Heat transfer characterization of support structures for catalytic combustion

Convective heat transfer and pressure drop characteristics within metal foil catalyst structures are determined with a unique experimental procedure. Various honeycomb-type structures with 100, 150, 160 and 200 cpsi (cells per square inch) are investigated at empty tube air velocities ranging from 0.5 to 10 m/s at atmospheric pressure. Both commercially available and novel structures, designed and manufactured by the authors, are compared. The convective heat transfer between fluid and substrate can be well described by the correlation Nu=¢Re mPr 1/3 . The experimental method to obtain values of ¢ and m is described in detail and is based on unsteady state cooling of the hot structures in an air stream. The data are discussed in view of application of the structures as catalyst supports and are compared with a 400 cpsi conventional, parallel-channel, Cordierite honeycomb. Results show that the novel structures offer greater heat transfer per unit volume but at the cost of higher pressure drop and thus lower heat transfer per unit pressure drop, relative to the 400 cpsi, parallel-channel honeycomb.