A Novel Honeycomb for both Downsizing and Significant PGM Saving

Mansour  Masoudi, Emissol LLC

A Novel Honeycomb for both Downsizing and Significant PGM Saving

M. Masoudi1, E. Tegeler1, J. Hensel1, V. Balakotaiah2,  O. Deutschmann3, P. Lott3, A.G. Konstandopoulos4
1 Emissol LLC, Mill Creek, WA, US
2 University of Houston, Houston, Texas, US
3 Karlsruhe Institute of Technology, Karlsruhe, Germany
4 Aerosol and Particle Technology Laboratory, CPERI/CERTH, Thessaloniki, Greece

A novel honeycomb having helical channels is presented. The channels form strong, stable, counter-rotating Dean vortex structures, dominating the flow field within. Unlike straight channels in conventional honeycombs where reactive species (CO, HC, NOx) are transported to the catalyst sites by diffusion across streamlines, mass transfer in the novel channel is instead dominated by convective transport; this brings the species faster and more efficiently to the immediate proximity of the reaction sites, enabling not only downsizing the honeycomb, but also saving costly precious metals.

Performance of a downsized honeycomb with 30% less precious metals, relative to a baseline,  conventional, straight channel honeycomb, is shown, indicating no loss in efficiency compared to the baseline. The downsized honeycomb with its lower thermal mass, also lights off faster, therefore reducing the instantaneous and cumulative emissions, especially during the most-polluting bag-1 phase. This enables fuel and CO2 savings during engine cold-start, as well as modestly reducing the emission control system weight.

Precious metal savings are even more pronounced in lean (Diesel) exhaust, such as in a Diesel Oxidation Catalyst. Further, heavier hydrocarbons, typically having poor diffusivity, show stronger activity and oxidize faster due to their enhanced transport to reaction sites by vortex structures.

The concept honeycomb can be constructed of any desired materials: Ceramic (e.g. cordierite) or metallic.

All the aforementioned benefits are observed with no increase in backpressure: During steady state, light-off and cycles, backpressure is shown to be comparable with that in a conventional honeycomb having straight channels.

Both high-fidelity reaction modeling data (based in part on the published works of the authors) and experimental measurements in microreactors will be shown.

Efforts are underway to extend the PGM savings and downsizing to 50%.