Residence time distribution and flow field study of aero-shielded solar cyclone reactor for emission-free generation of hydrogen

This paper provides a thorough analysis on the flow field and Residence Time Distribution (RTD) of our “aero-shielded cyclone solar reactor” designed to generate hydrogen from solar thermal methane cracking process. The analysis has been carried out based on the results from flow dynamics, and residence time distribution by using Computational Fluid Dynamics (CFD). Kinetics is taken from the literature and the reactor volume is estimated based on a plug flow reactor assumption. Residence time distribution characteristics are obtained by gas tracer injection method, and particle tracking method. Based on the results of our flow studies, “reactors in series model” is adopted to model the aero-shielded cyclone reactor. Path lines show that operating variables have significant effect on the flow behavior inside the reactor. Results show that thermo chemical properties of the gases have effect on the flow behavior which significantly affect the mean residence time in the reactor. Results also show that the residence time, spread of the tracer by variance, and the number of reactors in series are observed to be changed by change in the flow rate, type of screening gas, and methane mole fraction in the feed.

► We characterized flow behavior via residence time distribution analysis.
► Two different tracer methods were used and they are compared with space time based on entrance conditions.
► Increase in gas flow rate, type of screening gas and methane mole fraction yield significant difference in mean residence time.
► Type of screening gas is one of the key parameters in solar reactor determining flow dynamics, and number of ideal reactor in series.
► Thermo chemical properties of gases have significant effect on the mean residence time.