A study of the flow structures generated by oscillating flows in a helical baffled tube

McDonough, Jonathan; Ahmed, Safaa M.R.; Phan, Anh N.; Harvey, Adam P.

doi:10.1016/j.ces.2017.05.032

Cited by 25 publications

(28 citation statements)

References 20 publications

(47 reference statements)

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“…9 (Reo=0), the trends of TH data here in Fig. 10 (a) and (b) differ due to the different flow pattern of the fluid with applying oscillation where secondary mixing occurs as a result of formation of recirculation zones in the baffle cavities [4,8,10]. However, at Ren=640 (Fig.…”

Section: Thermal Performance Of Meso-obrmentioning

confidence: 88%

“…Consequently, this leads to significant boundary layer disruption and significantly enhanced rates of convection. The OHBR shows higher Nu enhancement than OOBR at Reo=360 indicating swirling flow formation, hence mixing enhances [10]. However, at Reo=1080, it shows insignificant enhancement indicating chaotic mixing formation [4,5,10] for both baffle designs.…”

Section: Effect Of Net Flowmentioning

confidence: 89%

“…14a and 14b), where λ is the coefficient of thermal performance which is dependent on the tube diameter and internals. The differing values of λ for each scale/baffle design accounts for how the mixing in OBRs differs depending on these design parameters, as shown in various previous works [4,5,6,8,10]. Table 4 1 Correlation may be valid outside of this range, but this is the proven range to date.…”

Section: Fig 8 Comparison Of Nusselt Number Prediction By Correlatimentioning

confidence: 91%

“…The pressure drop in the OCBR was substantially higher than the other designs: factors of 3, 5 and 15 greater than the OOBR, OHBR, and OR, respectively. This is probably due to the blockage in the midline flow resulting in higher shear stress [6,10]. The OOBR showed a greater ΔP than the OHBR (factor of around 2.6), likely due to the combined effect of the narrow orifice diameter and sharp baffle edge generating a high degree of shear stress (although less than that generated in the OCBR).…”

Section: Range Of Oscillatory Flow Reo 0 -1550mentioning

confidence: 94%

“…Increasing mixing intensity, Reo, from 360 to 1080 led to higher enhancement in heat transfer for the helical and orifice baffle designs, but had no effect for the central baffle design. This is probably due to the central baffle geometry which induces chaotic flow to occur at lower oscillation intensities than those required by the OHBR and OOBR [6,9,10].…”

Section: Effect Of Net Flowmentioning

confidence: 99%

See 4 more Smart Citations

Thermal performance of meso-scale oscillatory baffled reactors

Ahmed

Law

Phan

et al. 2018

Chemical Engineering and Processing - Process Intensification

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This study reports the evaluation of heat transfer characteristics and pressure drops in three designs of mesoscale oscillatory baffled reactors over the net flow range Ren = 60-2500 and the oscillatory flow range Reo = 0-1600. The three designs were the oscillatory central baffled reactor (OCBR), the oscillatory helical baffled reactor (OHBR), and the oscillatory orifice baffled reactor (OOBR). The designs were evaluated in terms of "thermal performance" to take the heat transfer and pressure drop into account.Interestingly, in all designs the pressure drop was observed to decrease with increasing oscillation, due to some degree of energy recovery. In all cases, oscillating the flow significantly enhanced the Nusselt number by upto a maximum of around 10-fold. The meso-OBRs were shown to achieve higher thermal performances than steady flows in smooth tubes in all cases. Up to 480%, 460%, and 300% improvements in thermal performance was achieved for the OHBR, OCBR, and OOBR, respectively. The OHBR exhibited the lowest pressure drop, resulting in the highest thermal performance of the designs investigated here. Hence, on the basis of this study, the OHBR design is recommended. New empirical correlations for predicting pressure drop and Nusselt number were established for each design, with data mostly lying in the range ±30% of the correlations.

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Section: Thermal Performance Of Meso-obrmentioning

confidence: 88%

Section: Effect Of Net Flowmentioning

confidence: 89%

Section: Fig 8 Comparison Of Nusselt Number Prediction By Correlatimentioning

confidence: 91%

Section: Range Of Oscillatory Flow Reo 0 -1550mentioning

confidence: 94%

Section: Effect Of Net Flowmentioning

confidence: 99%

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Thermal performance of meso-scale oscillatory baffled reactors

Ahmed

Law

Phan

et al. 2018

Chemical Engineering and Processing - Process Intensification

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Continuous Reactive Crystallization in a Mesoscale Oscillatory Baffled Reactor

et al. 2023

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Continuous reactive crystallization was carried out in a mesoscale oscillatory baffled reactor (meso‐OBR), using calcium carbonate as a case study to demonstrate the ability of high solid loadings and to examine the fouling potential in continuous processes. Plug flow behavior was easily achieved in reactive solid‐liquid phase reaction systems, as evidenced by the rapid establishment of a steady state. Effects of the operating conditions (reactant concentration, mixing conditions, and temperature) on the yield, particle size, and particle size distribution were studied. Increasing the reactant concentration and oscillation conditions reduced the particle size whereas increasing the operating temperature led to a large particle size. The meso‐OBR produced uniformly shaped spherical crystals, with a 35 % reduction in average particle size and high purity compared to conventional stirred tanks. The meso‐OBR could be used continuously for up to 6 h with less than 1 wt % of fouling (product loss).

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Oscillatory flow reactors for synthetic chemistry applications

2020

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Oscillatory flow reactors (OFRs) superimpose an oscillatory flow to the net movement through a flow reactor. OFRs have been engineered to enable improved mixing, excellent heat- and mass transfer and good plug flow character under a broad range of operating conditions. Such features render these reactors appealing, since they are suitable for reactions that require long residence times, improved mass transfer (such as in biphasic liquid-liquid systems) or to homogeneously suspend solid particles. Various OFR configurations, offering specific features, have been developed over the past two decades, with significant progress still being made. This review outlines the principles and recent advances in OFR technology and overviews the synthetic applications of OFRs for liquid-liquid and solid-liquid biphasic systems.

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A study of the flow structures generated by oscillating flows in a helical baffled tube

Cited by 25 publications

References 20 publications

Thermal performance of meso-scale oscillatory baffled reactors

Thermal performance of meso-scale oscillatory baffled reactors

Continuous Reactive Crystallization in a Mesoscale Oscillatory Baffled Reactor

Oscillatory flow reactors for synthetic chemistry applications

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