Performance Of Microreactor Research Articles

Locational Variance in Nuclear Microreactor Performance Under Net Zero Microgrid Conditions

Microreactors are expected to be deployed in locations or situations where standard macrogrid electricity is not readily or reliably available. Locations such as remote mining communities, military installations, and other similar communities may seek to decarbonize their electricity with a microreactor. Traditional remote communities typically pay much higher energy prices than nonremote communities, so there may be a higher degree of support for microreactors despite higher expected (per unit capacity) capital costs. There is also interest in deploying microreactors on sites that utilize their own microgrids, for example, federal installations or universities, in different locations across the United States. To model the deployment prospects of microreactors on microgrids, HOMER Pro was utilized to generate optimized microgrid configurations under an assumption of net zero, i.e. with no fossil fuels permitted. The economic performance of microreactors on microgrids was analyzed in a variety of locations throughout the United States. It was found that the minimal capital cost required for entry of a microreactor into the system was significantly higher in locations with both low solar resource (less than ~4.5kW∙h/m2∙day−1) and (in particular) low wind (<5 m/s average wind velocity at 80-m hub height), roughly corresponding to locations somewhat inland in both the eastern and the western United States. Under the financial assumptions made in this study, depending on location, the capital cost at which microreactors could enter the system varied from around $24 000/kW(electric) in areas of high wind and/or solar resource to over $90 000/kW(electric) in Alaska, with a range of intermediate results. It was found that the minimum allowed power level of the microreactor did not have a substantial impact on results. A utility presence was found to have a major impact on the financial performance of a microreactor, especially in locations that have strong renewable resources.

Multi-objective structure optimization and performance analysis of catalytic micro-reactor channel designed by an improved topology optimization model

Previous micro-reactor channel studies mainly focus on the limited design space or structure layout, rarely exploits design forms in which the procedural topology structure evolves freely. Therefore, a multi-objective topology optimization model are proposed for the inverse free evolution of micro-reactor channels, which can synergistically balance the effects among three objectives of reaction rate, flow loss and heat transfer to achieve optimal comprehensive performance. The topology optimization problem is formulated based on the material density-based design variable. The fluid dynamics response of design variables at each optimization iteration is updated by solving multi-physics governing equations, objective functions and variable constraints. Adjoint-based sensitivity analysis and GCMMA algorithm are used to obtain the gradient information of objective functions and update design variables, respectively. Additionally, the strict volume constraints and proposed pseudo-design-domain concept are introduced into the multi-objective function. In numerical examples, the influence of different Re conditions and different multi-objective weight-ratios on optimal designs is investigated, and their regular evolution mechanisms and the trade-off between performance optimization and structure evolution are analyzed. Then, the optimization principles for topology structure and performance parameters under the control of multi-objective functions are revealed. Finally, the comprehensive performance of micro-reactors under topology optimization method is compared with that of traditional micro-reactors to demonstrate the effectiveness of the improved method and reveal the physical mechanisms of multi-objective performance enhancement. The comparison results show that topology optimization designs can achieve 86.1% growth in reaction rate and 47.1% reduction in flow loss, and comprehensive performance coefficients have also been significantly optimized.

Enhancement of liquid–liquid micromixing performance in curved capillary microreactor by generation of Dean vortices

Micromixing efficiency is an important parameter for evaluating the multiphase mass transfer performance and reaction efficiency of microreactor. In this work, the novel curved capillary reactor with different shapes were designed to generate Dean flow, which was used to enhance the liquid–liquid micromixing performance. The Villermaux–Dushman probe reaction was employed to characterize the micromixing performance in different curved cpillary microreactor. The effects of experiment parameters such as liquid flow rate, inner diameter, tube length, and curve diameter on micromixing performance were systematically investigated. Under the optimal condition, the minimum value of the segmentation factor XS was 0.008. It was worth noting that at the low Reynolds number (Re < 30), the change of curved shape on capillary microreactor can significantly improve the micromixing performance with XS reduced by 37.5%. Further, the correlations of segment index XS with dimensionless factor as Reynolds number or Dean number were developed, which can be used to predict the liquid–liquid micromixing performance in capillary microreactor.

