Performance of a vapour absorption heat transformer operating with ionic liquids and ammonia

The performance of a single stage vapour absorption heat transformer operating with five different imidazolium based ionic liquids as the absorbent and ammonia as the working fluid has been studied in this work. The properties of pure components and their mixtures were calculated using the PC-SAFT equation of state. The performance of a heat transformer with different working fluid combinations is compared using performance parameters such as coefficient of performance (COP), second law efficiency (ηII), circulation ratio (f), molar circulation ratio (f′) and gross temperature lift (GTL). Exergy analysis was performed to quantify the losses occurring in different components. The results of our study shows that a second law efficiency of 50%, a GTL of about 30-35 K can be obtained with a heat transformer operating with ionic liquids [emim][AC] and [emim][SCN] as the absorbent and ammonia as the refrigerant. Ionic liquids and ammonia can be considered as possible alternative to the conventional working fluids for medium temperature lift applications in heat transformers.