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Aldehyde and unburned fuel emissions (UBF) were measured from experimental 6V-92TA and 6V-71N methanol-fueled heavy-duty diesel engines. The 6V-71N engine was tested with experimental oxidation catalytic converters. Formaldehyde accounted for 97-99% of the total aldehydes emitted from both engines. Aldehyde and unburned fuel concentrations were highest in the idle modes of the 13-mode test and decreased with increasing engine speed and load. The 13-mode weighted aldehyde and UBF emissions for the 6V-92TA engine were 0.10 G/BHP-HR and 2.01 G/BHP-HR, respectively. The 13-mode aldehyde and UBF emissions from the 6V-71N engine before catalytic treatment were 0.32 G/BHP-HR and 4.51 G/BHP-HR, respectively. These emissions were reduced to 0.19 G/BHP-HR and 1.10 G/BHP-HR with catalytic treatment. Total aldehyde emissions from the methanol-fueled engines compared favorably with the 0.07 to 0.28 G/BHP-HR range reported for heavy-duty conventionally fueld diesel engines.

This paper describes aldehyde and unburned fuel emissions (UBF) measurements made on several light-duty, methanol-fueled vehicles with developmental 2.5-L engines and production and three-way catalytic converters. Emissions data were obtained under both steady-state and Federal Test Procedure (FTP) driving-cycle conditions. The data were then compared to those from a similarly equipped production gasoline vehicle. Before- and after-catalyst aldehyde and UBF emissions data are presented for three vehicle types as a function of equivalence ratio. In addition, aldehyde emission data for one of the methanol vehicles using a base-metal catalyst are discussed. The steady-state tests showed that both before- and after-catalyst aldehyde and UBF emissions are minimized by vehicle operation at lean equivalence ratios. The data also showed that formaldehyde accounted for 98% of the total aldehydes from the methanol vehicles, and only 31-54% of the total aldehydes from the gasoline vehicle.