Slurry Flow Research Articles

Potential industrial approach for efficient dispersion of silica fume: Rapid wet-grinding dispersion technique

Silica fume (SF) has been used extensively in buildings with high strength and durability requirements, but it must be densified prior to transport, causing it to lose its original pozzolanic activity. The common methods of SF dispersion are stirring, soaking and ultrasonication, but there is still a lack of an efficient and fast dispersion method. In this study, a rapid wet-grinding dispersion technique was designed to achieve the dispersion of densified silica fume (DSF) within 5 min, and the results were better than stirring and ultrasonic dispersion. The results of the study show that the wet-ground silica fume (WSF) slurry has a lower zeta potential, electrical conductivity and better stability. Wet grinding dispersion restores the balling effect of SF, with WSF slurry flow improving by 139% compared to plus DSF, and the fluidity of WSF_8% improving by 21% with lower apparent viscosity and yield stress. Additionally, WSF has superior pozzolanic activity, with a 16% increase in compressive strength at 28 days and a 62% increase in C-S-H gel content at 28 days. A novel technique for the effective dispersion of silica fume was presented in this study.

Evaluation of the integrated performance for floor heating using micro-encapsulated phase change material slurry

The micro-encapsulated phase change material (MPCM) slurry has the advantage of high heat transfer performance and heat capacity. Using MPCM slurry in the radiant floor heating (RFH) system could improve the indoor environment, but the overall performance was highly affected by heat transfer and pressure drop. In this paper, the flow and heat transfer model of MPCM slurry was developed and verified. The performance of serpentine and counterflow spiral structures was compared. Afterward, the optimized MPCM slurry material was selected as the heat transfer medium in RFH systems. Meanwhile, the flow and thermal performance of water and MCPM slurry were compared. Finally, the effects of different volume fractions and inlet velocities on integrated performance were investigated. The results indicated that the comprehensive performance of the serpentine system was better than the counterflow spiral. When the volume fraction was 15%, the comprehensive evaluation coefficients of three MPCM slurry heat systems are 17.9%, 22.9% and 13.8% higher than water respectively. MPCMS2 (n-dodecane) was suitable to use as the heat transferring medium in RFH system. Furthermore, as the volume fractions were 10%, 20% and 30%, the optimized velocities were 0.5 m s−1, 0.9 m s−1 and 1.1 m s−1, respectively.

Numerical simulation study on multiphase flow pattern of hydrate slurry

The research on the multiphase flow characteristics of hydrate slurry is the key to implementing the risk prevention and control technology of hydrate slurry in deep-water oil and gas mixed transportation system. This paper established a geometric model based on the high-pressure hydrate slurry experimental loop. The model was used to carry out simulation research on the flow characteristics of gas-liquid-solid three-phase flow. The specific research is as follows: Firstly, the effects of factors such as slurry flow velocity, hydrate particle density, hydrate particle size, and hydrate volume fraction on the stratified smooth flow were specifically studied. Orthogonal test obtained particle size has the most influence on the particle concentration distribution. The slurry flow velocity is gradually increased based on stratified smooth flow. Various flow patterns were observed and their characteristics were analyzed. Secondly, increasing the slurry velocity to 2 m/s could achieve the slurry flow pattern of partial hydrate in the pipeline transition from stratified smooth flow to wavy flow. When the flow rate increases to 3 m/s, a violent wave forms throughout the entire loop. Based on wave flow, as the velocity increased to 4 m/s, and the flow pattern changed to slug flow. When the particle concentration was below 10%, the increase of the concentration would aggravate the slug flow trend; if the particle concentration was above 10%, the increase of the concentration would weaken the slug flow trend, the increase of particle density and liquid viscosity would weaken the tendency of slug flow. The relationship between the pressure drop gradients of several different flow patterns is: slug flow > wave flow > stratified smooth flow.

