Search

Due to its rich nutritional composition, biogas slurry can serve as a special liquid fertilizer. However, the application of slurry in agricultural fields currently faces challenges such as reliance on skilled famers' experience, low precision, and difficulty in accurately controlling the irrigation dosage. To address these issues, an agricultural biogas slurry mixing agricultural machinery and its system has been designed and developed with the aim of enhancing the precision and safety of slurry application. The structure of the device has been designed, filter components have been selected, and improvements have been made to the structure of traditional connectors. Taking into account factors such as soil and humidity, an algorithm based on biogas slurry conductivity for slurry mixing decisions and the feedback control mechanism has been designed. After assembling the prototype, experiments were conducted, and the results showed that after processing by the system, compared to the calculated theoretical optimum, the concentration error of each component in the mixed fertilizer was controlled within 10%, and the conductivity fluctuation range was within 5%. This indicates that the overall ratio accuracy and stability of the biogas slurry mixing system are high. The biogas slurry mixing agricultural machinery and its system provide a novel intelligent equipment solution for the precise application of slurry, effectively enhancing the accuracy and safety of slurry application, reducing the use of chemical fertilizers during agricultural irrigation, and minimizing pollution to the environment and soil. [ABSTRACT FROM AUTHOR]

In order to solve the problem of poor mixing effect of inclined spiral conveyor, this paper designed an inclined spiral and ribbon blade combination conveying device. The mechanics and kinematics analysis of the movement process of the material unit in each mechanism was carried out, on which key devices and components were designed based. Effects of the speed of main shaft (X1), the full coefficient (X2) and the angle of inclination (X3) on the mixing uniformity (Y1) and the residual rate of material (Y2) were explored. Three-dimensional quadratic regression orthogonal rotation central combination experiment method combined with response surface method was used to conduct experiments and explore the interaction effects of influence factors on indicators. A regression model of influence factors and evaluation indicators was established through the analysis of variance. The significant factors affecting Y1 were ordered of X3, X2, X1, and the significant factors affecting Y2 were ordered of X2, X1, and X3. In the interaction of factors, X1X2 had a significant impact on Y1 and Y2; X1X3 had an extremely significant impact on Y1; X2X3 had an extremely significant effect on Y1 and a significant impact on Y2. The optimal structure and working parameters combination were determined to be 50 rpm for the speed of main shaft, 60% for the full coefficient, and 19° for the angle of inclination, while the verification experiments demonstrated that the mixing uniformity and residual rate of material corresponding to the verification test were 90.37% and 5.31%, respectively. The inclined device with combined spiral and ribbon blade developed in this study meets the design requirements for the misprocess of the fertilizer utilization of agricultural organic wastes. [ABSTRACT FROM AUTHOR]

This article analyzes the turbulence dissipation rate in liquid steel in selected metallurgical equipment (i.e., electric arc furnace, ladle furnace, and tundish) based on advanced computational fluid dynamics simulations. The approach enables evaluation of the efficiency of electromagnetic stirrer (EMS) devices based on the molten steel flow behavior in comparison with the standard mixing process. Particular attention is put on the determination of the effectiveness of novel EMS with the horizontal stirring device, which supports the mixing process of molten steel. For that, the concept of the new formula to evaluate the stirring energy is presented and compared with the literature results to prove the correctness of the developed method. [ABSTRACT FROM AUTHOR]

Tundish is a crucial component just before casting and plays a pivotal role in enhancing the cleanliness and overall homogeneity of the final steel composition. The paper deals with the development of an advanced Computational Fluid Dynamics (CFD) model, specifically focusing on the molten steel flow within the tundish to numerically support its further improvements. A noteworthy addition to the model is the consideration of an electromagnetic stirring device. This device significantly influences steel cleanliness and composition, thereby affecting the final properties of the formed metallic parts in subsequent processing stages. The current investigation presents a comprehensive analysis of flow patterns and stirring energy distributions in relation to active and dead zones within the tundish. Through the developed coupled electromagnetic/fluid dynamic model, the paper demonstrates the feasibility of optimizing mixing processes to control the properties of the final product. [ABSTRACT FROM AUTHOR]

In January 2022 final electromagnetic stirrers were installed to improve billets' macrostructure and to reduce defects in ŠTORE STEEL, Slovenia. From January to September 2022 the material from 1121 batches, out of 2284 batches produced, was examined using ultrasonic testing. Among these 1121 batches, 270 batches were detected with defects larger than 2.5 mm. Based on various metallurgical reports made from samples taken after an ultrasonic inspection, the root causes were found to be shrinkage porosity and segregations. Based on the gathered parameters from this period (chemical composition, casting parameters, cooling or heating parameters of billets), the occurrence of inner defects was predicted using logistic regression and genetic programming. The genetic programming proved to be better than logistic regression. Based on modeling results, optimization of the final electromagnetic stirrers position for 51CrV4 spring steel was conducted. Consequently, out of 41 examined batches, only 2 were detected with defects larger than 2.5 mm. [ABSTRACT FROM AUTHOR]

