Methanol Preignition Temperature Behavior 912414

The preignition behavior of neat methanol in the four-stroke, naturally aspirated, watercooled, spark ignition engine is reported. Specifically, the preignition threshold (or minimum) temperature for a hot spot other than the firing spark plug is determined as a function of the engine variables, including compression ratio, fuel-air ratio, spark timing, coolant temperature, and intake charge temperature and degree of vaporization. These experimental results are quantitatively compared to a methanol preignition model available in the literature. The range of preignition threshold temperatures measured is 1020 to 1220K. The trend of decreasing preignition threshold temperature with increasing cylinder pressure is observed, consistent with the model. However, there is a quantitative difference between the measurements and model results, which is discussed in the paper. Also, briefly examined are the effects of charge swirl and lubricating oil composition on preignition tendency. The study was conducted with a single cylinder Cooperative Fuels Research engine, of simple combustion chamber geometry, and thus, the results are of value primarily for their fundamental content, and for comparison of behavior.