Mechanical Performance of Concrete Thermal Energy Storage Subject to Operating Thermal Demands

This paper presents a lab-scale investigation of the use of structural concrete for sensible heat storage in power plants. Transient thermal and mechanical analyses are simulated via coupled finite element models to study the thermo-mechanical performance of a cylindrical concrete block with 4-in diameter and 8-in length under thermal loading. The model is validated by performing experiments on high strength concrete (HSC) cylinders with this geometry in an oven, which heats the specimens from the outside. The models are then modified to simulate thermal energy storage (TES) application with thermal loading applied at the interior surface of a hole running through the longitudinal center of the cylinder. Thermal cycles have a varying heating rate (5, 10, or 24 hours) followed by consistent durations of soaking (2 hours) and cooling (13 hours). In the TES simulations, a steel jacket is also applied to the external surface of the concrete cylinder to provide confinement. The resulting thermal distribution and maximum principal stresses during heating and cooling are observed as a function of time. This study provides insight into the mechanical requirements and impact on material integrity for concrete modules subjected to representative TES heating regimes.