Simulation Research On Unregulated Emissions Of Direct Injection Spark-ignition Methanol Engine

With the aggravation of energy crisis and environmental pollution worldwide, todevelop of new clean energy is urgent. Based on years exploration, people begin to turn sightto methanol. Methanol the formula of CH3OH, it has a very distinct superiority in natural gasstorage and transportation, and compared with conventional fuel it has more optimalregular emissions, so methanol is regarded as one of the most potential biotechnologies inthe21st century. In addition to the above advantages, many problems need to be solvedimmediately. Especially, the widely using of fuel methanol is limited by its high unregulatedemissions.This paper carried out the transformation to a diesel engine, and made it become a directInjection spark-ignition methanol engine, optimized the model by Pro/E and export themodel in*.stl format, pretreated the model by AVL-FIRE, then simulated calculations underAVL-FIRE coupled with detailed chemical kinetics mechanism of methanol oxidation. Thesimulation Cylinder pressure curve was compared with which tested in experiments to makesure the accuracy of the simulation calculation. Through the simulation analysis of theeffects on the unregulated emissions under the cold start and steady conditions when raisedthe intake temperature (exceed air coefficient)、ignition timing、injection timing. We get thefollowing conclusions:1、Cold start condition：1. As intake temperature increases, the distribution of mixture becomes better, the qualityof mixture combustion can be improved and the emissions of unburned methanol andformaldehyde increases. When the intake temperature increases from283K to313K, theemissions of unburned methanol and formaldehyde decreases significantly, while when theintake temperature increases to over313K it decreases unconspicuous.2. Delays the ignition timing, it makes the mixture distribution in the cylinder deteriorate, and the flaming condition turns terrible, so the emissions of unburned methanol andformaldehyde increase. When the ignition timing postpones from20°CA BTDC to11°CABTDC the emissions of unburned methanol and formaldehyde increases unconspicuous,while it increases significantly when the ignition timing postpones from11°CA BTDC to8°CA BTDC.3. Delays the injection timing, the distribution of mixture becomes better, the quality ofmixture combustion can be improved and effectively reduce the emissions of unburnedmethanol and formaldehyde. When the ignition timing is57°CA BTDC the emissions ofunburned methanol and formaldehyde are very high, as the injection timing delays theemissions of unburned methanol are reduced, while the emissions of formaldehyde reach thehighest because of the temperature in cylinder maintain at about1000K, it promotes theunburned methanol oxidized into formaldehyde, while the injection timing is delayed furtherit decreases.2、Steady condition：1. As the λ increases, it makes the mixture distribution, in the cylinder, deteriorated, andthe flaming condition turns terrible, so the emissions of unburned methanol andformaldehyde increase. When the λ increases from1.5to2.5the emissions of unburnedmethanol and formaldehyde increases unconspicuous, while when the λ increased to3.0itincreases significantly.2. Delays the ignition timing, it makes the mixture,distribution in the cylinder,deteriorated, and the flaming condition turns terrible, so the emissions of unburned methanoland formaldehyde increases. When the ignition timing postpones from20°CA BTDC to11°CA BTDC the emissions of unburned methanol and formaldehyde increasesunconspicuous, while it increases significantly when the ignition timing postpones to8°CABTDC.3. Delays the injection timing, the distribution of mixture becomes better, the quality ofmixture combustion can be improved and effectively reduce the emissions of unburnedmethanol and formaldehyde. When the ignition timing is57°CA BTDC the emissions of unburned methanol and formaldehyde are highest. It decreases significantly when theinjection timing postpones to53°CA BTDC, while it decreases unconspicuous when theinjection timing delays further.