Study On Control-Strategy And Experiment Of Diesel-Methanol Compound Combustion Engine

Diesel engines have gotten more and more widely used in trucks, buses and even in passenger cars, because of its excellent fuel economy as well as performance and reliability. However, PM and NOx emissions from diesel engine restrict it for further development. With the economy development of china, oil demand increases rapidly. Therefore, to develop the alternative fuel for oil is an urgent task for us. China is abundant in coal resource, but less storage in oil. Methanol can be produced from various kinds of materials such as coal, natural gas and biomass, which is one of the best alternative fuels for oil in future.As cetane number of methanol is quite low, it is difficult to be applied to compression ignition engine. So diesel-methanol compound combustion (DMCC) was brought forward based on methanol's property. DMCC engine uses diesel fuel only in start, warming-up and idle operating condition. After water temp and engine speed rise up, diesel fuel model swiches to DMCC model.Six operation conditions were put forward according to DMCC engine characteristics. Each operation condition has its own control strategy. ECU controller software was compiled with language C and assembling language mixed programmed method. Controller software uses MC9S12DP256 chip as platform. Recognizing signals from sensors, software can judge operation condition of engine exactly.Calibration of MAP data has been undertaken on the engine bench. Using neural network optimize MAP data. This method makes the MAP data smoother. These data after optimization were tested on the bench test. The result showed that neural network can reduce the workload.Comparison of different control method, different proportion of methanol to diesel, with DOC and without DOC was conducted on the engine bench. The results showed that the proportion of methanol to diesel should be less at low load; the ratio 30%～40% at the medium load. Although the ratio could be higher at high load, it should not be more than 40%～50%. Additionally, the oxide catalyst had important impact to exhaust emissions,Economical performance gets better, HC and CO emission decrease using multi-point sequential injection. NOx emission almost remains the same.DMCC vehicle load test showed that the proportion of methanol to diesel was 36%, 1.66 kilogram methanol can replace 1.0 kilogram diesel, combustion efficiency increase 8.78%. DMCC vehicle reduce smoke emission in large extent during standing start.The exhaust experiments on the WD615 turbocharged, intercooled diesel engine showed that the emission quality of engine can be remarkably improved from basic ChinaⅡupgrade to ChinaⅢalthough the engine equipped with conventional in-line injection pump,line and injectors.