High Throughput Testing of Catalysts for The Hydrogenation of Carbon Monoxide to Ethanol

Chemical Engineering Journal

2009

a b s t r a c tA no-moving-part microfluidic oscillator was developed for mixing two reactants prior to their admission into a microreactor. Instead of the spatial periodicity produced by static mixers, it achieves essentially the same resultant effect by temporal periodicity. In one half of the oscillation period the oscillator directs into its output one reactant, followed by the other reactant during the other half-period. Since the periods are short, the flow in the output channel consists, like in the static mixers, of interleaved layers of the two fluids -here, however, oriented perpendicularly relative to the flow direction. The oscillation depends on dynamic effects so that there is a lower limit of Reynolds numbers at which the device can operate. In experiments this limit was at Re ∼30, which makes the device well suited for use with present-day microreactors, especially if the mixer is used to supply several reactors in parallel. Data from experiments with two different models agree with very simple kinematic theory for oscillation frequency and for the size of the generated layers in the output.

Section: Laboratory Modelsmentioning

confidence: 92%

Section: Laboratory Modelsmentioning

confidence: 99%

Oscillator micromixer

Chemical Engineering Journal

2009

“…9 (fluidic resistance of the output channel) plotted as a function of Reynolds number. Fluidic resistance as defined as the proportionality constant in the assumed linear dependence (3) between the pressure drop across the device and the volume flow rate passing through it. This direct analogy to the Ohm'slawof electric circuits assumes incompressible flow conditions, rarely a real problem.…”

Section: B Flow Interrupting Valvementioning

confidence: 99%

“…This is because of the desirability of very small size and also often due to small flow rates dictated by factors such as small sample volume or required residence time in microreactors. Not infrequently low Re is also caused by the high viscosity of the processed fluids, such as biological samples or hot gas in fuel synthesis applications [3].…”

mentioning

confidence: 99%

Subdynamic asymptotic behavior of microfluidic valves

J. Microelectromech. Syst.

Tippetts

Allen

et al. 2005

Self Cite

Abstract-Decreasing the Reynolds number of microfluidic no-moving-part flow control valves considerably below the usual operating range leads to a distinct "subdynamic" regime of viscosity-dominated flow, usually entered through a clearly defined transition. In this regime, the dynamic effects on which the operation of large-scale no-moving-part fluidic valves is based, cease to be useful, but fluid may be driven through the valve (and any connected load) by an applied pressure difference, maintained by an external pressure regulator. Reynolds number ceases to characterize the valve operation, but the driving pressure effect is usefully characterized by a newly introduced dimensionless number and it is this parameter which determines the valve behavior. This summary paper presents information about the subdynamic regime using data (otherwise difficult to access) obtained for several recently developed flow control valves. The purely subdynamic regime is an extreme. Most present-day microfluidic valves are operated at higher Re, but the paper shows that the laws governing subdynamic flows provide relations useful as an asymptotic reference.[1017]

“…The task was to sample small gas flows from 16 small catalytic reactors. The reaction investigated was the Fischer-Tropfsch hydrogenation of carbon monoxide to ethanol, typically at 400 C and at 4 MPa (Wilkin et al, 2002). The sampling unit consisted of 16 valves arranged in a radial array around the central outlet to the analyser.…”

Section: The Taskmentioning

confidence: 99%

Development of a Microfluidic Unit for Sequencing Fluid Samples for Composition Analysis

Chemical Engineering Research and Design

Tippetts

Low

et al. 2004

ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. A microfluidic sample-sequencing unit was developed as a part of a high-throughput catalyst screening facility. It may find applications wherever a fluid is to be selected for analysis from any one of several sources, such as microreactors operating in parallel. The novel feature is that the key components are fluidic valves having no moving parts and operating at very low sample flow Reynolds numbers, typically below 100. The inertial effects utilized in conventional no-moving-part fluidics are nearly absent; instead, the flows are pressure-driven. Switching between input channels is by high-Reynolds-number control flows, the jet pumping effect of which simultaneously cleans the downstream cavities to prevent crosscontamination between the samples. In the configuration discussed here, the integrated circuit containing an array of 16 valves is etched into an 84 mm diameter stainless steel foil. This is clamped into a massive assembly containing 16 mini-reactors operated at up to 400 C and 4 MPa. This paper describes the design basis and experience with prototypes. Results of CFD analysis, with scrutiny of some discrepancies when compared with flow visualization, is included. 0263-8762/04/$30.00+0.00 # 2004 Institution of Chemical Engineers www.ingentaselect.com=titles=02638762.htm Trans IChemE, Part A, June 2004 Chemical Engineering