Research On Energy Conversion And Transportation Mechanism Of Carbon Dioxide Capture In Artificial Photosynthesis

Photocatalytic reduction of carbon dioxide had been a promising way to control greenhouse gas emission. Optical fiber monolith reactor with catalyst coated on the inner surface attracts attention in recent years by its high light utilization ratio. Double skin-sheet reactor (DSSR) attracts attentions in recent years by its high performance and simple design in wastewater treatment. It is a new trial to investigate its performance for gaseous photocatalysis. The following investigations have been carried out as my Master thesis research:Firstly, A two-dimensional and a three-dimensional computational models to describe the photocatalytic reduction of carbon dioxide in a multichannel optical fiber monolith reactor, which had been experimentally investigated, and a DSSR reactor, is developed and simulated. Laminar fluid flow, empirical radiation field, solar flux distribution and a Langmuir-Hinshelwood kinetics submodel are incorporated in the models. The numerical results of optical fiber agree well with the experimental data. A method for performance evaluation of gaseous photocatalytic reaction in DSSR is proposed to guide performance optimization, and the transient and continuous solar light distribution of the reactor is presented.The variation of methanol concentration distributions of two reactors with the inflow water vapor concentration ratio, inflow velocity, light intensity input and transient solar light distribution are obtained and analyzed. The results show that the methanol concentration at outlet increases as the inflow water vapor concentration ratio, light intensity input and average solar flux increase, but decreases with increasing the inflow velocity, all of which cause the rise of overall methanol production.For optical fiber monolith reactor, the influence of the deviation of optical fiber installed in the monolith upon the methanol concentration and production efficiency is presented. With the increase of the optical fiber deviation from the monolith axis, the methanol production efficiency will decrease. Central and straight installation of the optical fiber is recommended either in experiments or scale-up photocatalytic industries.For DSSR reactor, with the increase of the number of parallel-flow channels and the decrease of the channel width-height ratio, the methanol production efficiency will decrease. Additional flow guiding measure is recommended for better flow field and higher methanol efficiency.