Study on numerical modeling and operating characteristics of air source heat pump systems for low-temperature and high-humidity environments

In this paper, a numerical model of an air source heat pump (ASHP) system for low-temperature and high-humidity environments was developed, considering the effects of atmospheric pressure, ambient air temperature (T_a), and relative humidity (φ) on the thermophysical properties of atmospheric air. The model was solved using the trial method and validated against measured data. The effects of T_a, φ, and temperature difference between supply and return water (DT) on the performance of the ASHP system were analyzed. The results show that the relative error (RE) between the measured and simulated values of heating capacity remains within ±10 %, and over 90 % of the RE values of power consumption are also within ±10 %. Under the same operating conditions or when φ exceeds 50 %, the power consumption increases as temperature decreases. When T_a exceeds 6 °C, an increase in φ leads to a decrease in the power consumption. The mean COP of the ASHP system increases with increasing DT, however, when DT exceeds 5.3 °C, the increase in mean COP is less than 0.1 %. This paper can provide a theoretical basis for exploring the operating characteristics of the ASHP system in low-temperature and high-humidity environments.