Search Results (68)

Static mixers have been widely used in marine research fields, such as marine control systems, ballast water treatment systems, and seawater desalination, due to their high efficiency, low energy consumption, and broad applicability. However, the turbulent mixing process and fluid–wall interactions involving complex structures make the mixing transport characteristics of static mixers complex and nonlinear, which affect the mixing efficiency and stability of the fluid control device. Here, the modeling and design optimization of the two-phase flow mixing and transport dynamics of a static mixer face many challenges. This paper proposes a modeling and problem-solving method for the two-phase flow transport dynamics of static mixers, based on the lattice Boltzmann method (LBM) and large eddy simulation (LES). The characteristics of the two-phase flow mixing dynamics and design optimization strategies for complex component structures are analyzed. First, a two-phase flow transport dynamics model for static mixers is set up, based on the LBM and a multiple-relaxation-time wall-adapting local eddy (MRT-WALE) vortex viscosity coupling model. Using octree lattice block refinement technology, the interaction mechanism between the fluid and the wall during the mixing process is explored. Then, the design optimization strategies for the flow field are analyzed under different flow rates and mixing element configurations to improve the mixing efficiency and stability. The research results indicate that the proposed modeling and problem-solving methods can reveal the dynamic evolution process of mixed-flow fields. Blade components are the main driving force behind the increased turbulent kinetic energy and induced vortex formation, enhancing the macroscopic mixing effect. Moreover, variations in the flow velocity and blade angles are important factors affecting the system pressure drop. If the inlet velocity is 3 m/s and the blade angle is 90°, the static mixer exhibits optimized overall performance. The quantitative analysis shows that increasing the blade angle from 80° to 100° reduces the pressure drop by approximately 44%, while raising the inlet velocity from 3 m/s to 15 m/s lowers the outlet COV value by about 70%, indicating enhanced mixing uniformity. These findings confirm that an inlet velocity of 3 m/s combined with a 90° blade angle provides an optimal trade-off between mixing performance and energy efficiency. Full article

The viscoelasticity of fluids have a significant impact on the process of heat and mass transfer, which directly affects the efficiency and quality, especially for highly viscous functional polymer materials. In this work, the effect of elasticity on hydrodynamic behavior of pipe flow for highly viscous non-Newtonian fluids was studied using viscoelastic polyolefin elastomer (POE). Two constitutive rheological equations, the Cross model and Wagner model, were applied to describe the rheological behavior of typical POE melts, which have been embedded with computational fluid dynamics (CFD) simulation of the laminar pipe flow through the user-defined function (UDF) method. The influence of both viscosity and elasticity of a polymer melt on the flow mixing and heat transfer behavior has been systematically studied. The results show that the elastic effect makes a relative larger velocity gradient in the radial direction and the thicker boundary layer near pipe wall under the same feed flow rate. That leads to the higher pressure drop and more complex residence time distribution with the longer residence time near the wall but shorter residence time in the center. Under the same conditionals, the pipeline pressure drop of the viscoelastic fluid is several times or even tens of times greater than that of the viscous fluid. When the inlet velocity increases from 0.0001 m/s to 0.01 m/s, the difference in boundary layer thickness between the viscoelastic fluid and viscous fluid increases from 3% to 12%. Similarly, the radial temperature gradient of viscoelastic fluids is also relatively high. When the inlet velocity is 0.0001 m/s, the radial temperature difference of the viscoelastic fluid is about 40% higher than that of viscous fluid. Besides that, the influence of elasticity deteriorates the mixing effect of the SK type static mixer on the laminar pipe flow of highly viscous non-Newtonian fluids. Correspondingly, the accuracy of the simulation results was verified by comparing the pressure drop data from pipeline hydrodynamic experiments. Full article

During crude oil exploration and extraction, the presence of H₂S not only poses a threat to operational safety but also accelerates equipment corrosion, highlighting the urgent need for efficient and cost-effective processing solutions. This study employs a coupled numerical simulation approach that integrates computational fluid dynamics (CFD) and population balance models (PBM) to systematically investigate the multiphase flow characteristics within SK static mixers. By embedding mass transfer rates and reaction kinetics equations for hydrogen sulfide and sodium hypochlorite into the Euler-Euler multiphase flow model using user-defined functions (UDFs), the effects of equipment structure on the efficiency of the crude oil desulfurization process are examined. The results indicate that the optimized SK static mixer (with 15 elements, an aspect ratio of 1, and a twist angle of 90°) achieves an H₂S removal efficiency of 72.02%, which is 18.84 times greater than that of conventional empty tube reactors. Additionally, the micro-mixing time is reduced to 0.001 s, and the coefficient of variation (CoV) decreases to 0.21, while maintaining acceptable pressure drop levels. Using the CFD-PBM model, the dispersion behavior of droplets within the static mixer is investigated. The results show that the diameter of the inlet pipe significantly affects droplet dispersion; smaller diameters (0.1 and 1 mm) enhance droplet breakup through increased shear force and turbulence effects. The findings of this study provide theoretical support for optimizing crude oil desulfurization processes and are of significant importance for enhancing the economic efficiency and safety of crude oil extraction operations. Full article

