The Effect of Compression Ratio on Small Two Stroke Cycle Spark Ignition Engine Fueled Methanol Containing Water

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We Studied on small two stroke cycle spark ignition engines fueled methanol contains 0%, 10% and 20% volume of water. Especially, we measured pressure change in the cylinder using strain-type pressure gage. Engine speed is constant(2200rpm). Delivery ratio is 0.4(constant). And compression ratio(CR)is changed(CR=7.1, 7.7 and 8.4). Under these condition, engine performance test was carried out, with variable excess air ratio(EAR).Experimental results in this investigation are following(1)At rich mixture, maximum output power using methanol contents up to 20% of water is approximately equal to maximum power using neat methanol. But, at lean mixture, maximum output power is decreased as the water contents rate increases.(2)As the water contents rate increases, ignition time lag is increased, but burning duration is not change. Then MBT(Minimum advance for Best Torque) isdecreased.(3)Under high compression ratio condition, thermal efficiency and output power or engines fueled methanol containing water is slightly increased. MBT is also decreased, and flammable mixture region is reduced.