Role of Cerium Oxide Nanoparticles as Diesel Additives in Combustion Efficiency Improvements and Emission Reduction

摘要

An experimental investigation is conducted to evaluate the performance, combustion, and emission characteristics of a diesel engine using cerium oxide (CeO2) nanoparticles as diesel fuel additives. Using cetyl trimethyl ammonium bromide (CTAB) as the cationic surfactant and with ultrasonic vibration, CeO2 nanoparticles at dosing levels of 50 and 100mg/L can be stably and uniformly dispersed in diesel. Physically, the mixing of fuel blends with air is enhanced by microexplosion events because of the large surface-volume ratio and intensified thermal transmissibility of nanoparticles. Moreover, chemically, CeO2 in diesel fuel plays a positive role in the dehydrogenation reaction at a high temperature because of its excellent redox ability. As a result, the addition of nano-CeO2 to neat diesel (50 and 100mg/L) leads to a gradual increase in the cylinder pressure compared with the reference neat diesel. Meanwhile, the ignition of fuel blends with a high dosing level of nano-CeO2 occurs earlier by approximately 1.2 degrees crank angle (CA) and 1.8 degrees CA, respectively. At full load, the effective thermal efficiencies for nano-CeO2 fuels are augmented by approximately 1.7 and 2.3%. Because of the distinctive merits of nano-CeO2 in promoting fuel atomization and its favorable intrinsic catalytic effect, the level of harmful pollutants (such as HC, CO, NOx, and soot) in exhaust gases is appreciably reduced to varying degrees.