The utilization of low-concentration coalbed gas as an energy source in coal mines has garnered significant attention due to the intensifying global warming trend. Achieving a uniform gas mixture is essential for the effectiveness of various gas utilization technologies. In this study, we conducted a series of numerical studies on the pressure loss and mixing uniformity of a swirl-type static low-concentration coalbed methane (SLCCM) mixer with spiral blades as turbulence elements. The results indicate that installing spiral blades at the low-concentration gas inlet can significantly improve gas mixing uniformity, while installing spiral blades at the air inlet has a relatively small impact on gas mixing uniformity. When spiral blades are installed at both the low-concentration gas and air inlets, and the spiral direction of the two sets of blades is the same, the pressure loss of the mixer is smaller than that of the mixer with opposite spiral directions. Moreover, the mixing uniformity of the former is better than that of the latter when the length of the mixing zone is shorter. However, as the length of the mixing zone increases, the mixing uniformity of the mixer with opposite spiral directions of the two sets of blades will be significantly improved and better than that of the mixer with the same spiral direction. When a set of spirals with opposite directions to the blades at the low-concentration gas inlet is added at the forefront of the mixing zone, the mixing uniformity at the outlet of the mixer can be greatly improved, but it will increase the mixing pressure loss of the system. When the two spirals are in the same direction, the impact on the system pressure loss and mixing uniformity is relatively small. The numerical simulation results show that by setting a set of spiral blades with the same rotation directions at the inlet of low-concentration gas and at the forefront of the mixing zone (i.e., b2-type structure), the spatial non-uniformity of the mixing is about 5.24%, and the system pressure loss is less than 400 Pa, which is significantly better than the requirement of less than 15% spatial non-uniformity for engineering requirements. Moreover, with the increase in the length of the mixing zone, the spatial non-uniformity still tends to decrease. Full article

This article deals with the removal of manganese from water via ultrafiltration and the oxidation of manganese with chlorine dioxide or potassium permanganate before ultrafiltration. The dose of oxidizing agents, time of contact with water, and manganese concentration in raw and treated water were monitored. A fully automated ultrafiltration device with membrane module UA-640 (Microdyn-Nadir) was used. A tubular reactor with a static mixer was used to reach a sufficient contact time for water with an oxidizing agent, enabling the oxidation of manganese in water. The concentration of Mn in the water source ranged from 0.150 to 0.250 mg/L Mn. The results of the experiments showed that in the case of chlorine dioxide, the efficiency of removing Mn from water of 74.31% was achieved at a flow rate of 60 L/h, a dose of 0.4 mg/L ClO₂ and a retention time of 30.5 min; the concentration of Mn in the treated water was 0.037 mg/L, while in the case of KMnO₄ the efficiency was up to 100% at a flow rate of 650 L/h, a dose of 0.3 mg/L Mn (determined after adding KMnO₄) and a retention time of 2.8 min; the concentration of Mn in the treated water was below the detection limit of 0.005 mg/L of the measuring device. Pilot plant experiments confirmed the efficiency of ultrafiltration, demonstrating the possibility of decreasing the manganese concentration below the limit for drinking water using the considered method. Full article

Hydrogen–methane gas mixtures are increasingly recognized as a viable path toward achieving carbon neutrality, leveraging existing natural gas infrastructure while reducing greenhouse gas emissions. This study investigates a novel static mixing device designed for blending hydrogen and methane, employing both experimental tests and three-dimensional computational fluid dynamics (CFD) simulations. Hydrogen was introduced into a methane flow via direct injection, with experimental mixtures ranging from 5% to 18% hydrogen. The mixture quality was assessed using a specialized gas chromatograph, and the results were compared against simulated data to evaluate the mixer’s performance and the model’s accuracy. The system demonstrated effective blending, maintaining uniform hydrogen concentrations across the outlet with minimal variations. Experimental and simulated results showed strong agreement, with an average accuracy error below 2%, validating the reliability of the CFD model. Smaller nozzles (0.4 mm) achieved greater mixing uniformity, while larger nozzles (0.6 mm) facilitated higher hydrogen throughput, indicating trade-offs between mixing precision and flow capacity. The mixing device proved compatible with existing pipeline infrastructure, offering a scalable solution for hydrogen integration into natural gas networks. These findings underscore the mixer’s potential as a practical component in advancing the hydrogen economy and achieving sustainable energy transitions. Full article

