米勒循環降低船用低速柴油機NOx排放

， ， ， ，

(大連海事大學 輪機工程學院， 遼寧 大連 116026)

米勒循環降低船用低速柴油機NOx排放

劉勤安，邢輝，武占華，段樹林，宋玉超

(大連海事大學輪機工程學院，遼寧大連116026)

為滿足日益嚴格的排放法規的要求，在船用低速二沖程柴油機中引入米勒循環技術。采用AVL BOOST軟件建立某船用低速二沖程柴油機的整機仿真模型，并根據臺架試驗結果進行標定和驗證，分析不同的米勒正時、幾何壓縮比和噴油正時對柴油機性能及NOx排放的影響。研究結果表明：米勒循環會使NOx排放降低，但會導致功率損失增大、油耗率升高；提高幾何壓縮比會使柴油機的經濟性改善，但會導致NOx排放升高、缸內爆壓劇增、機械負荷增大；推遲噴油會使燃燒延遲、缸內爆發壓力降低，同時NOx排放進一步降低。米勒循環、高壓縮比和推遲噴油等技術的結合可實現其油耗率僅增加1.17%的同時NOx排放降低14.6%，最高爆發壓力降低0.408 MPa。

船用低速柴油機； 米勒循環； 壓縮比； 噴油正時； NOx排放

Abstract: 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 NOxemission are analyzed. The results show that the NOxemission 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 NOxemission 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 NOxemission further. Miller cycle with high compression ratio and delayed injection timing can reduce 14.6% of NOxemissions while fuel consumption is increased by only 1.17% and the maximum firing pressure is reduced by 0.408 MPa.

Keywords: marine low-speed diesel engine；miller cycle；compression ratio；injection timing；NOxemission

國際海事組織(International Maritime Organization，IMO)對船用柴油機NOx排放控制的要求日趨嚴格，這會給船用柴油機的研發、制造及使用帶來巨大的影響，甚至會引導船用柴油機的發展方向。當前，降低柴油機NOx排放的措施主要有機內處理(包括加水處理、推遲噴油、高壓噴射、廢氣再循環及米勒循環等)和機后處理(催化轉化法)。[1]由于采用機后處理方式時需附加NOx后處理裝置，價格昂貴，且后續的維護管理較為復雜，因此柴油機生產商和相關研究人員更加傾向于從機內處理的角度探索一種可滿足未來排放法規要求的解決方案。……