Fluidisation and packed bed behaviour in capillary tubes

Doroodchi, Elham; Peng, Zhengbiao; Sathe, Mayur J.; Abbasi-Shavazi, Ehsan; Evans, Geoffrey M.

doi:10.1016/j.powtec.2011.08.011

Cited by 43 publications

(20 citation statements)

References 9 publications

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“…As steady bed behaviour was achieved about 30 s after the step change, the last 30 seconds at a given flow rate were the focus of the subsequent analysis. The decreasing of the flow rate here averts pressure overshoot, which may be present due to the large particle-to-bed size ratios of the system (dp/Dh ~ 0.12 to 0.16 based on the micro-channel hydraulic diameter, Dh ~ 243.5µm, see Table 1) [36]. As a baseline for comparison of mixing behaviour, identical trials were also carried out in the same channel with no particles present.…”

Section: Fluidizing Materialsmentioning

confidence: 99%

“…Since its initial introduction by Potic et al [33], only a small number of studies have been reported on liquid fluidization in µFB. Whilst some of these studies have been application-focused [34,35], the vast majority have focused on hydrodynamic aspects of µFBs [28,31,36,37] and the effects of surface forces and wall effects on their fluidization behaviour [28,29,38,39]. Of these, only Doroodchi et al [31] have focused in detail on mixing.…”

Section: Introductionmentioning

confidence: 99%

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Experimental study of efficient mixing in a micro-fluidized bed

Živković

Ridge

Biggs

2017

Applied Thermal Engineering

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Section: Fluidizing Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental study of efficient mixing in a micro-fluidized bed

Živković

Ridge

Biggs

2017

Applied Thermal Engineering

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“…We can see from this figure that the adhesion force becomes comparable to the drag force (ratio below 10) for approximately 300 µm glass particles and 2.5 mm PMMA particles, while they are equal for approximately 1 mm and 8 mm glass and PMMA particle diameter respectively. Based on this analysis and assuming a bed-to-particle ratio of 10, which is typical in micro-fluidized bed studies (Doroodchi et al, 2012;Potic et al, 2005;Zivkovic et al, 2013b), the rough boundary between micro-and macro-fluidization can be estimated to be between 1-10 mm for glass particles and between 10-80 mm for PMMA particles.…”

Section: Boundary Between Macro-and Micro-fluidizationmentioning

confidence: 99%

“…They have, however, not been exploited at all in the microfluidics context. Recent modelling (Derksen, 2008(Derksen, , 2009) and experimental work (Doroodchi et al, 2012;Potic et al, 2005;Zivkovic et al, 2013a;Zivkovic et al, 2013b) has demonstrated that microfluidic fluidized beds (termed henceforth 'microfluidized beds') are feasible, offering the potential to not only overcome diffusion-limited heat and mass transport in simple micron-sized channels, but also provide higher sensitivity and multi-modal detection in the diagnostic context by virtue of the large surface area per unit volume that comes from use of micro-particles (Derveaux et al, 2008;Lim and Zhang, 2007).…”

Section: Introductionmentioning

confidence: 99%

On importance of surface forces in a microfluidic fluidized bed

Živković

Biggs

2015

Chemical Engineering Science

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Fluidized beds potentially offer a means of significantly enhancing mixing, heat and mass transfer under the low Reynolds number flow conditions that prevail in microfluidic devices. However, as surface forces at the microscale can be significant relative to hydrodynamics forces, fluidization within a microfluidic channel can be potentially hindered or even prevented through particle adhesion to the channel walls.We have used the acid-base theory of van Oss, Chaudhury and Good to predict the propensity for adhesion of particles on microfluidic fluidized bed walls for various practically important wall material/particle/fluid combinations. Comparison of the results from this approach with experimental observations indicates it provides a robust means of predicting the adhesion propensity. It is also demonstrated how results from the model can be used to estimate for a system of interest the particle size range in which the particle-wall surface forces transition from being dominate to being insignificant.

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“…The small test volumes and short residence times also make µPBs ideal for rapid, highthroughput catalyst screening (Cao et al, 2007, Ehrfeld et al, 2000, and in the liquid chromatography context in the pharmaceutical sector (Jung et al, 2009). They are also of relevance to micro-fluidized beds (Zivkovic et al, 2013a, Zivkovic et al, 2013b, Doroodchi et al, 2012, Doroodchi et al, 2013 in that they are clearly formed from packed beds. Beyond the process engineering context, µPBs are used in Micro Total Analysis Systems (µTAS), which have long been used for chemical and biochemical analysis (Reyes et al, 2002), including in clinical chemistry (also known as lab-on-a-chip or LOC) (Schulte et al, 2002, Melin and Quake, 2007, Haeberle et al, 2012, Abgrall and Gué, 2007.…”

Section: Introductionmentioning

confidence: 99%

A new method for reconstruction of the structure of micro-packed beds of spherical particles from desktop X-ray microtomography images. Part A. Initial structure generation and porosity determination

Kashani

Živković

Elekaei

et al. 2016

Chemical Engineering Science

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Citation: NAVVAB KASHANI, M. ...et al., 2016. A new method for reconstruction of the structure of micro-packed beds of spherical particles from desktop X-ray microtomography images. Part A. Initial structure generation and porosity determination. Chemical Engineering Science, 146, Additional Information:• This paper was accepted for publication in the journal Chemical En- AbstractMicro-packed beds (µPBs) are seeing increasing use in the process intensification context (e.g. micro-reactors), in separation and purification, particularly in the pharmaceutical and bio-products sectors, and in analytical chemistry. The structure of the stationary phase and of the void space it defines in such columns is of interest because it strongly influences performance. However, instrumental limitations -in particular the limited resolution of various imaging techniques relative to the particle and void space dimensions -have impeded experimental study of the structure of µPBs. We report here a new method that obviates this issue when the µPBs are composed of particles that may be approximated by monodisperse spheres. It achieves this by identifying in successive cross-sectional images of the bed the approximate centre and diameter of the particle cross-sections, replacing them with circles, and then assembling them to form the particles by identifying correlations between the successive images. Two important novel aspects of the method proposed here are it does not require specification of a threshold for binarizing the images, and it preserves the underlying spherical geometry of the packing. The new method is demonstrated through its application to a packing of a near-monodispersed 30.5 µm particles of high sphericity within a 200 µm square cross-section column imaged using a machine capable of 2.28 µm resolution. The porosity obtained was, within statistical uncertainty, the same as that determined via a direct method whilst use of a commonly used automatic thresholding technique yielded a result that was nearly 10% adrift, well beyond the experimental uncertainty. Extension of the method to packings of spherical particles that are less monodisperse or of different regular shapes (e.g. ellipsoids) is also discussed.

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Fluidisation and packed bed behaviour in capillary tubes

Cited by 43 publications

References 9 publications

Experimental study of efficient mixing in a micro-fluidized bed

Experimental study of efficient mixing in a micro-fluidized bed

On importance of surface forces in a microfluidic fluidized bed

A new method for reconstruction of the structure of micro-packed beds of spherical particles from desktop X-ray microtomography images. Part A. Initial structure generation and porosity determination

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