VOLATILITY

CRC Project No. CM-138

Leader: L. M. Gibbs

Scope and Objective

The objective of this program is to investigate the relationship between vehicle performance/driveability and fuel volatility characteristics.

Current Status and Future Programs

2006 Hot-Fuel Handling Program

CRC conducted a Hot-Fuel-Handling Program at the GM Desert Proving Grounds in Mesa, AZ from May 15 to July 9, 2006.  The objective of the study was to determine under hot ambient temperature conditions the effect of fuel front-end volatility and ethanol content on hot-fuel-handling driveability performance in a large group of late-model vehicles equipped with fuel injection systems.  The study produced an assessment of hydrocarbon-only and various concentration ethanol blends (up to E20) under hot temperature ambient conditions.  The results showed lower than expected effects of the vapor lock protection temperature and ethanol content upon hot starting.  These results were compared to those from the 2001 CRC Hot-Fuel-Handling Program (CRC Report No. 629).

A matrix of 20 late model and five older model vehicles was tested against a fuel set of high, medium, and low volatility fuels ranging in ethanol content from E0-E20. The recent addition of E20 to the test program was selected in coordination with other E20 activities in the Emissions and AVFL Committees.  The Volatility Panel members met during the December 2006 ASTM Committee D2 meeting to finalize the report.  The report was approved by the committee and published as CRC Report No. 648.

2008 Cool Ambient Volatility Study

There are two parts to this volatility program:.  1) Determine the effect of vapor pressure of E85 Fuel Ethanol on cold-start and warm-up driveability performance under cool ambient conditions in a large group of late model flexible-fuel vehicles equipped with fuel injection systems, 2) Determine the effect of E15 and E20 on cold-start and warm-up driveability performance under cool ambient conditions in a moderate size group of late model and older conventional vehicles. 

The minimum vapor pressure required for the two warmer ambient conditions of the three volatility classes in ASTM Specification D 5798 (Classes 1 and 2) for acceptable cold-start and warm-up driveability will be determined.  A follow-on program  would  be required to  investigate  E85 properties for the coldest Class 3 fuels.  The cold-start and warm-up performance of E15 and E20 versus gasoline with similar vapor pressures will be determined.  This program was conducted in January and February 2008.  The project panel members are now preparing the final report and expect to have the report approved before the end of 2008.  The Renewable Fuels Association (RFA) and NREL contributed funding and manpower support to the project and Lubrizol contributed some test vehicles.  A follow-on program is in the planning stages to investigate E85 properties for Class 3 (i.e., winter E85) fuels.  The E85 Class 3 study will be conducted in a low temperature chassis dynamometer facility.

2008 Cold Ambient E85 Class 3 Volatility Study

This study, started in summer 2008, will evaluate 20 flexible fuel vehicles on 8 fuels with varying vapor pressure and hydrocarbon content.  The target test temperature levels are -10°C and -30°C, but these targets may be modified.  The AWCD facility at Imperial Oil in Sarnia, Canada will be used to complete the study by the end of 2008.  Raters from previous CRC programs will be used.  There are slight differences between road and dynamometer testing, but a trained rater can obtain consistent ratings on either the road or the dynamometer.

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