Carbon Dioxide + Fluoromethane and Nitrous Oxide + Fluoromethane: Solid−Liquid Equilibria Measurements

A recently built experimental setup was employed for the estimation of the solid-liquid equilibria (SLE) of alternative refrigerant systems. The behavior of two binaries, that is, carbon dioxide + fluoromethane (CO2 + R41) and nitrous oxide + fluoromethane (N2O + R41), was measured down to temperatures of 126.5 K. To confirm the reliability of the apparatus, the triple points of the pure fluids constituent of the binary systems were measured. All triple-point data measured revealed a generally good consistency with the literature. The results obtained for the mixtures were corrected by the Rossini method and interpreted by means of the Schröder equation. © 2010 American Chemical Society

P-V-T Behavior of 2,3,3,3-Tetrafluoroprop-1-ene (HFO-1234yf) in the Vapor Phase from (243 to 373) K

The P-V-T properties of 2,3,3,3-tetrafluoroprop-1-ene (CF 3 CFdCH 2 , HFO-1234yf), an environmentally friendly refrigerant, were measured using a constant volume apparatus. Measurements were carried out at temperatures from (243 to 373) K and at pressures from (84 to 3716) kPa. A total of 136 experimental points, taken along 12 isochores, were obtained. Our experimental results were compared with a preliminary equation of state. The measurements were also regressed to the Martin-Hou equation of state. No other data on this fluid were found in the literature for the superheated region

Identification of UNIQUAC binary interaction parameters in liquid-liquid equilibrium

An algorithm is presented for the estimation of the UNIQUAC interaction parameters for liquid-liquid equilibrium of ternary systems. The algorithm is based on two optimization levels. In the inner level the algorithm performs the minimization of an objective function based on the isoactivity conditions. The outer level aims to minimize the error between calculated and experimental compositions. The Common Tangent Plane condition is checked at the end to guarantee a thermodynamically consistent representation of the phase behavior of ternary liquid systems. The algorithm is challenged with a historical Type 1 ternary liquid-liquid equilibrium system from the seminal study of Anderson and Prausnitz in which the authors showed the limitations of the original UNIQUAC model and justified its amendment in the modified UNIQUAC model. The present algorithm makes available single temperature and temperature-dependent interaction parameters enabling accurate and thermodynamically correct description of the experimental data with the original UNIQUAC model, therefore without the need of any model modification. This outcome does not change when the interaction parameters from the binary partially miscible constituent pair are first regressed and kept constant during the estimation of the remaining parameters on ternary equilibrium data. This investigation confirms that a model cannot be judged if the correctness of the model parameters has not been proved first