Mass Transfer Characteristics Research Articles

Effect of Photolithographic Biomimetic Surface Microstructure on Wettability and Droplet Evaporation Process

In nature, engineering technology and daily life, wetting phenomena are widespread and have essential roles and significance. Bionics is becoming increasingly important nowadays and exploring the mechanism that influences biomimetic surface microstructure on droplet wetting process and heat and mass transfer characteristics is becoming more meaningful. In this paper, based on photolithography technology, SU-8 photoresist was used as raw material to prepare biomimetic surfaces with microstructures in various arrangements. The research results show that the wettability of biomimetic functional surfaces can be regulated by regulating the shape and arrangement of photoresist micro-pillars. At the same time, the effects of surface microstructure configuration and roughness on the heat and mass transfer processes within the droplets were also comprehensively studied. The results show that a biomimetic surface with cylindrical micro-pillars can effectively inhibit the evaporative cooling effect of the liquid–vapour interface. This effect becomes more evident with the increase in roughness, and the interface temperature difference can be reduced by up to 18%. Similarly, the biomimetic surface with cylindrical micro-pillars can also effectively promote the evaporation rate of sessile droplets, which can be increased by about 13%. In addition, the research also shows that regardless of the structure, substrate temperature changes will significantly impact the wetting phenomenon of the biomimetic surface. This study aims to guide the optimal design of biomimetic surfaces prepared based on photoresistance.

Achieving High Performance with Less Energy Consumption: Intermittent Ultrasonic-Mediated Operation Mode for Fe/V Non-Aqueous Redox Flow Battery

Deep eutectic solvents (DESs) have attracted much attention as sustainable electrolytes for redox flow batteries. Despite the tremendous advantages of DES-based electrolytes, their high viscosity property has a negative effect on their mass transfer, limiting current density and power density. The ultrasonic effect has been demonstrated as an efficient strategy to improve mass transfer characteristics. Incorporating ultrasonic waves into a deep eutectic solvent (DES) electrolyte enhances the mobility of redox-active ions, thereby accelerating the reaction dynamics of the Fe(III)/Fe(II) redox pair. This enhancement makes it suitable for use in non-aqueous electrolyte-based redox flow batteries. However, it is necessary to consider the loss of ultrasonic on the internal structure of the battery, as well as the loss of battery component materials and ultrasonic energy consumption in practical applications. Moreover, the continuous extension of the duration of ultrasonic action not only hardly leads to a more significant improvement of the battery performance, but is also detrimental to the energy and economic savings. Herein, intermittent ultrasound is used to overcome the quality transfer problem and reduce the operating cost. Good electrochemical performance enhancement is maintained with a roughly 50% reduction in energy consumption values. The mechanism as well as the visualization of the pulsed ultrasonic field on each half cell has been envisaged through fundamental characterization. Finally, the feasibility of interrupted ultrasonic activation applied to Fe/V RFB using DES electrolytes has been demonstrated, demonstrating similar behavior with continuous ultrasonic operation. Therefore, the interrupted ultrasonic field has been found to be a more effective operation mode in terms of energy cost, avoiding alternative undesirable effects like overheating or corrosion of materials.

Numerical Investigation of Heat and Mass Transfer Characteristics in MHD Boundary Layer Flow of a Nanofluid over a Stretching Sheet

Nanofluids, which are simply suspensions of nanoparticles in a base fluid, have greater mass and heat transfer capabilities compared to regular fluids. Nanofluids are distinguished by their ability to transmit heat and mass. The potential applications of nanofluids in the scientific community have seen a spike in attention as a result of this. Simulations of the mass and heat transport parameters in magneto hydrodynamic boundary layer flow of a nanofluid across a stretched sheet are presented in this paper. These simulations were carried out using numerical methods. This investigation is going to look at a lot of important aspects, such as thermophoresis, Brownian motion, and the presence of a magnetic field that is applied. Continuity, momentum, energy, and concentration are the equations that are responsible for controlling the problem. The momentum equation takes into account the opposing magnetic field by means of the Lorentz force component. On the other hand, the energy and concentration equations take into account the mobility of the nanoparticles in the nanofluid as a result of Brownian motion and thermophoresis. Because of similarity transformations, the controlling partial differential equations are reduced to a set of ordinary differential equations. This action is taken in order to make the numerical application of the solution more straightforward. Calculating numerical solutions to these modified equations using any common technique, such as the Runge-Kutta-Fehlberg algorithm, is the next step that has to be taken. Utilizing this method, which is not only accurate but also time-saving, it is possible to solve issues that are associated with nonlinear boundary layers.

