Improved Reverse Electro-Dialysis Using Membranes With Integrated Spacers

2011 ◽  
Author(s):  
O. Burheim ◽  
David A. Vermaas ◽  
Kitty Nijmeijer ◽  
J. G. Pharoah
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Large Scale ◽  
Surface Membrane ◽  
Ionic Current ◽  
Parallel Plates ◽  
Cross Sectional ◽  
Membrane Area ◽  
Number Range ◽  
Power Extraction

Reverse Electro-Dialysis, RED, utilises the energy of mixing between two solutions of different salinity by allowing ionic current to pass through the membranes and the two solutions such that cations are transport to the cathode and anions to the anode. [1–4.] The ionic current is converted to electronic current by red-ox reactions at the cathode and the anode. The membranes applied in this process are ionic selective, traditionally of uniform thickness and separated by a non-conductive spacer [5, 6]. Traditionally, non-conductive spacers have been deployed as eddy promoters and membrane spacers in salinity difference power extraction systems, such as Pressure Retarded Osmosis (PRO) and Reverse Electro-Dialysis (RED). For RED, traditional spacers inhibit parts of the ionic current paths in the fluid compartments and magnify the pressure drop imposed by the fluid flow between the membranes. [6] In a strive to lower the pressure drop in the fluid flow compartment and to increase the conductive region between the membranes, it is suggested to manufacture membranes with new shapes and profiles. [6] By modeling transport of mass and momentum in different geometries, spacing, mixing and active membrane area can be optimised with respect to increasing the power extraction. Such work has previously been done for traditional, i.e. non-electrochemical, flow in spacer separated membrane systems. A classical, approach has been to study submerged and non-submerged non-conductive spacer rods in fluid flow between two parallel plates (membranes) for Reynolds numbers (Re) from 50 and upwards. [7–17] This work discusses how spacers united with the reactant surface (membrane) will affect the mixing and the pressure drops of RED systems with Re numbers between 1 and 100, the expected operational Re number range for RED [6, 18, 19]. This is essential for the power production of RED. For a process converting renewable energy present in nature, such as RED, optimising these parameters is detrimental for the exergy yield. In going from a laboratory scale with a 10 × 10 cm2 cross sectional membrane to a large scale of 100 × 100 cm2, the Reynolds number (Re) increases from 10 to 100 simply because the volume flow is proportional to the flow length. Since it is within this range that eddies starts to get promoted by spacers, different mixing properties is expected exist when comparing laboratory and industrial scaled RED systems.

Parametric investigation of twin tube magnetorheological dampers using a new unsteady theoretical analysis

2019 ◽  
Vol 30 (6) ◽  
pp. 878-895
Author(s):  
Mohammad Mehdi Zolfagharian ◽  
Mohammad Hassan Kayhani ◽  
Mahmood Norouzi ◽  
Amir Jalali
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Static Analysis ◽  
Fluid Velocity ◽  
Magnetorheological Fluid ◽  
Magnetorheological Damper ◽  
Parallel Plates ◽  
Fluid Inertia ◽  
Time Duration ◽  
Inertia Term

In the present work, a new unsteady analytical model is developed for magnetorheological fluid flow through the annular gap which is opened on the piston head of twin tube magnetorheological damper, considering fluid inertia term into the momentum equation. This new unsteady model is based on Stokes’ second problem that is extended for magnetorheological fluid flow between finite oscillating parallel plates under the pressure gradient. A quasi-static analysis is also developed for magnetorheological fluid flow in twin tube damper, to compare its results with present unsteady solution and to show the effect of magnetorheological fluid inertia. The obtained results are validated experimentally and then, a parametric study is presented using both unsteady and quasi-static analysis. The effect of fluid inertia term is investigated on force–displacement and force–velocity loops, magnetorheological fluid velocity profile, pressure drop, phase difference between pressure drop and flow rate and change of plug thickness with time duration. According to the obtained results, quasi-static analysis included considerable error respect to new unsteady analysis as the gap height, magnetorheological fluid density, excitation frequencies and amplitudes are increased and yield stress is decreased. It is found that the plug thickness is considerably affected by inertia term of magnetorheological fluid.

