A MODIFIED BENEDICT-WEBB-RUBIN EQUATION OF STATE FOR THE THERMODYNAMIC PROPERTIES OF R152A (1,1-DIFLUOROETHANE)

A modified Benedict-Webb-Rubin (MBWR) equation of state has been devel oped for R152a (1,1-difluoroethane). The correlation is based on a sel ection of available experimental thermodynamic property data. Single-p hase pressure-volume-temperature (PVT), heat capacity, and sound speed data, as well as second virial coefficient, vapor pressure, and satur ated liquid and saturated vapor density data, were used with multi-pro perty linear least-squares fitting to determine the 32 adjustable coef ficients of the MBWR equation. Ancillary equations representing the va por pressure, saturated liquid and saturated vapor densities, and the ideal gas heat capacity were determined. Coefficients for the equation of state and the ancillary equations are given. Experimental data use d in this work covered temperatures from 162 K to 453 K and pressures to 35 MPa. The MBWR equation established in this work may be used to p redict thermodynamic properties of R152a from the triple-point tempera ture of 154.56 K to 500 K and for pressures up to 60 MPa except in the immediate vicinity of the critical point. (C) 1996 American Institute of Physics and American Chemical Society.