Over the past several years, monolithic catalytic converters with laminar flow profile are being used by automotive industry. These catalytic converters, though create some turbulence at the inlet, make the majority of the rest of the flow laminar, thereby reducing the mass transfer of the exhaust components to the effective catalytic sites. Improvements were achieved only through the higher cell densities so far.
If the design change in the substrates allows the change of exhaust flow from laminar to turbulent, longer residence time can be achieved and more unconverted gases from the core of the channel come closer to the catalyst surfaces facilitating more reaction with the active catalytic sites.
The turbulent technology has been successfully developed more recently with metal substrates to get the required turbulent flow characteristics in the substrate channels. The advantages of this technology include better conversion efficiencies, lesser volume of the catalysts and hence less packaging space requirements, lower system costs etc.
The present paper deals with the work done on a 2.6 l Common Rail Diesel Vehicle application with close coupled metal substrates. Various turbulent substrate configurations like Transverse Structure (TS) Longitudinal Structure (LS) and Perforated Structure (PE) foils were tested on this application and the results are discussed. The technical and commercial benefits of the turbulent technology catalysts are also presented.