Experimental study on heat transfer performance of mPCM slurry flow in microchannels

Experimental study on heat transfer performance of mPCM slurry flow in microchannels

Analysis of multi-particulate flow through the horizontal eccentric annulus considering the borehole cleaning

Multi-particulate flow CFD modelling is carried out while taking eccentricity into account considering drilling horizontal oil wells. The present work focuses on the effect of different cuttings sizes and their concentration on borehole cleaning. The carrier phase is a CMC-Bentonite solution which is a non-Newtonian fluid and the secondary phase is sand cuttings with different sizes. The RNG-k-ε turbulence mixture model is implemented along with the Eulerian-Eulerian multiphase model. The present CFD work has been validated with different experimental work and analytical results. The cutting size distribution in terms of volume fraction has been plotted along the various planes. Contours for volume fraction for different cutting size and inlet cuttings concentrations are also obtained. The increase in turbulence kinetic energy through increase inlet axial slurry velocity and drillpipe rotation (from v = 1 m/s, N = 50 rpm to v = 3.5 m/s, N = 100 rpm) is very effective in reducing cuttings accumulation for slurry A. The migration of cuttings from stationary zone to suspension zone is high for larger cuttings as compared to smaller cuttings from plane P2. The equivalent two-phase simulation for considered five-phase flow of slurry A has the similar cuttings distribution.

Numerical Study of Resistance Loss and Erosive Wear during Pipe Transport of Paste Slurry

Cemented paste backfill (CPB) as a solid waste treatment technology that prepares tailings as aggregate into a highly concentrated slurry to be transported to the underground mining area, is now widely used in mines. However, the pipeline resistance loss and erosion wear during CPB slurry transportation considering the coupling effect of inlet velocities, viscosities, and particle sizes have not yet been well evaluated and analyzed. Hence, the CFD-based three-dimensional network simulation of CPB slurry flow in an L-shaped pipe at different combinations of the three parameters was developed using COMSOL Multiphysics software. The results showed that the pipe resistance loss was most affected by the inlet velocity and viscosity, with the minimum pipe resistance loss occurring at an inlet velocity of 1.5 m/s, a viscosity of 2.0 Pa·s, and a particle size of 150 μm. In particular, pipe erosion wear was severest at the bend and was positively correlated with inlet velocity and particle size, and negatively correlated with slurry viscosity, with maximum pipe erosion wear occurring at an inlet velocity of 3.5 m/s, a viscosity of 3.0 Pa·s, and a particle size of 2000 μm. The findings would be important for the design of the CPB pipeline transportation, which will improve the safety and economic level of a mine.

Analysis of homogeneity and rheological properties of filling slurry during the mixing process through electrical resistance tomography

Mixing is a key process in the paste filling technology. This study utilized electrical resistance tomography and rheological experiments to examine the particle distribution and rheological properties of filling slurry at different shearing speeds, concentrations, and initial particle size distributions. The results indicated that filling slurry flow could be categorized into three states under different shearing speeds: insufficient mixing, full mixing, and excessive mixing. In combination with the rheological characteristics, the radial index and the filling slurry index could be used to measure homogenization. As the shearing speed increases, the homogeneity of the filling slurry improves, and the dynamic yield stress also changes. Increasing shearing speed has a negative impact on particle distribution as homogeneity is reached. The homogenization of the filling slurry is related to particle migration. Additionally, the mechanical response to shearing is discussed. Material and shearing conditions determine the interaction between particles.

An investigation on the variation of induction process in natural gas hydrate formation influenced by multiphase flow in a visual flow loop

One of the primary issues with natural gas transportation assurance is pipeline obstruction due to the formation and deposition of gas hydrates. Thus it is crucial to study the prevention and control methods of natural gas hydrateformation. A high-pressure visual flow loop was established in this study to investigate the effects of pressure, liquid velocity, and loop inclination angle on the formation of natural gas hydrates, hydrate slurry flow and morphology. For the formation of hydrates, it was demonstrated that the pressure was inversely related to the induction time and formation time. As the initial pressure increases, the conversion rate of water increases, leading to poor fluidity. With the increase of liquid velocity, the conversion rate of water increases and there is a threshold liquid velocity. Compared with horizontal loop, the hydrate particles in the slope were repeatedly deposited and removed off the surface of the sedimentary layer by gravity, and some large hydrate particles in the slope section gathered near the bottom of the pipeline. The induction time shortens and the formation time prolongs as the inclination angle increases. The inclination angle shows little effect on the final conversion rate of water, but it can delay the growth of hydrates obviously.

