A Fundamental Equation for Trifluoromethane (R-23)

Abstract

A new formulation for the thermodynamic properties of trifluoromethane (R-23) is presented. The formulation is valid for single-phase and saturation states for temperatures from the triple point (118.02 K) to 475 K, pressures up to 120 MPa, and densities up to 24.31 mol/dm3. The formulation includes a fundamental equation and ancillary functions for the estimation of saturation properties. The experimental data used to determine the fundamental equation included pressure-density-temperature (p - ρ - T), isobaric heat capacity (cp - p - T), isochoric heat capacity (cv - ρ - T), saturation heat capacity (cσ), speed of sound (w - p - T), and vapor pressure. A nonlinear regression algorithm was used to determine the constants and exponents of various functions within the formulation. Experimental data and values computed using the formulation are compared to verify the uncertainties in the calculated properties. The formulation presented may be used to compute densities to within ±0.1%, heat capacities to within ±0.5%, speed of sound to within ±0.5%, and vapor pressures to within ±0.2%, except near the critical point. © 2003 by the U.S. Secretary of Commerce on behalf of the United States. All rights reserved.