Heat Transfer to Gases through Packed Tubes

Leva, Max

doi:10.1021/ie50451a014

Cited by 81 publications

(44 citation statements)

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“…The values of U computed from the data are shown in Figures 8-10, plotted against superficial mass flow rate G kg/rrr' s, to remove the influence of particle diameter which appears in the Reynolds number. Over the range investigated here, U appears to increase linearly with G, in reasonably good agreement with the results of Leva (1947) who found U oc GO. 9 for heating.…”

Section: Overall Heat Transfer Coefficientsupporting

confidence: 91%

Wall and Particle-Shape Effects on Heat Transfer in Packed Beds

Dixon

1988

Chemical Engineering Communications

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The effective radial thermal conductivity and apparent heat transfer coefficient for a packed bed were experimentally determined for beds of spheres, full cylinders and hollow cylinders, for flow rates giving particle Reynolds numbers in the range 100-1000, and for tube to particle diameter ratios of 5-12. Over these ranges the radial Peclet number Per showed significant dependence on solid conductivity, gas flow rate and particle shape, while the wall Biot number Bi showed significant dependence on tube to particle diameter ratio, gas flow rate and particle shape. These dependencies were predicted well by equations incorporating the effects of these variables into individual gas and solid phase parameters, which were then combined to give the effective or lumped parameters.

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Section: Overall Heat Transfer Coefficientsupporting

confidence: 91%

Wall and Particle-Shape Effects on Heat Transfer in Packed Beds

Dixon

1988

Chemical Engineering Communications

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“…The convective heat transfer coefficient from the hot internal side of the wall of the bed packed tubular reactor to the process gas contained therein (α) was calculated by Leva correlation (Leva, 1947) modified with a correction coefficient (c = 0.75), which was defined on the basis of measurements cpe.czasopisma.pan.pl; degruyter.com/view/j/cpe taken in our experimental plant for heat transfer determination in a wide range of gas flow rates for various catalyst grain dimensions (Ziółkowski et al, 1982a):…”

Section: Methodology Of Investigations Of Parameters Required For Refmentioning

confidence: 99%

Influence of Steam Reforming Catalyst Geometry on the Performance of Tubular Reformer – Simulation Calculations

Franczyk¹,

Gołębiowski²,

Borowiecki³

et al. 2015

Chemical and Process Engineering

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A proper selection of steam reforming catalyst geometry has a direct effect on the efficiency and economy of hydrogen production from natural gas and is a very important technological and engineering issue in terms of process optimisation. This paper determines the influence of widely used seven-hole grain diameter (ranging from 11 to 21 mm), h/d (height/diameter) ratio of catalyst grain and S h /S t (hole surface/total cylinder surface in cross-section) ratio (ranging from 0.13 to 0.37) on the gas load of catalyst bed, gas flow resistance, maximum wall temperature and the risk of catalyst coking. Calculations were based on the one-dimensional pseudo-homogeneous model of a steam reforming tubular reactor, with catalyst parameters derived from our investigations. The process analysis shows that it is advantageous, along the whole reformer tube length, to apply catalyst forms of h/d = 1 ratio, relatively large dimensions, possibly high bed porosity and S h /S t ≈ 0.30-0.37 ratio. It enables a considerable process intensification and the processing of more natural gas at the same flow resistance, despite lower bed activity, without catalyst coking risk. Alternatively, plant pressure drop can be reduced maintaining the same gas load, which translates directly into diminishing the operating costs as a result of lowering power consumption for gas compression.

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“…[ N I B I N P I l r n + 01 /3 N P , W R~ (9) The physical interpretation of the two constants 01 and /3 may now be considered. The constant /3 = l,/D, is considered by Yagi and Kunii to be essentially unity.…”

Section: Vol 7 Nomentioning

confidence: 99%

“…It may then be expected to depend upon the fluid properties. Writing B = Po ( D J D , ) but retaining Q without modification for the present one obtains from Equation (9) k, k, --6'-= c ' . "IQ* N P , ] " -t k , k, CY 8.…”

Section: Vol 7 Nomentioning

confidence: 99%

“…Finally it is possible that a natural convection process may contribute significantly at low flow rates. Contribution of natural convection has not been taken into account in the model tubes has been under intensive inproposed by Yagi (9) have presented considerable data on this process for a wide range of The process of heat transfer from a operating and equipment variables.…”

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confidence: 99%

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Effective thermal conductivity in packed beds

1961

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dimensionless temperature in the pellet, ( T -T , ) / T , geometry factor [Equation (51) 1 ~ I geometry factor [Equation (47) 1 dimensionless distance in the micropore, z / L ; f = 0 at pore mouth, E = 1 at end of pore apparent or bulk density of the catalyst material macro mass transfer parameter, defined by Equation (42) macro heat transfer parameter, defined by Equation (43) micro mass transfer parameter, defined by Equation (13) Thiele number, value of T, when r = r micro heat transfer parameter, defined by Equation (14) T2/V?'2 ( a E,)'", defined by Equation (57) -Subscripts e = effective K = Knudsen I = linear case n = order of reaction o = conditions at the mouth of the micropore, that is conditions at the surface of the microporous particle s = conditions at the surface of the macropellet Superscripts G = Gaussian I = linear case M = Maxwellian T = Thiele Calculus Prime = differentiation ( j ) = evaluation at value of independent vaTiable = j LITERATURE CITED 1. Aris, Rutherford, Chem. Eng. Sci., 6, 265 (1957). Values of the effective thermal Conductivity Ke for liquids in packed beds have been obtained from heat transfer studies in such beds. The method applied by Yagi and Kunii for gases is clarified, their model is extended and is then applied to liquids. Experimental data for three different packings, glass, steel, and aluminum, with spheres of DP/DT ratio from 0.07 to 0.33 have been correlated. A brief comparison of the results from this analysis with previously published results from similar studies is presented.

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Heat Transfer to Gases through Packed Tubes

Cited by 81 publications

References 0 publications

Wall and Particle-Shape Effects on Heat Transfer in Packed Beds

Wall and Particle-Shape Effects on Heat Transfer in Packed Beds

Influence of Steam Reforming Catalyst Geometry on the Performance of Tubular Reformer – Simulation Calculations

Effective thermal conductivity in packed beds

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