Showing papers on "Volumetric flow rate published in 2016"

Effects of hall and ion slip on MHD peristaltic flow of Jeffrey fluid in a non-uniform rectangular duct

Abstract: Purpose – The purpose of this paper is to theoretically study the problem of the peristaltic flow of Jeffrey fluid in a non-uniform rectangular duct under the effects of Hall and ion slip. An incompressible and magnetohydrodynamics fluid is also taken into account. The governing equations are modelled under the constraints of low Reynolds number and long wave length. Recent development in biomedical engineering has enabled the use of the periastic flow in modern drug delivery systems with great utility. Design/methodology/approach – Numerical integration is used to analyse the novel features of volumetric flow rate, average volume flow rate, instantaneous flux and the pressure gradient. The impact of physical parameters is depicted with the help of graphs. The trapping phenomenon is presented through stream lines. Findings – The results of Newtonian fluid model can be obtained by taking out the effects of Jeffrey parameter from this model. No-slip case is a special case of the present work. The results ob...

A High-Energy-Density Multiple Redox Semi-Solid-Liquid Flow Battery

Abstract: A new concept of multiple redox semi-solid-liquid (MRSSL) flow battery that takes advantage of active materials in both liquid and solid phases, is proposed and demonstrated. Liquid lithium iodide (LiI) electrolyte and solid sulfur/carbon (S/C) composite, forming LiI-S/C MRSSL catholyte, are employed to demonstrate this concept. Record volumetric capacity (550 Ah L−1catholyte) is achieved using highly concentrated and synergistic multiple redox reactions of LiI and sulfur. The liquid LiI electrolyte is found to increase the reversible volumetric capacity of the catholyte, improve the electrochemical utilization of the S/C composite, and reduce the viscosity of catholyte. A continuous flow test is demonstrated and the influence of the flow rate on the flow battery performance is discussed. The MRSSL flow battery concept transforms inactive component into bi-functional active species and creates synergistic interactions between multiple redox couples, offering a new direction and wide-open opportunities to develop high-energy-density flow batteries.

4D ultrafast ultrasound flow imaging: in vivo quantification of arterial volumetric flow rate in a single heartbeat.

Abstract: We present herein 4D ultrafast ultrasound flow imaging, a novel ultrasound-based volumetric imaging technique for the quantitative mapping of blood flow. Complete volumetric blood flow distribution imaging was achieved through 2D tilted plane-wave insonification, 2D multi-angle cross-beam beamforming, and 3D vector Doppler velocity components estimation by least-squares fitting. 4D ultrafast ultrasound flow imaging was performed in large volumetric fields of view at very high volume rate (>4000 volumes s-1) using a 1024-channel 4D ultrafast ultrasound scanner and a 2D matrix-array transducer. The precision of the technique was evaluated in vitro by using 3D velocity vector maps to estimate volumetric flow rates in a vessel phantom. Volumetric Flow rate errors of less than 5% were found when volumetric flow rates and peak velocities were respectively less than 360 ml min-1 and 100 cm s-1. The average volumetric flow rate error increased to 18.3% when volumetric flow rates and peak velocities were up to 490 ml min-1 and 1.3 m s-1, respectively. The in vivo feasibility of the technique was shown in the carotid arteries of two healthy volunteers. The 3D blood flow velocity distribution was assessed during one cardiac cycle in a full volume and it was used to quantify volumetric flow rates (375 ± 57 ml min-1 and 275 ± 43 ml min-1). Finally, the formation of 3D vortices at the carotid artery bifurcation was imaged at high volume rates.

Pore‐scale simulation of carbonate dissolution in micro‐CT images

Abstract: We present a particle-based method to simulate carbonate dissolution at the pore scale directly on the voxels of three-dimensional micro-CT images. The flow field is computed on the images by solving the incompressible Navier-Stokes equations. Rock-fluid interaction is modeled using a three-step approach: solute advection, diffusion, and reaction. Advection is simulated with a semianalytical pore-scale streamline tracing algorithm, diffusion by random walk is superimposed, while the reaction rate is defined by the flux of particles through the pore-solid interface. We derive a relationship between the local particle flux and the independently measured batch calcite dissolution rate. We validate our method against a dynamic imaging experiment where a Ketton oolite is imaged during CO2-saturated brine injection at reservoir conditions. The image-calculated increases in porosity and permeability are predicted accurately, and the spatial distribution of the dissolution front is correctly replicated. The experiments and simulations are performed at a high flow rate, in the uniform dissolution regime – Pe ≫ 1 and PeDa ≪ 1—thus extending the reaction throughout the sample. Transport is advection dominated, and dissolution is limited to regions with significant inflow of solute. We show that the sample-averaged reaction rate is 1 order of magnitude lower than that measured in batch reactors. This decrease is the result of restrictions imposed on the flux of solute to the solid surface by the heterogeneous flow field, at the millimeter scale.

