Prediction of Catalytic Performance for Ultra Thin Wall and High Cell Density Substrates

Umehara, K.; Makino, Mikio; Brayer, Mickey; Becker, Ernst; Watson, Richard

doi:10.4271/2000-01-0494

Cited by 18 publications

(7 citation statements)

References 6 publications

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“…An increase in cell density means an enlargement of the geometrical surface area, a reduction in hydraulic diameter and high external mass transfer coefficients, but with the disadvantage of high back pressure due to the reduction of the open frontal area. However, this disadvantage can be overcome by reducing the substrate wall thickness (Umehara et al5). As an example, for the same open frontal area increasing the cell density from 400 cpsi to 800 cpsi and to 1200 cpsi increases the external mass transfer coefficient by 44% and 80%, respectively, without pressure loss penalties.…”

Section: Influence Of the Design Parameters On The Twc Conversionsmentioning

confidence: 99%

“…In general, the studies available in the literature demonstrate that the ignition in a TWC is controlled mainly by chemical reaction effects (e.g., Kašpar et al4), being the conversions dependent mainly on the external mass transfer process at normal operating temperatures (e.g., Umehara et al5, Brück et al,6 and Ramanathan et al7). However, in a recent article (Santos and Costa8), we have found that even at high temperatures and mass flow rates (MAFs), purely external mass transfer controlled regime is hard to obtain under realistic operating conditions.…”

Section: Introductionmentioning

confidence: 99%

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On the quantification of the controlling regimes in automotive catalytic converters

Santos

Costa

2010

AIChE Journal

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The conversion of pollutants in automotive catalytic converters is influenced by a number of physical and chemical processes that take place in the gaseous and solid phases as the exhaust gases flow through the converter. A detailed understanding of the complex processes involving flow dynamics, heat and mass transport and heterogeneous surface reactions is of crucial importance to improve the converter design. The main objective of the present study is to quantify the magnitudes of the external and internal mass transfer as well as chemical reaction limiting processes as a function of the converter operating temperature. To this end, experimental data, obtained for a three way catalyst (TWC) under real world operating conditions, are analyzed and compared against analytical expressions that allow for the quantification of the different limiting processes involved. The results demonstrate that (i) the external mass transfer resistance overlaps the reaction resistance only at moderate operating temperatures and not immediately above the ignition temperature as generally considered in the literature, (ii) the transport phenomena (external and internal mass transfer) represents 90% of the total resistance for temperatures higher than 792 K, (iii) the internal mass transfer in the porous washcoat presents a larger resistance than the external mass transfer from the bulk fluid to the washcoat wall even at high operating temperatures, and (iv) based on the quantification of the individual resistances as a function of the TWC operating temperature, it was demonstrated both the influence of the substrate cell density and of the effective diffusivity on the TWC conversions.

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Section: Influence Of the Design Parameters On The Twc Conversionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the quantification of the controlling regimes in automotive catalytic converters

Santos

Costa

2010

AIChE Journal

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“…Cold start emissions are handled by the EHC, a 186 cell per square centimeter metal foil unit with a .04mm wall thickness. The low thermal mass of this design provides a faster warm-up and a high surface area for improved gas interaction 9,10 . The 12-volt catalyst reaches a lightoff temperature of 275°C in 30 seconds.…”

Section: Co Emissions During Engine Startup and At Loadmentioning

confidence: 99%

Design and Development of the 2002 UC Davis FutureTruck

Meyr

Cardé

Nitta

et al. 2003

SAE Technical Paper Series

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Yosemite is an advanced hybrid electric vehicle built on the Ford U152 Explorer platform. The University of California, Davis FutureTruck team designed Yosemite to meet the following objectives: 1. Maximize vehicle energy efficiency 2. Reduce petroleum consumption by 80% 3. Reduce fuel cycle greenhouse gas emissions by 67% 4. Achieve California Super Ultra Low Emission Vehicle (SULEV) target 5. Deliver best-in-class performance Yosemite meets these goals with an efficient hybrid powertrain, improved component systems, and an advanced control system. The primary powertrain combines a 1.9L flexible fuel engine with a 75kW brushless DC motor. A 60kW AC induction motor and reduction transaxle gearbox drives the front wheels. This powertrain configuration is compact, reliable, provides 4WD, and allows flexibility in control strategy. A 16.5kWh nickel metal-hydride traction battery pack powers the electric motors, providing up to 45 miles (72.4km) of all-electric range and the ability to tow crosscountry without recharging. The high power hybrid powertrain allows Yosemite to achieve high efficiency under normal operating conditions while exceeding V8 Explorer performance in all categories. Yosemite's superior fuel economy, low operating cost, and high performance, combined with advanced composites and telematics make it a desirable and competitive vehicle in today's growing market for advanced vehicles.

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“…High cell density substrates with lower thermal mass and higher specific surface areas are developed to meet the application. The potential of high cell density technology compared to todays standard substrates was discussed earlier at [ 1], [ 2, [ 3], [ 4]. The results of these studies showed the improvement of the total emission performance using higher cell density substrates at the same volume and the same precious metal loading.…”

Section: Introductionmentioning

confidence: 99%

Advanced Performance of Metallic Converter Systems Demonstrated on a Production V8 Engine

Brueck¹,

Mueller-Haas²,

Breuer³

et al. 2002

SAE Technical Paper Series

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It has been shown within the catalyst industry that the emission performance with higher cell density technology and therefore with higher specific geometric area is improved. The focus of this study was to compare the overall performance of high cell density catalysts, up to 1600cpsi, using a MY 2001 production vehicle with a 4.7ltr.V8 engine. The substrates were configured to be on the edge of the design capability. The goal was to develop cost optimized systems with similar emission and back pressure performance, which meet physical and production requirements. This paper will present the results of a preliminary computer simulation study and the final emission testing of a production vehicle. For the pre-evaluation a numerical simulation model was used to compare the light-off performance of different substrate designs in the cold start portion of the FTP test cycle. Four sets of converters were aged for 72 hours at 1025°C on an engine dynamometer stand, which is equivalent to 50k mile road driving condition. The emission performance of the catalysts was tested according the FTP75 driving cycle in close coupled and toe board position. In addition emission testing, back pressure tests before and after aging were also carried out.

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Prediction of Catalytic Performance for Ultra Thin Wall and High Cell Density Substrates

Cited by 18 publications

References 6 publications

On the quantification of the controlling regimes in automotive catalytic converters

On the quantification of the controlling regimes in automotive catalytic converters

Design and Development of the 2002 UC Davis FutureTruck

Advanced Performance of Metallic Converter Systems Demonstrated on a Production V8 Engine

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