Thermal insulation of an ultra-high temperature thermal energy store for concentrated solar power

Abstract

This paper presents screening results of suitable thermal insulation materials and a thermal insulation concept for an ultra-high temperature latent heat thermal energy store. A multi-layer insulation concept was determined as it reduces heat losses and costs of the thermal insulation compared to one-layer insulation. Simulation studies with the software COMSOL Multiphysics 5.2a were performed to investigate heat losses and temperature propagation dependent on the thermal insulation materials, the thickness of the insulation layers and the atmosphere gas. The TES was modeled as a truncated cone with a height of 150 mm and diameters of 100 and 150 mm with a constant temperature of 2 300 K. The application of vacuum in the thermal insulation was found to be very promising in order to reduce insulation thickness as well as heat losses and consequently costs. A two-layer insulation of graphite fiber mat and fumed silica board with a total thickness of 500 mm in vacuum atmosphere resulted in less than half of the total heat loss rate compared to the same two-layer insulation with a total thickness of 540 mm in argon atmosphere.