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  • Impact of Wall Heat Transpo...
    Narendiran, K; Viswanathan, Ganesh A

    Industrial & engineering chemistry research, 08/2015, Letnik: 54, Številka: 30
    Journal Article

    Transversal hot zones have been reported to form in packed-bed reactors used to conduct exothermic reactions. Packed-bed reactors are usually operated under non-adiabatic conditions. Previous attempts to predict the formation of transversal hot zones have been made on both shallow and long reactors under adiabatic conditions; that is, wall heat transport is zero. We show that a rich variety of slowly oscillating transversal hot zones, such as rotating patterns, targets, and spirals, may form in shallow, non-adiabatic reactors. Under certain conditions, azimuthally symmetric target patterns coexist with azimuthally non-symmetric rotating patterns. Surprisingly, a small wall heat transport can force a traveling wave or band motion observed under adiabatic conditions into a rotating pattern. A transition from the rotating patterns and/or target patterns to spiral waves depends on the residence time, the reactor length scale, and the wall heat transfer coefficient. A shallow reactor model predicts that the spatiotemporal patterns oscillate at a very low frequency (order of 10–5 Hz), which is in agreement with predictions based on laboratory experiments.