Reduction in on-off operations of an air source heat pump with active thermal storage and demand response: An experimental case study

Abstract

The air source heat pump (ASHP) in an air-conditioning system encounters frequent start-stop operations due to the fluctuation of cooling and heating load in buildings. A energy-storage tank is widely used as an effective device to solve this problem, and its flexible use can help to improve the operating efficiency of air-conditioning systems. Through building an air-conditioning system that can flexibly control the energy storage tank in a VAV experimental platform, this paper studies the operation mechanism of the storage tank as a buffer device (i.e., an active energy storage device) participating in the demand response in winter and summer. When using the storage tank, the time taken by return water temperature to exceed the set temperature range of the ASHP in the operating state is prolonged and the frequency of the start-stop operations of the ASHP is reduced. In the operation case of “large flow rate, small load”, the differences of water temperature between the inlet and outlet of the energy storage tank can compensate for the deficiency of small water temperature difference of air heading unit. As an active energy storage device, the energy storage water tank can provide a stable shedding peak load of the power grid when participating in demand response (DR). On non-DR days, ASHP is turned off before the air-conditioning is off, and the energy-storage tank provides the required energy for the terminal room, which can realize efficient energy utilization in the tank. The experimental results presented in this study can provide a reference for the flexible use of small-scale water storage systems.