A Smart Solar Reactor for Environmentally Clean Chemical Processing

摘要

Solar thermal process reactors can convert intermittent solar radiation and reactants into energyrndense, storable and transportable chemical fuels. This method uses concentrated solar energy asrnthe source of high temperature process heat for the production of many commodities such as zinc,rncadmium, magnesium, hydrogen and carbon with zero or minimal emissions. Transientrninefficiencies due to natural fluctuations in solar radiation degrade product throughput in all solarrnreactors. It is therefore important to design a system that allows the reactor to respond tornenvironmental factors in order to maintain semi-constant temperatures inside the reactor.rnMaintaining reactor operating conditions stabilizes process efficiency. Previously, the effects ofrnvarious aperture geometries have been investigated through the use of ray-tracing and discreternordinance numerical simulations. In this paper, a more complete concept for the aperturernmechanism entitled the “sliding variable aperture” is presented. This variable aperture allows thernsolar reactor to dynamically respond to changing flux conditions. Optical simulations have beenrncarried out in conjunction with a numerical method for determining the output of the reactor withrna dynamic aperture and changing flux conditions. Historical weather data was gathered from thernNational Renewable Energy Laboratory (NREL). Convective losses were modeled based on arndesired isothermal temperature and static standard operating environmental temperatures. Resultsrnfrom the optics simulations, reaction kinetics and the heat transfer model were used to find thernrange for the area of the gap for the aperture mechanism, which resulted with ranges between 13.8rnto 52.3 cm~2 for beam normal insolation amounts between approximately 165-1100 W/m~2 in order tornmaintain a minimum 1500 K internal cavity temperature inside the solar reactor.