Mold electromagnetic stirring technology for optimizing the flow of molten steel is now widely used in the continuous casting production process of high-quality steels. However, studies on the case that the center of the electromagnetic stirrer is located outside the mold have not been reported. Herein, the effect of the electromagnetic stirrer centered outside the mold on the steel flow field was studied in detail by means of numerical simulations. A Gauss meter was used to measure the magnetic induction intensity at different positions, currents, and frequencies. The test results were compared with the simulation results of electromagnetic stirring to calibrate and verify the accuracy of the electromagnetic model. Then, electromagnetic force was introduced into the flow field model as a source term to study its effect on the flow field under anomalous conditions. The results show that when the center of the electromagnetic stirrer is located outside the mold, the magnetic field strength is about twice as strong as that located inside the mold. This also leads to an increase in the flow velocity near the electromagnetic stirrer. As a result, the optimal electromagnetic stirring parameters (200 A, 2.5 Hz) were specified when the center of the electromagnetic stirrer is located outside the mold. [ABSTRACT FROM AUTHOR]

This work is concerned with the improvement of silicon photovoltaic solar cells using elec- tromagnetic stirring in prior processing by controlling the hydrodynamics of the silicon bath during ingot solidification. The vertical Bridgman directional solidification furnace called VB2 was numerically investigated using a controlled power-down technique under forced convection generated by a travelling magnetic field, i.e. a full 3D numerical model of the VB2 furnace has been developed using the Comsol MultiphysicsTM software. Enthalpy formulation based on fixed-grid techniques is used for the phase-change phenomena considering magnetohydro- dynamic forced convection created by a Lorentz force generated by a specific cylindrical Bitter coil. The model provides the temperature distribution in the entire furnace as well as specific details regarding the solidification process (i.e. solidification fraction and solid-liquid interface shape), flow patterns and melt velocities. The obtained numerical results show good consist- ency with experimental measurements and analysis, on the one hand, and can be considered as useful orientation to improve the solidification process, on the other hand. It is shown that the travelling magnetic field acting in the melt drives a moderately turbulent flow which has a significant impact on the solid-liquid interface in terms of morphology and symmetry during silicon solidification and, consequently, on the tight control of the crystallization process that can affect the silicon crystal morphology and impurity distributions. [ABSTRACT FROM AUTHOR]

The following research presents a numerical evaluation of existing and conceptual urea-mixing devices used in close-coupled (to the engine) selective catalytic reduction (SCR) systems. The analysis was aimed at the assessment of urea-mixing devices that could considerably enhance the reduction of nitrogen oxides from the diesel-engine combustion process under a wide range of operating conditions, including cold starts. The analysis showed that replacing blade-equipped static mixers with perforated stationary mixing devices may provide a more uniform spatial distribution of ammonia at the inlet to the SCR catalyst and reduce pressure drops generated by mixing devices. Moreover, the conceptual mixing devices, based on combinations of the blade and perforated mixers to develop intensive turbulence, enabled the increase of the mixing length leading to effective decomposition of the urea-water solution (UWS), and provided uniform spatial distribution of ammonia, even for the small-sized mixing systems. However, the intensive mixing was often associated with a significant rise in the pressure drop. [ABSTRACT FROM AUTHOR]

Dust stop seals are widely used in powder and rubber mixing industries. Design of the sealing system requires a continuous supply of pressurised lubricant, which is not recycled because of the risk of contamination. There is also the potential of large volume leakage of oil due to poor sealing, increasing operational costs and necessitating remedial measures to avoid environmental protection. Furthermore, the seal faces are prone to failure in relatively short periods of time due to reduced gap and lubricant leakage. The paper presents an analytical method and numerical predictions based on Reynolds equation under combined hydrodynamic and hydrostatic conditions with the entrant lubricant through hydraulically loaded feedholes. The validity of these methods is ascertained through comparison with a more complex but time‐consuming solution of Navier–Stokes equations. The numerical predictions allow for determining the prevailing tribological contact conditions and assessing its suitability for evaluating the sealing performance of mixing machinery. [ABSTRACT FROM AUTHOR]

