Electro-Thermal Analysis of Inductively Heated and Aerated Rod Bundle for Adiabatic Compressed Air Energy Storage

Abstract

Utility-scale electricity storage in adiabatic compressed air energy storage (A-CAES) power plants offers the prospect of making a substantial contribution for energy efficient and flexible electricity transmission systems. For further improvements of flexibility, cost efficiency and performance, various power plant configurations for partial-adiabatic process have been developed and investigated. To this end, a novel concept for the integration of an electrical heating component in series with the thermal energy storage (TES) has been elaborated. The present contribution aims at developing a suitable design solution for the electric heating component using the induction heating technology: it investigates an aerated bundle of rods located inside a coil. In order to predict the heat input into the air flow and to assess the efficiency of the heating process an electro-thermal model has been developed and implemented. It forms the basis for a simulation study to identify energy-efficient and compact designs applied to A-CAES. The model describes the coupled electromagnetic and thermal phenomena using an equivalent circuit method approach. The electro-thermal model includes relevant design geometries of the inductions heating arrangement as well as down-scaled process parameters used for model validation. In order to identify compact and energy-efficient designs some of the geometrical parameters of coil and rod bundle have been varied. The increase of rod’s diameter Dr and the packing density of the bundle result in an improved coupling of the electro-magnetic field. Furthermore, a higher packing density also results in higher convective heat transfer and thus improves the overall efficiency of the process.