Comparison of the Performance of Single Effect, Half Effect, Double Effect in Series and Inverse Absorption Cooling Systems Operating with the Mixture H2O-LiBr

Abstract

This paper presents a performance comparison of four different configurations for absorption cooling systems operating with water-lithium bromide mixture. The configurations are: i) single effect, ii) half effect, iii) double effect in series, and iv) double effect inverse. Every system is described in detail and a mathematical model was developed for each one of them. Coefficients of performance and flow ratios are reported for the systems as function of their main operating temperatures, such as: generation, absorption, condensation, and evaporation. From the results analysis regarding to evaporation temperatures, this mixture is easily associated with air-conditioning applications. It is seen that the single effect obtains theoretical coefficients of performance up to 0.89 at generation temperatures between 100°C and 110°C. On the other hand, it was observed that half effect systems may operate with generation temperatures from 55°C, but obtaining coefficients of performance almost half of those obtained with single effect systems. Finally, it was found that double effect systems are the most efficient, reaching coefficients of performance up to 1.48, however, they are more complex and require generation temperatures as high as 158°C. It is important to mention that half effect systems work better than any other when condensation and absorptions temperatures are as high as 40°C.