High-temperature thermochemical energy storage using iron-manganese oxide particles in a packed-bed reactor

Abstract

The rising demand for electricity coupled with concerns about globally increasing greenhouse gas emissions has prompted greater interest in using renewable energy sources. One of the main drawbacks of renewable energy sources is their intermittency. For instance, solar energy experiences regular daily and annual cycles due to the earth's rotation, motion and axis inclination which leads to variations in solar irradiance. Furthermore, solar energy is unavailable during cloudy weather. One particularly promising solution to the intermittency of solar energy is implementing thermochemical energy storage (TCES) technology in the future concentrated solar power (CSP) plants. This would help to achieve the primary objective of providing non-intermittent clean electricity. In this thesis, a reactor packed with iron-manganese oxide particles is considered as the TCES system. First, the reduction reaction of particles is studied under non-isothermal conditions in argon and air atmospheres using a thermogravimetric analyzer (TGA). A shrinking core model along with a non-linear regression technique is used to model the thermal reduction of particles. Then, heat transfer of the reactor is studied when no chemical reaction occurs. The spatial temperature distribution in both axial and radial directions of a packed-bed reactor are measured experimentally. A two-dimensional, pseudo-homogeneous model is developed for the reactor, and effective thermal transport parameters are determined as functions of temperature by solving an inverse problem. Finally, these results are combined and used to describe the thermochemical performance of the particles in the packed-bed reactor during the reduction reaction. Results from the simulation are validated with the experimental data.