Methanol-gasoline blends containing 30 to 70 percent by volume methanol have potential to eliminate, or at least alleviate, major technical problems with the use of neat methanol such as safety, cold start and the reduced vehicle range. However, little information exits on their properties, performance and emissions.
Experiments were carried out in a spark-ignited, single-cylinder, variable compression ratio, Waukesha RDM engine with primarily commercial grade unleaded gasoline, commercial grade methanol, M30, M50 and M70 methanol-gasoline blends to compare efficiency, performance and emissions characteristics. The fuels were compared at their knock-limited compression ratios and MBT spark-timing. In addition, fuel properties, such as research and motor octane qualities, volatility, heating values and cloud points of methanol-gasoline blends were determined.
The addition of methanol to gasoline influenced favorably: octane quality, lean limit, knock-limited compression ratio, engine thermal efficiency power, and NOx emissions. Moreover, in all cases, the effect was nonlinear. Practically all of the benefit of methanol addition was achieved when the methanol content reached about 50 percent by volume. There were some undesirable effects of blending methanol into gasoline, namely phase separation, and increased emissions of unburned methanol and formaldehyde, particularly at higher methanol concentrations.