Advanced Ceramic Substrate: Catalytic Performance Improvement by High Geometric Surface Area and Low Heat Capacity

Umehara, K.; Yamada, Toshio; Hijikata, Toshihiko; Ichikawa, Y.; Katsube, F.

doi:10.4271/971029

Cited by 38 publications

(8 citation statements)

References 7 publications

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“…The rate of change of temperature of the exhaust gas and converter are obtained from the difference in heat entering and leaving the system (4) and (5) respectively, where "l", "x g ", and "C c " are the length, open frontal area, and heat capacity of the converter, respectively. The open frontal area is defined as the ratio of the cross-sectional areas of a channel to the repeating cell unit.…”

Section: Discussionmentioning

confidence: 99%

“…More than 75% of emissions of CO, NOx and HC from gasolinepowered vehicles equipped with close-coupled catalytic converters are released in the first few seconds after cold-start [4]. Times to catalytic light-off are shortened by reducing the volumetric heat capacity of the substrate [5]. Once heated, catalytic conversion is strongly affected by kinetics of mass transfer.…”

Section: Introductionmentioning

confidence: 99%

“…Once heated, catalytic conversion is strongly affected by kinetics of mass transfer. Substrates with thinner walls and higher cell density improve cold-start and hot-drive conversion of pollutants [5,6]. Wall thickness has been decreased progressively from 165 to less than 75 μm [6].…”

Section: Introductionmentioning

confidence: 99%

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High Porosity Substrates for Fast-Light-Off Applications

Tanner

Twiggs

Tao

et al. 2015

SAE Technical Paper Series

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Regulations that limit emissions of pollutants from gasoline-powered cars and trucks continue to tighten. More than 75% of emissions through an FTP-75 regulatory test are released in the first few seconds after cold-start. A factor that controls the time to catalytic light-off is the heat capacity of the catalytic converter substrate. Historically, substrates with thinner walls and lower heat capacity have been developed to improve cold-start performance. Another approach is to increase porosity of the substrate. A new material and process technology has been developed to significantly raise the porosity of thin wall substrates (2-3 mil) from 27-35% to 55% while maintaining strength. The heat capacity of the material is 30-38% lower than existing substrates. The reduction in substrate heat capacity enables faster thermal response and lower tailpipe emissions. The reliance on costly precious metals in the washcoat is demonstrated to be lessened. The microstructure of the new substrate material is optimized for washcoat compatibility and to maintain strength. The new materials are confirmed to be thermomechanically robust for service in the harsh exhaust system environment.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High Porosity Substrates for Fast-Light-Off Applications

Tanner

Twiggs

Tao

et al. 2015

SAE Technical Paper Series

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“…The honeycombs are supposed to be infinitely long in the x 3 -direction as well as in the x 1 -and x 2 -directions, leading to a generalized 2D deformation in whichu * 3 may not be zero, but ∂u * i /∂ x 3 = 0, i = 1, 2, 3. Incidentally, ceramic honeycombs used for catalytic converters have h/l ranging from about 0.05 to 0.1 [10].…”

Section: Loading Condition and Periodic Unitsmentioning

confidence: 99%

“…They are usually subject to considerably high in-plane compression in catalytic converters. Recently, their in-plane microscopic buckling has become more serious, as the thickness of cell walls has been decreased to increase the density of cells for the purpose of improving catalytic performance [10]. We note that metallic square honeycombs are also being developed as one of ordered metallic cellular solids [11].…”

Section: Introductionmentioning

confidence: 99%

Long-Wave In-Plane Buckling of Elastic Square Honeycombs

Okumura

Ohno

Niikawa

2005

Mechanics of Advanced Materials and Structures

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In this study, microscopic buckling of elastic square honeycombs subject to in-plane compression is analyzed using a two-scale theory of the up-dated Lagrangian type. The theory allows us to analyze microscopic bifurcation and post-bifurcation behavior of periodic cellular solids. Cell aggregates are taken to be periodic units so that we can discuss the dependence of buckling stress on periodic length. Then, it is shown that microscopic buckling occurs at a lower compressive load as periodic length increases, and that longwave buckling occurs just after the onset of macroscopic instability if the periodic length is sufficiently long. It is further shown that the macroscopic instability is of the shear type, leading to a simple formula to evaluate the lowest in-plane buckling stress of elastic square honeycombs.

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