Experiments on the pressure drop created by a sphere settling in a viscous liquid. Part 2. Reynolds numbers from 0·2 to 21,000

1968 ◽  
Vol 32 (4) ◽  
pp. 705-720 ◽  
Author(s):  
Guili A. Feldman ◽  
Howard Brenner
Keyword(s):  
Pressure Drop ◽  
Large Diameter ◽  
Reynolds Numbers ◽  
Cross Sectional ◽  
Number Range ◽  
Liquid Part ◽  
Small Spherical Particle ◽  
Quiescent Liquid ◽  
Limiting Value ◽  
Unbounded Fluid

The pressure drop ΔP created by the motion of a ‘small’ spherical particle settling along the axis of a large-diameter circular cylinder filled with a quiescent liquid was measured in the particle Reynolds number range (based on diameter) from Re = 0·2 to 21,000. For Re < 125 it was found that ΔPA/D = 2·0 (A = cylinder cross-sectional area; D = particle drag), in agreement with existing theory in the Stokes and Oseen regimes. Beyond Re = 125 a fairly abrupt transition occurs, the ΔPA/D ratio decreasing asymptotically towards 1·0, the limiting value predicted by elementary momentum principles for an ‘unbounded’ fluid, with increasing Re. At Re ≈ 6000 the transition is essentially complete.

scholarly journals Predicting the Pressure Drops across Cellulose Acetate Filters

1986 ◽  
Vol 13 (4) ◽  
pp. 157-168
Author(s):  
RW Dwyer
Keyword(s):  
Fluid Flow ◽  
Theoretical Model ◽  
Pressure Drop ◽  
Cellulose Acetate ◽  
Flow Rate ◽  
Fluid Flow Rate ◽  
Cross Sectional ◽  
Cigarette Filter ◽  
Pressure Drops

AbstractA theoretical model of the pressure drop across a fibrous cigarette filter is derived. The pressure drop is expressed as a function of the filter dimensions, the fiber tow characteristics, the filter weight, the fluid flow rate, and a filter fiber factor. The fiber factor is affected by the distribution of the fibers within the filter, the relative orientations of the fibers, and their cross-sectional shapes. The model allows one to accurately calculate the influences of these variables on the filter pressure drop. Additionally, it can be used to predict capability curves and select an optimum cellulose acetate tow for a given filter pressure drop.

scholarly journals Performance Comparison of Spiral-Wound and Plate-and-Frame Forward Osmosis Membrane Module

Membranes ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 318
Author(s):  
Sungyun Lee
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Large Scale ◽  
Forward Osmosis ◽  
Pilot Scale ◽  
Performance Comparison ◽  
Normal Operation ◽  
Membrane Area ◽  
Feed Pressure ◽  
Spiral Wound

We compared two representative forward osmosis (FO) modules—spiral-wound (SW) and plate-and-frame (PF)—to provide practical information for the selection of FO element for a large-scale FO process. The FO operating performance of commercially available SW FO and PF FO was explored under different membrane area and flow rate conditions. The performance trend as a function of the membrane was obtained by adjusting the number of serially connected elements. Although SW FO and PF FO elements exhibited comparable feed pressure drops, SW FO demonstrated a significantly higher draw channel pressure drop than PF FO. Furthermore, the significant draw pressure drop in SW FO increased the draw inlet pressure, consequently limiting the number of serially connected elements. For example, the maximum number of serially connected elements for the normal operation was three elements for SW FO (45.9 m2) but nine elements for PF FO (63 m2) when the flow rate of 10 LMP was applied for feed and draw streams. Additionally, a footprint analysis indicated that SW FO module exhibited a slightly larger footprint than PF FO. Under investigated conditions, PF FO exhibited relatively better performance than SW FO. Therefore, this pilot-scale FO study highlighted the need to reduce the flow resistance of SW FO draw channel to take advantage of the high packing density of the SW element.

Numerical and Experimental Prediction of Transitional Characteristics of Flow and Heat Transfer in an Array of Heated Blocks

1999 ◽  
Vol 121 (3) ◽  
pp. 202-208 ◽  
Author(s):  
Y. Asako ◽  
Y. Yamaguchi ◽  
M. Faghri
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Parallel Plate ◽  
Three Dimensional ◽  
Parallel Plates ◽  
Number Range ◽  
Flow And Heat Transfer ◽  
Numerical Predictions ◽  
Experimental Prediction

Three-dimensional numerical analysis, for transitional characteristics of fluid flow and heat transfer in periodic fully developed region of an array of the heated square blocks deployed along one wall of the parallel plates duct, is carried out by using Lam-Bremhorst low-Reynolds-number two equation turbulence model. Computations were performed for Prandtl number of 0.7, in the Reynolds number range of 200 to 2000 and for two sets of geometric parameters characterizing the array. The predicted transitional Reynolds number is lower than the value for the parallel plate duct and it decreases with increasing the height above the module. Experiments were also performed for pressure drop measurements and for flow visualization and the results were compared with the numerical predictions.

