基于模糊分析的船用柴油机燃用生物柴油性能优化

Optimization of biodiesel performance in marine diesel engines based on fuzzy analysis

为优化生物柴油/柴油船用发动机的综合性能,利用AVL-Fire软件构建混合燃料发动机燃烧室模型,将仿真值与台架试验值进行对比验证其准确性,并通过燃用不同比例的生物柴油确立其最佳掺混比;最后,采用正交试验设计安排5个发动机运行参数进行多参数优化匹配,将NO排放量和指示功率作为评价指标,权重分别设置为0.6和0.4,对试验结果进行模糊数学分析。结果表明:对发动机性能影响大小顺序为EGR率(a_(1))、进气压力(a_(2))、进气温度(a_(3))、喷油提前角(a_(4))、喷油孔直径(a_(5));最优参数组合为:生物柴油掺混比30%、a_(1)=12.5%、a_(2)=0.173MPa、a_(3)=315.15K、a_(4)=18.6°CA、a_(5)=0.32mm,该组指示功率为52.7kW与原机55kW相比略低,NO排放量为5.37×10^(-5)%相比于原机8.5×10^(4)%降低了94.7%。该方法可以在保证发动机动力性的前提下,大幅降低NO排放量。

In order to optimise the comprehensive performance of bio-diesel/diesel marine engine,firstly,the combus-tion chamber model of the blended fuel engine is constructed by using AVL-Fire software,and the simulation values are compared with the bench test values to verify its accuracy,and the optimal blending ratio is established by combusting differ-ent proportions of biodiesel;finally,orthogonal experimental design is used to arrange five engine operating parameters for multi-parameter optimisation and matching,and the NO emission and indicated power are set as evaluation indexes.Finally,the orthogonal test design was used to arrange five engine operating parameters to optimise the matching of multiple para-meters,and the NO emission and indicated power were taken as the evaluation indexes,and the weights were set to 0.6 and 0.4,respectively,and the test results were analysed by fuzzy mathematics.The results showed that the order of influence on the engine performance was as follows:EGR rate(a_(1)),intake pressure(a_(2)),intake temperature(a_(3)),injection advance angle(a_(4)),and injection hole diameter(a_(5));the optimal parameter combinations were as follows:biodiesel blending ratio of 30%,a_(1)=12.5%,a_(2)=0.173 MPa,a_(3)=315.15 K,a_(4)=18.6°CA,a_(5)=0.32 mm,the indicated power of the group was 52.7 kW which was slightly lower compared to the original 55 kW,and NO emission was 5.37×10^(5)% which was 94.7%lower compared to the original 8.5×10^(4)%.This method can significantly reduce NO emissions while maintaining engine power.