In order to prevent the formation or suppress the development of defects in strand-cast steel, such as center porosity, pipe segregation, and the developed dendritic structure of an ingot, and to obtain blanks and rolled metal having high-quality macrostructure, it is necessary to control the crystallization process of the continuously cast ingot. For this purpose, various external physical actions are used in the section of billet crystallization [2]. Among the most efficient and technological methods is the forced, controlled motion of a liquid phase in the crystallizing ingot, in particular, by means of electromagnetic stirring. In the article, the magnetohydrodynamic processes occurring during electromagnetic stirring of steel melt were investigated using mathematical modeling and experimental methods at laboratory installations and industrial facilities. On the basis of the research results, a comprehensive method for the design and testing of electromagnetic stirring systems for billet and bloom casters was developed. [ABSTRACT FROM AUTHOR]

Biodiesel is produced by transesterification reaction; animal or vegetable fatty acid reacts with the alcohol. Agitation of fluid in biodiesel production is required to develop the transesterification reaction in a biodiesel reactor. Agitation intends to decrease activation energy and increase the probability of collision between the materials. The objective of this research was to investigate fluid flow in a reactor with four kinds of agitators by using Computational Fluid Dynamics ANSYS FLUENT simulation and determine the optimum type of agitator in biodiesel production. The criteria of the agitation process which were studied include fraction and temperature distribution, turbulence, and fluid vorticity. The study used the helical screw, turbine, propeller, and anchor agitation types in transient and steady-state simulations. The material consisted of cooking oil and methanol with a mole ratio of 1:6 and used a rotational speed of 500 rpm with 60-65°C mixing temperature. The analytical hierarchy process method was used to decide the optimum agitator type. The result showed that the analytical hierarchy process score of each type of agitator was 0.314, 0.350, 0.249, and 0.087 for anchor, helical screw, propeller, and turbine agitator, respectively. Based on the analysis, the optimum agitator agreed on the helical screw type. [ABSTRACT FROM AUTHOR]

Due to the complex working medium of oil in construction engineering, the waterproof valve in mixing machinery can easily cause different degrees of failure. Moreover, under adverse working conditions and complicated noise backgrounds, it is very difficult to detect the fault of waterproof valves. Thus, a fault diagnosis method is proposed, especially for the fault detection of waterproof valves as a key component in the construction of mixing machinery. This fault diagnosis method is based on a new adaptive feature extraction model, with multi-path signals to the improved deep residual shrinkage network–stacked denoising convolutional autoencoder (named DRSN–SDCAE). Firstly, the noisy vibration signals collected by the two vibration sensors are preprocessed, and then transmitted to the parallel structure improved DRSN–SDCAE for adaptive denoising and feature extraction. Finally, these results are fused through the feature fusion strategy to realize the effective fault diagnosis of the waterproof valve. The effectiveness of this method was verified through theory and experiments. The experimental results show that the proposed fault diagnosis method based on the improved DRSN–SDCAE model can automatically and effectively extract fault features from noise for fault diagnosis without relying on signal processing technology and diagnosis experiences. When compared with other intelligent fault diagnosis methods, the features extracted from multi-path inputs were more comprehensive than those extracted from single-path inputs, and contained more complete features of hidden data, which significantly improved fault diagnosis accuracy based on these fault features. The contribution of this paper is to learn fault features autonomously in signals with strong and complex noise through a deep network structure, which extends the fault diagnosis method to the field of construction machinery to improve the safe operation and maintainability of engineering machinery. [ABSTRACT FROM AUTHOR]

Copyright of Studia Histórica: Historia Moderna is the property of Ediciones Universidad de Salamanca and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article describes a numerical model of solidification of the SnPb alloy with electromagnetic stirring. The model is based on two open access computational codes. Comparison of the results of the calculation of directional horizontal solidification with natural and electromagnetically forced convection forces is presented. It is shown that the electromagnetic driven flow can affect the final segregation map only at the first stage of the solidification process. [ABSTRACT FROM AUTHOR]

Adequate water-removal techniques are requisite to remain superior biofuel quality. The effects of vibrating types and operating time on the water-removal efficiency of molecular sieves were experimentally studied. Molecular sieves of 3 Å pore size own excellent hydrophilic characteristics and hardly absorb molecules other than water. Molecular sieves of 3 Å accompanied by two different vibrating types, rotary shaking and electromagnetic stirring, were used to remove initial water from the reactant mixture of feedstock oil in order to prevent excessive growth or breeding of microorganisms in the biofuel product. The physical structure of about 66% molecular sieves was significantly damaged due to shattered collision between the magnetic bar and molecular sieves during electromagnetic stirring for 1 h. The molecular sieves vibrated by the rotary shaker appeared to have relatively higher water-removal efficiency than those by the electromagnetic stirrer and by keeping the reactant mixture motionless by 6 and 5 wt.%, respectively. The structure of the molecular sieves vibrated by an electromagnetic stirrer and thereafter being dehydrated appeared much more irregular and damaged, and the weight loss accounted for as high as 19 wt.%. In contrast, the structure of the molecular sieves vibrated by a rotary shaker almost remained original ball-shaped, and the weight loss was much less after regenerative treatment for those molecular sieves. As a consequence, the water-removal process using molecular sieves vibrated by the rotary shaker is considered a competitive method during the biofuel production reaction to achieve a superior quality of biofuels. [ABSTRACT FROM AUTHOR]

