Mass Transfer to an Impinging Jet Electrode

Chin, D.‐T.; Tsang, Chi-Wei

doi:10.1149/1.2131697

Cited by 227 publications

(209 citation statements)

References 24 publications

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“…This interfacial resistance is in series with the diffusive resistance of the membrane and must be accounted for. For impinging-jet flow, the mass-transfer coefficient scales with the square root of the air-flow rate [41]. Therefore, a plot of 1/n 1 as a function of Re -1/2 should be linear.…”

Section: Apparatusmentioning

confidence: 99%

Steady-state diffusion of water through soft-contact-lens materials

et al. 2005

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Water transport through soft contact lenses (SCL) is important for acceptable performance on the human eye. Chemical-potential gradient-driven diffusion rates of water through soft-contact-lens materials are measured with an evaporation-cell technique. Water is evaporated from the bottom surface of a lens membrane by impinging air at controlled flow rate and humidity. The resulting weight loss of a water reservoir covering the top surface of the contact-lens material is recorded as a function of time.New results are reported for a conventional hydrogel material (SofLens TM One Day, hilafilcon A, water content at saturation w 10 = 70 weight %) and a silicone hydrogel material (PureVision TM , balafilcon A, w 10 = 36 %), with and without surface oxygen plasma treatment. Also, previously reported data for a conventional HEMA-SCL (w 10 = 38 %) hydrogel are reexamined and compared with those for SofLens TM One Day and PureVision TM hydrogels. Measured steady-state water fluxes are largest for SofLens TM One Day, followed by PureVision TM and HEMA. In some cases, the measured steadystate water fluxes increase with rising relative air humidity. This increase, due to an apparent mass-transfer resistance at the surface (trapping skinning), is associated with formation of a glassy skin at the air/membrane interface when the relative humidity is below 55-75%.Steady-state water-fluxes are interpreted through an extended Maxwell-Stefan diffusion model for a mixture of species starkly different in size. Thermodynamic nonideality is considered through Flory-Rehner polymer-solution theory. Shrinking/swelling is self-consistently modeled by conservation of the total polymer mass. Fitted MaxwellStefan diffusivities increase significantly with water concentration in the contact lens. Water Diffusion through SCLs

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Section: Apparatusmentioning

confidence: 99%

Steady-state diffusion of water through soft-contact-lens materials

et al. 2005

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“…The hydrodynamics associated with an impinging jet form a stagnation region at the center of the electrode surface that is surrounded by a decaying radial flow away from the electrode's center in the wall-jet region. 11 Impinging jet electrodes are generally classified according to two limiting types, wall-tube and wall-jet electrodes, whose classification is based on the electrode and the nozzle dimensions. 12 Wall-tube electrodes involve a smaller electrode with a jet formed from a larger nozzle in such a way that the electrode falls completely within the stagnation region, giving a uniformly accessible electrode surface.…”

Section: * S Supporting Informationmentioning

confidence: 99%

High Rate Detection of Volatile Products Using Differential Electrochemical Mass Spectrometry: Combining an Electrode-Coated Membrane with Hydrodynamic Flow in a Wall-Tube Configuration

et al. 2013

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We present an experimental system that combines differential electrochemical mass spectrometry with hydrodynamic flow consisting of an impinging jet in a wall-tube configuration. This assembly allows simultaneous detection of electrochemical signals along with monitoring of dissolved gas species using differential electrochemical mass spectrometry under well-defined hydrodynamic conditions and over a wide range of mass transfer rates. The working electrode is deposited directly onto a thin, hydrophobic membrane, which also serves as the inlet to the mass spectrometer. This inlet provides extremely rapid mass detection as well as a high flux of products from the electrode surface into the mass spectrometer. The impinging jet is designed in a wall-tube configuration, in which the jet diameter is large compared to the electrode diameter, thus providing uniform and rapid mass transfer conditions over the entirety of the electrode surface. This combination of rapid detection and controllable flow conditions allows a wide range of hydrodynamic conditions to be accessed with simultaneous electrochemical and mass spectrometric detection of dissolved gas species, which is important in the analysis of a range of electrochemical reactions. The capabilities of this configuration are illustrated using a platinum-coated electrode and several electrochemical reactions, including ferrocyanide oxidation, proton reduction, and oxalic acid oxidation. ABSTRACT: We present an experimental system that combines differential electrochemical mass spectrometry with hydrodynamic flow consisting of an impinging jet in a wall-tube configuration. This assembly allows simultaneous detection of electrochemical signals along with monitoring of dissolved gas species using differential electrochemical mass spectrometry under well-defined hydrodynamic conditions and over a wide range of mass transfer rates. The working electrode is deposited directly onto a thin, hydrophobic membrane, which also serves as the inlet to the mass spectrometer. This inlet provides extremely rapid mass detection as well as a high flux of products from the electrode surface into the mass spectrometer. The impinging jet is designed in a wall-tube configuration, in which the jet diameter is large compared to the electrode diameter, thus providing uniform and rapid mass transfer conditions over the entirety of the electrode surface. This combination of rapid detection and controllable flow conditions allows a wide range of hydrodynamic conditions to be accessed with simultaneous electrochemical and mass spectrometric detection of dissolved gas species, which is important in the analysis of a range of electrochemical reactions. The capabilities of this configuration are illustrated using a platinum-coated electrode and several electrochemical reactions, including ferrocyanide oxidation, proton reduction, and oxalic acid oxidation.

