Low-Polluting, High-Efficiency, Mixed Fuel/ Natural Gas Engine for Transport Application

This paper describes how mixed fuel (MF) technology was the first way proposed for natural gas (NG) utilization in heavy-duty transportation. The unsolved problems of high levels of unburned hydrocarbons (THC) and the low amount of possible substitution of diesel oil with NG lead to the renouncing of this technology in favor of spark ignited full NG engines. In many situations, mixed fuel could represent the only way to access the environmental benefits connected to NG use in the transport sector. Therefore, a new generation of mixed fuel systems was developed and analyzed the effects of intake throttling, catalytic exhaust gases and exhaust gas recycling (EGR). This paper presents the influence of each component on performance and emissions are evaluated and the results on the regulated test, for a heavy-duty engine, are reported.