During casting of steel, especially alloyed and high-carbon steel, in billet and bloom CCMs, segregation, shrinkage, and crystallization macrostructural defects may appear, and they cannot be completely eliminated even with rational design and process parameters. Various methods of physical action on crystallizing continuously cast ingots can be used to improve the quality of billets and rolled products. One of the most technologically advanced methods is electromagnetic stirring (EMS) of the liquid phase of crystallizing billets. The industrial CCMs currently operating in Russia and designed for the production of high-quality billets are mainly equipped with foreign-made EMS systems. Having a number of advantages, such as efficiency and commonality, such stirrers also have some disadvantages, including undismountable housing (cannot be repaired locally) and the need for several cooling circuits and boiler-type demineralized cooling water. Currently, the VNIIMETMASH Holding Company (Moscow) is the main developer and supplier of electromagnetic stirring systems for CCMs in Russia. Implementing an import-substitution program, the VNIIMETMASH has developed and put into operation mold EMSs (M-EMS), strand EMSs (S-EMS), and final EMSs (F-EMS) in billet and bloom CCMs, including horizontal ones. The stator poles are cooled with mold water in M-EMSs and with water for the process equipment in S-EMSs and F-EMSs. The coils are wo++und with a submersible double-insulated wire. A methodology for creating and testing EMS systems for billet and bloom CCMs has been developed based on theoretical and experimental studies, physical modeling, and industrial tests of electromagnetic stirrers designed by the VNIIMETMASH. [ABSTRACT FROM AUTHOR]

In this study, a new field-programmable gate array (FPGA)-based electromagnetic stirrer system was developed allowing mixing on a single axis, and the energy efficiency of the system was increased with fuzzy logic control. The electromagnetic stirrer system was designed with three phases and each phase is fed with pulsewidth modulation (PWM) voltage with 120° phase difference. Ranked control of phases in the system used the FPGA structure in the myRIO® embedded system to determine the PWM signal production, increase intervals for phase frequencies, and rotation rate of the magnetic stir bar. In the system, to increase the energy efficiency with fuzzy logic control, the ARM® microcontroller structure in the myRIO® embedded system was used. Programming of the myRIO® embedded system was provided through the graphic-based LabVIEW® software. In situations where the system is operated with 100% duty cycle, the force affecting the magnetic stir bar should be continuous and have fixed value until the next phase change. As a result, the magnetic stir bar performs more than 120° rotation and a braking effect of the force is observed. To resolve this situation, fuzzy logic control ensured operation of a different duty cycle without loss of speed of the stir bar. Thus, the energy efficiency of the system was increased with lower current and lower stimulation duration. Within the scope of this article, the experimental results obtained about the structure, control, and energy efficiency of the electromagnetic stirrer system are discussed in detail. [ABSTRACT FROM AUTHOR]

Twin screw granulation (TSG) has been applied to wet granulation, although its application in melt granulation has been more limited. This work explores potential advantages of hot melt granulation using twin screw extrusion. Four main operating and formulation parameters were investigated: screw speed, number of mixing elements, temperature, and binder percentage. Combinations of these factors were then studied to determine their impact on the quantity and characteristics of granules within the desired size range of 125 -- 1000 µm. A screening design of experiments (DOE) study was used with each factor set at three levels, to investigate individual factor effects and interactions. Two types of mixing elements were studied: kneading block (KB) and chaotic elements. The type and number of mixing elements were found to be paramount in contributing to the quantity and characteristics of granules formed. Results obtained agreed with previous findings in literature on the influence of different screw elements on the characteristics of granules formed by twin screw granulation. Additionally, the study revealed the unique impact which different mixer elements have on both granule production and characteristics. Depending on the specific need or use of granules in required applications, the granulation process can be effectively designed to meet the end product quality and outcome. [ABSTRACT FROM AUTHOR]

