Abstract
Most previous laboratory-scale deposit simulator studies have considered mainly fuel or lubricant composition and properties, with no consideration of possible effects of NOx, which may affect initiation of the deposit formation process and the overall rate at which deposition occurs. In this study a laboratory-scale deposit simulator was developed which produced thin deposit films by spraying gasoline on to a heated aluminium sleeve to investigate the effects of temperature, NO2 and possible gasoline blending components, on deposit formation. The amount of deposit collected is indicative of the deposit-forming tendency of the test fuel. The deposit film composition was analysed using Fourier transform infrared (FTIR) spectroscopy.
The results of the experiments indicate that deposit formation is indeed sensitive to NO2, in addition to the effects of temperature and the molecular structure of the hydrocarbons. Thus the effect of NOx in deposit-related studies is important and should not be ignored. The FTIR analyses showed that when using NO2 the deposits are of a very similar structure to those produced in a real engine test. The analyses also gave some insight into the role of NO2 in the deposit formation mechanism.
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