Modeling of an intermittent solar absorption refrigeration system operating with ammonia–lithium nitrate mixture

The theoretical performance of an intermittent absorption refrigeration system operating with ammonia–lithium nitrate mixture is presented. The analysis was done for representative days of each season of 2001. Meteorological data were taken from a local meteorological station installed in the Energy Research Centre of the National University of Mexico in Temixco, Morelos, Mexico. The system consists of a generator-absorber, a condenser, a valve and an evaporator. A compound parabolic concentrator (CPC) with a glass cover, operates as the generator-absorber of the cooling system. Since lithium nitrate does not evaporate during the generation, it is not necessary to use a rectifier. The theoretical efficiencies of the CPC varied from 0.78 to 0.33 depending on the time of the day and the season. Also, the results showed that with the proposed system it is possible to produce up to 11.8 kg of ice at generation temperatures around 120°C and condensation temperatures between 40°C and 44°C. These temperatures allow the system to be chilled with air or water. The overall efficiencies of the systems were between 0.15 and 0.4 depending on the generation and condenser temperatures. The efficiencies are satisfactory considering the simplicity of the system.