Impact of three-dimensional sphericity and roundness on heat transfer in granular materials

Fei, Wenbin; Narsilio, Guillermo A.; Disfani, Mahdi M.

doi:10.1016/j.powtec.2019.07.094

Cited by 34 publications

(22 citation statements)

References 49 publications

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“…2). This can lead to overestimation of surface area and consequently underestimation of sphericity, as detailed by (Fei et al 2019). Therefore, we acknowledge that our sphericity measurements are conservative but as the saw-tooth pattern effect is present for all grains measured, the results we present are still directly comparable between each other.…”

Section: Grain Measurementsmentioning

confidence: 52%

The Influence of Grain Shape and Size on the Relationship Between Porosity and Permeability in Sandstone

Payton,

Chiarella,

Kingdon

2021

Preprint

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An accurate and reliable description of the relationship between porosity and permeability in geological materials is valuable in understanding subsurface fluid movement. This is of great importance for studies of reservoir characterisation, useful for energy exploitation, carbon capture, use and storage (CCUS) and groundwater contamination and remediation. Whilst the relationship between pore characteristics and porosity and permeability are well examined, there is scope for further investigation into the influence of grain characteristics on porosity and permeability due to the inherent relationship between grains and related pores. In this work we use digital image analysis (DIA) of reconstructed 3D X-ray micro computed tomographic (μCT) images to measure porosity, permeability and segment individual grains enabling the measurement of grain shape (sphericity) and size (Feret diameter). We compare two marker-based watershed workflows to grain boundary segmentation before applying the most reliable one to our images. We found there to be a positive relationship between grain sphericity and porosity according to ϕ=1.22ϕs-0.42 whereas no such relationship exists with grain size. We applied our grain shape and size measurements to calculate a Kozeny-Carman (K-C) porosity-permeability fit which was found to be unsatisfactory, possibly due to significant deviation from the K-C assumption that grains are spherical. Therefore, we show that a simpler fit of the form K= 10^5.54 ϕ^3.7, excluding any influence of grain characteristics, is most suitable for the studied materials and that grain shape and size is not influential on the porosity-permeability relationship in a K-C paradigm.

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Section: Grain Measurementsmentioning

confidence: 52%

The Influence of Grain Shape and Size on the Relationship Between Porosity and Permeability in Sandstone

Payton,

Chiarella,

Kingdon

2021

Preprint

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“…(2017) use the discrete element method to find that the effective thermal conductivity of granular soils increases with the aspect ratio of ellipsoids. However, it should be noted that the conclusions from Gan et al (2017) and Fei et al (2019) are not on the basis of the same void ratio for all mixtures.…”

Section: Effect Of Particle Shape On Thermal Conductivity-void Ratio mentioning

confidence: 95%

“…In the current study, the mixtures possess the same mineral composition, mean particle size and particle size distribution, so the finding that the effect of the particle shape on thermal conductivity at a given void ratio is more reliable than the conclusions from the other studies. In addition, Fei et al (2019) found that thermal conductivity increases with increasing particle regularity through an analysis with the finite element method, primarily due to that observation that higher regularity may lead to a higher average coordination number. Gan et al…”

Section: Effect Of Particle Shape On Thermal Conductivity-void Ratio mentioning

confidence: 99%

“…Although it would be logical that particle shape has an effect on the thermal conductivity, conflicting trends have been noted in the limited studies performed on this topic (Côté and Konrad 2005;Yun and Santamarina 2008;Gan et al 2017;Lee et al 2017;Fei et al 2019). Accordingly, the main purpose of this study is to perform thermal needle tests on mixtures of angular and rounded glass particles having different particle shapes under a range of relative densities.…”

Section: Introductionmentioning

confidence: 99%

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Thermal Conductivity of Granular Soil Mixtures with Contrasting Particle Shapes

Xiao

Nan

et al. 2020

J. Geotech. Geoenviron. Eng.

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Particle shape is known to affect the mechanical behavior of sands as it influences packing density and particle contacts. Even though the thermal conductivity of sands also depends on packing density and particle contacts, the effects of particle shape on thermal conductivity are not well understood. A series of thermal needle tests were conducted on five granular soil mixtures with different proportions of rounded and angular glass particles having the same mineral composition and gradation. The maximum and minimum void ratios and the packing density of these mixtures were found to depend on the overall regularity, defined as the average value of the particle's aspect ratio, convexity and sphericity. For a given overall regularity, the thermal conductivity increases with decreasing void ratio or increasing relative density. Interestingly, the overall regularity has a small effect on the thermal conductivity at a given void ratio but has a significant effect on the thermal conductivity at a given relative density. A particle shape-dependent empirical equation is proposed to quantify the effects of relative density and overall regularity on the thermal conductivity of the tested sand.

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“…We focus on two similar grain segmentation workflows presented by Fei et al 31 and Thomson et al 32 . The Fei et al 31 approach is proven to be successful in segmenting individual 3D grains in μCT images of loosely packed grains of varying angularity which have been extracted as loose sand from geological materials. This means that the resulting μCT images have relatively few contact points between grains.…”

Section: Introductionmentioning

confidence: 99%

The influence of grain shape and size on the relationship between porosity and permeability in sandstone: a digital approach

Payton

Chiarella

Kingdon

2022

Sci Rep

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An accurate and reliable description of the porosity–permeability relationship in geological materials is valuable in understanding subsurface fluid movement. This is important for reservoir characterisation, energy exploitation, geological carbon storage (GCS) and groundwater contamination and remediation. Whilst the relationship between pore characteristics and porosity and permeability are well examined, further investigation into the influence of grain characteristics on porosity and permeability would be beneficial due to the inherent relationship between grains and pores. This work aims to determine whether incorporation of grain characteristics into a porosity–permeability model is effective in constraining this relationship. Two fully digital approaches to individual 3D grain analysis based upon watershed segmentation are compared to determine the most effective, yet simple, workflow applicable to core plugs of significantly compacted grains. The identification of an effective segmentation workflow will facilitate future work on similarly complex materials, removing the need for traditional time-consuming and manual techniques. We use the most effective approach of measuring grain shape (sphericity) and size (Feret diameter) alongside an established fully digital workflow to measure porosity and permeability to investigate the impact of grain characteristics on porosity and permeability. We show that grain sphericity and porosity exhibit a positive relationship whereas no such relationship exists with grain size. Measurements of grain sphericity are applied to calculate a Kozeny–Carman (K–C) type porosity–permeability fit which was found to be unsatisfactory, compared to a simpler fit excluding any grain parameters. This is possibly due to the lower sphericity of the studied grains, deviating significantly from the K–C assumption that grains are entirely spherical. The simpler fit is most suitable for the studied materials, showing that inclusion of grain characteristics is not effective for better defining the porosity–permeability relationship in a K–C paradigm for these samples. This highlights the need for a model capable of considering a range of grain sphericities to further constrain the porosity–permeability relationship.

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Impact of three-dimensional sphericity and roundness on heat transfer in granular materials

Cited by 34 publications

References 49 publications

The Influence of Grain Shape and Size on the Relationship Between Porosity and Permeability in Sandstone

The Influence of Grain Shape and Size on the Relationship Between Porosity and Permeability in Sandstone

Thermal Conductivity of Granular Soil Mixtures with Contrasting Particle Shapes

The influence of grain shape and size on the relationship between porosity and permeability in sandstone: a digital approach

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