Energy, exergy, and economic analysis of single and double effect LiBr–H2O absorption chillers

Abstract

In this study different water-cooled LiBr–H2O absorption systems under different operating and climatic conditions are analyzed and compared, and the effect of considering the chemical exergy of the LiBr–H2O solution on the second law analysis of such systems is probed as well. Results show that the EUF increases with increasing the generator and evaporator temperatures and decreases with the increase in the temperature and relative humidity of the ambient air. The total exergy efficiency increases with increasing the generator or ambient air temperature, decreases with increasing the evaporator temperature, and changes slightly with relative humidity. In Tamb=35°C and φ=30%, the system including direct-fired double-effect chiller has a EUF=1.20 and ψ=7.86% both of which are respectively 11% and 82% higher than the systems including hot-water double-effect and single-effect chillers. The economic analysis reveals that for the operating conditions presented here, the single-effect system is uneconomical and the payback period in the case of utilizing the direct-fired double-effect chiller instead of the hot-water one is about 3.5 years. Finally, the CO2 emission of the single-effect system is respectively about 1.9 and 1.7 times higher than direct-fired and hot-water double-effect ones.