 K and P = 6.0 MPa. In this regio
n, calculated mu are lower than the experimental data. By equalizing t
he value of enthalpy after expansion to that before expansion and usin
g the Peng-Robinson (PR) equation to calculate the departure function,
the values of T(a) can also be well predicted by the second method, e
xcept for P(b) > 3.5 MPa in the cases where T(b) = 170 and 150 K.