Uncertainty analysis of MHD oscillatory flow of ternary nanofluids through a diverging channel: a comparative study of nanofluid composites

Purpose This study aims to investigate the heat and mass transfer characteristics of a temperature-sensitive ternary nanofluid in a porous medium with magnetic field and the Soret–Dufour effect through a tapered asymmetric channel. The ternary nanofluid consists of Boron Nitride Nanotubes (BNNT), silver (Ag) and copper (Cu) nanoparticles, with a focus on understanding the thermal behaviour and performance across mono, hybrid and tri-hybrid nanofluids. This paper also examines the thermal behaviour of MHD oscillatory nanofluid flow and carries out an uncertainty analysis of the model using the Taguchi method. Design/methodology/approach The governing equations for this system are transformed into coupled linear partial differential equations using non-similarity transformations and solved numerically with the Crank–Nicolson scheme. The impact of temperature sensitivity at three distinct temperatures (5°C, 20°C and 60°C) is incorporated to analyse variations in viscosity and Prandtl number. The study also examines the combined effects of Soret–Dufour numbers and thermal radiation on heat and mass transfer within the nanofluid. Findings The results demonstrate that the inclusion of BNNT, Ag and Cu nanoparticles significantly enhances heat and mass transfer rate, with copper nanoparticles showing superior performance in terms of skin friction and heat transfer rates. The Soret and Dufour effects play critical roles in modulating heat and mass diffusion within tri-hybrid nanofluids. The study reveals that temperature sensitivity alters heat and mass transfer characteristics depending on the temperature range, with pronounced variations at elevated temperatures. The influence of thermal radiation and the Peclet number is found to significantly impact temperature distribution and overall heat transfer performance within the asymmetric channel. Originality/value To the best of the authors’ knowledge, this study is the first to analyse the heat and mass diffusion in a ternary nanofluid composed of BNNT, Ag and Cu nanoparticles, considering porous media, oscillatory flow and thermal radiation within a tapered asymmetric channel. The research extends to a novel examination of temperature sensitivity in mono, hybrid and tri-hybrid nanofluids at varying temperature gradients. Furthermore, a comparative analysis of skin friction and heat transfer rates between copper, alumina and ferro composites is presented for optimising the nanofluid performance.

Influence of laminated porous cathode structure on the performance and mass transfer of Li[sbnd]O2 batteries

The porous cathode is a crucial component of LiO2 batteries, and its porous structure significantly impacts the battery's performance. In this study, a stacked porous cathode was fabricated via roller pressing. The influence of the cathode structure on the battery performance and mass transfer characteristics were examined using experimental and simulation methods. The structural characteristics, electrochemical properties, and overall battery performance of the stacked porous cathode were analyzed. Furthermore, the effects of the cathode structure on mass transfer within the cathode and battery performance were explored through numerical simulation. The results indicate that when the mass ratio of CNTs to ACET on the diaphragm side is 5:1, the cathode exhibits optimal structural parameters, with an average pore size of 24 nm and a maximum pore volume of 0.85564 cm3/g. Concurrently, the battery demonstrates an exceptionally high area specific capacity of 30.35 mAh/cm2. Integrating the simulation findings, it was observed that adjusting the structural parameters of the cathode enhances material transfer efficiency, thereby improving battery performance.

Dynamic modeling of air–metal plasma mixture of single-turn coil with erosion at megaGauss magnetic field

Single-turn coil (STC) is a destructive pulsed magnet aiming at 100–300 T magnetic field. Due to the high discharge current, the conductor of STC is heated rapidly and undergoes melting and vaporization, leading to the generation of supersonic air–metal vapor mixed plasma jet and the magneto-fluid effect. In this study, the mixed plasma mass-transfer and fluid dynamic characteristics are modeled at megaGauss magnetic field, high temperature, high pressure, and supersonic conductor shock deformation. The collision integral method is employed to calculate the fluid transport properties. In addition, a boundary constraint model of fluid–structure interaction (FSI) compatible with both fluid wall boundary condition and plasma jet entrance condition and a model to simultaneously solve the thermal ionization and high electric field ionization of the mixed vapor are proposed. As the result, the distributions of plasma electrical conductivity, current density, electron, heavy particles, temperature, air body load, and velocity are derived. Especially, the region of highest electrical conductivity is not the air domain near the inner surface of the conductor with the highest electron density and the highest magnetic field, but the air domain near the outer surface of the conductor with the relatively higher electron density and lower magnetic field.

