Diesel engines have been widely used due to the higher reliability and superior fuel conversion efficiency. However, they still generate significant amount of carbon dioxide (CO2) and particulate matter (PM) emissions. Natural gas is a low carbon and clean fuel that generates less CO2 and PM emissions than diesel during combustion. Replacing diesel by natural gas in internal combustion engines help reduce both CO2 and PM emissions. Natural gas – diesel dual fuel combustion is a practical and efficient way to replace diesel by natural gas in internal combustion engines. One concern for dual fuel combustion engines is the diesel injector tip temperature increase with increasing natural gas fraction.
This paper reports an experimental investigation on the diesel injector tip temperature variation and combustion performance of a natural gas – diesel dual fuel engine at medium and high load conditions. The natural gas fraction was changed from zero to 90% in the experiment. The results suggest that the injector tip temperature increased with increasing natural gas fraction at a given diesel injection timing or with advancing the diesel injection timing at a given natural gas fraction. However, the injector tip temperature never exceeded 250 °C in the whole experimental range. The effect of natural gas fraction on combustion performance depended on engine load and diesel injection timing.