Fabrication of super hydrophilic surface on FeCrAl-WM with ridged microstructure for Joule-heating catalyst support by UV-laser microprocessing

The catalyst support with super hydrophilic surface facilitates uniform loading and firm adhesion of the catalyst. In this paper, ridged microstructures were fabricated on the surface of FeCrAl wire mesh (FeCrAl-WM) by UV-laser processing. The mechanism behind the formation of ridged microstructures was elucidated. The influence of scanning interval on the stacking and separation of recast layers was analyzed. The effects of laser processing parameters on surface roughness and hydrophilicity of FeCrAl-WM surface with ridged microstructures were investigated. By adjusting laser processing parameters, it is possible to regulate both the roughness factor and oxygen content of the FeCrAl-WM surface, thereby controlling its hydrophilicity and varying contact angles between 0° and 90°. Catalyst loading experiments were conducted on FeCrAl-WM after laser processing, followed by testing the performance of MSR microreactor for hydrogen production using FeCrAl-WM as a catalyst support material. At an inlet flow rate of 4 ml/h at 280 °C, a maximum hydrogen production rate of 0.21 mol/h was achieved with a methanol conversion rate reaching 91.5 %. We envision that the laser microprocessing offers a convenient and effective approach to develop super hydrophilic surface on FeCrAl-WM materials for use as Joule-heating catalyst support.

A convenient method for measuring gas-liquid volumetric mass transfer coefficient in micro reactors

The research on gas-liquid multiphase reactions using micro reactors is becoming increasingly widespread, given their excellent mass transfer performance. Establishing an accurate and reliable method to measure the gas-liquid mass transfer performance of micro reactors is crucial for evaluating and optimizing the design of micro reactor structure. In this paper, the physical absorption method of aqueous solution-CO2 and the chemical absorption method of sodium carbonate solution-CO2 were proposed. By analyzing the chemical reaction equilibrium during the absorption process, the relationship between the mass transfer of CO2 and the solubility of hydroxide ions in the solution was established, and the total gas-liquid mass transfer coefficient was immediately obtained by measuring the pH value. The corresponding testing platform and process have been established based on the characteristics of the proposed method to ensure fast and accurate measurement. In addition, the chemical absorption method takes into account temperature factors that were not previously considered. The volumetric mass transfer coefficient measured by these two methods is in the same range as those measured by other methods using the same microchannel structure in previous literature. The methods have the advantages of low equipment cost, faster measurement speed, and simpler procedures, which can facilitate its wide application to the evaluation of the mass transfer performance and hence can guide the structure optimization of microchannel reactors.

Dry reforming of methane using a novel microreactor fabricated from stacking of stainless steel wire-mesh support catalysts

We fabricated a novel microreactor with stainless steel wire-mesh supports coated with Ni-based hydrotalcite catalysts for dry reforming of methane (DRM) reaction. Catalytic performance and long-term stability of microreactor was tested by stacking the stainless steel wire-mesh support catalysts to allow parallel and cross-sectional flow to stacking configurations. Conversion rates of CH4 and CO2 were measured and found to be 92% and 95% respectively, and syngas ratio of 0.92 was obtained. Only a small decrease of about 3–4% in conversion rates was observed after 100 h of reaction which could be due to whisker like carbon formation as carbon nanofibers (CNFs). Investigation of spent catalysts revealed that surfaces of support catalysts were not fully covered with CNFs, leaving active sites for reactant gases with little effect on long-term stability. In addition to CNFs, in situ formation of γ-Al2O3 flakes were obtained during long-term DRM reaction from the parent FeAl powder that was used for annealing of stainless steel wire-mesh supports to increase the adhesion of hydrotalcite-derived spinel catalysts. Effect of γ-Al2O3 flakes on microreactor's performance turned out to be very useful because sites of γ-Al2O3 flakes further prevented the deposition of carbon on surface and acted as active sites for reactant gases. Moreover, stacking of stainless steel wire-mesh support catalysts for parallel and cross-sectional flow configurations caused the better mixing of reactant gases due to the tortuosity of the narrow porous microstructure of the support. The excellent throughput was verified by numerical calculations using CFD simulations.

