Mixer Design Research Articles

CFD-aided contraction-expansion static mixer design for oil-in-water emulsification

Abstract Contraction-expansion (CE) static mixers can enable solid-liquid and liquid-liquid dispersion with low energy dissipation, low risk of obstruction, and without moving parts. In this work, the influence of CE elements of different geometries on the imposed turbulence of a flowing liquid has been assessed by a two-dimensional computational fluid dynamic (2D-CFD) simulation. The effect of CE on the dispersion of droplets of an immiscible liquid has also been analysed from simulations, using the volume of fluid (VOF) approach. Direct numerical simulation (DNS) performed by the open-source Gerris Flow Solver software was used to get the velocity fields and turbulence characteristics. Different ratios of CE diameters and lengths were analysed for liquid Reynolds numbers from 500 to 20,000. From simulations, the CE geometry that maximised the average root mean square velocity, as an indicator of turbulence, was determined for different liquid flow rates. It was found that the average RMS had a maximum for a wide range of liquid flow rates when the CE diameter ratio was between 0.55 and 0.59 and the length ratio was between 0.2 and 0.3. Then, a device with seven CE elements with geometrical features within this range was built and used for preparing an oil-in-water emulsion. The test system contained water and sunflower oil (5 % v/v) with the further addition of TritonX100 (0.5 % in volume of the solution) as surfactant. The stability of the emulsions was assessed by measuring the time evolution of turbidity (absorbance at 860 nm), to get the initial separation velocities. The emulsions prepared using the CE device showed initial phase separation rates lower than the one obtained in a stirred flask, evidencing the feasibility of using CE static mixers for preparing emulsions with relatively low energy consumption. Moreover, the emulsions obtained with the CE device, although dependent on the flow rate, showed similar features when obtained with 10, 100 and 250 passes through the CE static mixer.

Novel spacer geometries for membrane distillation mixing enhancement

Membrane distillation is an emerging promising desalination method that requires further improvement in order to become industrially viable. Due to the fact that evaporation is the primary process in membrane distillation, one strategy to boost membrane permeate flux is to optimize the energy supply to the water interface by increasing mixing in the hot channel via the use of optimized spacers. Contemporary spacer designs predominantly induce turbulence, resulting in elevated pumping energy requirements. This study introduces novel spacer geometries, inspired by industrial mixer designs, to surmount the limitations of conventional spacer configurations. The mixing efficiency, thermal performance, and pressure drop induced by the two novel geometries are studied and compared to those of commonly utilized spacer designs. It is confirmed, that the first of these novel geometries significantly enhances mixing, whereas the other causes a lower pressure drop and appears to be a viable solution when a spacer is a necessary structural component. In the course of the analysis, it is also shown that the coefficient of variation coupled with the Nusselt number at the membrane can be used to assess spacers' performance.

A universal inverse design methodology for microfluidic mixers.

The intelligent design of microfluidic mixers encompasses both the automation of predicting fluid performance and the structural design of mixers. This article delves into the technical trajectory of computer-aided design for micromixers, leveraging artificial intelligence algorithms. We propose an automated micromixer design methodology rooted in cost-effective artificial neural network (ANN) models paired with inverse design algorithms. Initially, we introduce two inverse design methods for micromixers: one that combines ANN with multi-objective genetic algorithms, and another that fuses ANN with particle swarm optimization algorithms. Subsequently, using two benchmark micromixers as case studies, we demonstrate the automatic derivation of micromixer structural parameters. Finally, we automatically design and optimize 50 sets of micromixer structures using the proposed algorithms. The design accuracy is further enhanced by analyzing the inverse design algorithm from a statistical standpoint.

