We report on the improved operational performance and energy conversion efficiency of a 5-kW solar chemical reactor for the combined ZnO-reduction and CH4-reforming SynMet process. The reactor features a pulsed vortex flow of CH4 laden with ZnO particles, which is confined to a cavity-receiver and directly exposed to solar power fluxes exceeding 2000kW/m2. Reactants were continuously fed at ambient temperature, heated by direct irradiation to above 1350°K, and converted to Zn and syngas during mean residence times of 10 seconds. Typical chemical conversion attained was 100% for ZnO and up to 96% for CH4. The thermal efficiency was in the 15–22% range; the exergy efficiency reached up to 7.7% and may be increased by recovering the sensible and latent heat of the products. The SynMet process avoids emissions of greenhouse-gases and other pollutant derived from the traditional fossil-fuel-based production of zinc and syngas, and further converts solar energy into storable and transportable chemical fuels.

Issue Section:
Technical Briefs
Keywords:
zinc compounds, solar absorber-convertors, solar heating, chemical reactions, vortices, latent heat
Topics:
Latent heat, Methane, Solar chemistry, Solar energy, Solar power, Syngas, Temperature, Thermal efficiency, Exergy, Particulate matter, Vortex flow
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 by ASME
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