An overview of combined absorption power and cooling cycles

This paper presents an overview of the absorption cycles proposed in the literature for producing combined power and cooling. The dual output nature of these cycles makes it difficult to evaluate their performance so the various criteria used in the literature are presented and discussed. A combined system that simultaneously produces power and cooling can adapt to the whole range of energy demand – from only power to only cooling – with intermediate operation modes producing different ratios of power and cooling. This type of cycle uses highly concentrated ammonia vapour in the expander which can be expanded to a very low temperature without condensation and uses an absorption–condensation process instead of the conventional condensation process. The main advantage of these configurations is that they enable low-grade heat such as solar energy or waste heat to be used. The most suitable combined power and cooling systems for applications characterised by small-to-medium power and cooling capacities seem to be those that are directly derived from high-performance absorption chiller cycles.