Abstract:

Heating systems based on the clean energy heat pump achieve energy conversion through electrical power. The economic efficiency of the system can be drastically improved by leveraging time-of-use electricity pricing policies and utilizing the heating pipe network as a thermal storage medium for peak-valley load shifting. Addressing the conflict arising from peak-valley electricity pricing for clean energy heating systems in northern regions, this study proposes an energy storage solution based on existing heating pipe networks to construct a "source-storage-load" coordinated direct pipe network storage system.Taking the Qingdao High-tech Zone project (a heating area of 227,400 m² and a pipe network water capacity of 2000 tons) as an engineering case study, a multi-source parallel architecture was adopted. Three key technologies were implemented: ① integrating the primary pipe network and heat exchangers into distributed thermal storage units, ② developing a "quality-quantity dual regulation" control algorithm, and ③ establishing a SCADA real-time monitoring and cloud-based control platform.Operational data indicate that the system can achieve a rise of 8.25 ℃ in the primary network temperature during off-peak electricity periods. Although measured data indicate that R134a units can reach temperatures of up to 75 ℃, long-term operation under these conditions is not recommended. This rise allows for a complete shutdown for 10 h during the peak and flat electricity-price periods, while maintaining secondary network temperature fluctuations within 0.8 ℃.An economic assessment revealed that through the time-of-use pricing strategy (peak price: 1.25 RMB/kWh; deep valley price: 0.28 RMB/kWh), the project could achieve an annual revenue of 1.161 million RMB, with a dynamic payback period of 1.75 years. The study also confirmed that in this project, the investment cost per unit building area is only 8.3 RMB.This technology provides a flexible control solution for regional integrated energy systems. This solution is both economical and reliable, holding significant value for achieving the "dual carbon" goals.

Key words: network thermal storage, clean heating, time-of-use (TOU) Pricing, flexible control