High-viscosity Liquid Research Articles

Thermo-kinetic synergy in separating dimethyl carbonate/methanol/water mixtures using ionic liquids-based mixed solvents

The low selectivity of traditional organic solvents and the limited mass transfer efficiency caused by the high viscosity of ionic liquids (ILs) pose challenges in separating of dimethyl carbonate (DMC)/methanol/water mixtures. Therefore, a novel mixed solvent is proposed with a mass ratio of methyl salicylate to 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide of 6:4. The synergistic effects of thermodynamic, kinetic, and economic performance using the mixed solvent are investigated. Comparisons of overall efficiency and total annual cost (TAC) for four process configurations using direct and indirect extractive distillation sequences to produce industrial and battery-grade DMC products are conducted. The results indicate that direct extractive distillation outperforms the indirect sequence, reducing TAC by 6.1–14.3 % for producing industrial-grade DMC and 6.6–15.8 % for battery-grade DMC. Additionally, using mixed solvents in direct extractive distillation is more effective than using pure solvents, enhancing mass transfer coefficients by 2.8–20.9 % for industrial-grade DMC and 1.8–17.8 % for battery-grade DMC. This approach also reduces TAC by 3.2–3.6 % for industrial-grade DMC and 4.7–5.7 % for battery-grade DMC.

Extraction of rare earth ions using thermomorphic ionic liquid: In situ spatial and temporal distribution combined with thermodynamic description

Homogeneous Liquid–Liquid Extraction (HLLE) provides a valuable opportunity for recycling Rare Earth Elements (REE) by circumventing the liquid–liquid interface and avoiding the problems linked to the high viscosity of ionic liquids (IL). For optimizing these processes with the ultimate goal of implementing them at the industrial scale, it is crucial to understand the mechanisms at play at various scales. In this study, we focused on the extraction of two REE elements, La(III) and Ce(III) with an HLLE system composed of the IL [Chol][TFSI], water and betaine as the extractant. We first established the phase diagram of [Chol][TFSI]/betaine/water using 1H nuclear magnetic resonance (NMR) spectroscopy. We then determined the efficiency E and distribution ratio D of the HLLE for different betaine concentrations. HLLE was modeled thermodynamically to access the most likely number of betaine molecules involved in the extraction process, which appears to be 2. Finally, we monitored in situ the extraction using X-ray Absorption Spectroscopy (XAS) at the K-edge of both lanthanum and cerium. It allowed us on one hand, to get some insight into the local environment around the REE, and on the other hand to measure the local concentration of REE at each position within the extraction system. In this latter process, we could evidence an accumulation of REE accumulates close to the liquid–liquid interface, a feature that was suggested by some recent simulations.

A Study on Two-Phase Flow with High Viscosity and Low Surface Tension Liquid in a 40-Degree Inclined Mini Channel

There are numerous applications of two-phase flow in mini pipes, including electronics cooling systems, microreactors in the chemical industry, and material development and manufacturing. This application requires a thorough understanding and is supported by complete data and information. However, the data and information are currently limited. Experimental research has been carried out on flow patterns, void fractions, and two-phase flow pressure gradients in small pipes. This study aims to obtain primary data on the subject. Dry air and a mixture of 67% distilled water, 30% glycerin, and 3% butanol represent the gas and liquid phases, respectively. The addition of butanol and glycerin each aims to reduce surface tension and improve the viscosity of the liquid phase, respectively. The density, kinematic viscosity, and surface tension of the liquid were 1,080.4 kg/m3, 2,368 mm2/s, and 38.6 mN/m, respectively. The test section was a 1.6 mm diameter glass pipe equipped with an optical correction box. The gas superficial velocity (JG) ranged from 0.025 to 66.3 m/s, whereas liquid superficial velocity (JL) varied from 0.033 to 4.935 m/s. The experiment was conducted under adiabatic conditions. Plug, slug-annular, annular, disperse bubbly, and churn flow patterns emerged, while separated flow was not discovered. For plug, slug-annular, and dispersed bubbly flows, the increase of JG proportionally affected the void fraction. However, for churn and annular flows, no particular relationship existed between JG and void fraction due to the slip between the real velocities of the gas and the liquid. The pressure gradient rose as JG and JL increased.

