Thermal conductivity of packed

Bauer R, Schliinder EU (1978) Effective radial thermal conductivity of packings in gas flow. Part 11. Thermal conductivity of the packing fraction without gas flow. Int Chem Eng 18 189-204... 

Flow through the porous bed enhances the radial effective or apparent thermal conductivity of packed beds [10, 26]. Winterberg andTsotsas [26] developed models and heat transfer coefficients for packed spherical particle reactors that are invariant with the bed-to-particle diameter ratio. The radial effective thermal conductivity is defined as the summation of the thermal transport of the packed bed and the thermal dispersion caused by fluid flow, or ... 

Figure 9.2 shows existing data for the effective thermal conductivity of packed beds. These data include both ceramic and metallic packings. More accurate results can be obtained from the semitheoretical predictions of Dixon and Cresswell (1979). Once Kr is known, the wall heat transfer coefficient can be calculated from... 

G. R. Hadley, Thermal Conductivity of Packed Metal Powders, Int. J. Heat Mass Transfer, (29) 909-920,1986. 

Investigator Type of correlation Phases involved Model associated Model equation Kunii and Smith [29] Effective thermal conductivity of packed bed Fluid-solid One-dimensional heat transfer model Spheres in cubic array = <°- W>(K K) (in - ) .21 ... 

Figure 5.16 Effective thermal conductivity of packed beds.

To estimate the values of the thermal conductivity of packed beds of either monodispersed or polydispersed spherical or nonspherical particles within the temperature range of 100-1500 K and the pressure range of 10" to 100 bar the following correlations may be used (Schliinder, 1984) ... 

Effective Radial Thermal-Conductivity of Packings in Gas-Flow. 2. Thermal-Conductivity of Packing Fraction without Gas-Flow. International Chemical Engineering, 18(2) 189-204. 

Elsari M, Hughes R. Axial effective thermal conductivities of packed beds. Applied Thermal Engineering 2002 22 1969-1980. 

Heat transfer in the bed of a rotary kiln is similar to heat transfer in packed beds except that in addition to the heat flow in the particle assemblage of the static structure (Figure 8.3), there is an additional contribution of energy transfer as a result of advection of the bed material itself. The effective thermal conductivity of packed beds can be modeled in terms of thermal resistances or conductance within the particle ensemble. As shown in Figure 8.3 almost all the modes of heat transfer occurs within the ensemble, that is, particle-to-particle conduction and radiation heat transfer as well as convection through the interstitial gas depending upon the size distribution of the material and process temperature. Several models are available in the literature for estimating the effective thermal conductivity of packed beds. 

A. J. Slavin, F. A. Londry, and J. Harrison. "A new model for the effective thermal conductivity of packed beds of solid spheroids Alumina in helium between 100 and 500°C," Int J. Heat Mass Transfer, 43, 2059-2073, 2000. 

N. Wakao. "Effect of radiating gas on effective thermal conductivity of packed beds," Chem. Eng. Sci., 28, 1117-1118, 1973. 

K = effective thermal conductivity of packed bed Tk = temperature at inside radius of the vessel... 

Figure 12, Thermal conductivity of packed beds of hollow cylinders at various temperatures according to Ref. and Equation 23. (a) Ceramic- nitrogen (h) steelnfiitrogen.

Figure 13b. Thermal conductivity of packed beds of binary mixtures of ceramic spheres as a function of the mass fraction Afi at normal pressure according to Ref. 60 and Equation 23. Various temperatures.

Cheng GJ Structural evaluation of the effective thermal conductivity of packed beds, Sydney, Australia, 2003, The University of New South Wales. 

Zehner P, Schlunde EU Thermal conductivity of packings at moderate temperatures, Chem Ing Tech 42 933-941, 1970. 

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