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

Abstract

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