Mixing Performance Research Articles

Development and evaluation of mixing performance of new type pitched paddle impeller (HR1000) for wastewater treatment

AbstractSATAKE MultiMix Corporation developed a new type of pitched paddle impeller for low power consumption turbulent mixing for wastewater treatment and its performance was evaluated by measuring power consumption, mixing time, and particle suspension. The power number of the new impeller was lower than that of the existing pitched paddle, which could be constructed by modifying the correlation equation. For the same power consumption per unit volume, the mixing performance was almost the same as that of other axial flow impellers. The particle suspension performance was also the same as that of other axial flow impellers.

Jet mixing optimization using a flexible nozzle, distributed actuators, and machine learning

In this paper, we introduce the first jet nozzle allowing simultaneous shape variation and distributed active control, termed “Smart Nozzle” in the sequel. Our Smart Nozzle manipulates the jet with an adjustable flexible shape via 12 equidistant stepper motors and 12 equidistantly placed inward-pointing minijets. The mixing performance is evaluated with a 7 × 7 array of Pitot tubes at the end of the potential core. The experimental investigation is carried out in three steps. First, we perform an aerodynamic characterization of the unforced round jet flow. Second, we investigate the mixing performance under five representative nozzle geometries, including round, elliptical, triangular, squared, and hexagonal shapes. The greatest mixing area is achieved with the square shape. Third, the symmetric forcing parameters are optimized for each specified nozzle shape with a machine learning algorithm. The best mixing enhancement for a symmetric active control is obtained by the squared shape, which results in a 1.93-fold mixing area increase as compared to the unforced case. Symmetrically unconstrained forcing achieves a nearly 4.5-fold mixing area increase. The Smart Nozzle demonstrates the feasibility of novel flow control techniques that combine shape variation and active control, leveraging the capabilities of machine learning optimization algorithms.

Evaluation of surface texturing on chrome-coated cylinder liners via deterministic mixed lubrication simulation

This study investigates the mixed lubrication performance of various surface texture configurations in the piston ring/cylinder liner conjunction of a two-stroke internal combustion engine using a deterministic mixed lubrication model. The numerical model simultaneously solves the Reynolds equation with mass-conserving cavitation to calculate inter-asperity hydrodynamic pressures and an elastic, perfectly plastic, rough contact model to determine contact pressures at each asperity interaction. Gaussian Mixture Model clustering was employed to enhance surface characterization. The deterministic simulation approach considers the full-scale representation of the cylinder liner topography to accurately capture the influence of surface features on the hydrodynamic support and friction under mixed lubrication conditions. The investigated cylinder liners were initially hard-chrome-coated and honed, resulting in a stochastic arrangement of surface pores, and then deterministic patterns of surface pockets were created by micro electrodischarge machining (EDM). Surface measurements were performed using laser interferometry, providing input for the mixed lubrication simulations. The study also explored the virtual removal of ridges formed around the pockets by the EDM technique. Key findings indicate that the stochastic texture outperformed the hybrid texture (stochastic + deterministic) in the boundary and mixed lubrication regimes, showing higher hydrodynamic support at low separations but increased hydrodynamic shear stresses at higher speeds. Conversely, deterministic textures exhibited a significant decrease in average hydrodynamic shear stress at high velocities. These results highlight the critical role of surface texture in tribological behavior and suggest that localized textures on cylinder liners can potentially optimize engine performance. The study recommends further exploration of a broader range of texture geometries, densities, and distribution patterns to enhance engine design strategies.

Effects of axisymmetric confinement on vortical structures emanating from round turbulent jets

Confined jets occur in many engineering applications including combustion chambers, jet pumps, and chemical reactors. The effects of axisymmetric confinement on the vortical structures identified in a turbulent jet are investigated using large eddy simulation at a Reynolds number of 30 000 (based on nozzle exit conditions) and expansion ratio (chamber-to-nozzle diameter ratio) of five. The results obtained from the confined jet are compared with those of a free jet under the same nozzle exit flow conditions. A prominent recirculation zone forms between the expanding jet and the confining wall, resulting in early shear layer distortion and a shorter interaction length in the confined jet (0.85 jet diameters) compared to the free jet (1.15 jet diameters). Using the λ2 criterion for vortex identification, two dominant structural modes are identified in the near-exit region of the free jet: ring and helical modes. However, in the confined jet, the helical mode is absent, and the turbulent confined fluid accelerates the breakup of the ring vortices. The interaction of the secondary line vortices with the breaking structures leads to the formation of new hairpin-like vortices, which also contribute to further vortex breakup. These results explain the enhanced mixing performance of confined jets as the mixing is directly tied to the breakup of large vortical structures. Proper orthogonal decomposition modes are also presented to identify the structures/events with the highest contribution to the total turbulent kinetic energy in both flow fields.

