Structure and Drag Characteristics of Fluidized Nanoparticle Agglomerates at the Bottom of the Bed

Liu, Huanpeng; Yang, Changqing

doi:10.1021/acs.iecr.9b04775

Cited by 5 publications

(16 citation statements)

References 37 publications

(117 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At present, only a few experimental studies have been done on the drag force coefficient model of NP agglomerates . Some experimental works of porous particles or grains can be found in the literature. − For example, Matsumoto and Suganumo carried out experiments with a model aggregate made of steel wool at Re ≈ 0.1.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Analysis on the Hydrodynamic Behaviors of Nanoparticle Agglomerates at Moderate Reynolds Numbers

Liu

2020

Ind. Eng. Chem. Res.

Self Cite

View full text Add to dashboard Cite

In this study, the hydrodynamic characteristics of agglomerates are studied experimentally for the Reynolds numbers (Re) up to ∼200, and their fluid dynamic behaviors are analyzed numerically taking their nonhomogeneous structures into account as 50 ≤ Re ≤ 400. The results show that both the Reynolds number and the fractal dimension (D f) of agglomerates significantly affect the flow field around and through the agglomerate. The drag ratios obtained from the numerical simulation show good agreement with the experimental data. The values of drag ratios are all lower than 1 at Re < ∼100 and are all larger than 1 for D f = 2.6 and 2.7 as Re > ∼100. A peak value in drag ratio is observed for D f = 2.6 as Re > 100. A new formula of drag ratio as a function of Re and D f is derived based on the simulated results. Comparisons with the homogeneous permeable sphere show that the effect of the radial variation of permeability on the drag force seems almost negligible in this range of moderate Reynolds numbers.

show abstract

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Analysis on the Hydrodynamic Behaviors of Nanoparticle Agglomerates at Moderate Reynolds Numbers

Liu

2020

Ind. Eng. Chem. Res.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Nearly 40% of the pores between simple agglomerates are hundreds of nanometers in size, and others are of micrometre scale. According to our earlier work, [ 21 ] there might be some pores of dozens of micrometres or larger for some FNPAs, and the large‐sized pores may obviously affect the hydrodynamics of some FNPAs. Unfortunately, we did not observe the large‐sized pores by TEM due to the high magnification of TEM.…”

Section: Resultsmentioning

confidence: 99%

“…The fluidized system is the same that was used in our earlier work. [ 21 ] As shown in Table 1, the initial bed height is 23 cm and the fluidization time is 1 hour. The minimum fluidization velocity measured from bed pressure drops curves is about 4 cm/s.…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

“…[ 15 ] It was also observed that the FNPAs at the bottom of the fluidized bed have a similar hierarchical structure as FNPAs in the middle and upper parts of the bed. [ 21 ] Considering the bottom FNPAs have larger sizes and higher strength as compared with the mid‐upper ones, they were sampled through the sampling port by aspiration at the bottom of the bed for the research. The chemical reagent composed of epoxy resin E‐44, curing agent 651, and butyl glycidyl ether at the volume ratio of 1:0.2:0.8 was used to solidify the samples.…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

“…[ 20 ] FNPAs can be solidified at atmospheric pressure by the chemical reagent with original inner structure retained and then the thin slices of them can be observed by TEM. [ 21 ] In this regard, the two‐dimensional TEM image analysis of the ultrathin slice of solidified FNPAs was conducted in this study.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental investigation on the microstructure of fluidized nanoparticle agglomerates by TEM image analysis

Liu

Yang

2020

Can J Chem Eng

Self Cite

View full text Add to dashboard Cite

In this paper, the hierarchical solid structures and multiscale pore structures inside fluidized nanoparticle agglomerates (FNPAs) are qualitatively revealed in the transmission electron microscope (TEM) images of ultrathin slices of solidified FNPAs from the bottom of the bed. The micromorphology of aggregates and simple agglomerates, the porosities of pores intra and inter simple agglomerates, and pore size distributions inside FNPAs are quantitatively analyzed by image analysis. The average fractal dimensions of aggregates of about 300 nm‐1000 nm and simple agglomerates of several micrometres are around 1.9 and 2.6 respectively. The pore structure of FNPAs is complex and heterogeneous and displays a multiscale feature. Nearly 50% of the pores intra simple agglomerates have sizes of tens of nanometers and more than half the pores between simple agglomerates are of micrometre scale. The porosities of the pores intra and inter simple agglomerates are about 0.82 and 0.85 respectively.

show abstract

Hydrodynamics of inhomogeneous agglomerates for a fractal dimension of 2.5 at intermediate Reynolds numbers: Effect of agglomerate sizes and Reynolds numbers

2023

Self Cite

View full text Add to dashboard Cite

In this study, the effect of agglomerate sizes for a fractal dimension (D f ) of 2.5 on the hydrodynamics at intermediate Reynolds numbers (Re) of 1-120 was assessed. The results show that a core behaves like a solid sphere that exists in the central region inside the agglomerate. In addition, increasing the agglomerate diameter represents adding an extra permeable layer outside the agglomerate. For a larger Re or a smaller agglomerate diameter, the fluid can enter and penetrate through the agglomerate more easily, and the hydrodynamic characteristics of agglomerates deviate more from those of solid spheres. The effect of diameters on the velocity and pressure profiles becomes less significant with the increase in the diameter. Based on the simulated results, the drag ratio has an approximately linear relationship with Re, and its intercept has an exponential relationship with the dimensionless agglomerate diameter. Compared with homogeneous porous spheres, the drag ratio of the agglomerate is different. The effect of diameters on the drag ratio decreases as the diameter increases. It should be noted that the effect of radially varying permeability on inhomogeneous agglomerates should not be ignored and that the effect weakens as Re increases.

show abstract

Structure and Drag Characteristics of Fluidized Nanoparticle Agglomerates at the Bottom of the Bed

Cited by 5 publications

References 37 publications

Numerical and Experimental Analysis on the Hydrodynamic Behaviors of Nanoparticle Agglomerates at Moderate Reynolds Numbers

Numerical and Experimental Analysis on the Hydrodynamic Behaviors of Nanoparticle Agglomerates at Moderate Reynolds Numbers

Experimental investigation on the microstructure of fluidized nanoparticle agglomerates by TEM image analysis

Hydrodynamics of inhomogeneous agglomerates for a fractal dimension of 2.5 at intermediate Reynolds numbers: Effect of agglomerate sizes and Reynolds numbers

Contact Info

Product

Resources

About