The static mixer is one of the key equipment for dilution transportation of heavy oil. To enhance the mixing performance of heavy oil dilution, a static mixer featuring a parabolic blade has been developed through an innovative redesign of the traditional Kenics blade. Numerical simulations of the parabolic static mixer were conducted using Fluent 2022 R1 software. The coefficients of concentration variation (COV) and pressure drop (∆P) served as evaluation indexes, and the effects of parabolic focal length (P), torsion angle (α), and length–diameter ratio (Ar) of the mixing blade on mixing performance were thoroughly analyzed. The research indicates that setting the mixing blade parameters to P = 60, α = 180°, and Ar = 1.5 results in improved mixing performance compared to the traditional Kenics static mixer, achieving a COV of 0.036, which signifies nearly complete mixing of heavy oil and light oil. As parabolic P increases, ∆P exhibits a decreasing trend, while the COV begins to show a significant difference at the outlet of the third mixing blade. As α increases, ∆P rises, while the COV decreases. A decrease in Ar causes ∆P to increase sharply. Although heavy oil and light oil can mix rapidly over a short distance, their influence on the final mixing effect is relatively minor. This study offers significant theoretical insights and practical implications for high-efficiency heavy oil dilution transportation technology. Full article

High-precision and real-time modeling are crucial for accelerating the research cycle of next-generation aero-engines. The volumetric dynamics method is acknowledged as the most accurate approach to capture the engine’s transition state process. Nevertheless, the traditional volumetric method encounters challenges, such as neglecting static pressure equilibrium within the mixer and complexities in ascertaining the component volume size when the dynamic simulation time step varies. To address these issues, an improved volumetric dynamics modeling method featuring pressure ratio collaborative updating and the adaptive virtual volume method has been proposed, and a real-time component-level model of a variable cycle engine is established based on this method. The pressure ratio collaborative updating method dynamically updates the pressure ratio of rotating components by inversely calculating the internal and external bypass pressure of the mixer according to static pressure equilibrium constraints and the momentum conservation principle. The adaptive virtual volume method determines the optimal virtual volume size using the particle swarm optimization algorithm, with cosine similarity serving as the evaluation metric. The simulation results indicate that the model based on an improved volumetric dynamics method achieves high accuracy and superior real-time performance. Moreover, compared to traditional modeling methods, the co-operating line of the improved volumetric dynamic method exhibits a smoother transition, signifying a closer resemblance to the real physical process. Full article

The aim of this research was to prepare pH sensor films based on litmus using the sol–gel method with tetraethoxysilane (TEOS) and phenyltrimethoxysilane (PTMS) as precursors. The pH sensor film was then applied to millireactors to evaluate its performance on the intricate geometries of static mixers commonly found in millireactor designs. Millireactors were made from Formlabs High Temp resin using stereolithography (SLA) and from Anycubic Basic resin using digital light processing (DLP) technology. The performance of the pH sensor films was evaluated by tracking color changes in the pH sensor films and analyzing RGB (red, green, blue) and hue values through a smartphone application. The experiment involved mixing solutions with different pH values at varying flow rates within the millireactor channels. Furthermore, along with analyzing the hue values, characterization techniques involved measuring contact angles with water and diiodomethane. A film combining a litmus indicator with titanium dioxide (TiO₂) displayed a color change within one minute and maintained this color throughout the study, confirming its reusability. Sensor films exhibited excellent reversibility (RSD = 2.4–3.3%) and stability. The findings demonstrate that the pH-sensitive films perform robustly across varying geometries, paving the way for their integration into advanced millireactor systems with static mixers and continuous chemical monitoring within Industry 4.0. Full article

The modeling of a mixer used for mixing ammonia and flue gasses is considered. Simulations were performed using Flow Vision 3.14 (TESIS LLC). As a result of the simulation, the distribution of concentrations along the mixer length was obtained at 50%, 65%, 85%, and full flue gas loading. It was found that operations at 100% and 85% gas loads are accompanied by an acceptable distribution of ammonia in the mixer volume (Cov = 0.05). The development and creation of an experimental model in real production was carried out according to the results of the numerical simulation. The simulation results were compared with experimental data on the speed and concentration of ammonia in the control section. The discrepancy, in general, did not exceed 15%. The developed mixer corresponds to modern developments in terms of mixing quality but is simpler in design and more compact. Full article

This research on biodiesel production aims to improve energy processes to advance towards a sustainable economy. This study focuses on improving the biodiesel conversion efficiency in a helical tubular reactor coupled with a static mixer. A 2³ factorial design was used to evaluate how variables such as the molar ratio of alcohol–oil (4:1–8:1), residence time (4–8 min), and catalyst concentration (0.5–1 wt%) affect the transesterification process. Soybean oil and methanol were used, with NaOH as a catalyst at 60 °C. The results show that the residence time and catalyst concentration are key factors in increasing biodiesel production by up to 10%. An experimental yield of 84.97% was obtained with a molar ratio of 6:1 alcohol–oil, 0.9 wt% NaOH, and a reaction time of 6 min. The experimental design predicted a yield of 91% with a molar ratio of 4:1 alcohol–oil, 1 wt% NaOH, and a reaction time of 8 min, with a deviation of 1.88% from the experimental values. The fit of the experimental model was R² = 0.9632. These findings are valuable for improving the transesterification process and the development of biodiesel in continuous flow reactors. Full article

