Dynamic characteristic analysis of vertical screw conveyor in variable screw section condition

Vertical screw conveyors are used widely in industry for elevating bulk materials over relatively short distances, but the problem of insufficient feeding and low conveying efficiency always exist in the vertical conveying process. In this paper, a vertical screw conveyor with variable screw section is presented, and the characteristics of vertical screw conveyor are investigated under the variable screw sections using discrete element method (DEM). The results show that the particle volume fraction in the inlet and the mass flow rate increase in the condition of variable screw section, and the screw rotational speed has a significant influence on mass flow rate. It is evident that the design of variable screw section provides an effective way in improving the particle feeding rate and the conveying efficiency.

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Effects of Fe3O4/Water Nanofluid on the Efficiency of a Curved Pipe

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4044184 ◽

2019 ◽

Vol 11 (4) ◽

Cited By ~ 2

Author(s):

Milad Kelidari ◽

Ali Jabari Moghadam

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Volume Concentration ◽

Volume Fraction ◽

Working Fluid ◽

Radius Of Curvature ◽

Dean Number ◽

Curved Pipe ◽

Overall Efficiency

Different-radius of curvature pipes are experimentally investigated using distilled water and Fe3O4–water nanofluid with two different values of the nanoparticle volume fraction as the working fluids. The mass flow rate is approximately varied from 0.2 to 0.7 kg/min (in the range of laminar flow); the wall heat flux is nearly kept constant. The experimental results reveal that utilizing the nanofluid increases the convection heat transfer coefficient and Nusselt number in comparison to water; these outcomes are also observed when the radius of curvature is decreased and/or the mass flow rate is increased (equivalently, a rise in Dean number). The resultant pressure gradient is, however, intensified by an increase in the volume concentration of nanoparticles and/or by a rise in Dean number. For any particular working fluid, there is an optimum mass flow rate, which maximizes the system efficiency. The overall efficiency can be introduced to include hydrodynamic as well as thermal characteristics of nanofluids in various geometrical conditions. For each radius of curvature, the same overall efficiency may be achieved for two magnitudes of nanofluid volume concentration.

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Numerical Study of Laminar Mixed Convection of a Nanofluid in a Horizontal Curved Tube with Constant Heat Flux and Mass Flow Rate

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.110-116.3657 ◽

2011 ◽

Vol 110-116 ◽

pp. 3657-3662

Author(s):

S. Alikhani ◽

A. Behzadmehr ◽

S. Mirmasoumi

Keyword(s):

Heat Flux ◽

Mixed Convection ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Volume Fraction ◽

Numerical Study ◽

Two Phase ◽

Curved Tube ◽

Laminar Mixed Convection

Fully developed laminar mixed convection of a nanofluid (water/Al2O3) in a horizontal curved tube is numerically investigated. Three-dimensional elliptic governing equations have been solved to show how nanoparticle concentration affects on thermal and hydrodynamic parameters while these parameters are impressed by centrifugal and buoyancy forces under constant mass flow rate and heat flux. Comparisons with previously published experimental works on horizontal curved tubes show good agreements between the results. Results which are obtained using the two – phase mixture model indicate that adding the nanoparticles causes changes in the properties of nanofluid and finally increases the temperature of the flow. Furthermore, increasing nanoparticles volume fraction at first augments the heat transfer coefficient of nanofluid and then, for higher concentration of particles, decreases this thermal parameter of nanofluid.

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Particle Optimization of Ceo2/Water Nanofluids in Flat Plate Solar Collector

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.b3476.129219 ◽

2019 ◽

Vol 9 (2) ◽

pp. 1467-1474 ◽

Cited By ~ 1

Keyword(s):

Flat Plate ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Solar Collector ◽

Volume Concentration ◽

Particle Volume ◽

Wide Range ◽

Flat Plate Solar Collector ◽

Flat Plate Collector

The present research focuses on the role of CeO2/water nanofluid for estimating the performance of flat plate solar collector in respect of energetic and exergetic performance. Based on our experimental findings on varying mass flow rate, the present analysis focuses on a wide range of concentrations to find optimum volume concentration for which thermal performance is maximum. CeO2/water nanofluid exhibits high thermal conductivity improvement (~41.7%at 1.5% volume concentration) and comparatively lower dynamic viscosity. Performance evaluation of flat plate collector is based on first law analysis and qualitative nature of energy flow based on second law analysis. Experiments indicate that for~1.0% particle volume concentration at a mass flow rate of 0.03 kg/s, maximum collector efficiency is obtained up to 57.1% instead of water as the base fluid. Exergetic efficiency observed 84.6%at optimum concentration (~1.0% particle volume) of nanofluid at0.01 kg/s flow rate.

