A Study on In-plant Measurement of LiBr Concentration in an Absorption Refrigerator with the Absorbent of LiBr Aqueous Solution and the Coolant of Water : Part 1-A Study on the application of Capacitance Sensor Method

Abstract

We are researching and developing the in-plant technology for LiBr concentration measurement in an absorption refrigerator with the absorbent of LiBr aqueous solution and the coolant of water. In this paper, the application of a capacitance sensor composed of a cylinder electrode with two different diameters to the LiBr concentration measurement was experimentally studied using 3 kinds of non-hygroscopic strong electrolyte i.e. NaCl, KCl and K_2SO_4 aqueous solutions, before using LiBr aqueous solution with strong hygroscopicity. As a result, it was clarified that capacitance and pH could be respectively expressed as a approximate function of non-dimentional solubility of solute without regard to kinds of electrolyte, and that the solute concentration could be measured in the high precision and wide range by using the above two functions. Also, it was clarified that the specific dielectric constant of the above salt aqueous solutions in saturated concentration range could be estimated by introducing an electric equivalent diameter method instead of the geometrical diameter for the upper vessel part of the cylinder electrode with two different diameters.