To alleviate macrosegregation, it is the first time that an electromagnetic nozzle swirling flow is applied with a mold electromagnetic stirrer (M-EMS) during continuous casting of square and round billets. Compared with those by only M-EMS, the carbon ranges in square and round billets can be reduced to 0.022 and 0.046 pct, respectively, and the equiaxed crystal ratios are 18 and 33 pct, respectively, by using opposite nozzle swirling flow. [ABSTRACT FROM AUTHOR]

Concentration process of cucumber juice is an essential step in cucumber extracts and juice production in the industry in order to minimise the volume and weight for storage and handling purposes. Progressive freeze concentration (PFC) is a non-thermal concentration process that can be used in which water content in the juice will be frozen out in the form of an ice block layer by layer. The ice crystallisation process forms ice crystal lattice that rejects all impurities and in turn will leave behind highly concentrated cucumber juice. This research aimed to optimise the operating parameters involved in concentration of cucumber juice via PFC. The operating parameters involved were operation time, initial concentration, coolant temperature and speed of stirrer. Optimization of the PFC process was carried out with the effective partition constant, K as the indicator of the performance by using Response Surface Methodology (RSM) in STATISTICA software. Highest total phenolic content (TPC) increment achieved was 38.83 % with operating condition at -12 °C of coolant temperature, 413 rpm of stirrer speed, 37.8 min of operation time, and 11 mg/mL of initial concentration and lowest effective partition constant, K value obtained was 0.261 with operating condition at - 13.8 °C of coolant temperature, 435 rpm of stirrer speed, 30 min of operation time, and 10.5 mg/mL of initial concentration. The results were supported with good value of R-squared obtained which was 0.85899 for Kvalue and 0.79365 for TPC increment. The linear effect of operation time was found to be the most significant factor to the response in this study. This work has clearly shown that PFC has potential to be used in concentration of cucumber juice as a non-thermal operation. [ABSTRACT FROM AUTHOR]

The usage of electromagnetic actuators in the continuous steel‐casting process is on a steady rise, due to its possibilities for a sophisticated, contactless flow control. The complexity of the casting process and the ever‐increasing quality demands require a well‐founded knowledge of the interaction between the electromagnetic actuators and the liquid steel flow. Numeric modeling provides a detailed view and is therefore crucial for understanding the interaction between the electromagnetic fields and the liquid steel flow. Only a deep insight into the coupling between the liquid steel flow and the electromagnetic forces makes it possible to improve/optimize the continuous casting process. The work presented here is part of an ongoing research to bridge the gap between the liquid steel flow and the grain structure of the end product. The article's focus lies on the liquid steel flow modified by a traveling magnetic field—relying mainly on numerical simulations. Different modeling approaches are used to simulate linear electromagnetic stirring in the secondary cooling zone of a slab caster. An appropriate model is chosen to investigate the influence of various stirring parameters, stirring modes, and stirring positions. From the results, conclusions for the real casting process can be drawn. [ABSTRACT FROM AUTHOR]

The multiphase flow, initial solidification and solute diffusion and their interactions in a mold region of 380 × 280 mm2 casting bloom under different installation positions of in-mold electromagnetic stirring (M-EMS) were analyzed and compared by a multi-physical model. The results showed that the simulated electromagnetic field and solute carbon distribution in initial solidified shell are basically consistent with measurements. As the distance from EMS center to the meniscus increases (from 0.32 to 0.62 m), the level fluctuation decrease from 7.2 to 4.5 mm, while the volume of turbulent zone clearly expands. Additionally, the solidified shell thickness at the mold outlets increase from 12.90 to 16.32 mm and from 26.41 to 28.97 mm at outlets of computational domain as EMS center moves down, while the surface temperature decreases. The maximum negative segregation deteriorates from 0.95 to 0.83 at the bloom corner while increasing from 0.84 to 0.92 in the thickness direction, and the difference between the minimum and maximum carbon concentrations at center of computational outlets is only about 0.0029 pct. The EMS should be installed around 0.42 m below the meniscus, by which the disqualified rate of non-metallic inclusions and the level fluctuations are within a low level. [ABSTRACT FROM AUTHOR]