Innovative thermodynamic modeling for enhanced yeast dough mixing: energy perspectives and applications

A thermodynamic model for the calculation of energy exchange in the chamber of a new mixer with effective use of structural and technological parameters of the mixing process without the necessary introduction of experimental data correlations in the distribution of fluid velocities is proposed, which determines the relevance of this direction of calculation with the perspective of its development. The purpose of the presented work is to determine the specific power by substantiating the effective mode parameters of the preparation of the mixture (dough) as a result of evaluating the thermodynamic energy parameters of the kneading process. The assessment was carried out by developing a methodology for determining specific costs for creating a viscous medium when mixing components, which allows you to establish the required power depending on the design and technological parameters of the new mixer. The considered principle of the proposed open-type thermodynamic system of the description of the working process of mixing made it possible to reveal and determine the ways of converting energy into useful work of interphase heat and mass transfer of a heterogeneous medium. In the conditions of circulation mixing with multiple mechanical effects on the mixture of components in the closed circuit of the cylindrical working chamber, which is an effective way to achieve homogeneity of the environment, it was possible to obtain an analytical determination of the specific work and power of the drive in the absence of a clear description of the model of the interconnection of components. The proposed thermodynamic description of the system's energy balance allows to perform only a few experiments. In general, the practical value of the given calculations is of practical importance for improving productivity and efficiency and minimizing energy consumption for the process while reducing the dynamic loads of the designed mixer.

Modified Broadband Ruthroff-Type Transmission Line Transformer Balun for Isolation-Enhanced Passive Mixer Design.

Generalized broadband operation facilitates multifunction or multiband highly integrated applications, such as modern transceiver systems, where ultra-wideband bidirectional passive mixers are favored to avoid a complex up/down-conversion scheme. In this paper, a modified Ruthroff-type transmission line transformer (TLT) balun is presented to enhance the isolation of the mixer from the local oscillator (LO) to the radio frequency (RF). Compared to the conventional methods, the proposed Ruthroff-type architecture adopts a combination of shunt capacitors and parallel coupled lines to improve the return loss at the LO port, thus effectively avoiding the area consumption for the diode-to-balun impedance transformation while simultaneously providing a suitable point for IF extraction. In addition, a parallel compensation technique consisting of an inductor and resistor is applied to the RF balun to significantly improve the amplitude/phase balance performance over a wide bandwidth. Benefiting from the aforementioned operations, an isolation-enhanced 8-30 GHz passive double-balanced mixer is designed as a proof-of-principle demonstration via 0.15-micrometer GaAs p-HEMT technology. It exhibits ultra-broadband performance with 7 dB average conversion loss and 50 dB LO-to-RF isolation under 15 dBm LO power. The monolithic microwave integrated circuit area is 0.96 × 1.68 mm2 including all pads.

An Efficient 3D-Printed Gravity Mixer for Lab-on-a-CD Applications.

We introduced a new, highly efficient, and uncomplicated mixing device for centrifugal microfluidic platforms, called the gravity mixer. The gravity mixer featured a slope channel that can precisely and sequentially control micro-volume liquids using centrifugal, capillary, and gravitational forces to achieve the desired mixing effect. By adjusting the angular velocity, micro-volumes of liquids in the slope channel of the gravity mixer could be precisely controlled across a wide range. We evaluated the change in mixing efficiency by varying the slope geometry, including the slope angle and the number of mixing cycles. Our study of gravity mixers with different slope angles revealed that the 80° angle gravity mixer achieved the best mixing efficiency, with a standard deviation of 2.39. Additionally, the mixing process in the gravity mixer is highly repeatable, achieving the desired mixing efficiency after only three cycles of operation. Our gravity mixer design and implementation can facilitate the development of more complex 3D-printed lab-on-chip devices.

MetaFormer Baselines for Vision.