Pressure Drop for Fully Developed Turbulent Flow in Circular and Noncircular Ducts

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Zhipeng Duan ◽  
M. M. Yovanovich ◽  
Y. S. Muzychka
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Square Root ◽  
Sectional Area ◽  
Cross Sectional ◽  
Physical Behavior ◽  
Frictional Pressure Drop ◽  
Fully Developed Turbulent Flow ◽  
The Cross

The objective of this paper is to furnish the engineer with a simple and convenient means of estimating frictional pressure drop in ducts and the original physical behavior can be clearly reflected. Fully developed turbulent flow frictional pressure drop in noncircular ducts is examined. Simple models are proposed to predict the frictional pressure drop in smooth and rough noncircular channels. Through the selection of a novel characteristic length scale, the square root of the cross-sectional area, the effect of duct shape has been minimized. The proposed models have an accuracy of 6% for most common duct shapes of engineering practice and can be used to predict pressure drop of fully developed turbulent flow in noncircular ducts. It is found that the hydraulic diameter is not the appropriate length scale to use in defining the Reynolds number to ensure similarity between the circular and noncircular ducts. By using the Reynolds number based on the square root of the cross-sectional area, it is demonstrated that the circular tube relations may be applied to noncircular ducts eliminating large errors in estimation of pressure drop. The square root of the cross-sectional area is an appropriate characteristic dimension applicable to most duct geometries. The dimensionless mean wall shear stress is a desirable dimensionless parameter to describe fluid flow physical behavior so that fluid flow problems can be solved in the simple and direct manner. The dimensionless mean wall shear stress is presented graphically and appears more general and reasonable to reflect the fluid flow physical behavior than the traditional Moody diagram.

Numerical Analysis of Fluid Flow and Heat Transfer of Flow Between Parallel Plates Having Rectangular Shape Micromixer

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Sudip Shyam ◽  
Aparesh Datta ◽  
Ajoy Kumar Das
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Secondary Flows ◽  
Parallel Plates ◽  
Maximum Enhancement ◽  
Maximum Heat ◽  
Maximum Heat Transfer ◽  
Study Results ◽  
Study Heat Transfer

In this study, heat transfer and fluid flow of de-ionized water in two-dimensional parallel plates microchannel with and without micromixers have been investigated for various Reynolds numbers. The effects of heat transfer and fluid flow on height, diameter of micromixer, and also distance between the two micromixers are carried out in the study. Results showed that the diameter of the micromixer does not have much effect on heat transfer with a maximum enhancement of 9.5%. Whereas heat transfer gets enhanced by 85.57% when the height of the micromixer is increased from 100 μm to 400 μm, and also heat transfer gets improved by 11.45% when sb2 is increased from 4L to 5L. The separation and reattachment zone at the entry and exit of the micromixer cause the increase in heat transfer with the penalty of pressure drop. It is also found that increase of Reynolds number increases the intensity of the secondary flows leads to rapid increase in heat transfer and pressure drop. Finally, the optimized structure of micromixer is found out based on maximum heat transfer and minimum pressure drop.

scholarly journals An investigation into the controls on fracture tortuosity in rock sequences and the impact on fluid flow in the upper crust

2020 ◽  
Author(s):  
Nathaniel Forbes Inskip ◽  
Tomos Phillips ◽  
Kevin Bisdom ◽  
Georgy Borisochev ◽  
Andreas Busch ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Large Scale ◽  
Small Scale ◽  
Fine Scale ◽  
Geothermal Systems ◽  
Parallel Plates ◽  
Core Flooding ◽  
Fracture Surfaces ◽  
Fracture Orientation ◽  
The Impact

