Experimental study of a high-temperature porous-medium filled solar thermochemical reactor for CO production

Abstract

Solar thermochemistry via a two-step cycle has been considered as a promising technology as it is feasible to convert solar energy into fuels directly. The improvement of solar-to-fuel energy efficiency is strongly dependent on the heat recovery during the temperature swing between the reduction and oxidation steps. The present article describes the experimental results of a solar thermochemical reactor with gas-gas heat recovery. The reactor's inlet and outlet gases are exchanged through the heat exchanger, thereby improving the energy utilization efficiency, and a series of experiments are carried out to further demonstrate the feasibility of this technology. The influence of the pressure of the endothermic reduction step and the influence of the concentration of reactants in the exothermal oxidation step on the experimental results are analyzed. The experimental results show that vacuuming condition further promoted the reduction kinetics compared with Ar purging, and the yield of CO increases from 1.13 mL/gCeO2 to 1.32 mL/gCeO2 within 60 min. Therefore, the following experiments are completed under vacuuming condition for the endothermic reduction reaction. The yield of CO is favored at higher CO2 partial pressure, and the yield of CO increases from 44.65 mL to 279.42 mL as the volume flow rate of CO2 increase from 0.5 L/min to 4 L/min. This research provides useful information on the industrial implementation of the thermochemical technology.