Laminar burning velocities of iso-octane, toluene, 1-hexene, ethanol and their quaternary blends at elevated temperatures and pressures

Increasing environmental concerns caused interest in alternative fuels among which ethanol is regarded as possibly the best candidate to augment fossil fuels. Ethanol can easily be blended with hydrocarbons. Laminar burning velocity is a fundamental property of fuel for spark ignition engines. Adiabatic laminar burning velocities have been measured using the constant volume method along with the Schilieren optical system, for iso-octane, toluene, 1-hexene, ethanol and the quaternary blends with ethanol volume fractions of 0%, 20%, 50%, and 85% and equal fraction of other three components. Measurements were conducted for equivalence ratios from 0.7 to 1.4, temperatures of 298 K, 380 K and 450 K, and pressures of 1 bar, 2 bar and 4 bar. Close agreements were found between the present results and literature data for pure components. Adding 20% ethanol doesn't increase the burning velocity of the blend by much, particularly for lean mixture. Higher volume fraction of ethanol (over 20%) leads to a higher laminar burning velocity of the blend and the burning velocity peaks at richer mixture. High temperature and high volume fraction of ethanol lead to earlier cellular flame of the quaternary blends.