Effect of amide-functionalized carbon nanotubes as commercial diesel and palm-oil biodiesel additives on the ignition delay: A study on droplet scale

• Published in: Fuel (Guildford) Vol. 338; p. 127202
• Main Authors: Rentería, Jorge, Gallego, Anderson, Gamboa, David, Cacua, Karen, Herrera, Bernardo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.04.2023
• Subjects: Amide-functionalization; Biodiesel; Carbon nanotubes; Diesel; Ignition delay; Carbon nanotubes; Amide-functionalization; Diesel; Ignition delay; Biodiesel
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2022.127202

•Diesel-biodiesel-carbon nanotube droplets expand before ignition.•Functionalized and non-functionalized CNT reduces the ignition delay.•Functionalized CNT in biodiesel had a greater effect on ignition delay reduction.•Functionalized and non-functionalized CNT affect equally the diesel ignition delay. The wide use of diesel in transport and industry demands actions to reduce the emissions of harmful pollutants in the scenario of the energy transition to renewable energy, which is currently the trend in most countries around the world. Carbon nanomaterials added to diesel have been identified as a promising alternative for reducing particulate matter and NOx emissions. However, the stability of the dispersions of these nanomaterials in liquid fuels is an issue of major concern because it determines the applicability of nanofuels to internal combustion engines. That is why some alternatives, like carbon nanomaterial functionalization, have been explored to increase the stability of nanofuels, but the addition of these functionalized nanomaterials could have an effect on the combustion properties of the blends. This work explores for the first time the effect of using amide-functionalized carbon nanotubes on the ignition delay of blends of these nanomaterials (50 and 100 ppm) and Colombian commercial diesel (90 % petroleum diesel and 10 % palm-oil biodiesel) and palm-oil biodiesel. The characterization of the ignition delay was conducted on a droplet scale through the shadowgraph technique since this property is an indicator of the performance of real compression ignition engines in terms of combustion efficiency and pollutant emissions. Results showed that the addition of carbon nanotubes, either functionalized or not, increased the volumetric expansion of the droplets before ignition by up to 1.6 % in comparison with the raw fuels. Also, the addition of carbon nanotubes reduced the ignition delay of the blends in comparison to the raw fuels by about 18.3 % and 13.1 % for biodiesel with functionalized carbon nanotubes at 50 ppm and 100 ppm, respectively; 9.4 % and 11.8 % for biodiesel with no-functionalized carbon nanotubes at 50 ppm and 100 ppm, respectively; 12.3 % and 18.3 % for commercial diesel with functionalized carbon nanotubes at 50 ppm and 100 ppm, respectively; and 14.9 % and 14.7 % for commercial diesel with no-functionalized carbon nanotubes at 50 ppm and 100 ppm, respectively. However, the reduction for biodiesel with functionalized carbon nanotubes at 100 ppm was not significantly different from that of the biodiesel added with no-functionalized carbon nanotubes at 50 and 100 ppm. In the case of commercial diesel, despite the reduction of the ignition delay for all the nanofuels in comparison with the raw fuel, there was not a significant difference between the functionalized and no-functionalized blends.