Numerical simulation study of liquid–liquid mixing of high-viscosity fluids under laminar flow in a reverse flow multi-stage Tesla valve

In this study, computational fluid dynamics was employed to conduct a numerical simulation of the mixing performance and flow characteristics of two highly viscous liquids under laminar flow conditions within a reversed Tesla valve. Scalar transport techniques are employed to analyze the efficiency of liquid–liquid mixing in high-viscosity fluids. The focus of this study is to investigate the optimal mixing behavior between different parameters. Results indicate that an increase in Reynolds number leads to intensified Dean vortices, thereby promoting liquid–liquid mixing efficiency. Additionally, the mixing coefficient shows a negative correlation with Schmidt number (Sc), with a diminishing impact on the mixing coefficient when Sc ≥ 104. This is attributed to the dominance of fluid flow in controlling mixing within the channel at higher Schmidt numbers. Furthermore, this study compares the influence of valve angles (α) and stage numbers (n) on the mixing coefficient under identical Reynolds and Schmidt number conditions. As the number of Tesla valve stages increases, fluid acceleration within the pipeline is enhanced. Moreover, larger valve angles result in increased lengths of the curved section, leading to higher mixing efficiency. Therefore, to enhance mixing efficiency, it is recommended to increase the valve angle and the number of stages in the Tesla valve.

Characterization of chaotic mixing effects in hydrometallurgical leaching process based on deep learning

Traditional stirring methods in the wet metallurgy leaching process suffer from low efficiency, high consumption, and low output, leading to increased production costs and energy consumption. Therefore, this study evaluates reactor performance using deep learning and introduces variable-speed stirring to enhance laminar mixing and reduce stirring reactor power consumption. An S-Type acceleration and deceleration control algorithm is constructed to ensure that stepper motors do not experience step loss, stalling, or overshoot when the frequency changes abruptly. A deep learning tracking model based on dual cameras is established to dynamically track tracer particles inside the stirring reactor, and a Euclidean distance evaluation method is proposed to characterize and evaluate the mixing performance of the stirring reactor. Experimental results demonstrate that the use of complex function variable-speed stirring and shortening the variable-speed cycle both contribute to improving mixing efficiency. Under a variable-speed cycle of 5 seconds, chaotic speed increases mixing efficiency by 53.1% compared to constant speed. This study provides a theoretical basis for optimizing the wet metallurgy leaching process.

Mathematical model of the process of mixing semi-liquid feeds in a device with a propeller

The article considers the issues of using a propeller apparatus for mixing semi-liquid feed mixtures in a mixer with an eccentrically positioned working body in the form of a propeller (screw). Until now, when studying the mixing process, little attention has been paid to the transporting ability of the working body in the form of a propeller agitator. When preparing wet mixtures, agitators with a vertically positioned shaft, which is located in the center of a vertical cylindrical tank, are widely used. When installing the working body horizontally, the propeller having a pumping effect (axial movement), can be used not only for mixing, but also for unloading the finished feed mixture, as well as moving it through pipes over short distances. The existing models of the mixing process do not take into account its stochastic nature. Methods of mathematical description of mixing processes considering the prevailing axial movement of the flow are scarcely developed. The proposed mathematical models make it possible to determine the mixer's performance and the required mixing power. The research was aimed at increasing the effectiveness of preparing a feed mixture in a horizontal mixer of propeller type with an eccentrically positioned working body (screw) and saving energy costs along with raising the productivity. The object of the study was a mixing chamber with eccentrically located working bodies of various diameters (0.2, 0.25 and 0.35 m). During the experiments, the productivity required to drive the motor shaft was determined. It has been experimentally established that increasing the agitator rotation speed from 200 to 400 min-1 with a propeller diameter from 0.2 to 0.35 m and a feed mixture humidity of 84 % leads to an increase in power consumption to 3.5 kW and mixer productivity to 12 m3/h, and the degree of uniformity of feed mixtures is up to 98 %.

