Regulated emissions from a direct-injection spark-ignition methanol engine

The effects of injection timing, ignition timing, and injection nozzle parameters on the regulated emissions from a high-compression ratio direct-injection spark-ignition methanol engine were investigated experimentally and its emission characteristics were compared with the diesel counterpart. The experimental results indicated that the injection and ignition timings affect exhaust emissions significantly. Best compromises between the brake thermal efficiency and three emission pollutants at the optimal injection and ignition timings were obtained. The effects of injection nozzle parameters on emissions of methanol engine are significant. The THC (total hydrocarbon compounds) emission using an injector of a 10-hole x 0.30 mm nozzle is lower significantly than those of 7-hole x 0.45 mm nozzle in the overall load range and CO (carbon monoxide) emission is also lower, but NOx (nitrogen oxides) emission is higher at high load. The methanol engine is characterized by smokeless combustion. According to the ECE R49-13 mode test procedure, the brake specific NOx emission from the methanol engine is only nearly half that from the diesel counterpart and 11% lower for the CO emission, but 273% higher for the THC emission. (C) 2011 Elsevier Ltd. All rights reserved.