SIMPLE EQUATIONS FOR PREDICTING ENTROPY OF AMMONIA-WATER MIXTURE

This vork presents a set of three simple and explicit equations as a function oftemperature, pressure, and mass fraction for calculation of the entropy of the ammonia-water mixturein saturated and super heated conditions. they are intended for use in the optimization and secondlaw efficiency of absorption processes. the equations are constructed by the least square method forcurve fitting using the valid available data in the literature. the presented equations are valid for thecalculation entropy of the saturated liquid and vapor mixture within -40 :s t :s 140°c, and the superheated vapor mixture within 0.1 :s p ~ 10 mpa and tsat(p) :s t :s 350°c, and the entire compositionrange. the obtained results are compared with available data in graphical and statistical forms, andcomparisons reveal that the deviations are ±0.05 kj/kg.k in the saturated liquid mixture, within -0.04to +0.06 kj/kg.k in the saturated vapor mixture, and within -0.08 to +0.02 kj/kg.k in the superheated region.