Patent ID: 11940224
Assignee: STIESDAL STORAGE A/S
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F | IPC F

Claim 0:
1. A method of operating a thermal energy storage (TES) system comprising a thermodynamic fluid cycle including a first TES container and an energy converter for converting between electrical energy and thermal energy of working fluid in the thermodynamic fluid cycle; wherein the first TES container has a top and a bottom and contains a first TES medium for storing thermal energy, the first TES medium having an upper end and a lower end, wherein the top of the first TES container is connected to a hot working fluid section of the thermodynamic fluid cycle and the bottom of the first TES container is connected to a cold working fluid section of the thermodynamic fluid cycle, the method comprising:
during a period of charging, supplying electrical energy to the energy converter and converting the electrical energy to added thermal energy in the working fluid for raising a temperature of the working fluid to Tmax;
providing the working fluid at Tmax to the top of the first TES container,
transferring thermal energy from the working fluid to the first TES medium by flow of the working fluid from the upper end to the lower end,
providing a temperature gradient from Tmax to Tmin in the first TES medium, where Tmin<Tmax, and moving the temperature gradient towards the lower end during the charging,, wherein the temperature gradient is contained in a thermocline zone of the first TES medium,
by supplying electrical energy to the TES system, raising the temperature of the first TES medium at the lower end (Tend) from Tmin only until Tend reaches a predetermined control temperature TC,
predetermining and selecting TC within a thermocline control interval defined by: TCϵ[Tmin+0.25 ΔT; Tmin+0.65 ΔT], where ΔT=Tmax−Tmin.