Mass‐transfer enhancement in a wavy‐walled tube by imposed fluid oscillation

Nishimura, Tatsuo; Bian, Yongning; Kunitsugu, Koji

doi:10.1002/aic.10070

Cited by 29 publications

(14 citation statements)

References 21 publications

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“…The pre-pump and post-pump reversals that lift mucus from the arches during feeding in O. aureus are comparable to the oscillatory or pulsatile flows that serve to improve the performance of industrial crossflow filtration. Also, pulsatile flow in industry over wall irregularities that resemble the furrows produced by gill rakers and branchial arches has been reported to generate minute vortices that enhance fluid exchange between the region near the filter surface and the mainstream flow, thereby disrupting the boundary layer over the filter surface and reducing particle accumulation near or on the filter surface (Sobey, 1980;Stairmand and Bellhouse, 1985;Nishimura et al, 2004). Swirling of particles was observed through the endoscope when transitions in flow direction occurred during O. aureus feeding, suggesting that there is substantial vortex-mixing during such transitions.…”

Section: Raker Conditionmentioning

confidence: 99%

Intra-Oral Flow Patterns and Speeds in a Suspension-Feeding Fish With Gill Rakers RemovedVersusIntact

Smith

Sanderson

2008

The Biological Bulletin

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Oreochromis aureus, a species of tilapia, is a suspension-feeding fish that employs a pumping action to bring water into its mouth for filtering.To address questions about water flow inside the mouth, we used a microthermistor flow probe to determine the speed of intra-oral flow during suspension feeding in this species before and after surgical removal of gill rakers. Synchronization with high-speed external videotapes of the fish and high-speed video endoscopy inside the oropharyngeal cavity allowed the first correlation of oral actions with intra-oral flow patterns and speeds during feeding. This analysis established the occurrence of a brief reversal of flow ( approximately 80-ms duration) from posterior to anterior in the oropharyngeal cavity prior to every feeding pump (250-500-ms duration). In industrial crossflow filtration, oscillating or pulsatile flow increases filtration performance by enhancing the back-migration of particles from the region near the filter surface to the bulk flow region, thus reducing particle accumulation that can clog the filter. In endoscopic videotapes, these pre-pump reversals, as well as post-pump reversals ( approximately 500-ms duration), were observed to lift mucus and particles from the branchial arches for subsequent transport toward the esophagus. Intra-oral flow speeds were reduced markedly after removal of the gill rakers. We hypothesize that the decrease in crossflow speed during feeding pumps following the removal of gill rakers and mucus could be due to increased loss of water between the anterior branchial arches.

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Section: Raker Conditionmentioning

confidence: 99%

Intra-Oral Flow Patterns and Speeds in a Suspension-Feeding Fish With Gill Rakers RemovedVersusIntact

Smith

Sanderson

2008

The Biological Bulletin

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“…The attractiveness of this method lies in its performance enhancements over the conventional impeller‐driven stirred vessel. This has been reported for processes such as heat‐ and mass‐ transfer,3, 4 gas‐liquid mixing,5 and solid‐liquid suspension 6. However, a comparatively little attention has been paid to studies of this type of mixing on a possible improvement of the quality of precipitated particles, particularly in crystallization of low output high added‐value products, such as pharmaceuticals, dyestuffs, catalysts and proteins.…”

