Date of Award
Master of Science (MS)
Chemical & Biochemical Engineering
Alan W. Weimer
David E. Clough
Nathan P. Siegel
An exploration was done on the feasibility of storing both sensible and thermochemical energy at high temperatures for concentrated solar power in order to mitigate issues with each type of energy storage alone. Two potential processes were suggested and discussed for use with a solid oxide reaction: an augmented solid particle receiver and a dish system with a gaseous heat transfer fluid and solid blocks of active material. Thermochemical energy storage using the "hercynite cycle" has been explored using the FACTSageTM Gibbs free energy minimization software, which predicted material compositions and enthalpy changes at conditions of interest. Calculations predict that the hercynite cycle material reduces above 1000°C and Various material formulations were cycled in a TGA/DSC at temperatures between 900°C and 1500°C using argon and air during reduction and oxidation. The observed oxidation enthalpies spanned an order of magnitude, from 10 - 100 kJ/kg. Isothermal energy storage was demonstrated at 1200°C, resulting in enthalpy values of 32.6 kJ/kg. Mixtures with excess Al2O3 tended to have lower observed specific heats of reaction due to the additional inert material. The heats of reaction obtained for the oxidation exotherms were lower than equilibrium predictions and it is suggested that side reactions not predicted by well-mixed thermodynamic equilibrium are occurring and contributing to changes the total reaction enthalpy; data from XRD and Raman Spectroscopy indicate that this may be occurring.
Ehrhart, Brian David, "Thermochemical Cycle of a Mixed Metal Oxide for Augmentation of Solar Thermal Energy Storage Using Solid Particles" (2013). Chemical & Biological Engineering Graduate Theses & Dissertations. 44.