Microfluidic production of silica nanofluids for highly efficient two-phase cooling with micro pin-fins structure

Flow boiling heat transfer in microchannels is fundamentally important for the thermal management of high-power electronics. The combination of silica nanofluids and micro pin-fins structure is expected to solve the limitations of the internal trade-off between the heat transfer coefficient (HTC) and critical heat flux (CHF). However, the high cost, preparation complexity, poor stability, and particle agglomeration limit the further development of silica nanofluids. Herein, we present a simple and straightforward microfluidic strategy for continuous, ultrafast, and high-throughput synthesis of functional silica nanofluids with excellent stability. Numerical simulation and experimental validation are conducted to investigate the excellent mixing performance of spiral microreactor. The morphology and size of SiO2 can be precisely controlled by simple flow rate. The excellent stability of time (∼30 d) and temperature (∼80 ℃) significantly improved the problem of easy aggregation of nanofluid particles previously used for heat transfer. The flow boiling heat transfer in microchannels on micro pin-fins silicon chip demonstrates the simultaneous enhancement of CHF (124%) and HTC (153%) at extremely low power consumption (pressure drop less than 1.5 kPa) compared to the base fluid. These findings provide important guidelines for the embedded cooling and shed new light on significant energy savings on electronics.

Modeling of an Energy-Diverse Embedded Grid for Microreactor Integration

Microreactors present an opportunity to revolutionize the role of nuclear energy via the development of these technologies in a diverse and distributed energy network for a clean energy future. Because of the limited output of these novel systems, the deployment of microreactors should be focused on high-value applications in order to realize their full potential. This involves understanding the microreactor performance and how it interacts with the preexisting infrastructure. In this work, an energy-diverse embedded grid is modeled using OpenModelica in order to study the impact of microreactor integration under several distinct deployment approaches. The University of Illinois at Urbana-Champaign (UIUC) is used as a prototypic market due to its well-characterized energy ecosystem with available extensive real-time and historical data. The UIUC model recreates the existing chilled-water, steam, and electricity infrastructure, including wind, solar, and cogeneration sources. The infrastructure model simulates the interplay between the three utilities and how different microreactor integration approaches would impact UIUC’s embedded grid. From this study, the deployment of a single microreactor under electric load-conditioning, steam production retrofit, or a hybrid of both is found to be the most appropriate in consideration of their unique advantages toward cost savings and grid resilience. Meanwhile, if grid resiliency is not a main objective, the greatest emissions reduction and cost-savings benefits can be obtained by operating the reactor in a base-loading configuration. This study employed historically low coal and gas prices and provided a conservatively low estimate for the benefits from a microreactor. Given the price volatility of fossil fuels, the benefits of the microreactor are expected to be greater than this estimate. Finally, the modular nature of the modeling framework allows for an extension of the analysis to other similar embedded grids.