Study on solid powder fuel transport characteristics and mixing degree in scramjet combustor

Abstract The powder scramjet engine is considered the best engine for hypersonic weapons because of its advantages of easy adjustment, flame stability, and high efficiency. However, due to the extremely short residence time of particle fuel in the combustion chamber under high Mach conditions, there is a risk of fuel mixing. Based on the existing combustion chamber models of scramjet engines, this paper proposes a new solid fuel blending enhancement structure by combining shock generator structure and transverse jet and compares the performance and mass transfer characteristics of different shock generators. The CFD method is used to solve the RANS formula to simulate the particle transfer process, and the SST k-ω model is used to calculate the complex turbulence. It was found that when the reverse shock generator was used, the mixing degree of solid particles was higher.

A novel leaf bionic flow field with structured multi-level channel based on Murray's law in proton exchange membrane fuel cell for enhanced mass transfer

The design of flow field has a significant impact on the performance of proton exchange membrane fuel cells (PEMFCs). In this study, a novel leaf bionic flow field is designed and optimized based on Murray's law. The power consumption ratio is first used in the bionic PEMFC. Additionally, an evaluation criterion, the mass transfer efficiency evaluation criterion (MTEEC), is proposed to characterize mass transfer efficiency, and field synergy theory is used to analyze performance differences in mass transfer among various flow fields. The results demonstrate that adding multi-level channel and obstacles in the flow field significantly enhances cell output performance and reduces voltage losses in mass transfer regions. Applying Murray's law to distribute multi-level channel improves the uniformity of oxygen concentration distribution in the flow field and alleviates under-rib water accumulation. Compared to the secondary stream flow field (SSFF), the structure mesh of leaf bionic flow field (SMLBFF) demonstrates a nearly 19% increase in current density output at 0.45 V. SMLBFF exhibits an 81.51% increase in convective mass transfer rate compared to SSFF at 0.4 V. Moreover, the MTEEC of SMLBFF shows improvements of 179.68% at 0.5 A/cm2 and 135.43% at 1.0 A/cm2, compared to SSFF.

Performance Investigation of a Novel Staggered Round Table Channel for Proton Exchange Membrane Fuel Cells

Based on the internal mass transfer of a proton exchange membrane fuel cell (PEMFC), a novel staggered round table channel is proposed, namely, round table stoppers are arranged on both sides of the channel and in the direction of gas flow. The study systematically investigates the effects of various structural parameters on the PEMFC performance, including the arrangement of round tables on both sides of the channel, radius, degree of sparseness, and number. It is found that the staggered arrangement can improve the cell performance more significantly, and the current density can be increased by 5.0% compared with the direct channel. With the proper increase of the radius and number of round tables, the round table stopper forces the reactant to diffuse downward and improves the uniformity of reactant distribution. Compared with other sparsity, the equidistant arrangement of stoppers in the channel is conductive to accelerating the convective mass transfer and drainage characteristics of the cell. As shown by numerical analysis results, the performance and dewatering efficiency of PEMFC are the best when the round tables on both sides are staggered, the radius is 0.65 mm, the number is 10, and the round table in the channel is arranged equidistantly.

Real Case Study of 600 m3 Bubble Column Fermentations: Spatially Resolved Simulations Unveil Optimization Potentials for l-Phenylalanine Production With Escherichia coli.

Large-scale fermentations (»100 m³) often encounter concentration gradients which may significantly affect microbial activities and production performance. Reliably investigating such scenarios in silico would allow to optimize bioproduction. But related simulations are very rare in particular for large bubble columns. Here, we pioneer the spatially resolved investigation of a 600 m³ bubble column operating for Escherichia coli based l-phenylalanine fed-batch production. Microbial kinetics are derived from experimental data. Advanced Euler-Lagrange (EL) computational fluid dynamics (CFD) simulations are applied to track individual bubble dynamics that result from a recently developed bubble breakage model. Thereon, the complex nonlinear characteristics of hydrodynamics, mass transfer, and microbial activities are simulated for large scale and compared with real data. As a key characteristic, zones for upriser, downcomer, and circulation cells were identified that dominate mixing and mass transfer. This results in complex gradients of glucose, dissolved oxygen, and microbial rates dividing the bioreactor into sections. Consequently, alternate feed designs are evaluated splitting real feed rates in two feeds at different locations. The opposite reversed installation of feed spots and spargers improved the product synthesis by 6.24% while alternate scenarios increased the growth rate by 11.05%. The results demonstrate how sophisticated, spatially resolved simulations of hydrodynamics, mass transfer, and microbial kinetics help to optimize bioreactors in silico.

Heat and mass transfer and deformation during chiffon cake baking

The structural transformation from a foam liquid to a porous solid during cake baking involves pore development and solidification, resulting in complex coupled heat transfer, mass transfer, and deformation processes. Studying the mechanisms can provide important references for understanding the physical processes of numerous foods containing gas pores. We constructed a multiphase flow-deformation model for chiffon cake baking, and validated its accuracy by comparing the experimental results of temperature and height. Based on the model, the heat transfer, mass transfer, and deformation characteristics were investigated. In the pore-closed region, the evaporation-diffusion-condensation process of water vapor enhances heat transfer, and its contribution to heat transfer has an equivalent thermal conductivity of up to 0.64 W/(m·K), which increases the heating rate. In the pore-opening region, the water vapor evaporates from the high-temperature, high-water activity region and is transported towards the lower-temperature region and external environment. This process enhances heat transfer and induces an evaporative cooling effect, resulting in a uniform temperature distribution that remains below 100 °C across the majority of the region. Cake expansion occurs in the low-viscosity, pore-closed region, and the water vapor generated at high temperatures serves as the primary driving force source, contributing up to 84.6%.

Microscale heat and mass transfer characteristics of CO2 flooding in nanotubes of tight oil reservoirs

AbstractThe mechanism of heat and mass transfer in tight oil reservoirs after CO2 injection is complex. In this paper, first, a CO2 transfer model within microscale adjacent nanotubes in tight oil reservoirs is established. Then, the typical heat and mass transfer characteristics of microscale CO2 in tight oil reservoirs is analyzed, and the influence of grid density on the calculation results is discussed. Finally, the influence of thermal conductivity of tight oil reservoirs on CO2 physical properties parameters is revealed. Results show that: (a) From the inlet end of the thick nanotube to the outlet of the nanotube, the pressure of CO2 drops from 3.5 to 3.3697 MPa. (b) When the mesh length is equal to 5 nm, the CO2 pressure in the thin nanotube drops from 3.5 to 3.3329 MPa, and the CO2 pressure in the thick nanotube drops from 3.5 to 3.2018 MPa. (c) Organic amines react with CO2 to form salts, which can seal high permeability layers and cracks, but there is a risk of environmental pollution.

Theoretical analysis of heat and mass transfer characteristics of a counter-flow packing tower with different heating modes

Mass extraction/injection and multi-stage system have been proven to be effective approaches to improve the performance of humidification and dehumidification (HDH) desalination system. However, these two optimization schemes cause that the flow ratios of water to air at different positions of humidifier or that of different humidifiers have great difference. A single heating mode is inapplicable to all flow ratios of water to air. Hence, it is necessary to reveal the relationship among mass flow ratio, heating mode and thermal efficiency of humidifier for the selection of appropriate heating mode. A theoretical model of packing tower (typical kind of humidifier) which agrees well with experimental results was established in this paper, and the average relative errors of outlet air temperature, humidity and thermal efficiency are 2.3 %, 4.9 % and 5.8 %, respectively. A comparison among the thermal efficiencies of a counter-flow packing tower with different heating modes (I: solution heated, II: air heated, III: solution-air heated) was conducted. It is found that there exist two values of mass flow ratio (FRI-II and FRII-III) at which the thermal efficiencies of air heated and solution-air heated are equal and that of solution heated and solution-air heated are equal, respectively. However, the thermal efficiency of solution heated is always higher than that of solution-air heated (FRI-III does not exist). It seems clear that there is a relationship between FR and thermal efficiency (η) as follows: FR < FRI-II, ηI > ηIII > ηII; FRI-II < FR < FRII-III, ηI > ηII > ηIII; FR > FRI-II, ηII > ηI > ηIII. Additionally, the effects of inlet parameters on the FRI-II and FRII-III are also evaluated. The results show that the maximum temperature, inlet solution concentration and ambient temperature have positive effects on FRI-II and FRII-III, but ambient relative humidity has negative effect. In the final part, the selection of the heating mode of a counter-flow packing tower is taken as example to introduce the application of FRI-II and FRII-III proposed in this paper.