&lt;p&gt;Fractures are ubiquitous in geological sequences, and play an important role in the movement of fluids in the earth&amp;#8217;s crust, particularly in fields such as hydrogeology, petroleum geology and volcanology. When predicting or analysing fluid flow, fractures are often simplified as a set of smooth parallel plates. In reality, they exhibit tortuosity on a number of scales: Fine-scale tortuosity, or roughness, is the product of the small-scale (&amp;#181;m &amp;#8211; mm) irregularities in the fracture surface, whereas large-scale (&gt; mm) tortuosity occurs as a result of anisotropy and heterogeneity within the host formation that leads to the formation of irregularities in the fracture surfaces. It is important to consider such tortuosity when analysing processes that rely on the movement (or hindrance) of fluids flowing through fractures in the subsurface. Such processes include fluid injection into granitic plutons for the extraction of heat in Engineered Geothermal Systems, or the injection of CO&lt;sub&gt;2&lt;/sub&gt; into reservoirs overlain by fine-grained mudrocks acting as seals in Carbon Capture and Storage projects.&lt;/p&gt;&lt;p&gt;Although it is generally assumed that tortuosity is controlled by factors such as grain size, mineralogy and fracture mode, a systematic study of how these factors quantitatively affect tortuosity is currently lacking. Furthermore, in anisotropic rocks the fracture orientation with respect to any inherent anisotropy is also likely to affect tortuosity.&lt;/p&gt;&lt;p&gt;In order to address this gap, we have induced fractures in a selection of different rock types (mudrocks, sandstones and carbonates) using the Brazil disk method, and imaged the fracture surfaces using both a digital optical microscope and X-ray Computed Tomography. Using these methods we are able to characterise both the fine-scale (roughness) and large-scale tortuosity. In order to understand the effect of fracture orientation on tortuosity we have also analysed fractures induced at different angles to bedding in samples of a highly anisotropic mudrock taken from South Wales, UK. Results indicate that fine-scale tortuosity is highly dependent on the fracture orientation with regards to the bedding plane, with fractures normal to bedding being rougher than those induced parallel to bedding. Finally, in order to measure the effect of tortuosity on fluid flow, we have carried out a series of core flooding experiments on a subset of fractured samples showing that fracture transmissivity decreases with increasing tortuosity.&lt;/p&gt;

scholarly journals Prediction of pressure drop for turbulent fluid flow in 90° bends

2003 ◽  
Vol 217 (3) ◽  
pp. 153-155 ◽  
Author(s):  
N M Crawford ◽  
G Cunningham ◽  
P L Spedding
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Single Phase ◽  
Number Range ◽  
Turbulent Fluid Flow ◽  
Pressure Losses ◽  
Turbulent Reynolds Number ◽  
Proposed Model ◽  
Future Work ◽  
Phase Fluid

The pressure drop for turbulent single-phase fluid flow around sharp 90° pipe bends has proven to be difficult to predict owing to the complexity of the flow arising from frictional and separation effects. Existing models accurately predict the frictional effects, but no precise models are available to predict the flow due to separation. It is the purpose of this work to propose a model capable of such prediction. The proposed model is presented and added to an existing model to predict pressure losses over the turbulent Reynolds number range up to 3 × 105. The predicted data is within a spread of + 3 to − 2 per cent of existing experimental data. Future work will validate this model experimentally and computationally

Heat Transfer and Pressure Loss in a Two-Pass, Rectangular Channel Featuring a Reduced Cross-Sectional Area After the 180-Degree Tip Turn With Different Turning Vane Configurations

2020 ◽  
Author(s):  
Sulaiman M. Alsaleem ◽  
Lesley M. Wright ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
Cross Section ◽  
Pressure Loss ◽  
Circular Cross Section ◽  
Sectional Area ◽  
Cross Sectional ◽  
Number Range

Abstract Serpentine, varying aspect ratio cooling passages, are typically used in cooling advanced gas turbine blades. These passages are usually connected by sharp, 180-deg bends. In the open literature, most of the internal cooling studies use a fixed cross-sectional area for multi-pass channels. Studies that use varying aspect ratio channels, along with a guide (turn) vane to direct the flow with turning, are scarce. In general, studies show that the incorporation of turning vanes in the bend region of a multi-pass channel keeps the heat transfer rate high while reducing pressure loss. Therefore, the current study investigates the effect of using different guide (turn) vane designs on both the detailed heat transfer distribution and pressure loss in a multi-pass channel with an aspect ratio of (4:1) in the entry passage and (2:1) in the second passage downstream of the vane (s). The first vane configuration is one solid-vane with a semi-circular cross-section connecting the two flow passages. The second configuration has three broken-vanes with a quarter-circular cross-section; two broken vanes are located downstream in the first passage (entering the turn), and one broken vane is upstream in the second passage (exiting the turn). For a Reynolds number range 15,000 to 45,000, detailed heat transfer distributions were obtained on all surfaces within the flow passages by using a transient liquid crystal method. The results show that the turning vane configurations have large effects on the heat transfer, in the turning bend and second passage, and the overall pressure drop. Results show that including the semi-circular vane in the turning region of a multi-pass channel enhanced the overall heat transfer by around 29% with a reduction in pressure loss by around 20%. Moreover, results show that the quarter-circular vane design provides higher overall averaged heat transfer enhancement than the semi-circular vane design by around 9% with penalty of higher pressure drop by 6%, which yields higher thermal performance by 7%, over the Reynolds number range.

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