Study On Emissions Reduction Of Diesel/Methanol Compound Combustion Engine

Methanol is regarded as the right alternative fuel for the spark ignition engine because of the high octane number. The paper presents a new methanol combustion theory, DMCC (Diesel Methanol Compound Combustion), which accords with our technique level and energy condition.The DMCC engine can switch automatically between diesel mode and diesel/methanol mode according to the ECU. The DMCC engine is only fuelled with diesel during the starting-up, warming-up, low speed and low load, because of the high HC and CO emissions and poor fuel economy; When the engine speed, load and the temperature of coolant all go over the initialized values, methanol is injected into the inlet port and then ignited by certain diesel, so the DMCC engine runs in diesel/methanol mode, which can largely reduces the NOx and smoke emissions of the engine.From the former experimental data, we know that the DMCC can highly decrease the NOx and smoke emissions, but with the increase of the HC and CO emissions. So it is necessary to employ the after treatment device to decline the additive emissions. Technically, the oxidation catalytic converter is the proper device because the emissions emitted by DMCC are mostly HC and CO. But it is supposed to validate the performance of the oxidation catalytic converter and find the right one for DMCC.The experiments are performed on a modified DMCC engine. This paper studies roundly the performance of the DMCC engine at different substitution ratios and different after treatment devices.The experimental results show that, the DMCC engine can obviously improve the fuel economy except when the low load and the high substitution ratio, and after calibration of the ECU the fuel economy can be improved in every working condition, at the same time, the date of road test also proves the conclusion. The exhaust temperature, Smoke, NOx and CO2 emissions considerably are lower compared to the ones under normal engine and the decreasing values is increasing with the substantiation ratios. At the same time, the HC and CO emissions increase highly, and the values are adding up with substantiation ratios.We find that the A converter has been lighted up at the torque of 90 N·m, but B is not lighted up until at the torque of 120 N·m. Before being lighted-up, the catalytic efficiencies of both A and B are no more than 20%, but after being lighted-up the values are no less than 70%, when the HC and CO emissions are reduced effectively. Diesel/methanol compound combustion with oxidation catalyst converter can effectively decrease diesel engines harmful emissions, in a certain extent, relieve fossil oil consumption. Therefore, it is great beneficial to our national energy save and environment protection.