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A vehicle emissions round robin test program was conducted using a methanol-fueled vehicle operating on M85. Each of 16 participants conducted two to six Federal Test Procedure (FTP) emissions tests. All participants measured emission rates of hydrocarbon (HC), CO, NOx, methanol, formaldehyde, and acetaldehyde. One participant, designated as a reference lab, conducted emissions testing at the beginning, the end, and two intermediate times during the round robin. Results of the reference lab demonstrated that no significant drift in emissions levels occurred during the 2-year program. Relative lab-to-lab variability for FTP-composite emissions was lowest for NOx, with a coefficient of variation (C.V.) of 12%. CO variability was 16%, HC variabilities (by GC and bench FID) were 17 and 35%, respectively. Methanol, formaldehyde, and acetaldehyde were found to have variabilities of 34, 17, and 63%, respectively.

A methanol-fueled transit bus with a 1988-technology Detroit Diesel Corporation (DDC) 6V-92TA engine was chassis dynamometer tested using steady-state and transient cycles to determine exhaust emissions and fuel economy. With chemical-grade methanol (M100), the bus had lower particulate, NOx, and heavy aldehyde emissions than the comparable (though older) diesel bus; however, formaldehyde and organic emissions were higher. Two other approaches were tried: methanol with 15% added gasoline (M85) and an exhaust catalyst (with M100). Both reduced formaldehyde and organic emissions relative to M100 alone, but they both increased heavy aldehyde emissions. The exhaust catalyst also reduced particulate emissions.

A round robin study to measure the aromatic levels in diesel fuels was conducted by the Chemical Characterization Panel of the Coordinating Research Council Air Pollution Research. Advisory Committee (CRC-APRAC) In-house Program Group, CAPI-1-64. The fuels for this study consisted of a jet fuel, a No. 2 diesel reference fuel, and three fuels used in a CRC-sponsored diesel emission project (CAPE-32) These fuels had 90% distillation temperatures which ranged from 472° to 642° F and aromaticity levels from approximately 18 to 55% by volume. All participants used the American Society for Testing and Materials (ASTM) D1319 or modified D1319 methods to measure the aromatic levels in the selected fuels. Some participants concurrently analyzed the same fuels using other methods such as high-performance liquid chromatography, mass spectrometry, nuclear magnetic resonance spectrometry, and elution chromatography (ASTM D2549).

The effects of fuel composition on diesel exhaust particulate emissions have been studied at several steady-state operating conditions using a heavy-duty laboratory engine. Particulate emissions were influenced by three primary fuel factors: sulfur content, aromatics content, and volatility. At all but lightly loaded operating conditions, fuel sulfur was the dominant fuel factor in particulate formation. Fuel sulfur affects particulate emissions primarily by formation of sulfate (as sulfuric acid) and associated “bound” water and, to a lesser degree, by increasing the amount of soluble organic material collected. Aromatics and volatility influence the amount of carbonaceous material formed. Five polynuclear aromatic hydrocarbon (PAH) compounds were measured in the soluble organic fraction. Engine operating conditions greatly affected PAH levels; however, no strong influence of fuel composition on PAH concentrations was observed in the normal range of No. 1 - No. 2 diesel fuels.