Investigating Acoustic Excitation and Reburn Interaction on NOx Concentration in Bio-Fuel Engines Exhaust

Abstract

Abstract Although gasoline and diesel fuels are likely to continue fuelling the internal combustion engines for the near future, there is an increasing concern over the emission of greenhouse gases and other environmental pollutants. Alternative fuels such as biofuels are promising as they are renewable, sustainable, and reduce engine emissions. However, nitric oxides (NO) and nitrogen dioxides (NO2) are typically released in greater proportion, generally known as NOx. Applying acoustic excitation on a biofuel operated engine exhaust gases is investigated with and without reburn. Four biofuels, namely Jatropha, Karanja, Palm and neem oils, are burned in a single-cylinder Internal Combustion Engine (ICE). The exhaust gases is carried out through a vertical tube where a trace of liquid petroleum gas (LPG) is injected before it passes an acoustic cross tube. Variable frequency acoustic waves were passed through the setup using a speaker and amplifier. NOx is sampled from the top of the vertical tube. Acoustic wave frequency, LPG reburn, and combination of both acoustic waves and reburn influence on NOx mitigation are investigated. The integration of acoustic wave excitation and reburn showed the most significant reduction in the NOx. The second-largest NOx reduction was achieved with the sole use of reburn technology. Integrating the acoustic excitation with reburning was found to produce about 80% NOx reduction at a range of 100–150 Hz for all tested biodiesel fuels. Out of the fuels under consideration, Neem Oil generated the lowest amount of NOx and showed 87% reduction in NOx.