Utilising natural pigments as a filler replacement on the mix design, performance and colorimetric characteristics of the microsurfacing mixture: laboratory evaluation

Coloured pavements enhance road safety and urban aesthetics. This study examined the use of bitumen emulsion and natural pigments as replacements for natural filler in coloured microsurfacing mixtures (CMMs). Coloured powders and natural fillers were analyzed, and seven colour combinations of red, yellow, and blue pigments with titanium dioxide (TiO2) were used to create CMMs. Performance was evaluated according to ASTM D6372, while colour evaluation was assessed using a colorimetric system and a spectrophotometer device. The results revealed that the mixture containing the red pigment exhibited the most appropriate performance, which was based on its particle size and properties among the CMMs. Compared to the control sample, the red combination showed improved cohesion (9.3-9.5% increase), reduced moisture sensitivity (40.1% decrease), and less vertical displacement under traffic (14.5% reduction). TiO2 was beneficial for blue and red compounds at 1-3% content, while 1% TiO2 yielded optimal results for yellow compounds.

Oil-based drilling cutting pyrolysis residues-recycled fine powder sintered ceramsite: Basic properties, microsintering mechanism, lightweight concrete application and heavy metals solidification

Oil-based Drilling Cutting Pyrolysis Residue (ODPR) is a waste produced during oilfield drilling using oil-based mud. Recycled Fine Powder (RFP) consists of particles less than 0.16 mm, crushed and sieved from waste concrete. China's solid waste is characterized by high production, low utilization rates, and high pollution levels. This study explores the feasibility of preparing ceramsite from ODPR and RFP. By examining the effects of varying temperatures and proportions on the macroscopic and microscopic properties of ODPR-RFP ceramsite (ORC), the optimal process was determined: ODPR: RFP = 7:3, 2 % borax flux, 10 minutes ball milling, 1200℃ sintering temperature, and 30 minutes insulation. The resulting ORC, with a bulk density of 1120 kg/m³, cylinder compression strength of 10.50 MPa, and water absorption rate of 7.8 %, meets the "Lightweight aggregates and its test methods (GT/B17431.2)" standard. Batch production of ORC products of various sizes was conducted to evaluate their practical application in LC30 lightweight aggregate concrete. Replacing the aggregate in lightweight concrete with ORC yielded a concrete with excellent mixing performance, reaching a maximum strength of 31.2 MPa after 7d and 44.8 MPa after 28d. The damage pattern of ORC lightweight concrete is characterized by longitudinal splitting, with varied crack initiation and expansion paths. In the interfacial transition zone of ORC concrete, the ORC form a strong bond with the cement mortar, enhancing the strength of the lightweight concrete. Additionally, the leaching of heavy metals (HMs) from the ORC was examined to assess potential environmental pollution. The results indicated that preparing ORC from these two types of solid waste can effectively immobilize HMs, with a solidification rate of up to 92.10 %. Pb with high content is mainly solidified in the form of solid solution to form (Ba, Pb) SO4. The ecological risk assessment method for HMs shows that using this solid waste and process to prepare ORC does not pose HMs risks and is an environmentally friendly building material.

Experimental and numerical study on the performance index of mixing for low aspect ratio serpentine microchannels

In this work, the effect of a range of Dean numbers (De) varying from 0.01–70 on low aspect ratio (AR = 0.05–0.2) serpentine microfluidic devices was studied experimentally and numerically. It was observed that the AR, the number of circular bumps, and the angular positions of bumps transverse to the flow have a significant influence on the pressure drop and flow features (i.e., the position and shape of flow separation zones). Mixing was exclusively driven by diffusive mechanisms at low De values and at high De values, it was primarily induced by Dean vortices. The lowest mixing index (MI) was observed for De = 1 in all channel types, highlighting the transition region between the diffusion and Dean vortices-dominant mixing regimes. The MI was generally increased by increasing the AR of the channels. However, at high De, Dean vortices became strong enough to induce rapid mixing that was largely independent of the AR and bump placement. A dimensional performance index (PI) was defined as a function of the MI and the pressure drop per unit length. Distinct flow patterns arising from various positioning of bumps resulted in significant variations in the MI and PI values, with different dependencies on De. This underscored the importance of bump positioning based on the operational De range to optimize the mixing performance. Despite minor deviations between the designed and fabricated channels, the use of 3D-printed molds proved effective even at scales close to the resolution of the printer, resulting in mixing patterns consistent with the designed channels. These findings provide valuable insights into optimizing serpentine microchannels for efficient mixing while considering the trade-offs between enhanced mixing and increased pressure drop.

