Optimising energy storage with enhanced PCM composites in solar collectors and underfloor heating, coupled with heat pump technology

Abstract

In response to the pressing environmental challenges of our era, advancements in sustainable energy technologies are imperative. This thesis investigates the enhancement of thermal conductivity in Phase Change Materials (PCMs) through the integration of thermal conductivity enhancers, specifically expanded graphite and copper powder. The study evaluates a combined renewable energy system comprising an air-to-water heat pump, an underfloor heating system, and a hybrid solar thermal panel. This system integrates water and PCMs as energy storage. Thermal conductivity enhancers are applied throughout the energy storage components to improve heat transfer and optimize the performance of the integrated system. A key aspect of this research is the exploration of how energy storage can shift peak load demand to off-peak hours, thereby enhancing the overall efficiency and performance of the renewable energy system. The methodology combines experimental tests and simulations in TRNSYS and ANSYS to evaluate energy performance and environmental benefits. Key findings demonstrate a substantial increase in thermal conductivity—16 and 17 times greater than that of pure paraffin—achieved with 25% expanded graphite and a mix of 25% expanded graphite with 2% copper powder, respectively. The PCM enhanced system sustains a warm floor surface for an additional 8 hours compared to an underfloor heating system with a sensible heat thermal mass. Furthermore, the system yields yearly cost savings of approximately £818.60 compared to an oil boiler, with an estimated payback period of 6 years

Thesis is embargoed until 31st December 2026

Date of Award	Dec 2024
Original language	English
Sponsors	Department for the Economy & Engineering and Physical Sciences Research Council
Supervisor	Neil Hewitt (Supervisor), Aggelos Zacharopoulos (Supervisor) & Ming Jun Huang (Supervisor)