The study by a team from the University of Birmingham and Newcastle University (UK) and Tsinghua University (China) examined DMF, ethanol, butanol and methanol.

The researchers focused on combustion performance and emissions sensitivity around the optimum spark timing, especially at 10 crank angle degrees retard (SR10). Such spark retard strategies are commonly used to reduce catalyst light-off times, albeit at the cost of reduced engine performance and increased CO₂.

The overall order of spark sensitivity at the highest load (8.5 bar IMEP) was: gasoline > butanol > DMF > ethanol > methanol.

The four biofuels widen the spark window due to improved anti-knock qualities and sometimes increased charge-cooling. This allows the increase of CO₂ to be better minimized than with gasoline. Furthermore, DMF is the only biofuel to produce high exhaust gas temperatures, similar to gasoline and helpful for fast catalyst light-off, whilst maintaining high combustion stabilities. This demonstrates the potentially favorable characteristics of DMF to become an effective cold-start fuel.

—Daniel et al.

Resources

• Ritchie Daniel, Guohong Tian, Hongming Xu, Shijin Shuai (2012) Ignition timing sensitivities of oxygenated biofuels compared to gasoline in a direct-injection SI engine, Fuel doi: 10.1016/j.fuel.2012.01.053