On-demand jetting of high-viscosity liquid by jet tube impact

The on-demand jetting of high-viscosity liquid has significant applications in fields such as electronic packaging and bioprinting. Conventional methods for high-viscosity liquid jetting often employ a needle propelling the liquid rapidly, which demands high precision in the manufacturing and assembly of the needle and nozzle, and can potentially damage biomaterials. In this study, a novel method utilizing jet tube impact for on-demand high-viscosity liquid jetting is proposed, leveraging the inherent inertia of the liquid to generate the pressure pulse necessary for on-demand jetting. This method reduces the precision requirements for the device, enables device simplification, and avoids harm to biomaterials. The feasibility of this approach for on-demand high-viscosity liquid jetting is validated through experiments, and by combining numerical simulations, the jetting mechanism is revealed and primary factors influencing jetting performance are investigated. It is found that the water hammer pressure wave induced by the liquid inertia during the sudden velocity change of the jet tube is the predominant driving force for jetting, and the peak pressure can exceed 1 MPa and the peak jet velocity can exceed 15 m/s. An increase in the jet tube impact velocity and an extension of the acceleration duration at the same impact velocity both lead to an increase in the pressure wave amplitude. In addition, a decrease in the liquid level height shortens the period of the pressure wave. These factors all have an influence on the jetting performance. This study provides a new insight and theoretical foundation for the on-demand high-viscosity liquid jetting.

Theoretical study on the energy storage performance of Electrical double layer supercapacitors with choline amino acid ionic liquids electrolyte

Choline amino acid ionic liquids have attracted much attention in recent years due to their simple extraction process, rich sources, and easy degradation. Due to the high viscosity of such ionic liquids, the addition of organic solvents can adjust the transport performance of ionic liquids. Here, we explore the effects of different solvents (methanol, ethanol) and different temperatures on the diffusion properties and conductivity of ionic liquids through molecular dynamics simulations. The results showed that with the increase of temperature, the conductivity linearly increased. The addition of organic solvents can improve the conductivity of ionic liquids, and the addition of methanol solvent has a higher compatibility with choline amino acid ionic liquids. The conductivity after mixing methanol and choline glycine in a certain proportion is 5 times higher than before. In addition, this article investigated the performance of choline glycine ionic liquid electrolytes in Electrical Double Layers (EDLs) near planar graphene electrodes. The results indicate that similar double layer structures and double layer capacitors can be observed regardless of whether solvents are added.

A simple mechanical spring-driven rheometer for measurement of Newtonian and non-Newtonian fluids—Design, validation, and input correction

This paper deals with the construction and validation of a new, very simple purely mechanical rheometer, which is assembled from a syringe and a steel spring. This rheometer does not require any expensive measuring equipment and yet can measure the viscosities of common Newtonian and non-Newtonian liquids with satisfactory results. By determining the temporary position of the piston, the force applied by the spring and the piston velocity can be ascertained and the viscosity of a given sample of Newtonian liquid can be calculated with repeatability of better than 2%. When measuring non-Newtonian and viscoelastic liquids, a camera is used to record the time course of the moving piston and the swelling ratio. Preliminary tests conducted on power-law liquids demonstrate reproducibility of rheological parameters even for very high viscosity liquids. A new correction to inlet effects is also derived as a function of Reynolds number.