The 3D-Printing Fabrication of Multichannel Silicone Microreactors for Catalytic Applications

Microstructured reactors (MSRs) are especially indicated for highly demanding heterogeneous catalysis due to the small channel dimensions that minimize diffusional limitations and enhance mass and heat transport between the fluid and the catalyst. Herein, we present the fabrication protocol of the fused filament 3D printing of silicone monolithic microreactors based on a multichannel design. Microchannels of 200 to 800 µm in width and up to 20 mm in length were developed following the scaffold-removal procedure using acrylonitrile butadiene styrene (ABS) as the material for the 3D-printed scaffold fabrication, polydimethylsiloxane (PDMS) as the building material, and acetone as the ABS removing agent. The main printing parameters such as temperature and printing velocity were optimized in order to minimize the bridging effect and filament collapsing and intercrossing. Heterogeneous catalysts were incorporated into the microchannel walls during fabrication, thus avoiding further post-processing steps. The nanoparticulated catalyst was deposited on ABS scaffolds through dip coating and transferred to the microchannel walls during the PDMS pouring step and subsequent scaffold removal. Two different designs of the silicone monolithic microreactors were tested for four catalytic applications, namely liquid-phase 2-nitrophenol photohydrogenation and methylene blue photodegradation in aqueous media, lignin depolymerization in ethanol, and gas-phase CO2 hydrogenation, in order to investigate the microreactor performance under different reaction conditions (temperature and solvent) and establish the possible range of applications.

Design and performance evaluation of flexible tubular microreactor for methanol steam reforming reaction

To obtain the flexible microreactor for potential application in constrained space, a novel flexible tubular microreactor was designed by using a corrugated shell and a high porosity porous copper fiber rod (PCFR) as catalyst support. The effect of placement position, bending direction, and bending angle on reaction performance of flexible tubular microreactor was investigated. Then, the stability of flexible tubular microreactor was further evaluated. The experimental results showed that the placement position and bending direction had a significant influence on the reaction performance of flexible tubular microreactor. Methanol conversion of flexible tubular microreactor with the vertical placement was 6.67% higher than that with horizontal placement. Higher methanol conversion and H2 flow rate were obtained when the microreactor bent along the vertical direction. The reaction performance of flexible tubular microreactor was found to decrease as the bending angle increased, and the methanol conversion decreased by around 14.07% with a bend of 90°. When the flexible tubular microreactor was horizontal placed with a bend of 60° in the vertical direction, the reaction performance of microreactor was not changed little after 20 cyclic bending. After continuous bending for 10 h, the methanol conversion and H2 flow rate of flexible tubular microreactor were 70.58% and 0.88 mol/h, showing good reaction performance.

Performance of catalytic cycloaddition of CO2 to styrene oxide in three-phase co-current (micro)fixed-bed and monolith reactors

Synthesis of cyclic carbonates via catalytic cycloaddition of CO2 to epoxides represents one of the most promising green routes for CO2 utilization. The present work investigates, from a multiphase reactor engineering perspective, the design of three-phase catalytic reactors for cycloaddition of CO2 to styrene oxide in the presence of non-deactivating silica-supported pyrrolidinopyridinium iodide catalyst via an exhaustive modeling framework containing a series of isothermal unsteady-state two-dimensional models. A comparative analysis is made for fixed-bed reactors/microreactors and three-phase monolith reactors. The results show a remarkable performance of fixed-bed microreactor which significantly outperforms both fixed-bed and monolith reactors and hold great promise for efficient implementation of CO2 cycloaddition process under relatively mild reaction conditions. At equal liquid space velocity, upflow monolithic reactor outperforms downflow/upflow fixed-bed reactors due to reduced resistance to external and internal diffusion in catalyst pore network, but it would require a higher reactor volume for the same amount of catalyst. A confinement-induced amplification of concentration of CO2 adsorbed on the surface of catalyst generates an enhanced performance of styrene carbonate synthesis process due to increased sorption of CO2. Fixed-bed microreactor generates the smallest confinement-induced performance improvement, possibly because catalytic process is controlled by the considerable improvement in mass transfer.

