Thermodynamic analysis of a novel air-cooled non-adiabatic absorption refrigeration cycle driven by low grade energy

Abstract

An air-cooled type absorption refrigeration cycle using ammonia–lithium nitrate and ammonia–sodium thiocyanate solutions as working fluids are thermodynamically studied in this paper. In the case of many occasions especially small cooling capacity occasion where water cooling is restricted or inconvenient, application of conventional adiabatic absorbers in air-cooled type absorption refrigeration system has been studied by many investigators. Comparing to the adiabatic absorber, a novel air-cooled non-adiabatic absorber is applied to the absorption refrigeration system in this study to improve system performance. It is shown that, system performance has a significant improvement when temperatures of rich ammonia solution at the outlet of absorber decrease under the effect of the heat dissipation capacity of the non-adiabatic absorber. Another advantage is that heat load of the system heat exchangers including generator, solution heat exchanger and air-cooler, decreases with the solution temperature decrease at the outlet of the absorber under the same system cooling capacity condition, which brings benefits to the system cost reduction. Variation of system performance and other system operation parameters with generator temperature, absorption temperature and absorption efficiency has been carried out. Effects of the self-circulation flow rate of the absorber have been studied. A datasheet of system operation parameters has been proposed.