MetaFormer, the abstracted architecture of Transformer, has been found to play a significant role in achieving competitive performance. In this paper, we further explore the capacity of MetaFormer, again, by migrating our focus away from the token mixer design: we introduce several baseline models under MetaFormer using the most basic or common mixers, and demonstrate their gratifying performance. We summarize our observations as follows: (1) MetaFormer ensures solid lower bound of performance. By merely adopting identity mapping as the token mixer, the MetaFormer model, termed IdentityFormer, achieves [Formula: see text]80% accuracy on ImageNet-1K. (2) MetaFormer works well with arbitrary token mixers. When specifying the token mixer as even a random matrix to mix tokens, the resulting model RandFormer yields an accuracy of [Formula: see text]81%, outperforming IdentityFormer. Rest assured of MetaFormer's results when new token mixers are adopted. (3) MetaFormer effortlessly offers state-of-the-art results. With just conventional token mixers dated back five years ago, the models instantiated from MetaFormer already beat state of the art. (a) ConvFormer outperforms ConvNeXt. Taking the common depthwise separable convolutions as the token mixer, the model termed ConvFormer, which can be regarded as pure CNNs, outperforms the strong CNN model ConvNeXt. (b) CAFormer sets new record on ImageNet-1K. By simply applying depthwise separable convolutions as token mixer in the bottom stages and vanilla self-attention in the top stages, the resulting model CAFormer sets a new record on ImageNet-1K: it achieves an accuracy of 85.5% at 224 ×224 resolution, under normal supervised training without external data or distillation. In our expedition to probe MetaFormer, we also find that a new activation, StarReLU, reduces 71% FLOPs of activation compared with commonly-used GELU yet achieves better performance. Specifically, StarReLU is a variant of Squared ReLU dedicated to alleviating distribution shift. We expect StarReLU to find great potential in MetaFormer- like models alongside other neural networks. Code and models are available at https://github.com/sail-sg/metaformer.

Design of Dodol Mixer on Based on Microcontroller Arduino Nano

In the process of cooking dodol dough requires the power of several people to continuously stir until the dough releases air bubbles. the process of making dodol generally takes time depending on how much dough you want to cook. If you want to cook 10 kg of dodol dough, then the time needed to cook it is approximately 8-10 hours with normal or medium heat. Currently, the household-scale dodol industry still uses the manual method for the dodol mixing process, which will require energy. more than one person to stir for a long time so that it will take time for one repetitive job and the production costs will be higher. With this tool, it is hoped that the household-scale dodol industry will become more efficient, because there is no need to manually stir and can do another work while the dodol dough is being stirred.

Comparative Study and Design of High Performance Mixer

In recent time the use of RF mixer has been increased greatly. Gilbert cell is widely used as core of the mixer because it provides high conversion gain, good port-to-port isolation and low even-order distortion. It is found that the linearity of mixer is very good for Multi-Tanh technique by incorporating multiple differential trans-conductance stage but it reaches to very low conversion gain whereas, use of current bleeding technique increase linearity and conversion gain of the mixer by adding current source to increase the bias current at the expense of power consumption. Since, CMOS technology has become dominant because of its several advantages such as low cost, low static power dissipation and low area, the design of low noise amplifier using CMOS technology was top choice for design of Low Noise Amplifier. The single ended and differential LNA was designed to operate in a WCDMA reception range using a BSIM3V2 model (Level 49) CMOS UMC 0.18μm technology in Xcircuit Open source EDA tool. The key issues in the design, gain, noise and linearity were considered. The LNA’s was designed to provide high gain, matching to 50Ω RF system, good linearity.

Auger feed mixer with perforated winding

The article presents the results of an analysis of existing feed mixers and feed mixer patents. Disadvantages such as high power consumption, low uniformity of mixed feed, and high metal consumption have been identified. We have presented the design of a screw feed mixer.

