Warm-up behavior of monolithic reactors under non-reacting conditions

The transient heat transfer characteristics of monolithic reactors are of major importance because the time for the reactor to reach the required reaction temperatures should be minimized. A common application is the automotive catalytic converter. A simple numerical model for the heat transfer in an adiabatic thin wall channel is presented, taking account of the gas-solid convection, axial wall conduction and heat capacity effects in the solid phase. With the aid of the numerical model and the dimensional analysis, the thermal response of the channel after a step change of the inlet feed gas temperature is studied. For the case of negligible axial conduction, the results can be expressed in a single curve using suitably modified coordinates. The critical design and operating parameters are recognized and discussed. The results can be also expressed using common engineering variables to provide reliable assessment of several design and operating parameters of a monolithic reactor, such as void fraction, cell density, space velocity, etc. (C) 1997 Elsevier Science Ltd.