Synergistic effect of reinforced cellulose nanofibrils/polyethylene glycol embedded particles in ammonia nitrogen wastewater: An in-depth microbial denitrification analysis

The encapsulation and immobilization technology provide a good growth environment for bacteria, strong protection ability, improved survival rate, and resistance to adverse environmental factors. Cellulose nanofibrils (CNF) with polyhydroxyl structure improve the elasticity, tensile properties, mechanical strength and gel strength of embedded particles through non-covalent forces. Polyethylene glycol (PEG) is a water-soluble polymer with unique carbon‑oxygen chain as the core skeleton. The ether bonds present in each unit give PEG extremely strong hydrophilicity and solubility. CNF and PEG to reinforce SA (sodium alginate) and PVA (polyvinyl alcohol)-SA embedded particle were adopted to treat ammonia nitrogen wastewater. The ammonia diffusion coefficients and oxygen diffusion coefficients of the CNF/PEG/SA and CNF/PEG/PVA-SA were 0.454 × 10−9, 0.286 × 10−9, 0.672 × 10−9 and 0.493 × 10−9 m2/s, respectively. The physicochemical properties of embedded particles were characterized by mass transfer characterization, SEM, XRD, FTIR, and BET analysis. The specific surface areas of CNF/PEG/SA and CNF/PEG/PVA-SA increased to 2.583 m2/g and 3.962 m2/g, respectively. The removal efficiency of NH4+-N, COD and TN in the CNF/PEG/PVA-SA system was 90 %, 74 % and 80 % at 30 °C. By HRT 8 h, the removal efficiency of NH4+-N, chemical oxygen demand (COD)and total nitrogen (TN) by the reinforced system was 94.35 %, 63.07 % and 73.84 %, respectively. The neutral to weakly alkaline pH range showed the highest removal efficiencies of NH4+-N, COD, and TN, at 88.51 %, 74.95 %, and 77.56 %, respectively. The half-saturation constant K was 82.98 mg/L, and the maximum ammonia oxidation rate (Vmax) was 358.92 mgN/(L-particles-h). The reinforced system showed zero-order reaction kinetics. Nonlinear fitting of each initial NH4+-N concentration and ammonia oxidation rate was carried out using the Michaelis-Menten equation. In reinforced embedded particles, microbial genomic data (KEGG; MetaCyc database annotation) analysis was conducted. The reinforced system demonstrated enhanced strength, specific surface area, mass transfer properties, resistance to adverse external environmental factors, and microbial survival rate for the effective treatment of NH4+-N wastewater.

Deep learning-assisted prediction and profiled membrane microstructure inverse design for reverse electrodialysis

Compared to traditional inter-membrane spacers, profiled ion exchange membranes significantly improve the energy harvesting performance of reverse electrodialysis (RED). Here computational fluid dynamics is employed to generate data regarding the flow and mass transfer characteristics and performance index under different profiled membrane microstructures. Data-driven deep learning models are constructed for microstructure shape generation, physics field prediction, and performance forecasting. Results show that the microstructure shape generation via the Bezier generative adversarial network, the physical field prediction via conditional generative adversarial network for the velocity field and the performance prediction via multi-layer perceptron for power number and Sherwood number achieves satisfied accuracy, respectively. The gradient descent algorithm is utilized to optimize the microstructure shape achieving higher mass transfer performance and lower pump power consumption. Compared to the traditional straight ridge channel, the optimized microstructure channel exhibits a reduction of 18.85 % in the power number and an increase of 41.00 % in the Sherwood number, rendering significantly boosted performance.

Mass transfer characteristics of water-driven partially submerged self-rotating disk-based mass exchanger

Mass transfer characteristics of water-driven partially submerged self-rotating disk-based mass exchanger

Assessment of the gas discharge characteristics during gas recovery by hydrate decomposition

Hydrate-based gas separation is a novel approach for the capture and recovery of hydrofluorocarbons. The gas discharge characteristics during hydrate decomposition need to be clarified for the efficient recovery of hydrofluorocarbons. In this study, we investigated the mass transfer characteristics during the gas recovery from hydrate particles by decomposing the HFC134a hydrates. First, the volumetric mass transfer coefficient was estimated from the gas recovery rate during the HFC134a hydrate slurry. The hydrate particles enhanced the gas recovery performance of the overall apparatus. Next, the mass transfer coefficient between hydrate and liquid was calculated. Ascending bubbles and the resulting change in the dispersion state of the particles significantly affected the mass transfer. Finally, we developed a mass transfer correlation equation between the solid and liquid phases by dimensionless numbers based on Kolmogorov’s theory. The experimental equation predicted the Sherwood number with ±40 % accuracy and an average absolute relative error of 19.0 %. The dispersion state of the hydrate particles was a significant factor in the estimation.

