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Experimental study on the heating performance of a transcritical CO2 heat pump water heater under Multi-Parameter coordinated matching operation.

Author(s) : HU R., JIN X., WANG Y., ZHANG Z., LIU Z., MENG X.

Type of article: IJR article

Summary

In CO2 heat pump (HP) water heaters, achieving optimal synergy among operating parameters is essential for maintaining high system performance under varying heating demands. This study investigates a CO2 HP system equipped with an electronic expansion valve (EEV) and ejector throttling. The comprehensive effects of operating parameters—compressor frequency, EEV opening, inlet water flow rate (IWFR), and temperature—on system performance were quantified through the mean normalization method, along with a comparative analysis of the performance under EEV and ejector throttling modes. The results show that ejector throttling improves the coefficient of performance (COP) by 6.5 %. Within a specific range, reducing the EEV opening improves COP, particularly at lower inlet water temperatures and higher IWFRs, achieving a COP of 3.49 (30 Hz, 60 % EEV, 20 °C, 0.6 m3⸳h−1). Compressor frequency, IWFR, and temperature are identified as the primary factors influencing heat transfer rate. The impact of compressor frequency and inlet water temperature on COP is more significant than that of IWFR and EEV opening. To meet hot water demand and maintain high system performance, the weighted influence of each parameter must be carefully evaluated during adjustments to ensure system stability and optimal performance. This study offers valuable insights for developing multi-parameter control strategies for CO2 HP water heaters.

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Pages: 212-228

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Details

  • Original title: Experimental study on the heating performance of a transcritical CO2 heat pump water heater under Multi-Parameter coordinated matching operation.
  • Record ID : 30033834
  • Languages: English
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 173
  • Publication date: 2025/05
  • DOI: http://dx.doi.org/10.1016/j.ijrefrig.2025.02.019

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