Performance of continuous-flow micro-reactors with curved geometries. Experimental and numerical analysis

One of the major challenges in the design of micro-devices, when very fast reactions are carried out, is to overcome the limited performance due to the poor mixing efficiency of the reactants. Here, we report a holistic analysis of reactants mixing and reaction rate in liquid phase flow micro-reactors with curved geometries. In this sense, a mathematical model that accounts for momentum and mass conservation equations, together with species transport and chemical reaction rate under isothermal conditions, has been developed using computational fluid dynamics techniques (CFD). To validate the predictive model, four micro-reactor geometries with different radius and curved length (straight reactor, two types of serpentines and an Archimedean spiral) have been evaluated. Simulated results proved that mixing is promoted through the formation of Dean vortices as a consequence of the reduction of the radius of curvature and at the same time of the extension of the curve. Thus, the overall performance of the micro-reactor is improved because mass transport limitations are minimized and the process kinetics are greatly enhanced. Accordingly, the spiral micro-reactor reported the best performance by reducing by half the time required to obtain 95 % conversion when compared with the straight reactor. Simulated findings have been confirmed with the experimental analysis of the reaction between aqueous ammonium and hypochlorite ions. Very good agreement between simulated and experimental results has been achieved with an error lower than 10 %. Therefore, the robust model herein reported is a novel and valuable tool to assist in the optimum design of micro-reactors for fluid-phase isothermal applications.

Development of a centrifugal coating method to load catalyst washcoat onto porous substrates with high uniformity and adhesive strength

Porous metal-based substrates with high porosity and surface/volume ratio have been widely used in microreactors for enhancing heat and mass transfer, while the generally poor uniformity and low adhesive strength of catalyst coating onto these porous substrates will limit the performance and service life of microreactors. Herein, we present a rapid centrifugal coating method to effectively and uniformly load γ-Al2O3 washcoat onto porous copper foam, which can be used to fabricate structured γ-Al2O3/Cu foam supports. The structural design of the centrifugal coating device and its coating loading mechanism are described. Hydroxyethyl methyl cellulose (HEMC) was used as the binder and its effects on the loading capacity and adhesive strength of γ-Al2O3 washcoat were studied. Then, the effects of loading parameters of the centrifugal coating process were carried out, and the relatively uniform γ-Al2O3 washcoat on the porous copper foams with different pores per inch (PPI) were obtained. The surface morphology, specific area, composition, and element distributions of the activated washcoat were characterized by using SEM, BET, XRD, and EDS, respectively. Results showed that the catalyst coating generally has a high specific surface area and uniform elements distribution, thus demonstrating our developed rapid centrifugal coating method has potential for the preparation of catalyst coating onto porous metal-based substrates in microreactors.

Thermal and flow characteristics of liquid flow in a 3D-printed micro-reactor: A numerical and experimental study

• Stereo lithography was utilised to construct pin–fin photo-thermal micro-reactors. • 3D printing was successfully utilised to print micro-pin fins inside microchannels. • Thermal and fluid characteristics of constructed micro-reaactors were assessed. • Validated CFD model was used to evaluate velocity and pressure profiles. • Size of pin-fins in micro-reactor was optimised with response surface modelling. In this article, we report on a unique design and build technique based on stereolithographic 3D printing technology (SLA) for constructing ultraviolet cured resin-made micro-reactors. The main objective of this study is gaining insight into the thermal performance of micro-reactors for optofluidic applications. Several micro-reactors equipped with pin fins were manufactured. A high-fidelity test-rig was developed and used to collect data from water flowing in the micro-reactors as they are exposed to various heat flux loading. The measured data was also used for validating the numerical (CFD) models. The CFD models provided in-depth spatial data on the pressure and temperature profiles in the microchannel, which could not be easily measured. The results showed that conventional empirical correlations failed to accurately predict the pressure drop of the system in the microfluidics regime (Re < 190), although are reasonably accurate in the conventional fluid regime (Re > 190). For both regimes, however, CFD results were sufficiently accurate in predicting the temperature and pressure differences across the micro-reactor. It was also identified that pin fins arrangements offer a great design benefit in enhancing heat transfer coefficient in micro-reactors, achieving values up to ∼2300 W/m 2 .K compared to a plain micro-reactor at ∼1875 W/m 2 .K (or 300 W/m 2 .K for conventional combustion systems). A multi-objective optimisation on the geometrical specifications of various pin fins showed that the micro-reactor with pin fins of 250 µm in diameter and 100 µm in height, yielded the best thermo-hydraulic performance of highest thermal transfer coefficient (2100 W/m 2 .K) and the lowest pressure- drop (∼0.1 kPa) across a wide range of heat flux loadings. The outcome of this study has created a significant knowledge and understanding of the flow behaviour in polymer-based micro-channels. It also established a methodology for designing and optimising the thermal–hydraulic performance of optofluidic micro-reactors, with potential loading of nano-photocatalyst mediated in pin fins sites. New correlations for predicting the pressure drop and temperature difference across polymer-based micro-reactors are also developed.

