Thermodynamic properties of ammonia in the critical region
Abstract A theoretically based crossover model, which incorporates a crossover from singular thermodynamic behavior at the critical point to regular thermodynamic behavior far away from the critical point, is presented for the thermodynamic properties of ammonia. The equation is capable of representing the thermodynamic properties of ammonia between 398 and 500 K in an appreciable range of densities around the critical density. The crossover equation of state was constructed so that it can be used in conjunction with the classical equation of state developed by Tillner-Roth et al. (TR EOS), which works well outside the critical region. We have also compared our crossover equation of state with the widely used equation of state for ammonia developed earlier by Haar and Gallagher (HG EOS).