Parametric Study of High-Temperature Thermochemical Energy Storage Using Manganese-Iron Oxide

Abstract

Abstract Continuous power supply in Concentrated Solar Power (CSP) plants can be achieved via integration of efficient, cost-effective and reliable Thermal Energy Storage (TES) system. The new generation of CSPs operates at higher temperatures and requires thermal storage systems with higher energy density at high storage temperature. Thermochemical Energy Storage (TCES) is the available solution which can meet performance requirements of energy density, temperature, and stability. TCES systems apply reversible endothermic/exothermic chemical reaction through which energy is stored as the enthalpy of reaction and released during the reverse mode. Among several available potential reversible chemical reactions, metal oxides, with high reaction temperature and enthalpy of reaction, have remarkable advantages compared to others. They use air both as Heat Transfer Fluid (HTF) and oxidation reactant, which eliminates the need for storage and intermediate heat exchanger integration between HTF and collector working fluid. Using air as HTF has made them perfectly fitted for the new generation of air operated solar collectors. Among several screened available potential metal oxides, cobalt and manganese oxides were selected as best candidates for high-temperature storage. Pure manganese oxide does not meet the cyclic operation requirement, but the iron-doped solid solution has proven reasonable cyclic storage performance. In this study, iron-doped manganese oxide (Fe-Mn 1:3 molar ratio) has been selected as a redox agent for TCES reactor. The cylindrical packed bed configuration is considered as a reactor bed configuration. A two-dimensional axisymmetric numerical model is developed using the finite element method. Performance analysis for both charge and discharge is provided separately. The effect of inflow rate and bed porosity variations on reactor performance in complete storage cycle were studied.