Combustion Characteristics of Aluminum Oxide Nanoparticles-Diesel Blends in a Constant Volume Chamber

Abstract

<div class="section abstract"><div class="htmlview paragraph">This study investigates the effects on combustion characteristics of aluminum oxide (Al₂O₃) nanoparticles as additives for diesel in a constant volume chamber. Depending on the amount of aluminum oxide nanoparticles added, the test fuels are labeled as DA25, DA50, and DA100, which represent 25, 50, and 100 mg of aluminum oxide nanoparticles into 1 L of pure diesel, respectively. The ambient temperature for this experiment ranged from 800 to 1200 K to cover conventional and low-temperature combustion regimes. The oxygen concentration ranged from 21% to 13% to simulate different levels of exhaust gas recirculation (EGR). Based on in-cylinder pressure traces and results of apparent heat release rates, there was an improvement in combustion characteristics with the addition of aluminum oxide nanoparticles. The best combustion characteristics improvement was obtained under 800K/13% oxygen concentration case, where peak combustion pressure and heat release rate increased by 1.84% and 5.42% respectively for the DA25 blend. For all the tested fuels, the ignition delay increased with the reduction of ambient temperature and increase of oxygen concentration. At 800K/13% oxygen concentration case, combustion duration and ignition delay decreased by 6.06% and 10.58% respectively for the DA25 blend. Results also showed that the addition of aluminum oxide nanoparticles shortened the ignition delay of tested blends, especially at a low ambient oxygen concentration of 13%. Flame images were captured by a high-speed camera and results showed that, by adding aluminum oxide nanoparticles, the flame structures were similar to that of pure diesel. Spatially integrated natural luminosity was also captured as the indicator of soot emissions, and the results showed the effect on soot emissions with the addition of aluminum oxide nanoparticles into diesel.</div></div>