Effect of pineapple core powder on white finger millet vegan probiotic beverage: Nutrition, sensory and storage

The present study aims to develop, optimize, and evaluate the effective incorporation of pineapple core powder (PCP) in plant-based probiotic beverages using Lactocaseibacillus rhamnosus (LGG). The optimization was carried out using pH, viscosity, and LGG viable load as response variables in the d-optimal mixer design. In optimized products, the changes in pH, titratable acidity (TA), and LGG viable load are observed during fermentation and storage conditions. The optimum condition for developing PCP-added white finger millet probiotic beverage (PAMPB) was 14:5:2:2 for white finger millet, sugar, PCP, and LGG inoculums, respectively. A PAMPB provided a higher LGG viable load of 11.34 log (CFU/mL) within 6 h of fermentation time. The PCP effectively increases the physiochemical properties like total phenolic count (17.64 mg GAE/g), total antioxidant activity, total flavonoid count (8.59 mg QE/g), and water holding capacity (41.52 %) of the PAMPB. In addition, the different sugar profiles and new pineapple aroma compounds like ethyl hexanoate and methyl hexanoate are identified in PAMPB. During the storage of PAMPB at 4⁰C for 21 days, the reduction in LGG viable count was observed from 11.54 to 9.39 log (CFU/mL). Incorporating PCP in millet beverages provides a positive result by increasing nutritional quality.

MICROWAVE MIXER ON RECTANGULAR WAVEGUIDES PARTIALLY FILLED BY DIELECTRIC

The article investigates and calculates the characteristics of microwave mixers on rectangular waveguides partially filled by dielectric. Presents diagrams of promising combined microwave radio engineering systems - two options for constructing mobile digital troposcatter-radiorelay stations, the antenna-feeder paths of which are implemented on rectangular waveguides partially filled by dielectric. At research of microwave mixers, suppression and the use of the mirror frequency are taken into account. The analysis of researches of microwave mixers is carried out. The design of a balanced-type microwave mixer based on rectangular waveguides partially filled by dielectric is developed. The mixer is used to convertion the microwave signal into an intermediate frequency signal. The signal conversion of the mixers takes place on the non-linear active resistance of the semiconductor diode. In article, an open nonlinear structure is used as such a diode. The following main parameters of microwave mixers are investigated: conversion losses, noise factor, operating frequency band, signal suppression at the mirror frequency. The conversion losses are determined for various mirror channel suppression conditions. Phase methods of mirror frequency suppression are considered, which are most suitable for the waveguide implementation of microwave mixers. A scheme of a microwave mixer of a balance type with a phase method for suppressing the mirror frequency is presented. The article notes that for significant suppression of the mirror frequency of more than 30 dB, a double frequency conversion mixer is used. A diagram of a slotted bridge based on rectangular waveguides partially filled by dielectric is presented. The dependences of the input impedance of the mixer, the impedance of the mixer at the intermediate frequency, the impedance of the mixer at the mirror frequency by the power of the local heterodyne are plotted.

Effect of the X-grid static mixer flow inserts on the performance of parabolic trough collector

Solar energy is a very convenient and reliable renewable energy source to fulfill our society's wide variety of energy requirements. Solar concentrator-based energy technologies are the best way to utilize solar energy nowadays. Among those technologies, PTC (Parabolic Trough Collector) is a well-mature and reliable concentrating solar power technology having various real-world applications with solar standalone as well as in hybrid modes. For improving the performance of PTC, flow inserts are a very promising technique. This work aims to investigate the X-grid static mixer flow inserts on the performance of the PTC module. Here, X-grid static mixer flow inserts are modeled and compared with the simple cylindrical tube without any inserts inside by using a validated model in Ansys Fluent 18.1. Evaluation criteria include flow analysis, overall efficiency, exergy efficiency and thermal efficiency. The overall efficiency and exergy efficiency are the most prominent factors for the evaluation of PTC performance. The PTC is analyzed with various inlet fluid temperatures ranging from 303 K to 653 K with a variation in the volumetric flow rate ranging from 50 LPM (Litre Per Minute) to 250 LPM. The enhancement in the thermal performance of PTC using an X-grid static mixer is more as the inlet fluid temperature increases. The pressure drop increases multiple times with the use of X-grid flow inserts, but the overall rise of pump work is low. Overall thermal efficiency is higher for the X-grid static mixer than the plain tube which is mainly used in the PTC. The presented investigation results can be helpful for the design of X-grid static mixer.

