Gas gap at the surface of a horizontal tube in a bubbling fluidized bed

Huang, De-Shau; Levy, Edward K.

doi:10.1016/j.powtec.2003.12.008

Cited by 8 publications

(4 citation statements)

References 5 publications

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“…Based on Figure 9, there is an upward trend of increasing the average heat transfer data with an increase in the superficial gas velocity, except for the values of the average heat transfer coefficient at mean bed particle sizes of 0.241 and 0.219 mm (8.1 < U g /U mf < 8.5). The predictions of this model represent the similar trend variation of average heat transfer coefficient with increasing superficial gas velocity, similar to the works of [16,17,24,34,[58][59][60][61][62][63]. In Figure 9, the red line represents the correlation equation obtained for the heat transfer data using a nonlinear regression in Origin 8 software [64].…”

Section: Discussionsupporting

confidence: 74%

Investigation of Heat Transfer in a Large-Scale External Heat Exchanger with Horizontal Smooth Tube Bundle

Błaszczuk

Jagodzik

2021

Energies

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In the research work, energy transport between a dense fluidized bed and submerged horizontal tube bundle is analyzed in the commercial external heat exchanger (EHE). In order to investigate the heat transfer behavior, the authors carried out eight performance tests in a fluidized bed heat exchange chamber with a cross-section of 2.7 × 2.3 m in depth and width and a height of 1.3 m. The authors have been developing a mechanistic model for the prediction of the average heat transfer coefficient, which includes the effect of the geometric structure of the tube bundle and the location of the heat transfer surface on the heat transfer rate. The computational results depict that the average heat transfer coefficient is essentially affected by superficial gas velocity and suspension density rather than bed particle size. The empirical correlations have been proposed for predicting heat transfer data since the existing literature data is not sufficient for industrial fluidized bed heat exchangers. On the basis of the evaluated operating conditions of an external heat exchanger, the optimal conditions where heat transfer occurs could be deduced. The developed mechanistic heat transfer model is validated by experimental data under the examined conditions.

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Section: Discussionsupporting

confidence: 74%

Investigation of Heat Transfer in a Large-Scale External Heat Exchanger with Horizontal Smooth Tube Bundle

Błaszczuk

Jagodzik

2021

Energies

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“…On the other hand, on the upper part of the cylinder the local gas velocities are maintained below the minimum fluidisation even when the superficial velocity U is higher than U mf , mirroring the occurrence of the aforementioned defluidised cap of solid [2,3,[12][13][14]37,39].…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, according to several authors [2,3,12,14,19,39] the emulsion in the upper part of the cylinder is almost defluidised, and is therefore denoted as Still Region. The extension of this region mainly depends on the collapse of the gas layer on the lateral surface and to the consequent creation of vortexes and indigenous bubbles [39]. The particles remain confined in the Still Region until the overall bubble flow does not induce large scale particle movements that involve the entire cylinder surface.…”

Section: Dimensionless Numbersmentioning

confidence: 99%

Heat transfer and void fraction profiles around a horizontal cylinder immersed in a bubbling fluidised bed

Natale

Bareschino

Nigro

2010

International Journal of Heat and Mass Transfer

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“…Various physical models needed to give an Eulerian formulation of the particulate enthalpy equations were formulated by Schmidt and Renz [8]. The experimentation to measure the thickness of the gas-gap was performed by Huang and Levy [9].They used fiber optic probe for measurement of gas film thickness. The gasgap thickness was found to depend strongly on angular position around the surface of horizontal tube and the powder properties and to vary slightly with SPL and superficial air velocity.…”

Section: ------------------**mentioning

confidence: 99%

Experimental analysis and computational fluid dynamics simulations for heat transfer in sound assisted fluidized bed of fine powders

Wankhede

Sonolikar²

2017

THERM SCI

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Fine powders in the size range of 20-200 μm are widely used in industries for fluid bed operations and are ideal for gas-solid reactions because of their large external surface areas and favorable heat transfer rates. The fine powders have very poor flow characteristics. Most of the earlier research work in heat transfer in bubbling fluidized beds is focused on coarse grained Geldart B and D particles. Acoustic energy of sufficient intensity and sound pressure level improved the quality of fluidization of fine powders. The objective of this investigation is experimental analysis and CFD simulations for heat transfer in a fluidized bed of fine powders at different acoustic conditions. The Eulerian approach has been identified as an efficient method for the numerical simulation of fluidized beds. The experimental and CFD results are in good agreement with each other.

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Gas gap at the surface of a horizontal tube in a bubbling fluidized bed

Cited by 8 publications

References 5 publications

Investigation of Heat Transfer in a Large-Scale External Heat Exchanger with Horizontal Smooth Tube Bundle

Investigation of Heat Transfer in a Large-Scale External Heat Exchanger with Horizontal Smooth Tube Bundle

Heat transfer and void fraction profiles around a horizontal cylinder immersed in a bubbling fluidised bed

Experimental analysis and computational fluid dynamics simulations for heat transfer in sound assisted fluidized bed of fine powders

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