The study on the influence of glycols on the vapor pressure, density and dynamic viscosity of lithium bromide aqueous solution

Abstract

This paper is a continuation of our comprehensive research on finding the most effective additive to the conventional {lithium bromide + water} system, which is commonly used in absorption refrigeration technology. Serious disadvantages of commercially used working pairs in absorption refrigeration make it necessary to modify them. Such modification can be carried out by finding and characterizing new additives to conventional systems that will improve the operation of the refrigerator, which this work relates to. The addition of a chemical compound to such a system is one of the possibilities to improve the properties of the working pair, increase the efficiency of the absorption refrigerator and eliminate their main disadvantages. The main disadvantage of {lithium bromide + water} system is the crystallization of this salt. In recent years, many compounds have been proposed as additives to this conventional system to improve the functioning of the absorption aggregate. Based on the results obtained in our previous research, we selected substances that most effectively affected the solubility of lithium bromide in water. In this work, tests on ethylene glycol, diethylene glycol, triethylene glycol, and glycerol (additive to LiBr mass fraction w2 = 0.3) which were added to the binary {LiBr (Boryta, 1970) [1] + water (Iyoki et al., 1990) [2]} system were performed. Measurements of vapor pressure, dynamic viscosity and liquid density were carried out over a wide range of temperatures and composition. Experimental VLE data were predicted using the conductor-like screening for real solvents model, COSMO-RS. Empirical equations were used to correlate dynamic viscosity and density data. Based on the comparison of results obtained in the case of ternary systems to the properties of a conventional binary system, the effect of the additive on physicochemical properties was characterized and the possibility of potential application of such new ternary systems in absorption refrigeration technology was determined.