Catalyst Heating Characteristics in the Traveling-Wave Microwave Reactor

A High-Efficiency Single-Mode Traveling Wave Reactor for Continuous Flow Processing

This paper proposes a high-efficiency single-mode traveling wave reactor based on a rectangular waveguide and its design method for continuous flow processing. The reactor has a large-capacity reaction chamber (1000 mm × 742.8 mm × 120 mm) that can provide high-energy-efficiency and approximately uniform microwave heating. The microwave heating uniformity is improved by maintaining single-mode microwave transmission and eliminating higher-order modes in such a multi-mode reaction chamber. The high energy efficiency of microwave heating is achieved by adopting impedance matching techniques. The incident microwave in the reactor can remain in a traveling wave state, and the power reflection can be minimized. Several numerical simulations based on multi-physics modeling are conducted to investigate the heating uniformity, the energy efficiency and the flexibility under different operation conditions. The results show the microwave energy efficiency can be higher than 99%, and meanwhile, the coefficient of temperature variation can be lower than 0.4. Furthermore, when the reactor is operated under different flow velocities and with different heating materials, both the energy efficiency and the heating uniformity can also meet the above requirements. The proposed reactor can be used in the applications such as oil processing, wastewater tackling, chemical synthesis, beverage sterilization and other microwave-assisted continuous flow processes that require high heating uniformity, high energy efficiency and good adaptability.

Energy Transport of Photocatalytic Carbon Dioxide Reduction in Optical Fiber Honeycomb Reactor Coupled with Trough Concentrated Solar Power

Thanks to the high photon efficiency and reaction density, the optical fiber monolith reactor (OFMR) for InTaO4-based CO2 photoreduction is regarded as a promising photoreactor. In this work, the OFMR coupling with parabolic trough concentrator (PTC) is proposed to enlarge the daylighting area by several times without increasing the cost of photocatalysts. Based on the Monte Carlo ray-tracing (MCRT) approach and the finite volume method (FVM), a computational model of the reaction module considering the light, heat, and mass transfer is developed to optimize the fiber honeycomb reactor coupled with the PTC. As a result, the volume-averaged concentration of production reaches 1.85 × 10−4 mol·m−3, which is much higher than the traditional OFMR with the production concentration of 9.61 × 10−6 mol·m−3 under the same condition. The optimized structure of the monolith for better photocatalytic performance is obtained. It shows that the diameters of gas channels ranging from 1.5 to 2 mm are beneficial to the reaction efficiency. Finally, the results suggested that the even number of the gas channel should be avoided due to the pseudo-steady zone in the middle of the monolith. The reaction element with the high serial number along the flow direction has the reduced reaction density and endangers the organic optical fibers especially when the serial number exceeds 5.