Direct numerical simulations of internal flow inside deformed bubble by phase-field-based lattice Boltzmann method

Internal flow mechanism inside deformed bubble was investigated through direct numerical simulation by Allen-Cahn phase-field-based lattice Boltzmann method and theoretical model developed from Bernoulli equations. The effects of key parameters such as bubble size and gas or liquid physical properties on bubble dynamic behaviors were systematically analyzed. The internal flow that gas flowed through bubble neck from the smaller part to the larger part was well simulated. Lower redistribution was observed at high gas viscosity due to enhanced viscous flow resistance, at low surface tension and high gas density due to the weaken driving force for internal flow, respectively. And, at high liquid viscosity, the time for cutting-off of bubble neck was longer than the time for internal flow due to decreased bubble rising velocity, finally the mother bubble failed to breakup. The internal flow velocity predicted by numerical simulation were in consistent with calculated value by theoretical model, which greatly validated our theoretical model and emphasized the great significance of internal mechanism.

Systematic error calibration of vertical dynamic interferometer with sloshing liquid plane

Liquid mirror can calibrate the interferometer system error by measuring the surface of a steady-state, high-viscosity liquid; however, strict environmental safeguards are typically required. To address this problem, we propose a new liquid mirror method based on liquid micro-amplitude sloshing to calibrate dynamic interferometer system error. According to the multimodal analysis method of fluid finite amplitude sloshing, the liquid surface sloshing surface was modeled and analyzed, a time dimensional mean model was established, and the minimum sampling time was calculated. Finally, the error of the liquid surface sloshing was reduced by time averaging to realize the absolute calibration of the dynamic interferometer's systematic error. According to the proposed minimum sampling time theory, when the mean processing time is greater than the minimum sampling time, the error in the sloshing liquid surface can be controlled to within λ/100. The method’s correctness is proven through an experimental comparison of different calibration methods.

Continuous casting process based on an optimized submerged entry nozzle

Continuous casting process is an important part in the steel manufacturing process. The slab production quality is commonly influenced by mould and flow pattern of submerged entry nozzles (SEN). Hence, the present work aimed to attain a more liquid flow rate to increase the slab production quantity within a certain period. Moreover, a novel African Buffalo Algorithm (ABA) is presented in this work to optimise the SEN parameters and the SEN was designed in the MATLAB environment. The developed ABA model optimises the design parameters of SEN such as the size of the nozzle, the shape of the port, length, submergence depth, etc. The fitness of buffalo effectively optimises the SEN parameters and by utilising the optimised design parameters, the SEN was resigned in the MATLAB to identify the proposed framework's effectiveness. The results demonstrated that the liquid flow rate is increased and surface tension gets minimised. When the flow rate of liquid grows, the wave amplitude also upturns. The effect of liquid and air flow rate, port shape and size, maximum wave amplitude, surface tension, etc., were calculated with 0° parallel port. In addition, the presented SEN's results were compared with other existing SEN to determine the optimised SEN's effectiveness. The comparison result demonstrated that the designed optimised SEN has a high liquid flow rate, casting speed, density and viscosity.

Perspective on oral processing of plant-based beverages.

Around the world, the market for plant-derived beverages is one of the fastest-expanding segments in the functional and specialty beverage areas of newer food product development. Consumers are increasingly likely to choose alternatives to bovine beverages due to factors including lactose intolerance, hypercholesterolemia prevalence, allergies to bovine beverages, and preference for vegan diets that contain functionally active ingredients with health-promoting characteristics. Due to health, ecological, and ethical concerns, many customers are interested in reducing their usage of animal products like bovine milk. A variety of plant-based beverage substitutes are being created by the food sector as a result. To create viable alternatives, it is first necessary to provide an overview of the chemical composition, structure, features, and nutritional attributes of ordinary bovine milk. Sensory acceptability in the case of substitutes for beverages made from legumes is a significant barrier to their widespread acceptance, and thus saliva acts as a sophisticated fluid that serves a variety of purposes in the cavity of the mouth. Designing and producing next-generation plant-based beverages that mimic the physicochemical and functional qualities of conventional bovine-based beverages is gaining popularity, and many of these products can be thought of as colloidal materials that contain the particles or polymers that give them their unique qualities NG-PB foods can have a wide range of rheological qualities, such as fluids with low viscosity (such as plant-based beverages), high-viscosity liquids (like creams), soft liquids (like yogurt), as well as hard solids (such as some cheeses).

