No abstract

No abstract

No abstract

Recently, Wijngaarden and Westerterp (1989) derived a dimensionless criterion as to whether or not a homogeneous model can be used instead of a heterogeneous one in modelling wall-cooled tubular reactors. Their work is an extension of the well-known criteria of e.g. Mears (1971) for the neglect of interparticle mass and heat transfer resistances. Important, but somewhat restrictive, assumptions in their article are the linearization of the reaction rate with respect to the coolant temperature and the neglect of an external mass @an&r limitation between the catalyst pellets and the gas phase. In this short communication we will demonstrate that simple extensions of their criterion, considerably enlarging its applicability, can be derived. Wijngaarden and Westerterp introduced a dimensionless number c: