Experimental and Numerical Study on the Effect of NO₂ on n-Butanol/Biodiesel Dual-Fuel Combustion in a Compression Ignition Engine

Abstract

Nitrogen dioxide (NO 2 ) is an active species of exhaust gas recirculation gas, and it has a significant impact on the autoignition and combustion processes of fuels. This study presented a comprehensive investigation of the effect of NO 2 on the combustion characteristics of the n -butanol/biodiesel dual fuel. Experiments were conducted on a single-cylinder engine with 0, 100, 200, and 400 v/v ppm NO 2 addition at two fuel injection ratios. The findings of the experiments indicated that adding NO 2 resulted in an earlier start of heat release and an increase in peak in-cylinder pressure as compared to experiments where no NO 2 was added. The evolutions of n -butanol, biodiesel, and OH radicals were evaluated using the computational fluid dynamics software coupled with the n -butanol–biodiesel–NO 2 mechanism. The results revealed that when 400 v/v ppm NO 2 was added, the consumption of n -butanol and biodiesel occurred earlier, and the formation of OH radicals was approximately an order of magnitude higher before the biodiesel was injected. Furthermore, reaction rate and flux analyses were performed to understand the effect of NO 2 addition on the reaction process. When NO 2 was added, 35% of the HO 2 radicals reacted with NO which converted from NO 2 via the reaction NO + HO 2 ⇌ NO 2 + OH, promoting the formation of OH radicals in the reaction system. The addition of NO 2 can also enhance the consumption of CH 3 radicals via the reaction CH 3 + HO 2 ⇌ CH 3 O + OH.

Royal Poinciana Biodiesel Blends with 1-Butanol as a Potential Alternative Fuel for Unmodified Research Engines

“…Adding 40% of 1-butanol to the biodiesel tends to improve the acceleration of OH radicals at a much faster rate to achieve fine BTE, lower the BSFC, and lower NO X emissions compared to diesel. 35 This study investigates the diesel engine performance, combustion, and emission parameters of the various test blends RP100, D90RP7B3, D80RP14B6, and D70RP21B9. Most of the literature that used 1-butanol with different biodiesel reported that it gives predetermined performance and minor emissions.…”

“…The NO X emissions were reduced by 4%. Adding 40% of 1-butanol to the biodiesel tends to improve the acceleration of OH radicals at a much faster rate to achieve fine BTE, lower the BSFC, and lower NO X emissions compared to diesel …”