A new thermodynamic model for ammonia-carbon dioxide-water-urea system at the condition of urea synthesis (T=438.15-478.15K

P=6.87-24.5 MPa

NH3/CO2 = 2.6-5.0

H2O/CO2= 0.2-1.2) is established on the basis of experimental data. Perturbed-hard-sphere equation of state and Wilson equation are use to treat the non-idealities of vapor and liquid phases. Correlations of the experimental data at 433.15K

438.15K

448.15K

458.15K

468.15K and 478.15K are made with this model. The mean relative deviation of molar fraction of ammonia and carbon dioxide in vapor phase is 3.05% and 8.27% respectively

and the mean relative deviation of total pressure is 3.31%. The calculated values of pressure with this mode] are in agreement with those of industrial synthesis of urea.