Sedimentation in heavy laden urban combined sewer conduits using a multi-phase Eulerian-Eulerian model

ABSTRACT To investigate the sedimentation through urban wastewater pipelines a semicircular polyethylene pipeline of diameter 0.40 m and length 18 m in nearly horizontal orientation with a longitudinal slope of 0.01 for a discharge capacity of 0.0147 m3/s and a volumetric flow concentration of 30% has been used. The solid phase consists of three different particle sizes i.e. 0.25 × 10−3m, 0.35 × 10−3 m and 0.50 × 10−3m with the greatest frequency in the wastewater flow being a density of 2650 kg/m3. The flow has been simulated by Ansys-Fluent (2020) software. The effects of particle size on various slurry flow parameters such as pressure drop, solid phase velocity distribution, friction factor, granular pressure, turbulent viscosity, turbulent kinetic energy and its dissipation all have been analyzed. The location of maximum deposition is also determined and it occurred at x/R = 77.5. Finally, a relationship between the thickness of sedimentation and volume concentration has been proposed.

‘Smart’ transonic atomization and heating of a pulsating non-Newtonian liquid sheet

We introduce proportional integral derivative (PID) controls into transonic pulsatile steam-assisted non-Newtonian slurry heating and disintegration. The purpose is to ensure consistent, reliable atomization during generic process upset scenarios, while this implementation involves a sudden pronounced slurry property shift. The uniquely interrelated physical responses of phase interfacial atomizer instabilities require continuously coupled PID controllers, the first of which automates slurry flow based on slurry pressure drop. The second compensates for the variable phase momentum ratio and sets a new heating steam flow based on the targeted droplet size. Three tests with increasing rigor were conducted to demonstrate successful coupled controller adaptability. During controller compensations, slurry and steam flows were significantly altered and drastically changed atomization characteristics. For a 100-fold increase in slurry viscosity, however, the controllers successfully maintained consistent droplet size and slurry flow resistance. The control methodology was shown to be mesh-independent and to operate across multiple atomization regimes.

An optimized miniaturized annular rotating flow reactor for controllable continuous preparation of functionalized polysilsesquioxane microspheres

A novel microreaction system based on a miniaturized annular rotating flow reactor (m-ARFR) was developed for the continuous preparation of functionalized polysilsesquioxanes (FPSQs). Compared to conventional batch processes, this new method enables accurate control and flexible adjustment of particle size and morphology of the prepared microspheres. The geometric structure and rotating speed were optimized through CFD simulations and energy analysis. In the optimized m-ARFRs, uniform shear stress and low back-mixing enable the controllable distribution of functional groups and stable slurry flow. By utilizing the flexibility of geometric design, we prepared uniformly functionalized PSQs (FPSQs-NH2) and surface-functionalized PSQs (PAPSQ@PMSQs). During hourly-level operation of m-ARFRs, the yield of microspheres remained at approximately 90% while maintaining a low internal pressure drop of less than 3 kPa, demonstrating the long-term operating stability of the system.

Study of Reasonable Grouting Pressure in the Process of Measuring Coal Seam Gas Pressure and Application.

Coal seam gas pressure is an important index to evaluate the risk of coal outbursts. The accuracy of measurement is closely related to the quality of hole sealing, and reasonable grouting pressure is one of the key factors to determine the quality of hole sealing. To obtain a reasonable grouting pressure, a mathematical model for slurry flow was established based on the relationship between the seepage law of the slurry and the properties of the borehole surrounding a rock. According to the conditions of the working face 11111 of the coal seam Ji15-17 in Pingdingshan No. 13 Coal Mine, the reasonable grouting pressure in the process of hole sealing and pressure measurement were simulated by COMSOL multiphysics numerical simulation software. After comparing the pressure distribution and slurry diffusion characteristics in the borehole under different grouting pressures, it is concluded that the reasonable grouting pressure is 4 MPa. When 4 MPa grouting pressure to seal the hole is used during actual engineering verification, the measured gas pressure is 2.7 MPa, which is more accurate than the result obtained under conditions of sealing with normal pressure grouting.

