CH-99-10-5 (RP-919) -- Secondary Properties of Aqueous Lithium Bromide Solutions ✓ Most Recent

Lithium bromide (LiBr) absorption chillers must be operated close to the temperature and mass fraction (concentra-tion) at which lithium bromide crystallizes in order to achieve the highest efficiencies. It may be possible to monitor the LiBr mass fraction by sensors that measure secondary properties that vary with concentration - including the index of refraction, speed of sound, dielectric constant, electrical conductivity/ resistivity, electromagnetic radiation absorption and transmission, and magnetic properties - to determine when the crystallization point is being approached. A recent project categorized and determined the availability of LiBr secondary properties and assessed current sensor technologies. Property/ sensor combinations were evaluated for cost, mass frac-tion accuracy, availability, reliability, effects of additives, and data availability, and an overall rating of the feasibility of each sensor was made. While no sensor was rated outstanding, five sensors (an ultrasonic concentration analyzer, a fiber optic refractometer, an electrical conductivity meter, a specific ion detector, and the Coriolis density meter) were rated as having the most potential.

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