Flow invariant droplet formation for stable parallel microreactors

Abstract: The translation of batch chemistries onto continuous flow platforms requires addressing the issues of consistent fluidic behaviour, channel fouling and high-throughput processing. Droplet microfluidic technologies reduce channel fouling and provide an improved level of control over heat and mass transfer to control reaction kinetics. However, in conventional geometries, the droplet size is sensitive to changes in flow rates. Here we report a three-dimensional droplet generating device that exhibits flow invariant behaviour and is robust to fluctuations in flow rate. In addition, the droplet generator is capable of producing droplet volumes spanning four orders of magnitude. We apply this device in a parallel network to synthesize platinum nanoparticles using an ionic liquid solvent, demonstrate reproducible synthesis after recycling the ionic liquid, and double the reaction yield compared with an analogous batch synthesis.

A Very Stable High Throughput Taylor Cone-jet in Electrohydrodynamics

Abstract: A stable capillary liquid jet formed by an electric field is an important physical phenomenon for formation of controllable small droplets, power generation and chemical reactions, printing and patterning, and chemical-biological investigations. In electrohydrodynamics, the well-known Taylor cone-jet has a stability margin within a certain range of the liquid flow rate (Q) and the applied voltage (V). Here, we introduce a simple mechanism to greatly extend the Taylor cone-jet stability margin and produce a very high throughput. For an ethanol cone-jet emitting from a simple nozzle, the stability margin is obtained within 1 kV for low flow rates, decaying with flow rate up to 2 ml/h. By installing a hemispherical cap above the nozzle, we demonstrate that the stability margin could increase to 5 kV for low flow rates, decaying to zero for a maximum flow rate of 65 ml/h. The governing borders of stability margins are discussed and obtained for three other liquids: methanol, 1-propanol and 1-butanol. For a gravity-directed nozzle, the produced cone-jet is more stable against perturbations and the axis of the spray remains in the same direction through the whole stability margin, unlike the cone-jet of conventional simple nozzles.

Simulation of CO2 absorption by solution of ammonium ionic liquid in hollow-fiber contactors

Abstract: Membrane-based chemical absorption of CO2 from gas mixtures containing CO2 using tetramethylammonium glycinate solution was studied in this work. The absorption media studied in this work involves a porous membrane contactor which is utilized as a physical barrier for contacting feed gas stream and the chemical solvent. The considered membrane module type was hollow fiber. The equations of concentration for both CO2 and solvent were derived and solved numerically using computational fluid dynamics (CFD) approach. The equations were solved in two dimensions and in cylindrical coordinate, i.e. axial and radial directions in order to obtain the concentration and mass transfer flux of CO2 and solvent in the hollow-fiber contactor. Both convection and diffusional mass transfers were taken into account in the simulations. The findings of CFD simulation demonstrated that as the flow rate as well as the concentration of the absorbent increased, the CO2 removal from gas mixture enhanced; while, the enhancement of gas flow rate declined the removal rate of CO2 in the contactor. The proposed simulation method revealed to be capable of predicting CO2 capture from gas mixtures in membrane contactors.

Stack Design and Operation for Scaling Up the Capacity of Flow-Electrode Capacitive Deionization Technology

Abstract: Flow electrodes have recently been studied for use in capacitive deionization applications because of their continuous and high desalting efficiency. The production capacity of desalinated water in the flow-electrode capacitive deionization (FCDI) system is limited compared to infinite ion capacity of the flow electrodes due to restrictions in the flow rate of the influent/effluent. Therefore, we designed and fabricated an FCDI stack with five unit cells in order to increase the production capacity of desalinated water. Through inlet pressure measurements of the flow electrodes in the FCDI stack, we confirmed that the flow electrodes were uniformly segmented from the manifold formed in the FCDI stack into the flow channels of each unit cell. We also confirmed that there was no pressure increase at the flow electrode in the flow channel caused by an increase in the number of unit cells in the FCDI stack. Also, the FCDI stack showed a similar desalting efficiency when compared to that of the FCDI unit cell....