Effect Of Methanol Substitution Rate Onthe Emissions Of Compression Ignition Engine

With increasingly stringent emission regulations and dwindling oil resources, thealternative fuel, with the advantage of clean and high efficient, has become the mainresearch orientation of the internal combustion engine industry. Methanol is a kind ofalternative fuel with broad application prospects. The Diesel/Methanol CompoundCombustion (DMCC) theory was proposed by Tianjin University and was used inheavy duty vehicles to carry out the road test. The test results show that when workingin DMCC mode, the methanol can replace diesel substantially as well as a distinctimprovement in thermal efficiency. This means that the DMCC mode has a broadapplication prospects. But the test results in partial load shows that the combustionand emissions may get deteriorated. So, even though the diesel is replacedsubstantially, the methanol is consumed much higher than the diesel with equal heatvalue. The fuel costs can’t be reduced significantly for the upper reasons.Therefore, the DMCC has huge potential in improving fuel economy, but itscombustion is complex. Based on the specific problems of vehicle operation and theresults obtained by the road test, this job focus on the effect of different ratios ofmethanol and diesel dual-fuel on the combustion and emission characteristics whenthe engine run in DMCC.The research was done on a turbocharged and intercooled EUP diesel engine.The engine was transformed to inject methanol in the intake manifold. The effect ofdifferent ratios of methanol and diesel fuel on the maximum torque speed and theminimum amount of ignite fuel under the rated power speed was tested in benchtesting. The result shows that:1.The selected speed are1000r/min、1400r/min、1800r/min、2200r/min. Thetorque was controlled at100N.m and then begins to inject the methanol to reach thetarget torque value. The emissions were also tested under specified workingconditions in DMCC mode in order to compare with the results acquired in purediesel conditions. The results show that the CO and HC emissions are much higherthan the pure diesel mode when working in DMCC mode. After being catalyzed, theCO and the HC decrease significantly with the transform efficient values more than 99%and80%separately.2..It can be seen from the experiment that NOx emissions from diesel engineusing diesel/methanol dual fuel decrease nearly by20%. The reasons may be that theinjected methanol vaporization has inhibition effect on intake air temperature andcylinder combustion temperature. Through the catalytic converter processing, NOxemissions increased slightly.3.Under different load conditions of1000r/min,1400r/min (maximum),1800r/min and2200r/min(rated output speed) engine speed, dry soot and lightobscuration are compared at diesel mode and dual fuel combustion mode. The resultsshow that:(1)Under common condition, compared to the diesel fuel mode, dry soot ofDMCC mode has greatly decreased and the highest drop is about95%. In the middleand high load, the average of soot reduction is50%.(2)The radio of methanol and diesel fuel has certain effect on the smokeemissions. Under the same load, with the increase of methanol quantity in dual fuelinjection, the dry soot reduced gradually, and the light obscuration emission firstdecreases and then increases. When the methanol substitution rate is between44.88%and56.73%, dry soot is the lowest and light obscuration is just about0.014m-1.(3)Under the same conditions, with the increase of radio of diesel and methanol,the dry soot and light obscuration of dual fuel are increasing.4. When engine running at the speed of1000r/min,1400r/min,1800r/min,2200r/min, and at beginning of50Nm and100Nm, the formaldehyde emissions ofdual fuel increase as the increase of the methanol substitution rate. This is because atlow load, the combustion temperature and exhaust temperature is low, and thesubsequent oxidation ability is poor. The formaldehyde cannot continue oxidative anddirectly expel from the exhaust pipes, thus more formaldehyde is detected. With theincrease of replacement rate, combustion and exhaust temperature rise again andsubsequent oxidation ability increases, the formaldehyde can be further oxidationdecomposition to be reduced. After the DOC, the formaldehyde emissions havedecreased significantly, the emission level is lower than the baseline engine.