Scale-up of high-pressure F-T synthesis in 3D printed stainless steel microchannel microreactors: Experiments and modeling

Scale-up of Fischer-Tropsch (F-T) synthesis using microreactors is very important for a paradigm shift in the production of fuels and chemicals. The scalability of microreactors for F-T Synthesis was experimentally evaluated using 3D printed stainless steel microreactors, containing seven microchannels of dimensions 1000 µm × 1000 µm × 5cms. Mesoporous silica (KIT-6), with high surface area, containing ordered mesoporous structure was used to incorporate 10% cobalt and 5% ruthenium using a one-pot hydrothermal method. Bimetallic Co-Ru-KIT-6 catalyst was used for scale-up of F-T Synthesis. The performance of the catalysts was evaluated and examined for three different scale-up configurations (stand-alone, two, and four microreactors assembled in parallel) at both atmospheric pressure and 20 bar at F-T operating temperature of 240 °C using a syngas molar ratio (H2:CO) of 2. All three configurations of microreactors yielded not only comparable CO conversion (85.6–88.4%) and methane selectivity (~14%) but also similar selectivity towards lower gaseous hydrocarbons like ethane, propane, and butane (6.23–9.4%) observed in atmospheric F-T Synthesis. The overall selectivity to higher hydrocarbons, C5 + is in the range of 75–82% at 20 bars.A CFD model was used to investigate the effect of different design features and numbering up approaches on the performance of the microchannel reactor. The effect of the reactor inlet, the mixing internals and the channel designs on the dead zone %, the quality index factor, the cooling requirement and the maximum dimensionless temperature within the microreactor were quantified. There is no significant effect of increasing the channel width on the microreactor performance and operation of the microchannel reactor at lower Nusselt number that results in higher CO conversion. Increasing the channel width reduced the maximum temperature exhibited in the channel. Finally, the effect of increasing the y/x stacking ratio, i.e. having more reactor units in parallel compared to series, was investigated. Increasing the y/x ratio increased the cooling requirement and the maximum dimensionless temperature increase within the unit decreased the productivity. To minimize the productivity losses, numbering up in series is the better approach; however further analysis must be done to delineate heat removal requirements.

Kinetic assessment of H2 production from NH3 decomposition over CoCeAlO catalyst in a microreactor: Experiments and CFD modelling

A flat-plate microreactor was designed, examined and modelled for the on-board hydrogen generation via the ammonia decomposition reaction over CoCeAlO mixed oxide catalyst. The tested catalyst was synthesised and immobilised using an inkjet printing-assisted self-assembly method. Inkjet printing technology is proved to be an efficient way for the direct synthesis, deposition and rapid screening of heterogeneous catalysts. A series of kinetic experiments were performed to analyse the influence of reaction temperature and NH3 flow rate on the microreactor performance. Two kinetic rate expressions were developed based on the conversion data and implemented in the CFD model. The simulation results showed good accuracy with respect to the experimental data, and the kinetic models could effectively predict the reacting flow properties along the microchannel. The microreactor is especially designed to operate under the kinetic-control conditions with negligible mass transfer resistance. Furthermore, the proposed design eases the assemblage and disassemblage of the microreactor components, and the probing of fresh catalysts for kinetic studies.

