Influence of surface forces and wall effects on the minimum fluidization velocity of liquid-solid micro-fluidized beds

Nascimento, Orlando L. do; Reay, David; Živković, Vladimir

doi:10.1016/j.powtec.2016.05.013

Cited by 27 publications

(16 citation statements)

References 41 publications

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“…Calibration was performed with and without particles to determine the flowrate at which liquid moves through the system. The minimum fluidisation velocity was determined in our previous study using micro-fluidised bed by observing visually the bed height expansion and also by extrapolation of a linear relationship between the superficial liquid velocity and ratio of bed expansion (do Nascimento, et al 2016). The theoretical minimum fluidization velocities, Umf,theory was calculated using the Ergun equation (Ergun 1952) with an estimated initial packed bed voidage of εmf = 0.40 ± 0.01 in line with previous experiments (Tang, et al 2015) and trend of rectangular packed bed voidage with particle-to-bed ratios (Navvab Kashani, et al 2016).…”

Section: Experimental Methodologymentioning

confidence: 99%

“…In the past decade lots of attention have been paid to fluidised beds at the micro-scale due to their excellent operation abilities and fast screening for various applications (Liu, et al 2008, Tang, et al 2015, Xu and Yue 2009. Micro-fluidised beds refers to a fluidised bed with the bed cross-section or inner diameter at micrometre or millimetre scale (do Nascimento, et al 2016, Potic, et al 2005, Zivkovic and Biggs 2015, Zivkovic, et al 2013. In terms of applications, the micro-fluidized bed holds promise in the micro-process and microfluidic context.…”

Section: Introductionmentioning

confidence: 99%

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Study of Transitional Velocities of Solid–Liquid Micro-circulating Fluidized Beds by Visual Observation

Nascimento

Reay

Zivkovic

2018

J. Chem. Eng. Japan / JCEJ

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Solid-liquid micro-fluidised beds (FBs), i.e. fluidisation of micro-particles in sub-centimetre beds, hold promise of applications in the microfluidics and micro-process technology context. This is mainly due to fluidised particles providing enhancement of mixing, mass and heat transfer under the low Reynolds number flows that dominate in micro-devices. Albeit there are quite a few studies of solid-liquid micro-fluidised beds, we are presenting the first study of a micro-circulating fluidised bed. The present experimental research was performed in a micro-circulating fluidised bed which was made by micro-machining channels of 1mm 2 cross section in Perspex. PMMA and soda lime glass micro-particles were used as the fluidised particles and tap water as the fluidising liquid to study flow regime transition for this micro-circulating fluidised bed. The results are in line with macroscopic observation that the critical transition velocity from fluidization to circulating regime is very dependent on solid inventory but once the inventory is high enough it is approximately equal to the particle terminal velocity. However, the transitional velocity is a weakly dependent on wall effect and surface forces confirming the importance of these two properties in a micro-fluidised bed systems. Similarly the transitional velocity to transporting regime is a strong function of surface forces. Finally, combining these results with our previous result on conventional fluidization indicated that map of solid-liquid fluidisation in a micro-circulating fluidised bed system is constructed showing conventional fluidisation, circulating fluidisation and a transport regime.

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Section: Experimental Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of Transitional Velocities of Solid–Liquid Micro-circulating Fluidized Beds by Visual Observation

Nascimento

Reay

Zivkovic

2018

J. Chem. Eng. Japan / JCEJ

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“…This makes particle aggregation and adhesion to the bed wall a potential issue, even to the point of preventing fluidization [28,29]. The acid-base model of van Oss, Chaudhury and Good combined with the Derjaguin approximation can be used to predict wall material/particle/fluid triplets that avoid this issue [29,38,39]. In the case of the wall material/particle pair considered here, we have both predicted and demonstrated [29] that ethanol is a suitable fluidizing medium, hence why it has been used in the work reported here.…”

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%

Experimental study of efficient mixing in a micro-fluidized bed

Živković

Ridge

Biggs

2017

Applied Thermal Engineering

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“…Rice husk had a lot of burrs, which led to the non-ignorable role of surface force compared with the gravity and inertia force in a small-scale fluidized bed. Simultaneously, the lower sphericity of rice husk also contributed to the increase in the Umf (Fotovat et al 2015;do Nascimento et al 2016). Moreover, increasing the M of biomass results in increased particle density and adhesive force, which led to the Umf increasing and the Pd decreasing considerably.…”

Section: Effect Of Moisture Content On Biomass Fluidization Charactermentioning

confidence: 99%

Fluidization Behavior of Biomass Particles and its Improvement in a Cold Visualized Fluidized Bed

Wu¹,

Li²,

Song³

et al. 2017

BioResources

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The fluidization behavior in a fluidized bed was visualized at room temperature under different conditions for two typical lignocellulosic biomass materials (rice husk and walnut shell) as representative samples of herbage and xylophyta, respectively. The effects of initial bed height, moisture content, and addition of sand particles on the quality of fluidization were analyzed, and the optimal operating parameters were determined. The initial bed height had a negligible effect on the minimum fluidization velocity but an obvious influence on bed stability. In addition, with an increase in moisture content, the minimum fluidization velocity showed the growth of an S-shaped curve and a constant decrease in the fluidization index in the fluidized region. Fluidization when performed on binary mixtures indicated that the proportion of sand-3 (60 to 80 mesh) in biomass and sand-3 in mixtures is a main factor contributing to the fluidizing quality of a bed. With larger proportions of sand-3, the fluidizing quality of the bed improved. Meanwhile, the differences in fluidization behavior between rice husk and walnut shell have been determined.

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Influence of surface forces and wall effects on the minimum fluidization velocity of liquid-solid micro-fluidized beds

Cited by 27 publications

References 41 publications

Study of Transitional Velocities of Solid–Liquid Micro-circulating Fluidized Beds by Visual Observation

Study of Transitional Velocities of Solid–Liquid Micro-circulating Fluidized Beds by Visual Observation

Experimental study of efficient mixing in a micro-fluidized bed

Fluidization Behavior of Biomass Particles and its Improvement in a Cold Visualized Fluidized Bed

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