Novel ionic-liquid-based low-GWP working fluids used for hybrid low-temperature absorption cooling

Abstract

Absorption cooling cycles are promising renewable/waste energy technologies for building energy efficiency. To overcome the two major shortcomings (working fluid and driving temperature) of conventional absorption cooling technologies, various ionic-liquid-based low-global-warming-potential working fluids were investigated for different hybrid low-temperature absorption cooling cycles. Results showed that the hybrid cycle not only greatly enhanced the coefficient of performance (COP) but also lowered the driving temperature from 60~70 ºC to below 45 ºC. R32 performed the best, with a maximum COP of 0.670, while R1234yf performed the worst, with a maximum COP of 0.430. The optimal compression ratio of the hybrid cycle is 1.9~3.4 for maximum COP and 1.3~2.2 for maximum exergy COP. The low-side hybrid absorption cycle is a better choice in terms of high cycle efficiency and low discharge temperature. This work can facilitate better utilization of lower-temperature renewable/waste energy.