The Effect of Gasoline Additives on Combustion Generated Nano-scale Particulates

Recent developments in measurement techniques enabled researchers to measure ultra-fine particulates of nano-scale range and provided more evidence that the smaller particulates typically emitted from gasoline engines may have more severe impacts on human respiratory system than the bigger particulates from diesel engines. The knowledge of the characteristics of particulates from gasoline engines, especially, the effect of fuel borne additives is sparse. This work presents the findings from a study into the effect of aftermarket additives on nano-scale particulates. Four commercially available fuel borne additives used in gasoline engines mainly by private vehicle owners in the United Kingdom were selected for this study. The combustion and emission performance of the additive fuels were compared against that of commercially available gasoline fuel using a 4-stroke, throttle body injected gasoline engine. The engine-out particulates in the range of 5 to 1000 nm were measured using a fast particle spectrometer along with the in-cylinder pressure trace. The work identified that the total particulate count for certain types of additives are two orders of magnitude greater than that of base fuel at the same engine operating condition. In contrast, other types of additives produce significantly lower levels of particulate when compared with the base fuel especially in the range of 10 nm size.