The additional element from the filler wire in the laser beam welding is usually distributed inhomogeneously in the final weld due to the high solidification rate of weld pool. It has been found that the electromagnetic stirring produced by an external oscillating magnetic field can enhance the material mixing in the weld pool to achieve a more uniform element distribution. However, the magnetic field has a highly nonlinear and multicoupled interaction with the weld pool behavior, which makes the quantitative explanation of the physical mechanism difficult. In this study, the effect of electromagnetic stirring on the transport phenomena in the wire feed laser beam welding is investigated by a numerical modeling. A 3D transient multiphysical model considering the magnetohydrodynamics, heat transfer, fluid flow, keyhole dynamics, and element transport is developed. The multiple reflections and the Fresnel absorption of the laser on the keyhole wall are calculated using the ray tracing method. The numerical results show that a Lorentz force produced by the oscillating magnetic field and its induced eddy current gives significant influence on the transport phenomena in the molten pool. The forward and downward flow is enhanced by the electromagnetic stirring, which homogenizes the distribution of the additional elements from a nickel-based filler wire in a steel weld pool. The numerical results show a good agreement with the high-speed images of the molten pool, the fusion line from the optical micrograph, and the element distribution from the energy dispersive x-ray spectroscopy. This work provides a physical base for the electromagnetic-controlled laser beam welding and some guidance for the selection of electromagnetic parameters. [ABSTRACT FROM AUTHOR]

The present paper outlines the main differences observed in the microstructure and hot workability of AA6082 alloys prepared via low-frequency electromagnetic casting (LFEC) and direct-chill casting, i.e. with and without the application of an electromagnetic stirrer to an innovative casting mould. The hot workability was evaluated through hot-compression tests in the temperature range 450-550 °C and at three different strain rates (0.001, 0.1, and 1 s−1). Metallographic analysis revealed a grain-size refinement due to the electromagnetic stirring, accompanied by a change in the extent and type of intermetallic compounds between the dendritic arms. A globular microstructure was observed only in the central part of the LFEC billet, where β intermetallic precipitates were observed. The shape of the true-stress versus true-strain curves indicated the occurrence of a dynamic recovery phenomenon. Although the values of the maximum stress were similar for all the samples, analysis of the hot-compression behaviour through a constitutive model revealed differences in the hot-deformation activation energy QHW, with the lowest value belonging to the sample cut from the centre of the LFEC billet, where the effect of stirring was most pronounced. [ABSTRACT FROM AUTHOR]

Rare earth extraction reactor with single-layer straight-blade stirrer and inclined-blade stirrer were self-designed. The fluid transport performance in the rare earth extraction reactor with straight-blade stirrer and inclined-blade stirrer were contrastively studied by numerical simulation method. The results show that the rare earth extraction reactor with inclined-blade stirrer has the optimized comprehensive performance. [ABSTRACT FROM AUTHOR]

A new micromixer design based on uniform circular obstacles and cross flow (UCCFM) of the fluid streams was proposed. Water-ethanol and oil-ethanol mixing was assessed for Reynolds numbers ranging from 0.1 to 100 by CFD simulations. The performance index was evaluated providing the ratio of fluid mixing degree (MI) to the unit of pressure drop along the micromixer. For both systems, the highest performance indexes were noticed at Re = 0.01, a flow regime characterized by molecular diffusion controlling the mass transfer. The UCCFM design with diameter = 600 µm allowed good fluid mixing for water-ethanol at Re = 0.01 (MI = 0.815) with a very low pressure drop of 0.123 Pa. For oil-ethanol mixing, the MI = 0.693 was obtained with a pressure drop of 76.06 Pa. The UCCFM presented a superior MI in low Reynolds number regarding other micromixer designs in literature. [ABSTRACT FROM AUTHOR]

This study focuses on an experimental investigation of the fluid flow in round bloom continuous casting using a 1:3 model of the industrial casting process. A swirling flow nozzle, represented by the specific design of the RHI Magnesita GYRONOZZLE, is used to produce a swirling motion in the cylindrical mold. The test section is integrated into the Mini-LIMMCAST facility at HZDR, which is operated at room temperature using the ternary alloy GaInSn. Systematic measurements of horizontal and vertical velocity profiles are performed by means of the Ultrasound Doppler Velocimetry. The second part of the study focuses on the interaction between the flow driven by the GYRONOZZLE and concurrent electromagnetic stirring in the mold (M-EMS) by applying rotating magnetic fields (RMFs) at different magnetic flux densities. The effect of the GYRONOZZLE on the flow pattern inside the mold is examined with and without superimposed RMFs and compared to those of a standard single-port nozzle. The measurements reveal that the GYRONOZZLE induces a swirling flow in the whole mold. It is further shown that the influence of a simultaneously applied RMF is mainly restricted to the lower part of the mold since the transport of angular momentum to the top is suppressed by the jets pouring out from the GYRONOZZLE. [ABSTRACT FROM AUTHOR]

