Abstract: To overcome the difficulty of cold start of spark methanol engine at low ambient temperature, the effects of the minimum amount of methanol injected per cycle, the ambient temperature, the angle difference between injection timing and ignition timing, preheating method and additional LPG injected into the inlet port on the critical firing boundary of the engine based on single cycle duel injection were investigated by experiments. Results show that the critical firing boundary is influenced by all the above factors, and by the angle difference between methanol injection timing and LPG injection timing. When the ambient temperature is below 16 ℃, an auxiliary start-aid must be used to support the cold start of the methanol engine. Glow plug preheating can ensure reliable firing of the methanol engine at ambient temperature above 0 ℃. Using an additional auxiliary start-aid, injecting LPG into the inlet port, can result in reliable firing at ambient temperature above -13 ℃.

Key words: power machinery and engineering, spark ignition engine, methanol, critical firing boundary, cold start