Comparison of Different Gasoline Alternative Fuels in Terms of Laminar Burning Velocity at Increased Gas Temperatures and Exhaust Gas Recirculation Rates

Abstract

The butanol isomers n-butanol and isobutanol as well as ethanol are among the biofuels most likely to be used for engine combustion and are likely to become more relevant as surrogate fuels or blend components in the future. To use the potentials of alternative fuels, the combustion mechanisms and, thus, burning behavior should be known. A key parameter for flame kinetic studies and combustion simulation is the laminar burning velocity. However, reproducible measurements of flame speeds of gasified liquid fuels are difficult. To reduce the scattering of experimental results to acceptable levels, there is a common research interest of several European institutes using so-called heat flux burners. In this work, a self-designed liquid fuel evaporation system has been combined with a precise droplet generator, which allows for measurements of adiabatic laminar burning velocity at elevated gas temperatures. The one-dimensional (1D) flame appears very stable, even close to its flammability limits. The boundary conditions are chosen to model exhaust gas recirculation (EGR) with different temperatures and compositions of the mixtures. The measurement data are compared to the corresponding results of other research groups, and the uncertainty of the burning velocity is estimated.

Experimental and numerical investigations on the laminar burning velocity of n-butanol + air mixtures at elevated temperatures

“…Knorsch et al[40] used a modified heat-flux method called 'HeatFluxER' to measure the burning velocity of n-butanol+air mixtures at 423 K. The present experimental data is in close agreement with predictions from Feng et al[60] model in the leaner regime and for Φ = 1.2 and 1.3. Predictions from the Liu et al[61] model match well with the present experiment only at Φ = 1.3.…”

Experimental and kinetic study on the laminar burning speed, Markstein length and cellular instability of oxygenated fuels

“…[53]. As can be seen from figure 2(a) for NB, our results are in good agreement with those of Zhang et al [54] at 393 K using spherical flame method, and Knorsch et al [55] at 423 K using heat flux method. However, our measurements are consistently lower than those of Broustail et al [56], with an average of 10% for 393 K and 3% for 423 K. Under 423 K, our results are lower than those of Gu et al [57], which are obtained at 428 K, for lean mixture, but close for stoichiometric and rich mixtures.…”

The effect of ethanol blending on mixture formation, combustion and soot emission studied in an optical DISI engine

“…Considering the flame propagation, isooctane combustion has progressed further than E20 combustion. In general the laminar flame velocity of ethanol is higher than that of isooctane [47]. This leads to faster flame growth speed for ethanol in comparison to isooctane [48].…”