A shear thinning fluid (1% carboxymethyl cellulose) was used to investigate mixing under laminar flow conditions in an unbaffled vessel. The effects of impeller modification in addition to eccentricity were studied. Quantitative measurements such as percentage of uncovered area and coefficient of variance (CoV) of a tracer solution distributed inside the vessel were obtained using planar laser-induced fluorescence (PLIF) method. Increased eccentricity was found to be more effective than increasing rpm alone in reducing isolated mixing regions size (determined by the percentage of uncovered area). The dual-flow pitched blade turbine (DF-PBT), which was the modified version of a standard pitched blade turbine (PBT), was designed to provide both upward and downward flow at the same time to induce more chaotic flow. Though numerical analysis showed this type of flow generated, DF-PBT did not return lower values for the percentage of uncovered area and CoV than PBT did. Power consumption data were also compared between the two impeller types and eccentric locations. Further analyses focusing on the interactions between the impeller blades and fluid rheology is needed to improve laminar mixing in stirred vessels by impeller modification. [ABSTRACT FROM AUTHOR]

Four‐blade static mixer was designed for inline mixing of Newtonian fluids at Reynolds numbers from 700 to 6800. The mixer consists of four equally spaced blades mounted on cylindrical housing with 45° rotation relative to the circumference. It was tested in three different compartments of 6, 8, and 10 mixing elements; each element rotated 45° relative to the adjacent one. Multipoint sampling was used to measure concentration downstream the mixer. The mixing quality was measured by the coefficient of variance (CoV). The CoV decreases as the energy input per unit mass increases. This effect is more pronounced when the number of mixing elements increases. For the case of 10 mixing elements, a good mixing performance (typically more than 95% mixedness or CoV < 0.05) achieved, although a marginally good mixing performance could also be achieved by eight mixing elements. The friction factors were correlated as f = C1/Re + C2/Ren with an average deviation of ±10% from experimental data. Furthermore, experimental friction factors were compared with existing models. For a wide range of Reynolds numbers, the friction factors are apparently smaller than those from SMV, KMX, and baffle‐type static mixers. © 2018 American Institute of Chemical Engineers AIChE J, 65: 1126–1133, 2019 [ABSTRACT FROM AUTHOR]

Liquid‐liquid two‐phase flow in a mixer of mixer‐settler has been studied via a computational fluid dynamics (CFD) simulation combined with the population balance model (PBM) and verified with particle image velocimetry (PIV) experiments. The simulation was performed using the multiple reference frame (MRF) approach, the Eulerian‐Eulerian two‐fluid model, and the standard k‐ϵ model. The effects of impeller speed, flow ratio, and impeller type on flow field, droplet diameter, and dispersed phase holdup were investigated. The results showed that CFD simulation combined with PBM could predict droplet size distribution (DSD). The smaller droplets were mainly in the bottom region of the mixer, larger ones were in the top part of the mixer, and the largest droplets appeared in the impeller centre region. The DSD and holdup were more sensitive to impeller speed than to the organic/aqueous flow ratio. A dual‐impeller mixer configuration was designed to enhance the mixing performance. Compared with single‐impeller, the installation of dual‐impellers could effectively avoid the dispersed phase dead zone above the lower impeller. When hc /T = 0.3, the best dispersing effect, such as uniform DSD and high mixing chamber space utilization, could be obtained. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate the ability to 3D print tightly integrated structures with active valves, pumps, and mixers, and we use our compact chip-to-chip interconnects [Gong et al., Lab Chip 18, 639–647 (2018)] to move bulky world-to-chip connections to separate interface chips for both post-print flushing and post-cure device operation. As example devices, we first examine 3D printed pumps, followed by two types of selectable ratio mixer pumps, a linear dilution mixer pump (LDMP) and a parallelized dilution mixer pump (PDMP), which occupy volumes of only 1.5 mm 3 and 2.6 mm 3 , respectively. The LDMP generates a selectable dilution ratio from a linear set of possibilities, while the PDMP generates a denser set of possible dilutions with a maximum dilution ratio of 1/16. The PDMP also incorporates a new 4-to-1 valve to simultaneously control 4 inlet channels. To characterize LDMP and PDMP operation and performance, we present a new, low-cost video method to directly measure the relative concentration of an absorptive dye on a pixel-by-pixel basis for each video frame. Using this method, we find that 6 periods of the active mixer that forms the core of the LDMP and PDMP are sufficient to fully mix the fluid, and that the generated concentrations track the designed dilution ratios as expected. The LDMP mixes 20 nl per 4.6 s mixer pump period, while the PDMP uses parallelized input pumps to process the same fluid volume with greater choice of dilution ratios in a 3.6 s period. [ABSTRACT FROM AUTHOR]

reviews are presented for several products, including the widepore phase for (U)HPLC by American manufacturer, YMC, the automated system to clean up samples in PCB designed by LCTech, and the Mixture Maker, a benchtop blending station and dedicated software developed by Gerstel.

