Effects of boron-based fuel additives on sequential-ignition engine characteristics and emissions

The experiment investigates the effects of boron-based oxygenated compounds as fuel additives on the performance and emission characteristics of a sequential-ignition spark-ignition engine. Fuel blends were prepared by adding 1%, 5% and 10% TMB and TEB to gasoline. Experiments were conducted on a commercial engine operating at 2800 rpm under 75% and 100% throttles. The addition of boron-containing oxygenates to gasoline reduced engine torque and brake mean effective pressure (BMEP) under the tested operating conditions, depending on the additive type and blending ratio. This reduction was attributed to the combined effects of fuel properties, mixture formation, and the fixed stock ECU calibration. In some cases, modest improvements in volumetric efficiency were observed. Both additives increased fuel consumption, while notable reductions were observed in carbon monoxide and unburned hydrocarbons. Carbon dioxide increased, indicating improved oxidation of carbon-containing species, whereas nitrogen oxide (NOx) emissions tended to increase at higher additive concentrations. Overall, the results indicate that TMB and TEB can improve certain emission characteristics, particularly by reducing CO and HC emissions, although this improvement is accompanied by reductions in engine torque and increases in BSFC. Among the tested additives, TMB exhibited a more pronounced effect on emission reduction.