Modulation of wetting state switching of droplets on superhydrophobic microstructured surfaces by external electric field

HypothesisElectrowetting on conventional dielectrics requires direct fluid-electrode contact to generate strong electric fields at the three-phase contact line to modulate the wetting. Since the electric field alters wetting, the modulation of wetting can be achieved by applying an external electric field through insulated electrodes, preventing the liquid from contacting the electrodes. ExperimentA simple and efficient method for non-contact between the fluid and the electrode external electric field modulation of fluid wetting was proposed. The switching ability of droplets on microgroove surfaces from Cassie-Baxter to Wenzel wetting state under an external electric field was used to drive and quantify the relationship between wetting, contact angle, and the applied voltage. FindingsApplying an external electric field modulates the wetting of deionized water, ionic liquids, and high-viscosity liquids on microgrooves. The wetting degree of liquid can be controlled by adjusting the external voltage parameters. The finite element simulations revealed that the Maxwell force drove this process. The effects of substrate size and liquid properties on wetting behavior were also examined. Post-application cross-sectional imaging showed the formation of a conformal interface, highlighting the relevance of the proposed method in advanced adaptive shape fabrication and microfluidic control, among other applications.

Unknown crystal-like phases formed in an imidazolium ionic liquid: A metadynamics simulation study.

Crystal polymorphism of complex liquids plays a crucial role in industrial crystallization, food technology, pharmaceuticals, and materials engineering. However, the experimental identification of unknown crystal structures can be challenging, particularly for high-viscosity complex liquids, such as ionic liquids (ILs). In this study, we performed a molecular dynamics simulation coupled with metadynamics to investigate an imidazolium IL (1-alkyl-3-methylimidazolium hexafluorophosphates). The simulation employed two distinct radial-distribution functions, represented by Gaussian window functions as collective variables, and revealed at least two crystal-like phases distinct from the known α and β crystal phases typically formed by this IL. Additionally, the simulation unveiled a unique phase characterized by the ordered spatial arrangement of anion aggregations. These crystal-like and unique phases emerged regardless of the potential used. The simulation methodology presented here is broadly applicable for exploring unknown phases in complex systems and contributes to the design of functional materials, such as porous ILs for gas molecule capture and separation.

Cavitation is the determining mechanism for the atomization of high-viscosity liquid

Piezoelectric atomization is becoming mainstream in the field of inhalation therapy due to its significant advantages. With the rapid development of high-viscosity gene therapy drugs, the demand for piezoelectric atomization devices is increasing. However, conventional piezoelectric atomizers with a single-dimensional energy supply are unable to provide the energy required to atomize high-viscosity liquids. To address this problem, our team has designed a flow tube internal cavitation atomizer (FTICA). This study focuses on dissecting the atomization mechanism of FTICA. In contrast to the widely supported capillary wave hypothesis, our study provides evidence in favor of the cavitation hypothesis, proving that cavitation is the key to atomizing high-viscosity liquids with FTICA. In order to prove that the cavitation is the key to atomizing in the structure of FTICA, the performance of atomization is experimented after changing the cavitation conditions by heating and stirring of the liquids.

Solar-heated mono-domain-structured ferrimagnetic cellulosic sponge fabricated by using bidirectional freeze casting for energy-efficient liquid adsorption

Liquid adsorption has a wide range of industrial and environmental applications. In recent years, interest in liquid adsorption technology that leverages porous materials has surged, primarily driven by these materials’ substantial surface area and adjustable wettability. However, high tortuous structures of conventional porous materials impede the flow of liquids, limiting their applicability in situations requiring rapid liquid adsorption such as oil spill cleanups. This study proposed two strategies for rapid liquid adsorption. We introduced a polydimethylsiloxane (PDMS) wedge to control ice crystal growth by generating a dual temperature gradient. This led to a mono-domain lamellar structure composed of vertically aligned channels. Cubic iron oxide nanoparticles (CION) were also utilized to enhance solar heating, that enabled rapid adsorption, even of high-viscosity liquids, without an external power supply unit for heating sorbents. The application of a solar-heated ferrimagnetic cellulosic sponge with precisely controlled channels facilitates the rapid removal of high-viscosity oils, which have traditionally been challenging for large-scale oil spill cleanups in oceans.

