HELMHOLTZ FREE-ENERGY FORMULATION OF THE THERMODYNAMIC PROPERTIES OF THE MIXTURE (WATER PLUS AMMONIA)

A thermodynamic model incorporating a fundamental equation of state fo r the Helmholtz free energy of the mixture {water+ammonia} is presente d which covers the thermodynamic space between the solid-liquid-vapor boundary and the critical locus. It is also valid in the vapor and liq uid phases for pressures up to 40 MPa. It represents vapor-liquid equi librium properties with an uncertainty of +/-0.01 in liquid and vapor mole fractions. Typical uncertainties in the single-phase regions are +/-0.3% for the density and +/-200 J mol(-1) for enthalpies. Details o f the data selection and the optimization process are given. The behav ior of the fundamental equation of state is discussed in all parts of the thermodynamic space. (C) 1998 American Institute of Physics and Am erican Chemical Society. [S0047-2689(98)00401-2].