Simulation and optimization of the operation strategy of ASHP heating system: A case study in Tianjin

Abstract

Air-source heat pump (ASHP) has been widely applied in heating systems of school buildings. In order to achieve building energy efficiency while ensuring indoor thermal comfort, the paper compared the effects of different operation strategies including intermittent heating mode in non-working hours and setpoint of return water temperature in working hours. A middle school building in Tianjin, China is chosen as a case study and its physical model is developed by using the EnergyPlus tool. After verifying the validity of the model, the article simulated 64 different operation conditions produced by combining 8 start-up times with 8 return water temperature setpoints to find a better operation mode of the intermittent heating. Results indicate that running at a lower water temperature with an earlier start-up time is more energy efficient compared with running at a higher water temperature with a later start-up time while meeting the thermal comfort requirement. In addition, by changing the return water temperature setpoints hourly based on the outdoor air temperatures, the situation of overheating and undercooling during working hours has been well improved and the energy saving rate is about 17% during the entire heating season.