Elaiza Luker

    PhD Student - Molten Salts Corrosion Fatigue for Concentrated Solar Thermal Power

    Principal Supervisor: Dr Veronica Gray

    Associate Supervisor: A/Prof Geoffrey Will and Prof Ted Steinberg (Mentoring Supervisor)

    PhD Overview

    As global energy demand continues to grow, harnessing the transient nature of renewable energy becomes increasingly important to achieving more economically viable, reliable and sustainable power generation. To address this requirement, Concentrated Solar Power (CSP) plants have been widely considered for industrial-scale clean energy generation. The backbone of the CSP is the Heat Transfer Fluid (HTF) used in heat exchangers and power cycles to generate electricity, and the Thermal Energy Storage (TES) medium that allow the plant to be operational when the primary energy source (the sun) is not available. In existing and next generation plants, molten salts are ideal for HTF fluids and TES due to their heat capacity for sensible heat storage, or high energy storage density for latent heat storage. However, the use of molten salts at high temperatures in CSP plants exposes materials to mixed-mode failure mechanisms. Specifically, corrosion fatigue comes into play accelerating the time to reach the critical damage threshold that cause cracks to initiate and propagate. In traditional fatigue conditions, materials spend most of its life within the crack initiation stage as dislocations develop within the microstructure to generate microcracks, which form an initial flaw. However, in the presence of a corrosive media, fatigue initiation life is reduced or eliminated with the introduction of corrosion damage as corrosion causes intergranular attack, pitting or localised material weakening. As a result, fatigue life can be reduced by as much as 90%, a life loss that is often not accounted for in relevant design guidelines and standards. This research aims to characterise the interaction and impact of corrosion fatigue on the fatigue performance of common CSP structural materials and molten salts to more accurately life CSP systems. To do this the project will develop corrosion fatigue testing techniques to quantify life loss, identify corrosion damage thresholds, corrosion rates and combination damage mechanisms of materials exposed to stress and molten salts. This information is critical to providing a more realistic guideline for designing more reliable and viable CSP infrastructure.