Effect of acetylene as a low reactivity fuel on performance, combustion, exergy and emissions of an acetylene/diesel RCCI engine with variable premix ratios

Abstract

This investigation is oriented mainly to evaluate the prospects of the diesel–acetylene-fuelled RCCI operation under different operating conditions. The combustion reactivity is controlled by directly regulating the acetylene and diesel flow rates. Moreover, an advanced pilot diesel injection angle of −110° aTDC and an acetylene injection angle of 10° aTDC are considered for more homogeneous combustion and better efficiency at different power outputs. The results showed improvement in combustion with increased average cylinder pressure (1.68%), heat release rate (1.55%) and reduced average cylinder temperature (−28.77%), CoVIMEP (−72.99%), and maximum pressure rise rate (−0.65%) compared to base diesel. Brake thermal efficiency also turned out to be maximum (31.88% higher) under this operating condition with minimum energy consumption. Exergetic efficiency and sustainability index increased by 33.05% & 12.46%, respectively. Entropy generation rate and depletion factor reduced by 29.18% & 10.44% w.r.t. base diesel operation. Interestingly, it is observed that all the emission parameters showed appreciable improvement with reduced NO_x (−20.54%), smoke (−63.53%), CO (−36.94%), CO₂ (−42.17%), and SO₂ (−43.83%) emissions with respect to base diesel operation. Thus, this study demonstrated the potential of acetylene as a low reactivity fuel in the RCCI combustion up to a usability limit of 40% premix for optimum outcome.