An investigation of scale effect and applicability of compact light sources in microchannel reactors applied to pollutant abatement.

In this work, the performance of microreactors irradiated with conventional (fluorescent) and UV-LED light was evaluated. For this purpose, a microfluidic reactor with an equivalent diameter of 133.5 μm was used. In addition, the effect of scale variation on the performance of photochemical reactors was assessed using reactors with three internal diameters (600, 1200, and 2300 μm), 2 residence times (30 and 60 s), and two sources of UVA radiation (A with irradiance of 115 W m-2 and B with irradiance of 44 W m-2). Also, the relationship between the configuration of the photocatalyst film and the effect of the scale on the performance of photochemical reactors was experimentally and theoretically investigated. For both cases, methylene blue dye was used as a model pollutant and titanium dioxide (TiO2) as a photocatalyst deposited on the inner wall of the photocatalytic reactors. For the residence time of 30 s, the smaller the reactor diameter, the greater was the degradation (22, 18, and 6%, respectively, for lamp A and 17, 16, and 8 %, respectively, for lamp B). The influence of the diameter of the reactor was also observed for the residence time of 60 s, but only for the reactor with a 2300-μm internal diameter. The reactors with diameters 600 and 1200 μm only showed different results when illuminated with lamp B (33 and 28% of methylene blue conversion, respectively). Moreover, computational simulation results suggested higher efficiency as the reactor's diameter is decreased and an optimum thickness of photocatalyst film to maximize the performance of devices in which photocatalytic reactions are carried out.

Towards controlled bubble nucleation in microreactors for enhanced mass transport

The exact location of bubbles with respect to the catalytic layer impacts the microreactor performance. In this work, we propose to control bubble nucleation using micropits to maximize the microreactor efficiency.

Photon Transport and Hydrodynamics in Gas‐Liquid Flows Part 1: Characterization of Taylor Flow in a Photo Microreactor

AbstractGas‐liquid photoreactions are increasingly implemented in microreactors. Taylor flows containing an inert dispersed phase were previously used to increase the conversion of photochemical reactions in comparison to using a single liquid phase. However, identifying the optimal flow conditions requires an extensive experimental effort. This work aims to understand the photon transport and hydrodynamics in a Taylor flow photo microreactor so that the reactor behavior can be understood and predicted. Chemical actinometry, flow imaging and residence time distribution experiments were used to develop a multi‐region photochemical reaction model. This model shows that the conversion is significantly affected by the liquid distribution, and not by the light scattering or liquid mixing. Moreover, an empirical relation was proposed to predict the optical pathlength in gas‐liquid flows. The knowledge gained in this study helps to optimize the performance of Taylor flow photo microreactors, but also to design improved multiphase flow photochemical systems.

Multi-scale microchannel processing and hydrogen production performance of microreactors for methanol reforming

The methanol reforming microreactor has the advantages of small size, high efficiency, and high safety and is one of the main ways of online hydrogen production. Considering the catalyst of traditional microchannel reactors falloff quite easily, this study designs and manufactures a microchannel with a secondary structure to address this problem. First, the base structure of the microchannel was processed by wire cut electrical discharge machining (WEDM), and then a reticulated secondary structure having a depth of 30 μm and a width of 50 μm was processed on the substrate of the microchannel by laser beam machining (LBM). In this study, the catalyst loading strength of the microchannel with a secondary structure was tested, and the influence of the secondary structure on the static performance of the catalyst was studied. Finally, hydrogen production experiments were carried out on microchannels with a secondary structure, and the influence of the secondary structure on hydrogen production performance and hydrogen production stability at different flow rates and temperatures was determined.