Comparison of the performance of single-effect, half-effect, double-effect in series and inverse and triple-effect absorption cooling systems operating with the NH3–LiNO3 mixture

Abstract

This paper presents the performance comparison of five different configurations of absorption cooling systems operating with ammonia–lithium nitrate. The configurations are: i) single-effect, ii) half-effect, iii) double-effect in series, iv) double-effect inverse and v) triple-effect. Mathematical models were developed for each one of the systems. Coefficients of performance are reported for the systems as function of their main operating temperatures, such as: generation, absorption, condensation, and evaporation. The results showed that the lowest evaporator temperatures can be achieved with half-effect systems at the lowest generator temperatures with coefficients of performance around 0.3. The single-effect system is the simplest configuration since it requires fewer components in comparison to the other systems. Its coefficients of performance are almost twice higher than those obtained with half-effect systems but requiring higher generator temperatures. With double-effect systems it is possible to obtain coefficients of performance as high as 1.12 at condenser temperatures of 30 °C but they need generator temperatures higher than 140 °C to reach evaporator temperatures as low as −5 °C. The highest coefficients of performance can be achieved with triple-effect systems but they are the most complex, they require the highest generator temperatures and they should be mainly used for air conditioning.