Solar Thermal Reactor Model

Solar reactors are devices that collect concentrated solar energy from systems such as the solar furnace in the James S. Markiewicz Solar Energy Research Facility for the purpose of supplying high-temperature process heat to endothermic chemical processes. In order to efficiently utilize the concentrated sunlight, solar receivers must be designed to have a high effective solar absorbtance, to evenly distribute the solar energy to the chemical reactions within the receiver, and to minimize heat losses. Radiation heat transfer plays a central role in each of these design challenges. An accurate model of the radiation heat transfer is thus desired. In this study, we develop a model of the radiation heat transfer in a solar reactor designed to reduce cobalt oxide (Co3O4) and ultimately, in a separate chemical step, hydrogen from water. Our model, which is based on the Monte Carlo Ray Tracing (MCRT) technique, predicts the distribution of thermal energy by radiation from the VU solar furnace over the internal surfaces of the solar reactor and also the distribution of thermal energy emitted from the hot reactor surfaces within the reactor. By including the VU solar furnace in the radiation model, the model resolves the unique and complex directional and spatial distribution of the concentrated solar energy streaming in to the solar reactor. The radiation heat transfer model is coupled to a transient model of the solar reactor developed in a prior study that predicts the reactor temperature, the rate of the reduction of the cobalt oxide, and the reactor solar thermal efficiency during start-up and steady operation. The transient reactor model coupled with the MCRT radiation heat transfer model suggests that the reactor will achieve efficiencies on the order of 30%. The location of peak flux within and maximum temperature within the reactor is also shown