Research on the effects of slurry uniformity and mixing power of continuous cementing slurry mixers based on statistical and CFD methods

To enhance the efficiency of continuous cement mixing in well cementing, a Computational Fluid Dynamics (CFD) approach was employed to investigate the mud flow and mixing processes within the continuous mixing system. This study aims to analyze the influence of various design factors and their interactions on the mixing of different slurries in the well cementing slurry continuous mixer. Using the Response Surface Methodology (RSM) with a Box-Behnken model, this work combines the Euler-Euler multiphase flow model, k-turbulence model, and the Multiple Reference Frame (MRF) method to simulate two-phase fluid flow and agitator rotation, establishing the CFD model of the mixing system. The CFD model, coupled with the RSM method, analyzed four design factors: impeller diameter (400–800 mm), design density (1.4–2.6 g/cm³), impeller speed (100–300 rpm), and particle size (20–500 μm), studying their impact on two response variables, slurry mixing uniformity, and total power consumption. Through RSM and multiple regression analyses, predictive models for slurry mixing uniformity and corresponding power consumption were established under different design factors. Data comparison analysis revealed excellent agreement between predicted and actual results. Findings indicate that, when using uniformity or power as evaluation criteria, the P-value is smallest for impeller speed and largest for particle size. Hence, the impeller speed exhibited the strongest correlation with both, followed by impeller diameter, and lastly, design density and particle size. Only the interaction between impeller diameter and impeller speed (P-value <0.0001) significantly influenced both power and mixing uniformity, with its significance ranking just below the linear effects of impeller speed and diameter. Slurry uniformity decreased with increased design density and particle size, while power consumption exhibited the opposite trend. Uniformity increased with increasing impeller speed, but when the uniformity reached its maximum, further speed increments led to a slight decrease in uniformity, accompanied by a sharp increase in power. This was significantly influenced by the quadratic effect of impeller speed (P-value <0.0001), with its significance weaker than the linear effects. The proposed predictive model accurately forecasts response values for any given design parameter, providing a research direction for optimizing mixer design and selecting corresponding design parameters. This approach streamlines the study of mud mixing systems, reducing research time and costs. Moreover, it offers scientific guidance for optimizing operational parameters corresponding to well cementing conditions.

RESEARCH OF TECHNOLOGICAL EQUIPMENT FOR THE PRODUCTION OF BULK FOOD MIXTURES

The development of technologies and modern equipment for the agricultural sector, as well as growing competition in the field of growing major agricultural products, lead agricultural producers to try to optimize their own production. The process of mixing can be thought of as the volumetric movement of particles of two or more components to obtain a homogeneous medium (in terms of composition, physical, mechanical, and other properties). To mix bulk materials, external forces must be applied to allow the particles of the components to be mixed to move relative to each other. The heterogeneity of the mixture depends on a number of reasons, in particular: the supply of the initial components to the vibrating mixer; insufficient mixing of the bulk mixture causes a deviation in the distribution of component particles, etc. An analysis of existing mixer designs has shown that most technological processes use rotary drum mixers and mixers with rotating working bodies - paddle, screw, frame. To study the process of mixing bulk food mixtures, a laboratory and experimental setup was developed, consisting of a vibration-centrifugal mixer, a loading hopper, and a control panel. The developed machine (mixer) is based on the task of intensifying the process of mixing materials by reducing the adhesive forces between material particles through the use of the gravitational effect. Vibrational impact on the mixing of materials and the mixer's working bodies significantly increases the process productivity, reduce energy consumption and improves the quality of the mixture. The developed design can be widely used in various industries in the production of spices, bakery mixes, feed, protein and vitamin supplements.

