Heat of Vaporization and Species Evolution During Gasoline Evaporation Measured by DSC/TGA/MS for Blends of C1 to C4 Alcohols in Commercial Gasoline Blendstocks 2019-01-0014
Evaporative cooling of the fuel-air charge is an important feature of direct-injection spark-ignition engines that improves fuel knock resistance but, in some cases, may increase fine particle emissions. We have reported on experimental approaches for measuring both total heat of vaporization and examination of the evaporative heat effect as a function of fraction evaporated for gasolines and ethanol blends. In this paper we extend this work to include other low-molecular-weight alcohols and additionally present results on species evolution during fuel evaporation by coupling of a mass spectrometer to our differential scanning calorimetry/thermogravimetric analysis instrument (DSC/TGA/MS). The alcohols examined were methanol, ethanol, n-propanol, i-propanol, 2-butanol, and i-butanol. The results show that total HOV of the alcohol gasoline blends is in line with the decreasing HOV in kJ/kg with increasing alcohol carbon number, as expected. The results are analyzed to understand how different alcohols affect species evolution during evaporation, especially evaporation of aromatic compounds that are precursors to soot particles.
Gina M. Fioroni, Earl Christensen, Lisa Fouts, Robert McCormick
National Renewable Energy Laboratory
International Powertrains, Fuels & Lubricants Meeting