Experimental study on the burning rates of Ethanol-Gasoline blends pool fires under low ambient pressure

Ethanol-Gasoline has been used as vehicles fuel in areas widely in world, especially in China with areas from plain to high altitude. The addition of ethanol in gasoline will change the physicochemical properties of pure fuels, and then affect the burning behaviors. In this study, the burning rates of blending fuels were mainly investigated in a full-scale cargo compartment with ambient pressure of 40 kPa, 61 kPa, 80 kPa, 101 kPa. A 20 cm round pool filled with fuels at ethanol ratio of 0%, 10%, 20%, 50%, 80% and 100% by volume was employed. Mass burning rate, flame temperature, fuel temperature as well as flame images were measured and analyzed. The results indicate that as ambient pressure decreases, the burning rate decreases, and flame height increases significantly, but only the temperature at the flame base region is affected obviously. With increasing ethanol ratio, the burning rate shows a non-monotonic variation with a peak value, and the maximum value occurs at a certain ethanol ratio varied with pressure; but the maximum value of flame height and flame temperature occurs at ethanol ratio of about 20% and ambient pressure of 40 kPa, and shows a monotonic decrease at relative large pressure. A simple empirical correlation for burning rate data is developed based on ambient pressure, stoichiometric ratio and the ratio of the heat of combustion to the heat of vaporization, which shows a good agreement with 15% deviation.