Mahdi Ghanbari - Department of Science, Rajaee Teacher Training University, Lavizan
GholamReza Check - Department of Chemical Engineering, University College of Engineering of Tehran-North, Islamic Azad University,

In the present work, the Soave-Redlich-Kwong (SRK) equation of state (EOS) is modified by fitting the Joule-Thomson Inversion Curve (JTIC) data on SRK EOS via the Cohesion Function. The requirement for this study is the valid JTIC data for the two important industrial substances of methane and carbon dioxide. Therefore, the best available data is selected for the purpose.Following modification, the modified SRK EOS for CH4 and CO2 is compared with the advanced EOS, namely, SUPERTRAPP, DDMIX, GERG-2004 and the four-parameter Trebble-Bishnoi (TB)EOS. The results show that the new EOS gives a better JTIC prediction for CH4 and a remarkable prediction for CO2 as compared with the other EOS. Moreover, evaluation of the new EOS in competition with the SRK EOS for nine substances of Ar, Ne, N2, O2, C2H4, C2H6, CO2, CH4 andCO indicates its good prediction ability. That is while the SRK EOS shows the same qualitative negative bias in all its predictions. Another evaluation was made for CO2 using Boyle Curve, Zeno Line and Compressibility Curve, which confirmed the results presented for JTIC.

equation of state; ideal curve; Joule-Thomson Inversion Curve; virial coefficients