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Computational Study of Fuel Dilution Effect on the Soot Formation in Methane-Air Laminar Confined Diffusion Flame

Volume 8A: Heat Transfer and Thermal Engineering ◽

10.1115/imece2013-62901 ◽

2013 ◽

Author(s):

Achin Kumar Chowdhuri ◽

Arindam Mitra ◽

Somnath Chakraborti ◽

Bijan Kumar Mandal

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Diffusion Flame ◽

Volume Fraction ◽

Soot Formation ◽

Soot Volume Fraction ◽

Flame Height ◽

Fuel Jet ◽

Fuel Stream

Although diffusion flame is free from many problems associated with premixed flame, soot formation is a major problem in diffusion flame. The techniques of dilution of fuel or air with inert gases such as nitrogen and argon are used to decrease soot level in the flame. In this work, a CFD code has been developed to predict the flame height, soot volume fraction and soot number density in an axisymmetric laminar confined methane-air diffusion flame after diluting the fuel with nitrogen. The temperatures of the air and fuel at inlet are taken as 300K. Mass flow rate of the fuel stream is considered as 3.71×10−6 kg/s and mass flow rate of the air is taken as 2.2104×10−6 kg/s. The total mass flow rate through the central jet (fuel jet) is, however, kept constant. The radiation effect is also included through an optically thin radiation model. An explicit finite difference technique has been adopted for the numerical solution of reacting flow and two equations soot model with variable thermodynamic and transport properties. The prediction shows that flame height decreases with the addition of nitrogen to the fuel. Temperature of the flame is considerably reduced in the given computational domain. Both soot volume fraction and soot number density decrease with dilution by adding nitrogen in the fuel jet. The soot formation at different nitrogen dilution level of 0%, 10%, 20%, 30%, 40% and 50% are plotted and the soot get considerably reduced as the concentration of nitrogen is increased in the fuel stream.

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On Necessary Pumping Pressures for Industrial Process-Driven Particle-Laden Fluid Flows

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4030620 ◽

2015 ◽

Vol 138 (3) ◽

Cited By ~ 3

Author(s):

T. I. Zohdi

Keyword(s):

Flow Rate ◽

Volume Fraction ◽

Particle Volume Fraction ◽

Industrial Process ◽

Fluid Flows ◽

Air Entrainment ◽

Particulate Composites ◽

Particle Volume ◽

Derived Relations ◽

High Reynolds

Due to increasing demands for faster and faster manufacturing of new complex materials, such as casting of particulate composites, the determination of pumping pressures needed for particle-laden fluids through channels is critical. In particular, the increase in viscosity as a function of the particle volume fraction can lead to system malfunction, due to an inability to deliver necessary pressures to pump the more viscous fluid through the system. This paper studies the pressure gradient needed to maintain a given flow rate, explicitly as a function of the volume fraction of particles present in the fluid. It is also crucial to control voids in the casted products, which can be traced to air-entrainment, spurious internal reactions, dewetting, etc., which can be traced to high Reynolds numbers. Accordingly, an expression for the resulting Reynolds number as a function of the particle volume fraction and flow rate is also developed. Numerical examples are provided to illustrate the practical use of the derived relations to characterize the necessary pumping pressures for process-driven, particle-laden fluid flows.

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Investigation into the Mechanism of the Steel Particle Feeding Process: A Numerical and Experimental Study

Geofluids ◽

10.1155/2021/6691899 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Lei Li ◽

Xueyang Xing ◽

Fangxiang Wang ◽

Xiaodong Dai

Keyword(s):

Particle Size ◽

Water Content ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Force Model ◽

Feeding System ◽

Steel Particle ◽

Feeding Process ◽

Particle Feeding

The particle feeding system is a prerequisite for the realization of particle impact drilling technology. Because of the high density, the storage and flow of the steel particle are different from those of the other nonviscous particles. The differential equation of the particle movement was built with the liquid bridge force model and the discrete element method. The dynamic movement process and the distribution state of particles in the high-pressure tank were analyzed. For 1 mm steel particles, the mass flow rate decreased with the increase in water content. For 2 mm and 3 mm steel particles, the water content of 15% and 20% was the dividing point of the mass flow rate from increasing to decreasing. When the water content was 10% and 20%, the mass flow rate increased with the steel particle size. But when the water content was 30% and 40%, the mass flow rate decreased with the steel particle size. The study of the control mechanism of the uniformity and stability of particles showed that the funnel flow was the major reason causing the instability and blocking of the feeding process. This research results can provide a basis for the further improvement of the differential pressure feeding system.

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Measurement and simulation validation of numerical model parameters of fresh concrete

Science and Engineering of Composite Materials ◽

10.1515/secm-2021-0042 ◽

2021 ◽

Vol 28 (1) ◽

pp. 437-452

Author(s):

Ke Zhang ◽

Wenda Yu ◽

Dong Li ◽

Defang Zou ◽

Shiying Zhang

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Particle Density ◽

Rolling Friction ◽

Screw Conveyor ◽

Physical Parameters ◽

Model Parameters ◽

Batch Production ◽

Shape Coefficient

Abstract In the numerical simulation of the macroscopic flow of the concrete, it can optimize the performance indicators of the screw conveyor and improve the uniformity of the material to be discharged in the batch production. The discrete element method is effective. The accuracy of physical parameters of this method is a key issue for the reliability of the simulation results of concrete. In this study, we measured the parameters describing the interaction between gravel, mortar, as well as between these two materials and the wall (steel). The experimentally determined parameters include the particle density, size, shape, coefficient of restitution, coefficients of static, and rolling friction. The cohesion coefficient of mortar particles for batch time was obtained by comparing the spread diameter and flow time in V-funnel experiments and simulation. After these calibration steps, the DEM parameters were validated by comparison of the mass flow rate and driving power by the batch production of screw conveying in simulations and experiments. The calculated results are proved to be close to the experimental data, which demonstrates that the measured DEM parameters are of sufficient accuracy to be used in the simulation of concrete flow performance (mass flow rate, energy consumption) in the screw conveyors.

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