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“…Vallis et al [32], Kataoka et al [33] and Chin and Tsang [34] used this method for the local mass transfer measurement from a round impinging jet. Overall, there is a general consensus that the mass transfer is an increasing function of the Reynolds numbers.…”

Section: Introductionmentioning

confidence: 99%

“…Chin and Tsang [34] proposed a correlation (Eq. 6) to approach the stagnation Sherwood number in a round impinging jet having a Reynolds number ranging from 4000 to 16000 and a nozzle to plate distance H/D ranging from 0.2 to 6. we obtain a stagnation Sherwood number of 898 which is extremely close to the value (900) obtained by direct measurement in the case of the reference round jet.…”

mentioning

confidence: 99%

Impinging cross-shaped submerged jet on a flat plate: a comparison of plane and hemispherical orifice nozzles

et al. 2015

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To cite this version:Kodjovi Sodjavi, Brice Montagné, Pierre Bragança, Amina Meslem, Florin Bode, et al.. Impinging cross-shaped submerged jet on a flat plate: a comparison of plane and hemispherical orifice nozzles. Meccanica, Springer Verlag, 2015, pp.1-21. 10 AbstractIt is well known that the transfer of heat, mass and momentum to a wall by an impinging jet is partially linked to the way in which jet generation is realized. The organization of the vortices at the jet exit depends on the upstream conditions and on the geometry of the nozzle. Particle Image Velocimetry (PIV) and electrodiffusion techniques were used to investigate the characteristics of different impinging jets and the resulting wall shear rates and mass transfer. Two Cross-Shaped orifice jets, one produced by a plane orifice nozzle (i.e. a Cross-Shaped Orifice made on a flat Plate, CO/P) and the second by a hemispherical orifice nozzle (i.e. a Cross-Shaped Orifice made on a Hemisphere, CO/H), were compared to a reference round jet produced by a convergent nozzle. The distance between the jet exit and the target wall was equal to two nozzle equivalent diameters (De), based on the free orifice area. The Reynolds number, based on De and on the exit bulk-velocity, was 5620 for each flow. PIV measurements give an overall view of the flow characteristics in their free and wall regions. The switching-over phenomena observed in the CO/P nozzle case, and already described in the literature with similar nozzles, did not occur in the jet from the CO/H nozzle. Electrodiffusion measurements showed differences in the shape and level of radial distribution of the wall shear rates and mass transfer. One of the most important observations is the large difference in wall shear stress between the three jets. For the same exit bulk-velocity, the maximum wall shear rate in the CO/P and CO/H nozzle jets was almost two and three times higher, respectively, than that of the reference convergent jet. This higher wall shear rate is accompanied

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Mass Transfer to an Impinging Jet Electrode

Cited by 227 publications

References 24 publications

Steady-state diffusion of water through soft-contact-lens materials

Steady-state diffusion of water through soft-contact-lens materials

High Rate Detection of Volatile Products Using Differential Electrochemical Mass Spectrometry: Combining an Electrode-Coated Membrane with Hydrodynamic Flow in a Wall-Tube Configuration

Impinging cross-shaped submerged jet on a flat plate: a comparison of plane and hemispherical orifice nozzles

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