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Kur, Anti (2025) Novel thermochemical energy storage system: from material development to evaluation. PhD thesis, University of Nottingham.

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Abstract

The building sector is a major contributor to global energy consumption and carbon emissions, with heating demand predominantly met by fossil fuels. As the integration of variable renewable and waste heat sources into urban heating networks expands, thermochemical energy storage (TCES) presents a promising solution, offering high energy density and the potential for long-duration storage. However, the practical deployment of TCES has been limited by material and reactor inefficiencies critical for industrial waste heat recovery.

This research aimed to develop and evaluate a novel TCES material tailored for medium-temperature waste heat applications. A new composite based on Mg(OH)₂ doped with 5 wt% KNO₃ and 15 wt% Al₂O₃ was synthesized and characterized. The doped material exhibited a reduced dehydration temperature from ~317 °C to 293 °C, enabling more efficient waste heat capture within the 293–400 °C range. The energy storage capacity increased from 1246 J/g to 1317 J/g. Molecular simulations predicted a thermal conductivity of 0.708 W/mK, an enhancement of 12.9% over pure Mg(OH)₂, which aligned well with experimental values (0.6484 W/mK).

Reactor-scale numerical modelling of 1.5 kg of the composite in an agitated fluidized bed reactor showed that dehydration began at 300 ℃ with an airflow of 28.95 kg/h, achieving a minimum fluidization velocity of 0.1850 m/s and a 99.99% reaction efficiency, releasing +5 kW of heat. Hydration initiated at 200 ℃ using a humidified air stream, with a minimum fluidization velocity of 0.01598 m/s and a 99.21% reaction efficiency, releasing −4.8 kW of heat. A water vapour to MgO molar ratio beyond 4:1 showed saturation effects, indicating water as a limiting factor in hydration.

These findings demonstrate the potential of the developed Mg(OH)₂-KNO₃-Al₂O₃ composite for efficient medium-temperature TCES. Future work should focus on long-term material stability, advanced reactor modelling, and full-scale validation to support real-world deployment in building energy systems.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Darkwa, Jo Calautit, John
Keywords:	Thermochemical energy storage, reactor modelling, fluidized bed reactor, magnesium hydroxide, doping, materials development
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ807 Renewable energy sources
Faculties/Schools:	UK Campuses > Faculty of Engineering > Built Environment
Item ID:	81891
Depositing User:	Kur, Anti
Date Deposited:	31 Dec 2025 04:40
Last Modified:	01 Jan 2026 04:30
URI:	https://eprints.nottingham.ac.uk/id/eprint/81891

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