Effects of liquid viscosity and air injection rate on air invasion in a highly compacted granular material

Using laboratory experiments on a network scale together with numerical simulations on a granular scale, we investigate the displacement process as air invades a highly compacted granular material. Experiments in a vertically placed Hell-Shaw cell reveal a non-monotonic behavior of branching formation as air injection rate Q increases from 0.1 to 50 ml min–1 when the liquid viscosity is less than 22.5 mPa s. In the low-injection-rate region where Q < 1 ml min–1, fractures grow in random directions, and the number of branches increases as the air injection rate decreases. However, after the transition to the high-injection-rate region where Q≥ 1 ml min–1, the number of branches increases with increasing air injection rate. At a given air injection rate, increasing the liquid viscosity from 1.01 to 219 mPa s leads to an increasingly concentrated air flow. The numerical simulations exhibit good agreement with the experimental results. More importantly, they shed light on the physics underlying the growth of the fractures by capturing the distribution of the magnitude of velocity, as well as computing the inter-grain force chains in the granular material. The simulations suggest that a high liquid viscosity concentrates the velocity field and force chains and reduces the speeds and inter-grain forces of the grains adjacent to fractures, while a higher air injection rate increases the grain speeds and inter-grain forces. In addition, the distribution of the forces chains behaviors non-monotonically as the air injection rate decreases, which explains the non-monotonic behavior of branching formation observed in the experiments.

The Coiling Effect in Ether Ionic Liquids: Exploiting Acetate as a Probe for Transport Properties and Microenvironment Analysis.

The inherently high viscosity of ionic liquids (ILs) can limit their potential applications. One approach to address this drawback is to modify the cation side chain with ether groups. Herein, we assessed the structure-property relationship by focusing on acetate (OAc), a strongly coordinating anion, with 1,3-dialkylimidazolium cations with different side chains, including alkyl, ether, and hydroxyl functionalized, as well as their combinations. We evaluated their viscosity, thermal stabilities, and microstructure using Raman and infrared (IR) spectroscopies, allied to density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. The viscosity data showed that the ether insertion significantly enhances the fluidity of the ILs, consistent with the coiling effect of the cation chain. Through a combined experimental and theoretical approach, we analyzed how the OAc anion interacts with ether ILs, revealing a characteristic bidentate coordination, particularly in hydroxyl functionalized ILs due to specific hydrogen bonding with the OH group. IR spectroscopy showed subtle shifts in the acidic hydrogens of imidazolium ring C(2)-H and C(4,5)-H, suggesting weaker interactions between OAc and the imidazolium ring in ether-functionalized ILs. Additionally, spatial distribution functions (SDF) and dihedral angle distribution obtained via AIMD confirmed the intramolecular hydrogen bonding due to the coiling effect of the ether side chain.

Influence of dispersed phase flow-rate pulsations on the liquid–liquid parallel flow in a T-junction microchannel

Active flow control in microfluidic devices to broaden the range of desired conditions is a significant practical concern. In this study, we experimentally investigate liquid–liquid parallel flow under the dispersed phase flow-rate pulsations in a T-junction microchannel. Sinusoidal flow rate disturbances with variations in amplitude and period were applied to dispersed phases of different viscosities. The study involves flow visualization and velocity field measurements using the micro-PIV technique for both free and excited flow conditions. The analysis of flow pattern maps, velocity fields, velocity gradients, and phase-averaged velocity profiles in a T-junction region and far downstream provided insights into the evolution of disturbances, which is different in low- and high-viscosity liquids. In the less viscous liquid, transverse waves amplify longitudinal ones due to relaxation of the liquid–liquid interface, while in the high-viscosity dispersed phase, longitudinal waves are damped significantly, with the transverse wave amplitude remaining almost constant. As a result, we revealed two distinct mechanisms of disturbance wave propagation and the loss of parallel flow stability, which are both dependent on the Ohnesorge number of the dispersed phase. Destabilization of the parallel flow led to the formation of plugs with a narrow length distribution. Single-mode, double-mode, triple-mode, and multi-mode plug formation regimes were identified. The results of the study can potentially be used to extend the range of segmented flow regimes and generate plugs of a desired length.