Mathematical model and numerical investigation of the influence of spray drying parameters on granule sizes of mold powder

In this work, the formation mechanism of the droplet-to-granule was investigated in detail based on mold powder manufacturing. A specific mathematical model of two-stage spray drying was established to describe droplet and granule motion, heat and mass transfer, and granule morphology during spray drying. Then, the relationships between spray drying parameters (inlet temperature, atomization pressure, slurry mass flow rate) and the properties of the drying tower (temperature and velocity fields) and mold powder granules (temperature, evaporation rates, moisture content, and diameter) were simulated and calculated using ANSYS/Fluent software. To ensure that the granule size of mold powder was controlled within the ideal range (0.2–0.6 mm) for producing granules with appropriate mechanical and metallurgical properties, the following optimum spray drying parameters were chosen based on the results of the numerical simulation: inlet temperatures, 873 K; slurry atomization pressure, 1.8 MPa; slurry mass flow rate, 0.05 kg s−1. Among these parameters, the slurry mass flow rate has the most significant effect on granule size.

Effects of platelet addition and loading direction on the mechanical properties of textured alumina fabricated by ceramic mask stereolithography

In order to simultaneously enhance the bending strength and fracture toughness of alumina, this research incorporated different amounts of alumina platelets into the ceramic slurry. Based on the shear force generated by the slurry flow during platform positioning, the platelets in the slurry were aligned. The green bodies were then sintered to prepare textured alumina. The results showed that the addition of 5 vol% alumina platelets in the slurry yielded the highest mechanical performance for the textured alumina. When the load was perpendicular to the printing direction, the bending strength and fracture toughness were measured to be 272 MPa and 4.41 MPam1/2, respectively, demonstrating an increase of 132 MPa and 1.25 MPam1/2 compared to non-textured alumina ceramics. Similarly, When the load was parallel to the printing direction, the bending strength and fracture toughness were 318 MPa and 3.4 MPam1/2, respectively, displaying improvements of 149 MPa and 0.65 MPam1/2 compared to non-textured alumina ceramics. The combination of ceramic mask stereolithography additive manufacturing technology and ceramic texturing techniques in alumina fabrication not only shortened the preparation cycle but also improved the bending strength and fracture toughness of alumina, thus expanding their potential applications.

Study on Slurry Flow Characteristics and Diffusion Law of Superfine Cement-Based Composite Grouting Material

The soft surrounding rock of deep roadways is in the state of “micro-fracture and low permeability”. In order to solve the problem of grouting reinforcement of micro-fractures surrounding rock in deep roadways, the influence characteristics of auxiliary materials and additives on slurry flow were analyzed, and the composition and proportion of superfine cement-based composite grouting materials were determined: superfine cement accounted for 89.4%, superfine coal ash accounted for 5%, ultrafine mineral powder accounted for 5%, naphthalene water reducing agent accounted for 3~5‰, and lignin sulfonate calcium accounted for 1~3‰. The effects of water–cement ratio and water reducer content on slurry viscosity and water bleeding rate were tested by laboratory experiments. Based on the fracture characteristics of surrounding rock and the “Liu Jiacai Formula”, the influence law of fracture opening, grouting pressure and slurry viscosity on the slurry diffusion radius was analyzed. The results show that the slurry viscosity decreases with the increase of water–cement ratio and water reducer content, but the bleeding rate increases obviously with the increase of the two factors; when the water–cement ratio is 1.0 and the water reducer content is 3‰, the slurry has the advantages of “strong permeability, strong flow and low water bleeding rate”; the smaller the fracture opening is, the greater the required grouting pressure and the lower the required slurry viscosity. Aiming at the “micro-fracture zone” of surrounding rock in deep roadways, when the dynamic viscosity of the slurry is 2.0 mPa·s, the reasonable grouting pressure should be 12 MPa to meet the needs of grouting reinforcement engineering. The high-pressure grouting test of surrounding rock in the “micro-fracture zone” was successfully carried out by using the superfine cement-based composite grouting material.

