Abstract
Heating electrification is a trend for the current carbon neutrality setting. The air-source heat pump (ASHP) has been widely used in residential or commercial buildings to replace household coal-burning stoves due to its higher operating efficiency. Previous studies mainly focused on the heat pump equipment, ignoring the whole system performance in practical application. Among the auxiliary system of the ASHP heating system, the power consumption of water pump cannot be ignored, especially in residential district heating with a large amount of pipeline. This paper proposes the coefficient of performance (COP) improvement of the ASHP heating system through variable temperature difference and flow rate of circulation water loop, showing the feasibility and benefit of large temperature difference with small flow rate. A high-fidelity dynamical model is first built using Dymola, followed by the experiments verification at the environmental laboratory. On all testing conditions, the system COP of large temperature difference with small water flow rate shows average 6% to 8% improvement compared to small temperature difference with large water flow rate. Further, a demonstration heating project of the ASHP system was tested onsite under a realistic operating condition. The recorded hourly operation data showed an average system COP of 2.15 at the condition of large temperature difference, which is about a 7% improvement compared to the small temperature difference condition for the typical heating day.
NSTL
Elsevier