Understanding the operating limitations of an internal-mixing Air-Core-Liquid-Ring (ACLR) nozzle for process intensification in spray drying

Spray drying is a widely used method for producing food powders in large quantities, but it also has a high energy demand. To address this, researchers have long aimed to increase the solid content of liquid feeds, which poses the challenge of atomizing high-viscosity liquids into fine droplets. The Air-Core-Liquid-Ring (ACLR) nozzle offers a potential solution by inducing an internal annular flow, though it faces its own limitations due to internal flow instabilities. This study investigates how the nozzle flow conditions impact spray performance under different process conditions and liquid viscosities. We found that internal lamella thickness and atomization uniformity vary with pressure, viscosity, and liquid volume flow. Nonetheless, pressure appears to be the real critical factor in that case. The Air-to-Liquid Ratio (ALR) might be more decisive for the droplet size distribution than liquid viscosity. Future research should explore higher viscosities and consider simulations to circumvent experimental limitations.

Behavior of Compound Materials on Superhydrophobic Cylinders: Effects of Droplet’s Size and Interface Angle

Compound droplets can consist of two or more immiscible substances sharing an interface. Among such droplets, the low-viscosity component of Janus droplets can exhibit peculiar bouncing behavior on nonwettable surfaces. There have been recent advances in droplet control technologies, however the impact dynamics of droplets on complex surfaces, and strategies to control their behavior, have not been extensively studied. This study employs the volume of fluid method to analyze the effects of Janus droplet size and the initial interface angle on the dynamics of the two fluidic components in droplets on superhydrophobic cylinders. Janus droplets are composed of low-viscosity (W-) and high-viscosity liquid (G-component). The dynamic characteristics of Janus droplets are investigated as a function of Weber number (<i>We</i>), initial interface angle, the ratio of the droplet’s diameter to the cylinder’s diameter, and viscosity ratio (α). Numerical models provide a regime map of the separation ratio of Janus droplets based on We and α, and the influence of droplet size on asymmetric bouncing is discussed. This study also examines the threshold We at which separation begins after impact, varying with droplet size and α. In addition, the shape evolutions of the droplets are discussed for various initial interface angles to understand the bouncing behavior and separation efficiency. This study is expected to provide valuable strategies for controlling droplet behavior and separation in applications such as liquid purification, rheology, and solidification.

Immiscible invasion of granular suspension by high-viscosity liquid

We investigate the morphology and dynamics of the pattern of immiscible invasion by injecting a high-viscosity liquid into a granular suspension consisting of movable solid grains in a low-viscosity liquid. Laboratory experiments conducted in a Hele–Shaw cell shed light on how the frictional forces of the grains and the viscous forces of the liquids affect the instability of the liquid–liquid interface and the formation of viscous fingers. The frictional force increases with an increase in either the volume fraction or the size of the grains, leading to higher resistance to the invading pattern. Upon changing the grain shape from spherical to irregular, both the frictional force and the rotational energy of the grains increase, resulting in more numerous but narrower fingers. Increasing either the injection rate or the viscosity of the injected liquid increases the viscous pressure within the fingers, promoting the splitting of the pattern. Although the defending liquid always has a lower viscosity than the invading liquid in this study, the former's viscous force becomes non-negligible as the viscosity ratio of the invading liquid to the defending liquid decreases to near unity, which destabilizes the fluid–fluid interface and causes a transition to an asymmetric pattern.