Heat and mass transfer performance of multi-solute electroplating wastewater in spray evaporation separation process

Electroplating wastewater is complex in composition and contains many harmful substances. Based on the single droplet heat and mass transfer method, a one-dimensional mathematical model for the evaporation separation heat and mass transfer process of multi-solute electroplating wastewater is established. In order to validate the model, the experimental system of evaporation separation tower is established, and Nusselt numbers corresponding to metal ion solutions are fitted, reliabilities of models are also verified. The maximum relative errors of mathematical models are within 10.0 %. In addition, effects of the type and concentration of metal ions and air inlet temperature on heat and mass transfer characteristics of spray separation tower are investigated. Experimental results show that when the wastewater inlet concentration is the same, the improvement effects of increasing air inlet temperature on evaporation and separation performance from high to low are ZnCl2, CuCl2, and NiCl2 solutions. When the air inlet temperature increases from 90 °C to 130 °C, the evaporation speed of ZnCl2, CuCl2 and NiCl2 solutions increase by 90.3 %, 84.3 % and 45.7 %, respectively. When the air inlet temperature is the same, with the increase of wastewater inlet concentration, the evaporation separation performance of electroplating wastewater in descending order is ZnCl2, CuCl2, and NiCl2 solutions.

Hydrodynamic and mass transfer characterization of an internally illuminated airlift photobioreactor for growing Spirulina platensis

Abstract The dimensions of the of a photobioreactor play a major role in its hydrodynamic and mass transfer characteristics that also affect its growth performance. In this study, a bench-scale airlift photobioreactor (PBR) was designed and fabricated to have a riser-to-diameter ratio (Ar/Ad) equal to 0.42 and an aspect ratio (H/D) equal to 1.53. These dimension ratios are different from typical values wherein most airlift photobioreactors are designed to have Ar/Ad of at least 1.0 and H/D of at least 2.0. It was hypothesized, based on the results of Hwang and Cheng [1], the fabricated PBR in this study will have better hydrodynamic and mass transfer characteristics such as lesser mixing time, better liquid circulation and lesser gas entrainment that may lead to better growth performance. Due to the different dimension ratios from other studies, characterization of the PBR and testing of its performance are required. The hydrodynamic and mass transfer characteristics of the fabricated airlift photobioreactor in this study were measured at varying superficial gas velocities (UGR) from 0.0017 ms−1 to 0.0124 ms−1. The growth parameters of the Spirulina platensis were then tested at different aeration rates to relate the hydrodynamic and mass transfer characteristics to the photobioreactor performance. This study has proven that a photobioreactor that is designed and operated to have the best hydrodynamic and mass transfer characteristics will have the best growth performance at the same light intensity and initial optical density.

CFD simulation of liquid-liquid extraction mechanism and enhancement schemes in microchannels based on three mass transfer models

Microreactors are highly efficient devices with a large specific surface area to improve the mass transfer efficiency. In this paper, a comprehensive three-dimensional CFD model was constructed based on three mass transfer theories to simulate the liquid-liquid two-phase flow and mass transfer process in a microchannel reactor, and two enhancement schemes were proposed. The multiphase flow and mass transfer characteristics were investigated by visualization and extraction experiments. The results indicated that the extraction efficiencies (E) and overall mass transfer coefficients (KLa) calculated by the penetration model and surface renewal model were within ±15 % errors compared to the experimental values. Moreover, E primarily increases with the increase of fluid residence time, while KLa increases with increasing flow rate. As the flow rate increases from 0.3 ml/min to 1.5 ml/min, E decreases by 15 %, and KLa rises from 0.78 s⁻¹ to 2.65 s⁻¹. Whereas the channel width decreases from 0.8 mm to 0.3 mm, E decreases by 3 %, and KLa rises from 0.44 s⁻¹ to 2.77 s⁻¹. Finally, microchannel with necked structure and baffles in mixing zone both improve the mass transfer efficient to some extent.