Numerical Simulation of Energy and Mass Transfer in a Magnetic Stirring Photocatalytic Reactor

Abstract

Hydrogen production via photocatalytic water splitting is one of the promising solutions to energy and environmental issues. Understanding the relationship between hydrogen production in suspended photocatalytic reactions and various influencing factors is crucial for expanding the scale of the system. However, the complexity of physical and chemical factors involved in hydrogen production via photocatalytic water splitting makes systematic research of this technology challenging. In recent research, the simulated light source reactor has become a preferred study object due to its strong controllability. This paper presents a comprehensive energy and mass transfer model for the suspended photocatalytic reaction in a magnetically stirred reactor. The mutual impacts between the flow field, radiation field, and reaction field are analyzed. The simulation results show that the rotating speed of the stirring magneton in the reactor has a significant influence on the flow field. The rotation of the stirring magneton generates a vortex in the central axis area of the reactor, with the relationship between the depth of the vortex f(s) and the rotating speed of the magneton s described as f(s) = 0.27e0.0032s. The distribution of radiation within the reactor is influenced by both the incident radiation intensity and the concentration of the catalyst. The relationship between the penetration depth of radiation g(i) and the incident radiation intensity i is described as g(i) = 10.73ln(i) − 49.59. The relationship between the penetration depth of radiation h(c) and the particle concentration c is given as h(c) = −16.38ln(c) + 15.01. The radiation distribution in the reactor has a substantial impact on hydrogen production, which affects the concentration distribution law of hydrogen. The total amounts of hydrogen generated in the reactor are 1.04 × 10−3 mol and 1.35 × 10−3 mol when the reaction times are 1.0 s and 2.0 s, respectively. This study serves as a foundation for the future scaling of the system and offers theoretical guidance for the optimization of the photocatalytic reactor design and operating conditions.