Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Some process like as air conditioning absorption systems have been developed as a feasible and economical alternative to help to reduce the consumption of fossil fuels and prevent the impact of gas emission produced by electrical air conditioning. However, a main disadvantage of these systems is the absorbents crystallization phenomenon in the working mixture, which occurs when the absorbent concentration is higher than the saturation point. Among the aqueous working mixtures, NaOH solution shows several advantages for absorption system applications. The aim of this paper is to propose new mathematical correlations in order to predict or estimate the NaOH concentrations and refractive index in aqueous solutions (H2O-NaOH) for an air conditioning absorption system application. The experimental concentrations measurement of NaOH and refractive index was made in-situ from aqueous solutions with concentrations between from 20 to 50% (weight/weight %, in increases of 5%) and temperatures between 10 to 60C (with increments of 1C). Two correlations for predicting the concentration of NaOH and refractive index based on cubic regression models with R2 of 0.99704 and 0.99918, respectively are presented for the first time. The normalized error for NaOH estimation using experimental data lies between -0.026 to 0.040 and for refractive index estimation between -0.002 to 0.001. Both correlations present a good fit to predict the NaOH concentration between 25 to 45% of concentration ratio.