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

Heat Transfer in Fixed Beds at Very Low (<4) Tube-to-Particle Diameter Ratio

“…Overall, the data presented in Figures 2-11 confirm and extend the trends reported earlier for packings in the range 5 e N e 12 (Dixon, 1988b). The ratio k r /k f is higher for higher conductivity packings and is dependent on particle shape, being higher for full and hollow cylinders than for spheres.…”

“…The k r /k f results for nylon/polystyrene spherical packings shown in Figure 2 exhibit a very wide spread of values. The results for N ) 6.4 and N ) 4.0 lie close together (and are also close to values for higher N, not shown here but see Dixon (1988b)). By comparison, lower k r /k f are seen for N ) 2.7, and then the k r /k f for N ) 2.0 are consistent with those from the higher N again, only for very low k r /k f values to be seen again at N ) 1.8.…”

Heat Transfer in Fixed Beds at Very Low (<4) Tube-to-Particle Diameter Ratio

“…Overall, the data presented in Figures 2-11 confirm and extend the trends reported earlier for packings in the range 5 e N e 12 (Dixon, 1988b). The ratio k r /k f is higher for higher conductivity packings and is dependent on particle shape, being higher for full and hollow cylinders than for spheres.…”

“…The k r /k f results for nylon/polystyrene spherical packings shown in Figure 2 exhibit a very wide spread of values. The results for N ) 6.4 and N ) 4.0 lie close together (and are also close to values for higher N, not shown here but see Dixon (1988b)). By comparison, lower k r /k f are seen for N ) 2.7, and then the k r /k f for N ) 2.0 are consistent with those from the higher N again, only for very low k r /k f values to be seen again at N ) 1.8.…”

Length Effects on PRCFD-Derived Fixed-Bed Radial Heat Transfer Parameters

“…In the case of no wall conduction (no flow preheating) the trend is the same, but more pronounced and showing a decrease to a deeper minimum followed by an increase to close to the asymptotic value. These simulations provide support to the idea that the behavior of Nu w in early experiments 4,30 was real and not due to experimental variability.…”

Influence of tube and particle diameter on heat transport in packed beds

“…For glass spheres with dE = 3.7 mm, we find Bo&= 8.8: Pecfet number based on the superficial velocity PeS, instead of the interstitial velocity Pe;, as used in Figures 4a-4c. The values for the Bor, number are close to those by Gunn (1987), being 11 for spheres, 8 for full cylinders, and 5.7 for hollow cylinders, and those by Dixon (1988) being 12, 7, and 6, respectively. Best-fit values for the wall heat-transfer coefficient are given in Figures 6a-6c.…”

Heat Transfer in Fixed Beds at Very Low (<4) Tube-to-Particle Diameter Ratio

“…Overall, the data presented in Figures 2-11 confirm and extend the trends reported earlier for packings in the range 5 e N e 12 (Dixon, 1988b). The ratio k r /k f is higher for higher conductivity packings and is dependent on particle shape, being higher for full and hollow cylinders than for spheres.…”

“…The k r /k f results for nylon/polystyrene spherical packings shown in Figure 2 exhibit a very wide spread of values. The results for N ) 6.4 and N ) 4.0 lie close together (and are also close to values for higher N, not shown here but see Dixon (1988b)). By comparison, lower k r /k f are seen for N ) 2.7, and then the k r /k f for N ) 2.0 are consistent with those from the higher N again, only for very low k r /k f values to be seen again at N ) 1.8.…”

Length Effects on PRCFD-Derived Fixed-Bed Radial Heat Transfer Parameters

“…In the case of no wall conduction (no flow preheating) the trend is the same, but more pronounced and showing a decrease to a deeper minimum followed by an increase to close to the asymptotic value. These simulations provide support to the idea that the behavior of Nu w in early experiments 4,30 was real and not due to experimental variability.…”

Influence of tube and particle diameter on heat transport in packed beds

“…For glass spheres with dE = 3.7 mm, we find Bo&= 8.8: Pecfet number based on the superficial velocity PeS, instead of the interstitial velocity Pe;, as used in Figures 4a-4c. The values for the Bor, number are close to those by Gunn (1987), being 11 for spheres, 8 for full cylinders, and 5.7 for hollow cylinders, and those by Dixon (1988) being 12, 7, and 6, respectively. Best-fit values for the wall heat-transfer coefficient are given in Figures 6a-6c.…”

Heat Transfer in Fixed Beds at Very Low (<4) Tube-to-Particle Diameter Ratio

“…Overall, the data presented in Figures 2-11 confirm and extend the trends reported earlier for packings in the range 5 e N e 12 (Dixon, 1988b). The ratio k r /k f is higher for higher conductivity packings and is dependent on particle shape, being higher for full and hollow cylinders than for spheres.…”

“…The k r /k f results for nylon/polystyrene spherical packings shown in Figure 2 exhibit a very wide spread of values. The results for N ) 6.4 and N ) 4.0 lie close together (and are also close to values for higher N, not shown here but see Dixon (1988b)). By comparison, lower k r /k f are seen for N ) 2.7, and then the k r /k f for N ) 2.0 are consistent with those from the higher N again, only for very low k r /k f values to be seen again at N ) 1.8.…”

Length Effects on PRCFD-Derived Fixed-Bed Radial Heat Transfer Parameters

“…In the case of no wall conduction (no flow preheating) the trend is the same, but more pronounced and showing a decrease to a deeper minimum followed by an increase to close to the asymptotic value. These simulations provide support to the idea that the behavior of Nu w in early experiments 4,30 was real and not due to experimental variability.…”

Influence of tube and particle diameter on heat transport in packed beds

“…For glass spheres with dE = 3.7 mm, we find Bo&= 8.8: Pecfet number based on the superficial velocity PeS, instead of the interstitial velocity Pe;, as used in Figures 4a-4c. The values for the Bor, number are close to those by Gunn (1987), being 11 for spheres, 8 for full cylinders, and 5.7 for hollow cylinders, and those by Dixon (1988) being 12, 7, and 6, respectively. Best-fit values for the wall heat-transfer coefficient are given in Figures 6a-6c.…”