Phase equilibrium data for development of correlations for coal fluids: Report period, February 1, 1987 to August 15, 1987

During this report period, a study was completed of the abilities of the Soave (SRK) and Peng-Robinson (PR) equations of state to represent the phase behavior of ethane + n-paraffin and CO/sub 2/ + n-paraffin systems. As reported earlier, such cubic equations are capable of well describing the phase behavior of the systems considered. Depending on the level of precision desired, however, various degrees of complexity are required in defining the mixing rules used in the equations. For ethane/CO/sub 2/ + n-paraffin binary systems extending from C/sub 3/ to n-C/sub 44/, a precision of about 1% is obtained for the bubble pressure and 0.005 mole fraction in solubility predictions when two interaction parameters per isotherm are used. Simple generalized correlations are presented for the EOS interaction parameters which allow prediction of the bubble point pressures with an expected uncertainty of about 4%. 44 refs., 11 figs., 8 tabs.