米勒循环降低船用低速柴油机NO_x排放

Miller Cycle to Reduce NO_x Emission for Marine Low-Speed Diesel Engine

捅要:为满足日益严格的排放法规的要求,在船用低速二冲程柴油机中引入米勒循环技术。米用AVL BOOST软件建立某船用低速二冲程柴油机的整机仿真模型,并根据台架试验结果进行标定和验证,分析不同的米勒正时、几何压缩比和喷油正时对柴油机性能及NO_x排放的影响。研究结果表明:米勒循环会使NO_x排放降低,但会导致功率损失增大、油耗率升高;提高几何压缩比会使柴油机的经济性改善,但会导致NO_x排放升高、缸内爆压剧增、机械负荷增大;推迟喷油会使燃烧延迟、缸内爆发压力降低,同时NO_x排放进一步降低。米勒循环、高压缩比和推迟喷油等技术的结合可实现其油耗率仅增加1.17%的同时NO,排放降低14.6%,最高爆发压力降低0.408 MPa。

In order to meet the requirements of increasingly stringent emission regulations,the miller cycle technology is introduced for the marine low-speed two-stroke diesel engine.The simulation model of a marine low-speed two-stroke diesel engine is set up by AVL BOOST software.The model is verified by comparing the simulation results with actual engine bench test data.The effects of miller cycle,compression ratio and injection timing on performance and the NO_x emission are analyzed.The results show that the NO_x emission is reduced by means of miller cycle,but the loss of power and the fuel consumption are increased.Enhancing compression ratio can effectively improve the fuel economy,but the NO_x emission and maximum firing pressure significantly increase and diesel engine mechanical load grows worse.Delayed injection timing can make the combustion lagging and reduce the maximum firing pressure and the NO,emission further.Miller cycle with high compression ratio and delayed injection timing can reduce 14.6%of NO,emissions while fuel consumption is increased by only 1.17%and the maximum firing pressure is reduced by 0.408 MPa.