Experimental and Numerical Analysis of Laser-ignition of Wet Ethanol with Elevated Water Content

Abstract

Higher production cost of anhydrous ethanol associated with distillation and dehydration process could be reduced through the direct use of wet/hydrous ethanol in engine applications. In this study, both experimental investigation and numerical analysis were carried out to quantify the effect of water content on laser ignition characteristics of premixed charge of wet ethanol with different water concentration and over a range of equivalence ratios. Combustion of wet ethanol was initiated through laser-induced breakdown from a Q-switched Nd:YAG laser. A high-speed camera is used to visualize the ignition event and flame propagation. Results demonstrated that, presence of water in ethanol up to 20% by volume accelerated the initial combustion reactions and led to faster burning. Adverse effects of elevated water concentration in ethanol at and beyond 30% (v/v), are more pronounced in fuel lean combustion region compared with fuel rich combustion. Laser-induced breakdown spectroscopic (LIBS) measurements revealed that, plasma temperature slightly increased with added water in ethanol up to 20% (v/v) as water in ethanol results in enhanced ionization of the gas mixture during laser breakdown, which leads to more intense absorption of laser energy. Therefore, this study demonstrates the potential of direct use of wet ethanol as an attractive fuel for IC engine.