Computer Subroutines for Rapid Calculation of the Liquid Entropies of Ammonia/NaSCN and Ammonia/LiNO3 Solutions

Abstract

This paper proposes an alternative for the calculation of the liquid entropy of binary solutions is proposed in this paper in the form of correlation equations with higher computation speed. These correlation equations were obtained by using both the least squares method for the modelling of the reference liquid entropy and a classical matrix computer solving for modeling the liquid entropy. Goodness-of-fit parameters such as sum of squares of estimation errors (SSE), Pearson's factor (R-squared), root mean square error (RMSE) and relative error (ε) were computed and the different results were compared with those of the digitized data. The suggested correlations showed good accuracy in estimating the liquid entropy of ammonia/NaSCN and ammonia/LiNO3 solutions, with an average SSE of 1.23.10^(-4), R-squared of 0.99, RMSE of 2.90.10^(-3) and ε of 0.59 % for ammonia/LiNO3, and SSE of 1.57.10^(-4), R-squared of 0.99, RMSE of 3.2.10^(-3) and ε of 0.83 % for ammonia/NaSCN. These correlations are for the temperature range from 0 to 100 °C, and are decision support tools for combined systems for waste heat recovering at very low temperature and in which the couples ammonia / NaSCN and ammonia / LiNO3 must be used.