Investigation On Combustion Characteristics Of A Locomotive Diesel Engine With Diesel/Methanol Compound Combustion Mode

Railway construction in our country has got fast development in recent years,although the electrification is an important direction, but the internal combustion enginecar still play an irreplaceable role in the national economy. Diesel locomotive in Chinais given priority to with diesel, although the number is small, but the fuel consumptionis a big deal, the consumption of diesel locomotive diesel annually accounts for aboutdiesel to about6%of the total consumption for the whole year in china. The petroleumresources of our country is insufficient, imports have been close to60%a year, whichtake a lot of pressure to oil energy security to us. So finding clean and effectivealternative fuels becomes very important. methanol is mainly derived from coal, maturetechnology, low cost, it is very match with the energy structure of our country which isrich in coal. Therefore, methanol is an ideal alternative fuel of internal combustionengine, the research about use methanol as diesel fuel is becoming more and moreattractive for us.Our Research Team proposed diesel/methanol compound combustion few yearsago. Which successful applied on high speed vehicle diesel engine. Previousexperiments and vehicle road experiment results show that using this method canreplace the diesel effectivein the case of performance does not reduce significantly,improve the fuel economy and the effective thermal efficiency, at the same time canreduce carbon smoke and NOx emissions.This test is about a locomotive with medium speed diesel engine for mechanicalparts modified, to realize the diesel/methanol compound combustion on this engine.Add methanol supply and injection system on this machine, we use the electroniccontrol unit (ECU) which we design it by ourselves to control methanol injectionvolume and injection time timely adjustment according to the actual engine operationcondition; And to install the cylinder pressure sensors to collect the engine operatingparameters, using the parameters obtained from the sensors to analysis the combustioncharacteristic of engine which run on diesel/methanol compound combustion mode; Inaddition, make a comparative study of combustion performance on the machine rundiesel/methanol mode to the original machine burning diesel mode.The results show that, on the condition of maintain its performance, locomotivemedium-speed diesel can run on diesel/methanol compound combustion mode. Withthe increase of methanol injection, Dual fuel combustion mode compared with the pure diesel mode. The ignition delay is extended and the combustion duration is shorten. Atlow and middle load conditions, it gives single peak and rapid heat release. At high loadconditions, there is still two-stage heat release though the premixed combustion part isincreased. The peak cylinder pressure and the peak rate of pressure rise of dual fuelcombustion are higher than those of the baseline engine. The maximum combustiontemperature is increased with the increase of methanol injection. In addition, thethermal efficiency of dual fuel combustion is closely relative to the load, In the lowspeed of600r/min, the effective thermal efficiency is reduced with the increase ofmethanol injection, when33%replacement rate fell by9.06%。In the high speed of1000r/min, after injection of methanol, with the increase of injection quantity, effectivethermal efficiency is rising trend，higher load gives higher thermal efficiency.