Formulation of Correlations for Calculating Densities and Thermal Conductivities of an Ammonia-Water Solution

Liquid and vapour density and thermal conductivity values are essential properties necessary for designing and simulating ammonia-water refrigeration systems. Previous works on the estimation of these thermodynamic properties have shown varying results. It is therefore necessary to develop correlations that can accurately depict the variations of these properties with relevant variables and compare the results with experimental data. This paper presented procedures for developing correlations for the pure components and then used the correlations to generate liquid and vapour densities and thermal conductivity values for the solution of the mixture. The values were compared with experimental data. Comparing the values generated from the correlations for liquid density with two sets of experimental data values gave average percentage deviations of ±2.18% and ±3.12 %. For vapour solution densities, the average percentage deviation was ±1.23%. For liquid thermal conductivity, the average percentage deviations were ±3.67%, ±4.82%, and ±0.076% for data provided by Baranov, Shamsetdinov and Conde-Petit respectively. For vapour thermal conductivity, the data generated showed increasing deviations from 1.43% to a maximum of 12.8% when compared with the data generated by Conde-Petit for the pressure values considered. . Without taking vapour conductivity into account, the low maximum percentage deviations for the calculated values for liquid density, liquid thermal conductivity and vapour thermal conductivity indicated that the correlations and procedures presented in this study could be used to calculate values of these properties.