Erosion by turbulence: Discovering the counter-wise vortex events and their effect on wear

Understanding the wear process has been critical for developing and maintaining engineered systems handling particle-laden flows, such as pipelines, valves, pumps, and mixers. This work explores the use of ultrasound velocimetry for determining the velocity and impact angle of particles projected from a turbulent slurry flow onto a moving target surface. The flow is generated in a slurry pot configuration at four levels of rotational frequency: 1900, 2200, 2500 and 3300 rpm. Acoustic images acquired in the B-mode are processed by Ultrasound Particle Tracking Velocimetry (U-PTV) and Ultrasound Particle Image Velocimetry (U-PIV) to determine the impact velocities and impact angles of individual particles in the radial plane. Particle impacts at velocities higher than the tangential velocity of the rotating axis are observed and named counter-wise impact due to their association with counter-wise vortices impacting in the direction contrary to the translation of the moving surface. The applicability of U-PTV and U-PIV for the study of particle-laden turbulent flow is discussed and a statistical analysis of particle impacts energy is conducted. The counter-wise impacts are found relevant to erosive wear because of their relatively high velocity (upper quartile) and because most of the impact energy is conveyed through the tangential component.

Numerical Study of Non-Newtonian Ceramic Slurry Flow in Extrusion based Additive Manufacturing

Numerical Study of Non-Newtonian Ceramic Slurry Flow in Extrusion based Additive Manufacturing

Investigation of the Behavior of Hydrate Slurry Flow in the Bend Based on the CFD-PBM Approach

Investigation of the Behavior of Hydrate Slurry Flow in the Bend Based on the CFD-PBM Approach

Influence of hydrodynamic parameters in plate heat exchangers in ice slurry transport

Ice slurry is applied in different refrigeration and air conditioning systems, and among its main advantages is the ability to store latent heat and be pumpable as cold water. This fluid can be used for thermal storage instead of cold water or solid ice, since, at certain concentrations, it can be pumped through heat exchangers. For this technology to be widely used, the equipment must be designed considering the heat exchange characteristics. This study developed an experimental system to study the parameters that influence heat exchange, using ice slurry in a plate heat exchanger and water as a thermal load. Several situations with different flows and initial fractions of ice in ice slurry were analyzed. The input conditions of the thermal load were kept constant, the temperature, the pressure drop and the flow of the ice slurry in the heat exchanger were controlled, according to the Nusselt, Prandtl, and Reynolds coefficients. Results show that the global heat exchange coefficient increases with the increase of the initial ice fraction; the cooling capacity of the heat exchanger increases when ice slurry is used as a fluid. For flow rates greater than 0.16 kg/s and ice fractions above 11%, ice crystals are generated at the heat exchanger outlet, due to the ice slurry’s higher viscosity, at approximately 0.003 Pa at the outlet, since the pressure drop increases as the initial ice fraction increases. Results show ice slurry thermohydraulic behavior. Its use shows favorable characteristics in heat exchange.

Gas Hydrate Formation and Slurry Flow Characteristics of Gas–Liquid–Solid Multiphase Systems

Hydrate formation, aggregation, and deposition have become major hazards for the safe transportation of oil and gas pipelines. Although there has been a great deal of research into the behavior of particles during hydrate formation and transport, there is less research into the multiphase generation and flow characteristics of hydrate gas and liquids. In this paper, the flow characteristics of hydrate slurry and the flow pattern transition in gas–liquid multiphase system were studied, and the generations of it were compared between a gas–liquid multiphase system and oil–water emulsion system. The results showed that the flow parameters such as pressure, pressure drop, and density fluctuated more drastically in the gas–liquid system than that in the emulsion system, the higher fluctuation meant a higher risk of pipe plugging. At the same time, the influence of pressure and dosage on multiphase flow pattern transformation and boundary change conditions were studied. A gas-slurry flow pattern transformation diagram was drawn based on the defined transformation conditions between flow patterns. The results also indicated that, with the increase of pressure from 5 to 6 MPa, the boundary of slug flow and air mass flow changed to the direction of higher gas and liquid flow velocity. While the boundary of slug flow and wave flow, stratified flow and wave flow changed to the direction of higher gas flow velocity. The boundary of slug flow and air mass flow changed to the direction of lower liquid flow velocity. In contrast, the boundary of slug flow and wave flow, stratified flow and wave flow, slug flow and stratified flow changed to the direction of higher gas flow velocity and lower liquid flow velocity in the 1% inhibitor period compared with that without the inhibitor. This study will provide theoretical references and technological supports for the safety of multiphase transportation pipelines and the safety of deep water production.