Performance analysis of a novel high temperature heat pump based on various CO2-functionalized ionic liquids

To address the technical bottleneck of rapid performance degradation in conventional heat pumps under high-temperature operating conditions, this study proposes a novel high-temperature chemical heat pump utilizing functionalized ionic liquids (ILs) paired with CO 2 . Three functionalized ionic liquids featuring distinct anionic structures, namely [ P66614 ][Lys], [ P66614 ][Triz], and [ P66614 ][Pyr], were selected as absorption working fluids. A thermodynamic cycle model was established by integrating density functional theory (DFT), COSMO-RS property prediction, and Aspen Plus process simulation to investigate the effects of absorption temperature, absorption pressure, desorption temperature, and desorption pressure on system performance. The results indicate that as the absorption temperature increases from 293 K to 353 K, both the useful heat output ( Q useful ) and the coefficient of performance ( COP ) decrease for all three working fluids, with the COP of [ P66614 ][Pyr] declining from 7.96 to 6.49. With an increase in absorption pressure from 2 MPa to 6 MPa, the COP exhibits an initial upward trend followed by a subsequent decline, reaching peak values of 6.44 and 6.96 for [ P66614 ][Triz] and [ P66614 ][Pyr], respectively, at 4 MPa. Conversely, increasing the desorption temperature from 313 K to 353 K reduces both COP and exergy efficiency, with [ P66614 ][Pyr] achieving a COP of 6.30 at 353 K, which is 1.43 and 1.69 times those of [ P66614 ][Triz] and [ P66614 ][Lys], respectively. In contrast, increasing the desorption pressure from 0.2 MPa to 0.6 MPa enhances COP and exergy efficiency while reducing total exergy destruction; notably, the total exergy destruction of [ P66614 ][Pyr] decreases from 3.58 to 1.36 kJ/s, and its COP reaches 7.16 at 0.6 MPa. Notably, under all investigated operating conditions, [ P66614 ][Pyr] consistently demonstrates the superior cycle performance, thereby serving as the optimal working fluid for the functionalized IL-CO 2 high-temperature chemical heat pump proposed herein. Overall, this study establishes a theoretical foundation and provides crucial data support for further research into functionalized IL-CO 2 chemical heat pumps.