Numerical Insights Into Gas Mixing System Design for Energy Conversion Processes

Abstract Uniform gas mixing is important in various scientific and engineering domains, particularly in a chemical reactor design employing pre-mixed gases for processes. Assessing the performance of different mixer designs through physical prototypes can be resource-intensive and time-consuming. Consequently, this study underscores the significance of numerical simulations to optimize gas mixing and distribution systems in energy conversion applications. The research primarily focuses on varying the base mixer geometry by modifying the configuration of cross-flow inlets alongside the chambers. By employing numerical simulations, critical factors influencing mixing uniformity are identified, and innovative solutions are proposed to enhance system performance. Additionally, this work extends its application to improving the operational conditions of an industrial biomass gasifier, underlining the practicality of numerical modelling in addressing complex engineering challenges.

A Proof of Concept Balanced Mixer with the use of a Digital IF Power Combiner to Improve LO Noise Rejection

In this work we present a novel digital technique, that allows local oscillator (LO) noise cancellation using a digital power combiner in a balanced mixer receiver architecture. A theoretical analysis of the noise cancellation using the proposed technique is derived and a proof of concept experiment is made for the Ku-Band. This experiment includes the design and construction of a custom balanced mixer and an artificial noise source. Experimental results show a consistent noise temperature reduction in comparison with a full analog mixer, and in some cases reaching noise temperature levels similar to the receiver operating without the artificial LO noise.

A novel relaxation drift model for simulating liquid-vapor momentum non-equilibrium in two-phase ejectors

A novel relaxation drift model (RDM) was proposed to simulate the interphase momentum non-equilibrium (slip) inside two-phase work-recovery CO2 ejectors. The RDM was validated using the experimental data of 5 different ejectors under 15 trans-critical conditions in total. The proposed model was compared with the existing homogeneous model (HM) and algebraic slip model (ASM) through case studies. The effects of ejector mixer design and nozzle expansion state were also disclosed. The results showed that the prediction errors of ejector performance by the RDM were within 17 %, which was smaller than the maximum error of 23 % predicted by the HM and the ASM. The numerical results demonstrated that the liquid droplets had lower velocities than the vapor when the liquid-vapor mixture accelerated, but the droplets travelled faster than the vapor during deceleration of the mixture. It was also revealed that the velocity slip would affect the shock pattern at the diffuser inlet if the mixer was choked. The effects of slip, however, became insignificant when the mixer was designed too large. In addition, the RDM might overestimate the ejector performance if the motive nozzle was strongly under-expanded. This study facilitates understanding of interphase velocity slip in two-phase CO2 ejector flow.

Design and evaluation of novel static mixers for SCR application

Static mixers are widely used in selective catalytic reduction (SCR) systems to improve the conversion efficiency and service life of the catalyst by better mixing ammonia and the exhaust stream. However, the structure of the mixer needs to be designed carefully to minimise the loss of the system pressure caused by its installation. In this work, experiments and simulations are conducted to evaluate the mixing performance of the static mixers and the system pressure loss. The simulations and experimental results have good agreement. Four novel static mixers are designed and compared with a commercial static mixer to demonstrate their performance. The results show that the box mixer can accomplish less pressure loss (690 Pa) and more homogenous mixing (CoV = 5.4%), and it can thus be used to improve the mixing of ammonia and the exhaust stream in SCR systems.

Design and Testing of Segmented Spiral Total Mix Ration Mixer

To address the challenges of non-uniform mixing in total mixed diet forage and the high power consumption of the required device, we developed a segmented spiral total mixed diet device. This development involved theoretical analysis to determine the structural parameters of the main body of the segmented spiral blades, the churn, and the creation of a test bed for the segmented spiral total mixed diet device. Taking mixing speed, mixing time, filling coefficient, and segmented spiral blade spacing as test factors and mixing uniformity and energy consumption per unit mass as test indexes, the optimal combination of operating parameters of the device was determined by using a four-factor, three-level orthogonal test method. The results of the validation test showed that the mixing uniformity of the device under these conditions was 93.41%, the energy consumption per unit mass was 4723.69 J, and the errors between the mixing test values of the device and the optimized values of the model were all less than 5%. This study can provide a reference for improving the working quality of the segmented spiral TMR mixer.