Wrong‐way behavior of packed‐bed reactors: Influence of interphase transport

Large transient temperature excursions may be caused by a sudden reduction in the feed temperature to a packed‐bed reactor operating at an intermediate conversion. When a unique steady state exists for all feed temperatures, the magnitude of the wrong‐way behavior predicted by a two‐phase model is very close to that predicted by a pseudohomogeneous model if Pe H is equal to the dimensionless heat transfer coefficient H . The two‐phase model enables a more efficient numerical simulation in such cases. The predictions of these two models may be rather different when steady‐state multiplicity exists for some feed temperatures. In such cases, a two‐phase model, which accounts for the axial dispersion of heat, should be used to simulate the transient behavior. The wrong‐way behavior may lead to an ignition of a low‐temperature state or an upstream propagation of a transient temperature wave.