With thermal storage technology, electric energy is converted into heat energy (and/or cold energy) in the form of storage, and converted into electrical energy output when needed. With advantages of high energy storage density and low cost, it is expected to become the backbone of large-scale energy storage in the future, and play an important role in the realization of the "double carbon" goal. There is still a big gap between thermal energy storage technology and electrochemical energy storage in terms of energy conversion efficiency. Heat pump energy storage technology based on thermodynamic cycle (also known as Carnot battery) has the highest energy conversion efficiency among the current thermal energy storage technology, and has attracted the focus of attention at home and abroad in recent years. Since 2015, the Energy Storage R&D Center of the Institute has carried out the research and exploration of heat pump electricity storage technology based on Bretton cycle. Recently, new progress has been made in the theoretical system, system optimization, operation regulation and application technology of heat pump electricity storage technology.
Progress in a
◆ Based on the entropy increase theory, a theoretical analytical optimization method for heat pump electric storage system is proposed, and the optimal analytical solution for system parameters is obtained, which gives consideration to both efficiency and energy storage density. The method increases the energy storage efficiency ceiling of the existing Bretton Heat pump electric storage system by 10%~20%.
◆ Published in Journal of Energy Storage (IF=6.583), link:
https://www.sciencedirect.com/science/article/pii/S2352152X21013384.
Progress in two
◆ A new strategy for operation control of cold and heat storage array -- "dynamic temperature compensation" is proposed, which effectively solves the output temperature attenuation of heat pump storage system. At the optimized dimensionless target temperature, 64.2% storage efficiency can be obtained and the release power fluctuation can be reduced from 43% to 13%.
◆ Published in Applied Energy(IF=9.746), link:
https://www.sciencedirect.com/science/article/pii/S0306261921003214.
Progress in three
◆ A heat pump power storage system that is more suitable for large-scale, long-term and low-cost indirect cold and heat storage is proposed. The results of system optimization and technical-economic analysis show that the system has technical and economic advantages in long-term storage of more than 6 hours.
◆ Published in the journal Energy(IF=7.147), link:
https://www.sciencedirect.com/science/article/pii/S0360544221022143.
Progress on four
◆ The flexible conversion and utilization mode of cold, heat and electricity based on Brayton heat pump electric storage system is proposed and analyzed. The analysis results show that the system has wide working conditions, high efficiency and flexible adjustment ability of cold, thermal and electrical load demands. The COP of the system energy storage can reach 1.88, and the exergic efficiency of energy storage reaches 63.9%.
◆ Published in Applied Energy(IF=9.746), link:
https://www.sciencedirect.com/science/article/pii/S0306261920311144.