Gas plays a crucial role in cell culture as cells require a specific gas environment to maintain their growth, reproduction, and function. Here, we propose a gas supply system for tri-gas multi-channel cell incubators to meet the specific needs of various cells. The system utilizes a circulating gas supply method powered by air pumps for each chamber. Gas inflow from the cylinder is independently controlled by Mass Flow Controllers (MFCs), and a quantitative step-by-step adjustment control strategy is employed to calculate the volume of different gases being introduced. Through mixing simulations and experiments, we identified the SV static mixer with an L/D ratio of 2.5 as the optimal choice. To evaluate the concentration accuracy and gas consumption of the gas system, we conduct gas mixing and distribution experiments under different conditions. The results show that the system could achieve a concentration range of 0–100% for O₂ with an accuracy of ±0.5%, and a concentration range of 0–10% for CO₂ with an accuracy of ±0.1%. The daily gas consumption during cultivation is 3570 mL of N₂, 330 mL of CO₂, and 115 mL of O₂, significantly lower than conventional incubators. Overall, our system can effectively manage dynamic gas concentration changes, particularly in high O₂ concentration environments. It offers advantages such as low gas consumption, a wide concentration range, and high accuracy compared to existing incubators. Full article

This article studies the influence of structural parameters of the optimization model for the gas–liquid mixing device of a fire truck (compressed air foam lift fire truck, model JP21/G2, made in China) on the liquid phase volume fraction, static pressure, velocity streamline, and the influence of smaller flow rates on the mixing effect. By using the computational fluid dynamics (CFD) software FLUENT 2021 R2, numerical simulations were conducted on the fluid domain model of the gas–liquid mixing device of the JP21/G2 fire truck. The changes in the mixing effect time dimension, liquid phase volume fraction, static pressure, and velocity streamline inside the gas–liquid mixing device were obtained. The optimal mixer structure combination in practical applications was inferred through orthogonal experiments, and the influence of flow rate on the optimal pipe diameter and shortest mixing distance was obtained through variable flow rate simulation experiments. The numerical simulation results show that the presence of bent pipes in the JP21/G2 real vehicle model hinders the gas–liquid mixing process. A straight pipe section of at least 8 m was added after the bent pipe to ensure the mixing effect. The optimal parameter combination for orthogonal experiments had an accurate value of 50°-50°-220 mm. Under the same pipe diameter, using a larger flow rate can achieve better mixing effects. Full article

Biomaterials, like hydroxyapatite (HAp), are the subject of many scientific investigations. Their specific application, however, is determined by the form and some characteristic features of the resulting material. Synthesis methods and optimization procedures leading to a product of predetermined characteristics are therefore of great interest. To broaden the existing knowledge, sonoprecipitation was investigated as a potential method for the production of nanosized HAp particles. The research was carried out in a static mixer (STM) immersed in the ultrasonic bath. The influence of operating conditions, e.g., ultrasonic power P_US (ε_US), ultrasonic frequency (f_US), and unit mixing power (ε_mix), was investigated in terms of nucleation intensity, product quality, and characteristics (particle size distribution (PSD), mean size, shape, etc.). As a result, the optimal conditions for the HAp nanoparticles synthesis (mean size: d~150 nm; length: L₁~250 nm; width: L₂~80 nm) in the form of needles/whiskers/rods—similar to the shape of the HAp present in natural human bones, free from agglomerates, with negligible signs of particle destruction—were determined. The formation of HAp of smaller sizes (d ≤ 100 nm) and more compact shapes (L₁~155 nm, L₂~90 nm), useful in bone regeneration processes, was also discussed. Full article

The addition of static mixers within reactors leads to higher productivity of a process and an additional increase in mass and energy transfer. In this study, we developed millireactors with static mixers using stereolithography, an additive manufacturing technology. Computational fluid dynamics (CFD) simulations were conducted to study the flow, identify potential dead volumes, and optimize the design of the millireactors. We produced five millireactors with various static mixers and one tubular reactor without static mixers, which served as a reference. The Fenton reaction was performed as a model reaction to evaluate the performance of the millireactors. We observed that some of the reactors with static mixers had air plugs that created a significant dead volume but still exhibited higher conversions compared to the reference reactor. Our results demonstrate the potential of stereolithography for producing intricate millireactors with static mixers, which can enhance the productivity of chemical processes. Full article