M.Sc Tezi Görüntüleme

      In this study the effects of using oxygenates, such as methanol and MTBE, instead of lead additives in the gasoline on engine performance and exhaust emissions have been investigated experimentally. For this purpose, a series of systematic experiments were carried out by using a single cylinder variable compression ratio SI engine, equipped with an electric brake dynamometer. The experiments have been performed with different compression ratios and spark timings at various engine speeds and 1/1 gas position. The blends used in the experiments have been obtained by adding methanol and MTBE to a base gasoline (the regular gasoline) in four different volumetric ratios (5, 10, 15, 20%). In addition to blends the leaded and unleaded gasoline have also been examined for comparison. The results such as brake power, brake torque, brake mean effective pressure, brake thermal efficiency, brake specific fuel consumption, and CO emissions obtained from the experiments have been evaluated at different engine operating conditions.

       The results have showed that adding of methanol and MTBE into base gasoline affected the engine performance and CO emissions positively at most of operating conditions. The best engine performances have been obtained with the MET5 and MET10 blends followed by MTBE15 and MTBE20 blends in terms of engine output. On the other hand, in terms of brake thermal efficiency, the methanol blends have given the best results followed by unleaded gasoline and then MTBE blends. The MET20 and the MTBE15 blends are the best ones among the methanol blends and the MTBE blends, in respect of brake thermal efficiency, respectively.

      When compared to the regular, leaded and unleaded gasoline the oxygenated blends have generally decreased the CO emissions. The MET20 and MTBE10 blends have given the least CO emissions among the tested fuel and fuel blends for the all operating conditions.

      Key Words : Oxygenates, methanol-gasoline blends, MTBE-gasoline blends, Exhaust emissions, SI engine performance, gasoline additives