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The primary objective of this work is to demonstrate that an extruded metal electrically heated catalyst (EHC) in combination with a traditional converter can achieve the Low and Ultra-Low California standards. With various aged EHC/converter systems and various heating strategies, typical FTP non-methane hydrocarbon (NMHC) emissions range from .015 to .030 g/mi. However, NMHC emissions as low as .008 g/mi are achieved. In addition to reducing emissions, experiments were conducted to investigate the impact various heating strategies and system design parameters have on electrical energy usage. The conclusions are that electrical energy requirements can be significantly reduced by: Locating the EHC close to the main converter. Locating the EHC and main converter close to the engine. Reducing the mass of the EHC. Heating the EHC prior to engine start-up.

Improved designs of extruded metal electrically heated catalysts (EHC) in combination with a traditional converter achieved the California ultra-low emission vehicle (ULEV) standard utilizing 50% less electrical energy than previous prototypes. This energy reduction is largely achieved by reducing the mass of the EHC. In addition to energy reduction, the battery voltage is reduced from 24 volts to 12 volts, and the power is reduced from 12 kilowatts to 3 kilowatts. Also discussed is the impact EHC mass, EHC catalytic activity, and no EHC preheating has on non-methane hydrocarbon emissions, energy requirements, and power requirements.

Low mass, extruded electrically heated catalysts (EHC) followed directly by a light-off and main converter reduced cold start non-methane hydrocarbons (NMHC) by greater than 80 percent. These reductions were demonstrated on several vehicle applications operating over the Light Duty Federal Test Procedure (FTP). To achieve this level of reduction, the design of the EHC cascade system, power level and heating time must be appropriately established. This paper discusses the impact of these design parameters on cold-start emissions reduction. From the test results, a generic empirical model was developed to predict EHC system conversion efficiency as a function of EHC power, heating time, and inlet exhaust temperature to the EHC.

The emission and flow restriction characteristics of three different ceramic substrates with varying wall thickness and cell density (400 cpsi/6.5 mil, 600/4.3, and 600/3.5) are compared. These 106mm diameter substrates were catalyzed with similar amounts of washcoat and fabricated into catalytic converters having a total volume of 2.0 liters. A Pd/Rh catalyst technology was applied at a concentration of 6.65 g/l and a ratio of 20/1. Three sets of converters (two of each type) were aged for 100 hours on an engine dynamometer stand. After aging, the FTP performance of these converters were evaluated on an auto-driver FTP stand using a 2.4L, four-cylinder prototype engine and on a 2.4L, four-cylinder prototype vehicle. A third set of unaged converters was used for cold flow restriction measurements and vehicle acceleration tests.