Experimental and Modeling Study of the Flammability of Fuel Tank Headspace Vapors from High Ethanol Content Fuels

摘要

An experimental and modeling study was done to determine the flammability of fuel tank headspace vapors as a function of ambient temperature for seven E85 (85% ethanol, 15% gasoline) fuel blends, two types of gasoline, and denatured ethanol at a low tank fill level. Samples in small, closed chambers were tested simultaneously in a cold chamber to determine flammability and pressure rise when ignited by a strong electric spark. Gasoline and E85 fuels were flammable below a critical temperature; above it, the vapor was too rich to burn. Denatured ethanol was flammable at room temperature and colder, down to a critical temperature; below it, the vapor was too lean to burn. The flammability limit temperature of the E85 and gasoline fuels related to the dry vapor pressure equivalent (DVPE), but DVPE did not reliably rank the low-temperature flammability hazards of fuel tank headspace vapors when conventional gasolines were compared with alcohol blends.