Method for charging and discharging a heat accumulator and system for storing and releasing thermal energy suitable for said method

A method for charging and discharging a heat accumulator, comprising:

• during a charging cycle, heating up the heat accumulator by a working fluid, a pressure rise being generated in the working fluid, before it runs through the heat accumulator, by a first thermal fluid energy machine, connected up as a working machine, and, after running through the heat accumulator, the working fluid undergoes the substantial part of its expansion, and,
• during a discharging cycle, cooling the heat accumulator by a working fluid, a pressure rise being generated in the working fluid before it runs through the heat accumulator, and, after running through the heat accumulator, the working fluid being expanded via a second thermal fluid energy machine connected up as an engine,
• wherein the discharging cycle is configured as a Rankine process, in which
• the working fluid is first conducted through a first line system running in the heat accumulator,
• subsequently, the working fluid is expanded via a high-pressure part HP of the second thermal fluid energy machine,
• subsequently, the working fluid is conducted through a second line system running in the heat accumulator, and
• subsequently, the working fluid is expanded via a low-pressure part LP of the second thermal fluid energy machine.