Research On Particulate Emissions Characteristics Of Lean Burn Gasoline Engine With Locally Rich Hydrogen In Cylinder

As people’s lives become richer, automobile becomes the major transport. Thedevelopment of automotive technology decreases the car cost, which let the price of the carcould be accepted by more people. Thus, the whole number of cars keep increasing and theincreasing speed is astonishing. The increasing of car number brings a series of problems, astraffic congestion, excessive consumption of the energy and environmental pollution, etc.Recently frequent fog weather in the big cities has close relationship with particulate matteremissions which come from the car exhaust. The auto industries have to face to the problemof energy consumption and the environment pollution, how to make a compromise betweenenergy and environment is the researching direction of automotive industries.This paper is based on the national nature fund project,“the research on the local richhydrogen diluted hydrogen gas in cylinder direct injection combustion gasoline engine andmechanism of hybrid electric vehicle energy conservation”. Researching the particulatematter emissions characteristics of lean burn gasoline with hydrogen locally rich engine byexperiment method. The main research content is the particle emission characteristics, by theway of changing the combustio parameters to measure the engine particles. In the same timethe engine characteristics ofcombustion and the conventional emissions have been researched.The influence of dilution ratios, heating temperatures and evaporation temperatures havebeens researched at the beginning, which is the basement to determine the appropriatedilution ratio and the temperatures. The purpose is to keep the original state of particulateemissions from the engine.According to the experimental results, the conclusions are as follows, 1.With the increase of excess air coefficent, the peak pressure in the cylinder decreases,while the position of the peak pressure gradually postponed and the peak heat release rateincreased. The average temperature in engine cylinder with excess air coefficent increasesgradually reduces. CO emissions gradually reduce while THC compound graduallyincreased with the increase of the excess air coefficent and NOx emissions graduallydecreases. When the hydrogen blending ratio is12%, the engine particle concentration of thetotal number increases at first and then decreases with the increase of excess air, but whenthe excess air coefficient is1.0the particle concentration of the total number comes tominimum. When hydrogen blending ratio is4%and8%and the result is same to12%,which shows that the addition of hydrogen increases the number of particulate emissions inlean burn engines.2. As the ignition timing is advanced, the peak cylinder pressure, the peak heat releaserate increased, the position of the peak cylinder pressure and the location of the peak heatrelease rate are advanced continuously. The average temperature in cylinder as the ignitiontiming advanced constantly increased. According to the peak cylinder pressure in the bestposition, the20°CABTDC ignition advance angle is the best ignition timing. From theview of emissions, CO and THC emissions increasing as ignition timing advanced, whileNOx emissions increases with the ignition timing advanced. When the increase of hydrogenblending ratio, especially when it reaches12%, the total particle number concentrationjumped sharply. It means ignition timing needs match mixing hydrogen properly, otherwiseit will lead to rising number of particulate emissions.3. With the increase of the engine throttle opening, the peak cylinder pressure rising, theposition of the peak cylinder pressure advances continuously. The peak heat release rateincreases with the increase of the throttle opening, while the position of the peak with theincrease of the throttle opening and constantly advances. The temperature of the engine incylinder gradually increases with the increase of the throttle opening. The CO and THCemissions reduce, with the increase of throttle opening, while NOx gradually increased withthe increase of the throttle opening. Throttle opening impact air flow movement, directlyinfluence the formation of mixture, indirect effects engine combustion, with the increase of hydrogen mixing ratio, the particle concentration of the total number is reduced, but theinfluence is not significant.4. The cylinder pressure decreases gradually with the increase of engine speed, and theposition of the peak cylinder pressure gradually postponed, while the regular pattern of theheat release rate curve and the rule of cylinder pressure curve similar to the averagetemperature in cylinder engine with the increase of rotational speed. The CO emissions firstincrease then decrease with the increase of rotational speed, while THC and NOx emissionsdecreased with the increase of rotational speed. In terms of particle concentration of the totalnumber the hydrogen blending ratio is adaptable to different speeds, as the speed change,changed hydrogen blending ratio on particle emission concentration of the total number haslittle effect.5. Researching the engine emissions in each experiment groups, there are threehydrogen blending ratios. No matter which control parameters changed, with the increase ofmixing hydrogen the CO and THC emissions are gradually reduced, and the NOx emissionsincrease gradually. From the influence of hydrogen about the combustion terms, withhydrogen mixing ratio increases, the combustion of engine has been optimized, while thecylinder peak pressure, peak position advance ceaselessly, and heat release rate and theaverage temperature in cylinder change which is the same regular pattern as the cylinderpressure.