Performance optimization of space heating using variable water flow air source heat pumps as heating source: Adopting new control methods for water pumps

In recent years, the application of air source heat pumps (ASHPs) in centralized heating has grown rapidly in North China. However, there is still lack of theoretical investigation on the control methods of water pump. To decrease the system power consumption, a mathematical model of variable-frequency ASHP used for supplying heating for ten users was established in this work. Meanwhile, three control methods of water pumps were proposed. The heating performance of ASHP system under the three control methods was investigated. Besides, the appropriate control methods of heating terminals under the three control methods were analyzed. Results showed that the minimum relative water flow rate is 30%. Among the three proposed control methods, the power input of water pump is the minimum in the pressure differential control method of the most unfavorable terminal, and its difference with the highest value is 0- 31.84%. For the power input of ASHP system, it is always the maximum in constant flow control method, while the minimum in the pressure differential control method of the most unfavorable terminal. Compared with the values in the former control method, the power input of ASHP system in the latter control method decreases by an average of 13.40%. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

In recent years, the application of air source heat pumps in centralized heating in North China has rapidly increased. However, there is a lack of theoretical investigation on the control methods of water pumps. This study established a mathematical model of variable-frequency air source heat pumps for heating and proposed three control methods for water pumps. The heating performance of the system and appropriate control methods for heating terminals were analyzed. The results showed that the power input of the water pump was the minimum in the pressure differential control method, and the power input of the ASHP system decreased by an average of 13.40% compared to the constant flow control method.