Determination of Concentration of the Aqueous Lithium–Bromide Solution in a Vapour Absorption Refrigeration System by Measurement of Electrical Conductivity and Temperature

Abstract

Lithium-bromide/water (LiBr/water) pairs are widely used as working medium in vapour absorption refrigeration systems where the maximum expected temperature and LiBr mass concentration in solution are usually 95°C and 65%, respectively. Unfortunately, published data on the electrical conductivity of aqueous lithium-bromide solution are few and contradictory. The objective of this paper is to develop an empirical equation for the determination of the concentration of the aqueous lithium-bromide solution during the operation of the vapour absorption refrigeration system when the electrical conductivity and temperature of solution are known. The present study experimentally investigated the electrical conductivity of aqueous lithium-bromide solution at temperatures in the range from 25°C to 95°C and concentrations in the range from 45% to 65% by mass using a submersion toroidal conductivity sensor connected to a conductivity meter. The results of the tests have shown this method to be an accurate and efficient way to determine the concentration of aqueous lithium-bromide solution in the vapour absorption refrigeration system.

Maximum Exergetic Efficiency Operation of a Solar Powered H2O-LiBr Absorption Cooling System

“…This complementary process is applied in the case of crystallization risk, to dilute the solution. As explained by Osta-Omar and Micallef [23], the critical point in which crystallization tends to occur is in the weak solution between the throttling valve and the absorber since the solution is characterized here by a dangerous combination of the lowest temperature and the highest concentration; crystallization of a salt takes place if the temperature of a saturated solution drops. For the present numerical simulation, we considered the case with no recirculation (a = 0), but we have verified the crystallization absence at each time step.…”