Section: Summary Of Different Methods Used In the Assessment Of Partimentioning

confidence: 62%

Crystallization by oscillatory and conventional mixing at constant power density

Chew¹,

Ristić²

2005

AIChE Journal

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The influence of mixing on crystallization processes has long been recognized. 1,2 The significance of mixing in crystallization is attributed to its role in the development and distribution of supersaturation, as well as the shear forces associated with the velocity field imposed by the impeller motion. These aspects of mixing are paramount to the quality of the precipitates (particles), often characterized by their crystal size distribution (CSD), surface characteristics, chemical purity, and crystalline imperfections (defect contents).Impeller driven stirred vessel has always been the prevalent choice in industrial crystallization for the production of pharmaceutics and specialty chemicals. However, in recent years, there has been an increasing interest in oscillatory flow mixing (OFM) as an attractive alternative mixing method, where intense eddy mixing is achieved in a baffled column by fluid oscillations. The attractiveness of this method lies in its performance enhancements over the conventional impeller-driven stirred vessel. This has been reported for processes such as heat-and mass-transfer, 3, 4 gas-liquid mixing, 5 and solid-liquid suspension. 6 However, a comparatively little attention has been paid to studies of this type of mixing on a possible improvement of the quality of precipitated particles, particularly in crystallization of low output high added-value products, such as pharmaceuticals, dyestuffs, catalysts and proteins.This article reports, for the first time, on the feasibility of OFM to improve the quality of pharmaceutical particles. For this purpose, paracetamol (4-acetaminophenol, 99ϩ%, Merck) was used as a model system.Experiments were conducted in parallel using a specially designed oscillatory baffled batch crystallizer (OBBC) ( Figure 1a) and classical impeller driven batch crystallizer (IDBC) (Figure 1b). The experiments were performed in both crystallizers under the same conditions of residence time ( r ϭ 30 min), temperature of crystallization (T ϭ 20°C), initial supersaturation (20 -50%), volume (500 mL) and power density (1.5 kW/m 3 ), but at distinctly different hydrodynamic environment. Paracetamol solution was prepared using the method previously described. 7 In each experiment, the solution was cooled down to a desired supersaturation before the agitation was initiated. The constant power density applied to both crystallizers was used as the reference criteria in these comparative studies. As we shall see later, this criteria is quite informative, because under the same conditions of residence time, temperature, initial supersaturation and volume of the two crystallizers, it enables us to assess the effectiveness of both mixing methods, in terms of quality of precipitated particles, for a given power input.The power density of IDBC was estimated by the PowerReynolds numbers correlation, which is common for most impeller driven systems; 8 while the power density of OBBC was estimated by the eddy acoustic model suitable for oscillations with frequencies and amplitudes in th...

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“…The mass transfer enhancement by fluid pulsation was estimated by measuring the transfer rates using the electrochemical method [11]. The method estimates the mass transfer rate on a cathode by measuring the current i d , produced by the potential field between anode and cathode.…”

Section: Experimental Apparatus and Proceduresmentioning

confidence: 99%

Mass transfer enhancement by pulsatile flows in grooved channels (the effects of groove length on the resonant mass transfer enhancement)

Kunitsugu

Nishimura

Tanoue

2008

Heat Trans. Asian Res.

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The effect of groove length on the resonant mass transfer enhancement by pulsatile flow in grooved channel at intermediate Reynolds number was studied for five channels using experimental methods. The mass transport processes from the bottom of the groove to the channel were visualized by an electrolytic precipitation method, and overall and local mass transfer rates were measured by electrochemical methods with a high Schmidt number fluid. The qualitative and quantitative observations show that the range of Strouhal numbers, which gives inertia-dominated flow, is extended to the low-value region with groove length. Moreover, it is revealed that a noticeable enhancement is obtained in a specific channel at a Reynolds number for a wide range of Strouhal numbers. The results indicate that there is a specific Reynolds number for transfer enhancement in a channel.

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Mass‐transfer enhancement in a wavy‐walled tube by imposed fluid oscillation

Cited by 29 publications

References 21 publications

Intra-Oral Flow Patterns and Speeds in a Suspension-Feeding Fish With Gill Rakers RemovedVersusIntact

Intra-Oral Flow Patterns and Speeds in a Suspension-Feeding Fish With Gill Rakers RemovedVersusIntact

Crystallization by oscillatory and conventional mixing at constant power density

Mass transfer enhancement by pulsatile flows in grooved channels (the effects of groove length on the resonant mass transfer enhancement)

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