The application of constant temperature anemometry to membrane processes

Le‐Clech, Pierre; Cao, Zhengjun; Wan, Pingyu; Wiley, Dianne E.; Fane, Anthony G.

doi:10.1016/j.memsci.2006.08.015

Cited by 9 publications

(5 citation statements)

References 18 publications

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“…Le-Clech et al [76] firstly incorporated CTA technology into membrane channels to precisely measure the local flow velocity. The potential of the CTA sensor was confirmed for the measurement of the velocity distribution in a spacer-filled channel fed with pure water or solutions containing dissolved solutes, and in the submerged membrane module with air sparging.…”

Section: Constant Temperature Anemometermentioning

confidence: 99%

In-situ monitoring techniques for membrane fouling and local filtration characteristics in hollow fiber membrane processes: A critical review

et al. 2017

Journal of Membrane Science

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Membrane fouling is the most serious challenge in the hollow fiber microfiltration (MF) and ultrafiltration (UF) processes. A number of in-situ monitoring techniques including optical and non-optical probes have been developed so that membrane fouling is better understood and controlled. This will help advance the membrane technology. In addition, the local filtration hydrodynamics wield a great influence on the membrane fouling formation and system operation stability. State-of-the-art in-situ monitoring techniques for membrane fouling and local filtration characteristics in hollow fiber MF/UF processes are critically reviewed. The principles and applications of these techniques are addressed in order to assess their strengths. This study demonstrated that the real-time observation techniques mainly focus on idealized laboratory apparatus and little on commercial membrane modules. Consequently, more attention should be paid to the development of simple and effective methods or integrated detecting technology so as to satisfy the real status of hollow fiber filtration processes and the optimization of membrane module. On the basis of this review, future analyses considering practical requirements are suggested as R&D priorities.

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Section: Constant Temperature Anemometermentioning

confidence: 99%

In-situ monitoring techniques for membrane fouling and local filtration characteristics in hollow fiber membrane processes: A critical review

et al. 2017

Journal of Membrane Science

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“…It has also been shown that biofilm formation can be measured by a heat transfer sensor 16 . In membrane filtration, heat transfer has been measured by constant temperature anenometry to monitor flow distribution on membrane surfaces 17,18 . This method applies a heating current to a thin platinum wire that is integrated into the feed side spacer of a membrane.…”

Section: Introductionmentioning

confidence: 99%

“…This method applies a heating current to a thin platinum wire that is integrated into the feed side spacer of a membrane. The wire voltage is measured and used to determine the convective heat transfer from the heated element to the surrounding fluid, which has been shown to depend on fluid velocity 17 . The method can describe the heterogeneity of fouling across a membrane, and detect areas with poor aeration or crossflow 18 .…”

Section: Introductionmentioning

confidence: 99%

Membrane fouling monitoring by 3ω sensing

Jørgensen,

Paulsen,

Bentien

et al. 2023

Preprint

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A platinum wire with a diameter of 20 µm and length of 14 mm was attached to the surface of a ceramic membrane for in situ fouling monitoring. By measuring the voltage across the wire while applying an AC current, the amplitude of the third harmonic wave, the so-called 3ω signal, which is inversely proportional to the thermal conductivity around the wire, was obtained. It was demonstrated that the 3ω signal is influenced by changing the environment around the wire as a result of differences in thermal conductivity and heat convection. Measurements of the 3ω signals on the membrane surface covered in varying amounts of acrylic varnish showed an increase in 3ω signal amplitude as the thermally insulating varnish layer increases. At higher AC frequencies, the effect becomes more pronounced as the penetration depth of the thermal wave is decreased. Thus, the frequency of the AC current can be varied to measure thermal conductivity inside and beyond the fouling layer. The method was applied in semi-dead-end filtration of polymeric core-shell particles and crossflow filtration of diluted milk. Results showed increasing 3ω signals over time and correlates directly to the hydraulic resistance of the formed fouling layer, as the fouling layers have low thermal conductivity and because the fouling layers reduced heat convection by crossflow. After membrane cleaning, the magnitude of the 3ω signal is restored to its initial level as before filtration, showing that the 3ω method can be used to monitor and control cleaning. Hence, the 3ω method is a novel and highly promising method to characterize and quantify fouling during filtration and cleaning, and to assess flow conditions locally on membranes.

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“…It has also been shown that biofilm formation can be measured by a heat transfer sensor 17 . In membrane filtration, heat transfer has been measured by constant temperature anenometry to monitor flow distribution on membrane surfaces 18,19 . This method applies a heating current to a thin platinum wire that is integrated into the feed side spacer of a membrane.…”

mentioning

confidence: 99%

“…This method applies a heating current to a thin platinum wire that is integrated into the feed side spacer of a membrane. The wire voltage is measured and used to determine the convective heat transfer from the heated element to the surrounding fluid, which has been shown to depend on fluid velocity 18 . The method can describe the heterogeneity of fouling across a membrane, and detect areas with poor aeration or crossflow 19 .…”

mentioning

confidence: 99%

Membrane fouling monitoring by 3ω sensing

Jørgensen,

Paulsen,

Bentien

et al. 2023

Sci Rep

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Membrane fouling significantly reduces membrane permeability, leading to higher operational expenses. In situ monitoring of membrane fouling can potentially be used to reduce operation cost by optimizing operational parameters and cleaning conditions. In this study, a platinum wire with a diameter of 20 µm was attached to the surface of a ceramic ultrafiltration membrane, and by measuring the voltage across the wire while applying an AC current, the amplitude of the third harmonic wave, the so-called 3ω signal, was obtained. Results showed increasing 3ω signals during formation of fouling layers, which correlates directly to the hydraulic resistance of the formed fouling layer in semi-dead end filtration of polymeric core shell particles and crossflow filtration of diluted milk. This is explained by the insulating effect of the fouling layers which reduces heat convection by crossflow and the different thermal conductivity in the fouling layer compared with the feed. After membrane cleaning, the permeability and the magnitude of the 3ω signal were partly restored, showing that the 3ω method can be used to monitor the effect of cleaning. The frequency of the AC current was varied so it was possible to measure the heat conductivity in the fouling layer (high frequency) and heat convection due to cross-flow (low frequency). This may potentially be used to get information of the type of fouling (heat conductivity) and thickness of the fouling layer (AC frequency where heat conductivity becomes dominating).

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The application of constant temperature anemometry to membrane processes

Cited by 9 publications

References 18 publications

In-situ monitoring techniques for membrane fouling and local filtration characteristics in hollow fiber membrane processes: A critical review

In-situ monitoring techniques for membrane fouling and local filtration characteristics in hollow fiber membrane processes: A critical review

Membrane fouling monitoring by 3ω sensing

Membrane fouling monitoring by 3ω sensing

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