Completed: THERMCAST: Valorisation of foundry sands as medium-high temperature waste heat recovery materials

In collaboration with Kelvin Thermotech Ltd and the Confederation of British Metalforming

The industrial sector in the UK accounts for ~17 % of its overall energy consumption, the majority of which is in the form of heat (BEIS, 2017). Waste heat recovery (WHR) and reuse are thus the next frontiers for energy-intensive industries. Thermal energy storage (TES) is a cost-effective and versatile solution for WHR. Latent heat TES (LHTES), based on the isothermal heat absorption/release during phase change, is a promising sub-category of TES. THERMCAST demonstrated the technical and economical feasibility of using foundry sand as a TES material for medium-high temperature waste heat recovery and storage. The project developed a novel thermal energy storage (TES) material based on foundry sand for hybrid thermal energy storage up to 400 ℃. The optimal composition consisted of 60% NaNO_3, 30% foundry sand and 10% further additives. The material had good chemical and physical stability after 50 cycles (25-400 ℃) with energy storage density, 566 KJ/kg, and thermal conductivity, 1.23 W/mK. A TES system, based on the developed material, was designed using the waste heat data which gave 87% and 81% efficiency for charging and discharging respectively. Preliminary technoeconomic analysis suggested that a minimum payback period of ~5-6 years with 90% system efficiency.

THERMCAST therefore showcased an alternative utilization pathway for waste foundry sand as a thermal energy storage material. It demonstrated all the steps necessary to bring this technology to the market and evaluate its potential for energy-saving. Its theoretical implementation in a TES device was realized within an industrial setting in the co-sponsoring company. Throughout THERMCAST several UK companies and academics were approached to encourage more entities to further explore this technology in the future.

Publications

• From waste to value: Utilising waste foundry sand in thermal energy storage as a matrix material in composites,  https://doi.org/10.1016/j.solener.2023.112294

Dr Argyrios Anagnostopoulos

University of Birmingham

Email: a.anagnostopoulos@bham.ac.uk

Dr. Anangostopoulos is a Research Fellow at the School of Chemical Engineering at the University of Birmingham. He has an industrial engineering background with an MSc in renewable energy systems engineering. His PhD focused on enhancing the specific heat capacity of molten salts for medium-high temperature thermal energy storage applications. He is currently participating in a FET-Open European project focused on recovering the energy from vibrating machinery through spontaneous liquid intrusion/extrusion in superhydrophobic media. His interests lie in thermal energy storage, waste utilization, corrosion and surface science.