Heat loss from packed beds

In order to investigate convective heat and mass transfer, a laboratory reactor has been set up at the Research Centre Karlsruhe [16], see Fig.5. A hot gas flow is used to heat up the packed bed, which is located in a furnace pot suspended from a weighting cell. To minimise heat loss from the packed bed, the reactor wall is heated. Therefore radial temperature gradients are assumed to be negligible. Thermocouples arc used to determine the temperature distribution over the height. The maximum height of the packed bed in the reactor is 210 mm. 

Second, the efficiency of conventional reformer decreases at small scales due to heat transfer limitations and parasitic heat losses. The transfer of heat from the combustion products to the reactants is an inherently inefficient process, and in any practical system, especially for smaller scales, it is not possible to transfer all of the energy released by combustion into the process being heated. In UMR the heat transfer is more efficient as the packed bed is internally heated. The improvements in heat transfer to the packed bed are expected to result in a higher process efficiency. 

Loss of fluidizing gas will lead to collapse of the fluidized bed. If the process involves the emission of heat then this heat will not be dissipated as well from the packed bed as it was from the fluidized bed. The consequences of this should be... 

A sheep grows a wool fiber that possesses a corkscrew crimp in the dry state and affords the animal a bulky insulation blanket. When it rains, the fiber becomes wet and loses the crimp the wool strands then bed down to form a close-packed, rain-tight covering capable of reducing the loss of body heat in the damp conditions. This evolutionary wool fiber, whose properties are derived from its bicomponent nature, was simulated in the laboratory by preparing a two-component acrylic fiber. 

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