In this study, the consumer of the glass coffee stir bar design was used as the research object, and DEMATEL (Decision-Making Trial and Evaluation Laboratory) was used to explore the causality and importance of the evaluation factors for the purchase decision. The study found that the three most important key assessment factors before the purchase decision of glass coffee stir bars were 'beautiful', 'operability', and 'durability'; 'beauty' was the main influencing factor; 'operability' - this is the main factor affected. In addition, glass coffee stir bars are the three most important key assessment factors before the general consumer purchase decision. Therefore, it is recommended to use this method to verify the case study of glass coffee stirrer bar designs, and to study the possible development directions for evaluation. This model process can not only quantitatively evaluate the simple factors of complex interaction factors, but the results can also be used as a design to determine the direction of future development. [ABSTRACT FROM AUTHOR]

This paper presents a 75-90 GHz down-conversion mixer applied in automotive radar, which is characterized with high linearity, low local oscillator (LO) drive as well as high conversion gain (CG) using TSMC 65-nm CMOS general-purpose technology. The good linearity and isolation of mixer are required for automotive radar to cover short-middle-far range detection. The mixer includes an enhanced double-balanced Gilbert-cell core with series peaking transmission line and source degeneration technique for improving linearity and CG, two on-chip baluns and intermediate frequency (IF) buffer for IF test. Besides, to make the design more accurate and efficient, the modeling and design of millimeter-wave (mm-wave) passive devices are introduced. The mixer consumes 12 mW under 1.5 V. The input 1 dB compression point (P1dB) is 2.5 dBm as well as IIP3 of 13.2 dBm at 80 GHz. High performances are achieved with the CG of 5 dB at 76 GHz with LO power of 0 dBm for frequencies of 75-90 GHz which covers the application of automotive radar frequency band (76-81 GHz) and LO-RF isolation of 33-37 dB for frequencies of 60-90 GHz. The area of the mixer is 0.14 mm2, with PADs included. [ABSTRACT FROM AUTHOR]

A geared linkage driving mechanism of the drive of a non-stationary mixer the mechanical diagram of which is designed at the level of the smallest dimensions is developed. With such a design of the drive it becomes possible to improve the quality of manufactured products and accelerate the mixing process through continuous intra-cycle variation of the amplitude and angular spin rate of the working bodies. [ABSTRACT FROM AUTHOR]

The subsurface negative segregation behavior and its effect on componential homogeneity of as-cast bloom within a section size of 320 mm × 425 mm under different stirrer currents were investigated with the aid of numerical simulation. To this end, plant trials were conducted based on a curved bloom caster in Shaoguan steel. The results show that the minimum subsurface negative segregation degree is decreased from 0.977 to 0.858 and its corresponding location moves from 16 mm to 11.9 mm distance from strand surface as the stirrer current is increased from 100 A to 600 A. The carbon content fluctuation range of rolled product cross-section first reduces and then increases because of the integrated effects of two factors: melt temperature at the mold exit center decreases (that is, undercooling is increased), whereas the local segregation degree increases with the increase in the stirrer current. As compared to the normal M-EMS parameters (600 A/2.5 Hz), the fluctuation range of carbon content at the cross-section of rolled product is reduced from 0.038 to 0.012 wt.% under the optimized M-EMS parameters of 200 A/2.5 Hz. [ABSTRACT FROM AUTHOR]

ABSTRACT: The geometry of rotor cross section would affect the velocity profile of circumferential flow in continues mixer, which further dominated the mixing ability of rotor. To reveal the relationship between the geometry and mixing ability of rotor cross section, three rotor cross sections with different geometries were chosen, and the POLYFLOW simulations were applied to analyze the velocity profile and the flow stretching. The distribution for three rotors was evaluated both numerically and experimentally with the particle tracking technology. Then, the rotor geometry was quantified with pressurization coefficient S, which is a geometric parameter considering the wedge angle α, width of wing tip e, tip clearance h and the maximum clearance H0 between rotor and chamber wall. The results showed that the mixing ability and S for three rotor cross‐sections would vary with the rotor geometry changing, furthermore, the rotor cross‐section with larger S would have stronger mixing ability. Decreasing α or e, as well as increasing the H0, would induce the increase of S, and further resulting in the improvement of the mixing ability. Rotor geometry quantification with S would intuitionally reveal the relationship between rotor geometry and the mixing ability, and would contribute to the rotor cross‐section design and optimization. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46623. [ABSTRACT FROM AUTHOR]