Comparison of air-cooled and water-cooled (hot-water and direct-fired) double effect LiBr-H2O absorption systems: energy and exergy analyses

In this study, air-cooled and water-cooled cooling systems including hot-water and direct-fired double effect LiBr-H2O absorption chillers are analysed and compared in different operating and climatic conditions according to the first and second laws of thermodynamics. Unlike most articles in literature, in this paper all components engaged in cooling generation have been considered to attain the total energy utilisation factor (EUF) and exergy efficiency for the cooling systems. Results show that the EUF and second law efficiency of the systems including direct-fired chillers are a little higher than the hot-water chillers. Comparison between similar water-cooled and air-cooled systems illustrates that although the EUF of water-cooled systems is considerably higher than that of air-cooled systems, the difference between their second law efficiency, especially in temperatures below 37 degrees C, is very small. This fact attests to the potential of air-cooled systems to be used specially in moderate climatic conditions.