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Energy and exergy analysis of the air source transcritical CO2 heat pump water heater using CO2-based mixture as working fluid


Wang, Y and He, Y and Song, Y and Yin, X and Cao, F and Wang, X, Energy and exergy analysis of the air source transcritical CO2 heat pump water heater using CO2-based mixture as working fluid, Energies, 14, (15) Article 4470. ISSN 1996-1073 (2021) [Refereed Article]

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Copyright 2021 by the authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)

DOI: doi:10.3390/en14154470


Given the large demand nowadays for domestic hot water, and its impact on modern building energy consumption, air source transcritical CO2 heat pumps have been extensively adopted for hot water production. Since their system efficiency is limited by significant irreversibility, a CO2-based mixture could offer a promising drop-in technology to overcome this deficiency without increasing system complexity. Although many CO2 blends have been studied in previously published literature, little has been presented about the CO2/R32 mixture. Therefore, a proposed mixture for use in transcritical CO2 heat pumps was analyzed using energy and exergy analysis. Results showed that the coefficient of performance and exergy efficiency variation displayed an "M" shape trend, and the optimal CO2/R32 mixture concentration was determined as 0.9/0.1 with regard to flammability and efficiency. The irreversibility of the throttling valve was reduced from 0.031 to 0.009 kW⋅kW−1 and the total irreversibility reduction was more notable with ambient temperature variation. A case study was also conducted to examine domestic hot water demand during the year. Pure CO2 and the proposed CO2 blend were compared with regard to annual performance factor and annual exergy efficiency, and the findings could provide guidance for practical applications in the future.

Item Details

Item Type:Refereed Article
Keywords:transcritical CO2 heat pump, energy analysis, exergy analysis, CO2-based mixture, ambient temperature, case study
Research Division:Engineering
Research Group:Mechanical engineering
Research Field:Energy generation, conversion and storage (excl. chemical and electrical)
Objective Division:Energy
Objective Group:Energy storage, distribution and supply
Objective Field:Energy systems and analysis
UTAS Author:Wang, X (Professor Xiaolin Wang)
ID Code:145504
Year Published:2021
Deposited By:Engineering
Deposited On:2021-07-24
Last Modified:2021-11-22
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