Case study on flywheel energy storage systems: LPTN-based transient thermal analysis

Abstract

This study established a lumped parameter thermal network model for vertical flywheel energy storage systems, considering three critical gaps in conventional thermal modeling: oversimplified radiative heat transfer within sealed chambers, unquantified dynamic losses, including rotor eddy currents and flywheel friction, and transient hysteresis in stator water jacket cooling. Validated through extreme continuous charge-discharge experiments of 200–400 kW, the simulated temperatures exhibit a maximum deviation of 2 °C at steady-state, demonstrating superior accuracy in capturing both spatial distributions of the system and the temporal variations of coolant temperatures. Furthermore, most of the exergy loss in the heat transfer process is concentrated in the motor stator, casing, and cooling water. Improving the heat transfer paths in these areas would help enhance overall system efficiency. The outcomes offer valuable insights for correlative research on flywheel energy storage system thermal management technologies, providing significant references for the design and optimization of the system.