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Thermodynamic analysis of an indirectly coupled CO2 high-temperature heat pump for dual-temperature heat supply.

Author(s) : ZHANG M., BAI T., ZHANG H.

Type of article: IJR article

Summary

High-temperature heat pumps (HTHPs) are an effective means to enhance energy utilization efficiency. However, their development is constrained by environmentally friendly refrigerant substitution, large temperature-lift heating demands, and severe performance degradation in cold regions. To address these challenges, this paper proposes a modified dual-temperature heating air-source CO2 indirectly coupled high-temperature heat pump cycle (MHTHP). By leveraging the temperature glide characteristics during the cooling process in the gas cooler of the transcritical CO2 cycle and an intermediate thermal storage strategy, the MHTHP extracts heat directly from ambient air to achieve a large temperature lift exceeding 130 ◦ C, efficiently producing 140 ◦ C hot water or steam. Comprehensive evaluations demonstrate that the MHTHP significantly outperforms a conventional cascade system (BHTHP). Thermodynamically, the COP cycle and η ex_cycle are improved by 21.6%–38.5% and 21.4%–37.6%, respectively. Economically, despite a higher initial investment, the MHTHP reduces the specific exergy cost (c p ) by 21.4%–29.8% due to its superior operational efficiency. Furthermore, the incorporation of intermediate thermal storage enables temporal decoupling of the low-temperature stage, reducing its operating duration by approximately 50% and providing strong potential for grid peak shaving and valley filling. More over, the MHTHP is insensitive to the outlet water temperature under low-ambient-temperature conditions, which is favorable for achieving large temperature lifts in cold regions. In summary, the proposed MHTHP presents a promising solution for efficient, environmentally friendly, and grid-adaptive industrial high- temperature heat supply

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Details

  • Original title: Thermodynamic analysis of an indirectly coupled CO2 high-temperature heat pump for dual-temperature heat supply.
  • Record ID : 30034972
  • Languages: English
  • Subject: Technology
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 188
  • Publication date: 2026/08
  • DOI: http://dx.doi.org/10.1016/j.ijrefrig.2026.106976

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