One means of using natural gas in transportation is for it to serve as the primary fuel in a dual-fueled compression ignition engine, with a diesel pilot injection for combustion.

The Xi’an Jiaotong test results showed that, with increasing pilot quantity, the peak particle number concentration shifts from 29 nm to 100 nm while the peak particle mass concentration is stable and remains at 200 nm.

Increasing the pilot quantity improves the brake’s thermal efficiency at low- and medium-loads; the improvement is not obvious at high loads.

With increasing pilot quantity, the first-stage heat release appears earlier and its peak value is also increased, accompanied by a decrease in the peak value of the second-stage heat release. The increase in the pilot quantity reduces the carbon monoxide emissions and the hydrocarbon emissions but increases the nitrogen oxide emissions. In comparison with the diesel pilot case, the size distribution of the ultrafine particle emissions from biodiesel pilot operation changes little, but both the number concentration and the mass concentration are reduced.

—Liu et al.

Resources

• Yifu Liu, Lu Sun, Bo Yang, Lei Zhou, Ke Zeng and Zuohua Huang (2014) “Effect of the pilot quantity on the ultrafine particle emissions and the combustion characteristics of a biodiesel pilot-ignited natural-gas dual-fuel engine” Journal of Automobile Engineering doi: 10.1177/0954407014552537