Numerical Study on the Hydraulic and Mixing Performance of Fluid Flow within a Channel with Different Numbers of Sector Bodies

Numerical Study on the Hydraulic and Mixing Performance of Fluid Flow within a Channel with Different Numbers of Sector Bodies

Efficacy and safety of biotechnological drugs for the treatment of moderate-to-severe psoriasis in the elderly population: a single-center, Italian experience.

Demographic changes impose a number of issues regarding the biological treatment of elderly patients with moderate-to-severe psoriasis. A retrospective, single-center study was conducted on patients aged 65 years or older with moderate-severe psoriasis who had been undergoing treatment with biologic drugs for at least 60 weeks. A total of 168 patients aged 65 years or older with moderate-to-severe psoriasis undergoing biologic therapy were retrieved: 45 were women and with a mean age of 73.23 ± 6.53 years. The decline in mean PASI, BSA, DLQI and NAPSI values over the 60 weeks of treatment was found to be statistically significant at each interval (p < 0.05). Multivariate statistical analysis showed that nearly all the considered independent variables did not influence the response to therapy in terms of PASI score reduction, except for psoriatic arthritis (p = 0.03). We observed a better response by YOs, with 72.84% of subjects achieving PASI 75 and 71.6% achieving PASI 90 and 100 at the 60th week of treatment. The worst result was obtained by the MOs, with 60 percent of subjects reaching PASI 75 at the end of follow-up, while the OOs had a more mixed performance. The results obtained seem to indicate greater efficacy of anti-TNFα drugs, followed by the other classes of interleukin inhibitors. These results could provide a starting point for new and larger studies and guidelines for biologic treatment.

Laboratory characterisation of sand-tyre mix as bedding material for buried structures

Bedding material directly interacts with buried structures and supports to sustain external loadings such as traffic and overburden soil pressure. Therefore, soil-structure interaction plays an essential role in the stability and safety of buried structures. In particular focusing on underground pipelines, the annual rate of failures in Australia is around 19 % per 100 km of pipeline and can cost millions of Australian dollars in maintenance. Of these annual failures, ground vibrations from heavy traffic and construction activities are a major cause. In order to reduce such effects of ground vibrations on buried structures, this paper presents the possible application of sand-rubber mixes as a bedding material, where rubber is sourced from recycled tyres. The performance of sand-tyre mixes with regard to the potential for vibration reduction is assessed through this experimental study which comprises of particle size distribution, standard proctor compaction, permeability test, direct shear test, California Bearing Ratio and Repeated Load Test. From these tests, it was found that sand mixed with up to 20 % recycled tyre rubber was the most suitable mix for use as a bedding material.

Enhancing life cycle assessment for reversible ground-coupled heat pump systems through dynamic analysis

Ground-coupled heat pump (GCHP) systems can provide comfortable indoor environments, but also inevitably contribute to greenhouse gas emissions and other impacts on human health, ecosystems, and resources. Life cycle assessment (LCA) methodology has been widely adopted to estimate the environmental impacts associated with GCHP systems, with operational electricity consumption being the largest contributor among most categories. Given the data-intensive nature of LCA, operational electricity consumption should be prioritised to refine the accuracy of LCA results. Previous studies, however, have relied on static COP (Coefficient of Performance) and annual average data to obtain the environmental impacts and have disregarded the effect of long-term performance degradation caused by building thermal load imbalances. In this paper, to bridge this research gap, a dynamic operational environmental impact assessment (DOEIA) method was proposed to improve the precision of LCA results by incorporating higher temporal resolution data of electricity mix and real-time performance modelling of the reversible GCHP system. Impacts of different temporal resolutions (i.e. monthly, trimestral, and annual) on the accuracy of LCA results was examined and the operational performance degradation resulting from imbalanced building heating and cooling loads was considered. Results demonstrate that while performance degradation effects are evenly distributed across impact categories, gaps due to temporal resolutions vary significantly between different categories. Subsequent analysis of spatial variations in the latter further emphasises the importance of accounting for higher temporal resolutions. Finally, life cycle impact assessment (LCIA) results for reversible GCHP systems in different locations were obtained with the support of DOEIA method and the results underscore the necessity of a cleaner energy mix. The proposed DOEIA method can be applied to other energy systems for comparative analyses. It is replicable in other countries and regions and therefore is expected to provide methodological guidance for future decision-makers.

