Thermodynamic Performance of Absorption Heat Transformer Using a New Working Pair: Water+Ionic Liquid 1,3-dimethylimidazolium Dimethylphosphate

In present research ionic liquid, 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) and water were taken as the new working pair for absorption heat transformer (AHT). The thermodynamic cycle performance for this working pair was simulated based on its thermodynamic data, mass and energy balance for each component in a AHT. The effects of absorption and condensing temperature on the coefficient of performance (COP), exergy efficiency (ECOP), concentration deference between dense and dilution solutions and flow rate ratio were analyzed. The cycle performance comparison for AHT using two working pairs, H2O + [MMIM][DMP] and H2O + LiBr was carried out. The results indicate that the COP and ECOP of AHT for H2O+ [MMIM][DMP] are all lower than those for H2O + LiBr, but they can still reach 0.4 and 0.5 respectively when condensing and generation temperatures are 35 and 90 °C respectively. The excellent physical and chemical properties of ionic liquid mentioned above together with suitable cycle performance make this new working pair to have the potential application in absorption heat pump or absorption heat transformer.