Ionic liquid screening and performance optimization of transcritical carbon dioxide absorption heat pump enhanced by expander

Yunren Sui and Wei Wu

Energy, 2023, vol. 263, issue PA

Abstract: Absorption technologies show great potential in utilizing renewable energy and waste heat. In this study, novel CO2/ionic liquid (IL) mixtures are investigated to overcome the shortcomings of conventional working fluids. To screen the optimum ILs for a transcritical CO2/IL absorption heat pump (TsCO2-AHP), the absorption cycle models using 34 IL species are established to estimate the cycle performance. Within the selected candidates, [OMIM][Tf2N] yields the best cycle performance. For imidazolium-based ILs with different anions, the coefficient of performance (COP) is in the order of [Tf2N] > [C(CN)3] > [OTF] > [DCA] ≈ [PF6]. [EMIM][C(CN)3] yields the highest heat transfer coefficient of 0.520 kW/(m2·K) due to its better transport properties compared to other candidates. The high-side pressure optimization is conducted to maximize the COP. At the generator temperature of 138 °C, the COP of CO2/[OMIM][Tf2N] reaches the highest 0.2614 with the optimum Phigh of 10.289 MPa. By equipping an expander, the COP of the TsCO2-AHP is improved by 11.9% because of a larger cooling capacity and less electricity consumption. The main objectives are contributing novel potential working fluids, optimizing the cycle parameters, as well as selecting the best-performance CO2/IL mixture for improved development of absorption technologies.

Keywords: Ionic liquid; Absorption heat pump; Transcritical cycle; Carbon dioxide; Parameter optimization; Expander (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (8)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:263:y:2023:i:pa:s0360544222025750

DOI: 10.1016/j.energy.2022.125689

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