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

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.