Brayton-cycle-based pumped heat electricity storage with innovative operation mode of thermal energy storage array

As a novel physical energy storage technology with energy densities and efficiencies comparable to advanced compressed air energy storage, pumped heat electricity storage (PHES) has attracted significant attention in recent years. Arrayed multi thermal energy storage (TES) reservoirs have promising potential for large-scale TES storage, and the operation modes of TES arrays significantly affect the PHES system which has not been investigated in presented studies. By performing numerical simulations considering coupling dynamics, transient heat transfer, and thermodynamics, the transient behavior of the cyclic steady-state of a 10 MW/8 h Joule?Brayton PHES system under four operation modes including series, parallel, in-sequence, and the innovative ?temperature complementation? is investigated in this study. The PHES with series-connected reservoirs arrays has a round-trip efficiency of 64.9% and a delivery variation of 43.1%; these results are better than those obtained under the parallel and in-sequence operating modes of the singular reservoir PHES. Under the innovative ?temperature complementation? operation mode, the delivery stability improves further with a variation of 13.2%. The TES reservoirs could be reduced to 1.8 times the minimum volume with a round-trip efficiency of 63%?65%. Such a TES array with the ?temperature complementation? operation mode may facilitate the development and application of other fixed TES technologies by providing stable thermal energy delivery.