Study on the Performance of a New Ultra-Low Temperature Air Source Heat Pump (ASHP) Unit in Cold Regions

Low air temperature and frosting have been reported as the critical factors that greatly attenuate the efficiency and performance of the ASHP in cold regions. In order to ensure the potential prevalence of the ASHP in cold regions of China, a new ultra-low temperature ASHP unit was developed, and the field measurement was carried out in an office building where these ASHP units were installed in Shanxi Province. Results showed that a coefficient of performance (COP) of 1.83 was obtained at the ultra-low environmental temperature of −25 °C. Meanwhile, measured results indicated significant frosting suppression and improved heating performance under three typical frosting conditions. In addition, long-term measurement results revealed that the mean COP and COPsys reached up to 3.34 and 2.63, respectively, indicating a higher performance in the cold regions of China. Consequently, the corresponding CO2 emission reached 11.3 kg per year and per square meter, and the annual total cost on the unit reduced by 15.8% compared with the conventional ASHP, which meant that the total investment could be covered in the second year. The reduced CO2 emission and the annual cost implied that the ASHP unit could produce better environmental and economic benefits. Findings of this study revealed that this ultra-low temperature ASHP unit had a better performance under cold environment, which offered a possibility for the prevailing of the ASHP in cold or extremely cold regions, as well as could contribute to the carbon peaking and neutralization.

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