New universal parameters of the extended corresponding states (ECS) model are presented for hydrofluoroolefin (HFO) refrigerants. The ECS model employing the universal parameters successfully represents the saturation properties. For well-studied HFO refrigerants, which were used to determine the universal parameters, typical deviations between estimations with the ECS model and calculated values with accurate equations of state are within 1 % for vapor pressures and within 3% for saturated liquid densities at reduced temperatures from 0.6 to 0.9. Similar deviations are expected for other HFO refrigerants if reliable experimental values for the critical parameters and acentric factors are available. If these values are less reliable, larger deviations could be observed, up to 3 % and 8 % for vapor pressures and saturated liquid densities, respectively. The ECS model presented here is readily implemented and provides reasonable accuracies; therefore, it is suitable for the preliminary evaluation of novel refrigerants.
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