Resilient robust model predictive load frequency control for smart grids with air conditioning loads

AbstractThis paper investigates the robust model predictive load frequency control problem for smart grids with wind power under cyber attacks. To accommodate intermittent power generation, the demand response of the system is considered by involving the air conditioning loads in the frequency regulation. In addition, the system uncertainties produced by the air conditioning load users and wind turbines when replacing traditional generator sets are considered. By using the cone complementary linearization algorithm and the linear matrix inequality technique, a resilience robust model predictive control strategy with mixed performance indexes is proposed. Furthermore, a rigorous derivation of the recursive feasibility of robust model predictive control is given. Finally, the simulation results of the two‐area load frequency control scheme show that the proposed model predictive control strategy is capable of realizing the load frequency control of the multi‐area smart grid and is robust to the parameter uncertainties and frequency regulation of the system. The results also show that the proposed model predictive control strategy has some resistance to cyber attacks and external disturbances.

Exploring the potential of arecanut fibers and fly ash in enhancing the performance of self-compacting concrete

Self-compacting concrete (SCC) is an innovative material for construction that offers excellent workability and flowability while achieving effective and uniform compaction without the need for external vibration. Using an experimental approach, this study investigates the effect of incorporating arecanut fibers on the performance of self-compacting concrete (SCC). The focus is on optimizing the fiber content for improved concrete characteristics. The study examines three different fiber lengths (8 mm, 10 mm, and 12 mm) and three volume fractions (1%, 2%, and 3%) while partially replacing 30% of the cement by weight with fly ash. Tests on the workability of the SCC mixes revealed favorable characteristics: slump flow between 650 and 750 mm, T500 slump flow time of 2–5 s, V-funnel time of 5–10 s, L-box ratio of 0.8–1.0, and J-ring values within 0–10 mm as recommended by EFNARC guidelines. Furthermore, incorporating 30% fly ash and arecanut fibers significantly enhanced the hardened properties of the SCC, particularly its compressive strength. A concrete mix containing 2% of 10-mm long arecanut fibers achieved a compressive strength of 40.26 MPa, which is about 15.14% increase compared to the reference strength of 35 MPa. Similarly, using a 1% volume fraction of 12 mm arecanut fibers increased the split tensile strength by 14.04% and the flexural strength by 35.87% compared to the control mix. Fly ash and arecanut fibers enhance the durability of SCC by reducing Coulomb charges and improving resistance to chloride penetration. However, the increased water absorption rate of the fibers can lead to increased overall water absorption in the concrete. Microstructural analysis (SEM) revealed improved bonding and reduced voids, further supporting enhanced durability. Additionally, EDX analysis confirmed the presence of various elements from cement and fly ash, providing valuable data for evaluating the long-term performance of these SCC mixes.

Enhancing Hamburg Wheel Tracking Test Analysis: A Novel Energy-Based Performance Index

Rutting and moisture damage are the most common distress types in the pavement; therefore, agencies have adopted performance tests such as the Hamburg wheel tracking test (HWTT) to specify and screen the asphalt concrete rutting performance, following the AASHTO T324 standard. Many studies have shown that the AASHTO parameters can be used to characterize and rank the performance of asphalt mixes. Additionally, researchers proposed new analysis methods and performance parameters to provide a more systematic approach to analyzing the HWTT results. However, some of these performance parameters are determined subjectively by the operator, which may result in ambiguous values, preventing agencies from adopting them in the specification. On top of that, it is also unclear whether each analysis method or the performance parameters can universally distinguish the rutting performance when applied to various HWTT results. Thus, this study investigates the feasibility of different HWTT analysis methods among the performance parameters. 61 HWTT results from various material combinations were analyzed using three different data analysis approaches and calculating the performance parameters. The result showed that the current analysis methods and parameters have certain limitations in analyzing HWTT results. Therefore, a performance parameter, namely the Hamburg performance index (HPI), was introduced, incorporating the number of passes, maximum rut depth, and rut path history into one parameter. It was found that the HPI can resolve the limitation encountered by other analysis approaches and significantly improve the accuracy of distinguishing a mix's rutting and moisture resistance.

