Pragmatic investigation of the effect of ether additives on biodiesel combustion to reduce NOx and other harmful emissions

Abstract

The addition of oxygenated additives such as ethers has shown better results with improved combustion and reduced emissions. Ethers have a lower viscosity and higher oxygen concentrations that can improve combustion and have lower calorific value, which can control the cylinder temperature. Hence, three ethers: diethyl ether (DEE), Diethylene Glycol Dimethyl Ether (DME), and Tri-propylene-Glycol Monomethyl ether (TME) were selected as biodiesel additives to conduct engine tests for reducing NO_x and CO emissions. These three ethers were added at 10 % volume to the Tucuma B10 blend, and the results were compared with diesel, TB10, and TB20. The performance, combustion, and emission characteristics were investigated through engine tests conducted at 2400 rpm with varying loads of 25 %, 50 %, 75 %, and 100 %. The study found that adding oxygenated additives into the TB10 blend has led to a decrease in both CO and NO_x compared to the TB10 blend alone. However, the NO_x was higher for the ether-TB10 blends than diesel. At full load, TB10DME10 reduced CO emissions by 22.3 %, 45 %, and 38 %, compared to diesel, TB10, and TB20, respectively. Also, TB10TME10 showed reduced NO_x by 8.5 %, 5.2 %, 6.62 %, and 0.12 % compared to TB10 at 25 %, 50 %, 75 %, and 100 % loads, respectively. Peak pressure values for ether blends were lower than diesel but higher than TB10 and TB20. The study concluded that the TB10DEE10 has shown better results in reducing CO, NO_x, and BSFC and improved BTE. The study recommends a detailed computational fluid dynamics study to investigate more combustion aspects of ether blends. In addition, further investigation on oxidative stability, tribological behaviour, and cold flow performance of the ether blends is much needed.