Yesterday's solution: Do national economic and technological development zones promote industrial development in typical developing regions of China?

With the proliferation of special economic zones (SEZs) among emerging economies, their mixed performance has sparked discussions on contextual heterogeneity and underlying driving mechanisms. Characterized by an outward-oriented economy and industry-city interaction, the cross-stage establishment practice of China's national economic and technological development zones (ETDZs) is conducive to expanding existing research focused on cross-country analyses of SEZs. This study constructs difference-in-differences models to analyze the influence of national ETDZs on regional industrial development in the Yellow River basin, a typical developing region in China, from 2003 to 2019, evaluating their performance under a regional balanced development strategy and a within a lagging economic backdrop. The results indicate that (1) national ETDZs do not contribute to industrial growth and even exert a negative effect; (2) while they fail to perform better over time, their spatial spillover effect slightly benefits neighboring cities; (3) an optimal economic environment and proactive policy promotion can respectively mitigate and exacerbate their negative effects; (4) the inability to attract external enterprises and achieve industrial restructuring is the primary cause of the negative effect, highlighting a mismatch and discord between the economic and policy attributes of national ETDZs and evolving contexts. Based on these findings, recommendations are proposed to cultivate SEZs as suitable policy platforms and effective economic spaces.

Investigation of the dynamic and thermal performance of kinetic-static mixers: a numerical simulation study

In this paper, a numerical simulation was carried out to investigate the dynamic and thermal behaviors of various shapes of a kinetic static mixer. Three-dimensional model of the static mixer was designed using commercial Computational Fluid Dynamics (CFD) software, CFX 18.2. To examine the mixer's performance, five parameters have been considered including Re, Shear stress rate, Nu, fluid temperature and pressure drop. The fluid velocity was characterized by Reynolds numbers varying from 10 to 100, pressure drop, and shear rate has been considered for evaluating dynamic performance. Furthermore, fluid temperature and the Nusselt number was examinate to gain insights into thermal characteristics. In this study, the effectiveness of four different mixer shapes was evaluated. The outcomes underlined the significant impact changes in mixing geometry can have on the fluid's dynamic behavior, which in turn affects thermal performance. Notably, among the suggested mixer shapes, case three shows best mixing performance. This study offers significant knowledge about the dynamic and thermal behavior of kinetic static mixers, emphasizing the critical function of shape in raising overall performance.

Design and Microwave Absorption Performance Study of SiC-Fe3O4 Emulsified Asphalt Mixture.

To address the challenges of slow curing speed and suboptimal microwave absorption during the paving of cold-mixed and cold-laid asphalt mixtures, this study introduces SiC-Fe3O4 composite material (SF) into emulsified asphalt mixtures to enhance microwave absorption and accelerate curing via microwave heating. Initially, based on the maximum density curve theory, an appropriate mineral aggregate gradation was designed, and the optimal ratio of emulsified asphalt mixture was determined through mixing tests, cohesion tests, wet wheel wear tests, and load wheel sand adhesion tests. Subsequently, the influence of SF content on the mixing performance of emulsified asphalt mixtures was analyzed through mixing and consistency tests. Finally, the microwave absorption performance of the mixture was evaluated by designing microwave heating tests under different conditions, using temperature indicators and quality indicators. The experimental results indicate that when SF content ranges from 0% to 4%, the mixing performance of the emulsified asphalt mixture meets specification requirements. The dosage of SF, SF composite ratio, and microwave power significantly impact microwave absorption performance, whereas environmental temperature has a relatively minor effect. The optimal mix ratio for the emulsified asphalt mixture is mineral aggregate:modified emulsified asphalt:water:cement = 100:12.8:6:1. The ideal SF dosage is 4%, with an optimal SiC to Fe3O4 composite ratio of 1:1, and a suitable microwave power range of 600-1000 W.