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| Numerical Investigation of Effect of Miller Cycle and Exhaust Gas Recirculation on High-Pressure Direct-Injection Natural Gas Marine Engines |
| DOI：10.13949/j.cnki.nrjgc.2019.06.010 |
| Key Words:natural gas Miller cycle exhaust gas recirculation(EGR) pilot ignition low-speed marine engine computational fluid dynamics(CFD) |
| Author Name | Affiliation | | NIU Peizheng,WU Zhaohui,DONG Jingjin,LI Jingrui,LIU Haifeng,YAO Mingfa | 1.State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
2.China Shipbuilding Power Engineering Institute Co., Ltd., Shanghai 200120, China |
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| Abstract:Based on a three-dimensional simulation model established using CONVERGE, the effects of exhaust gas recirculation and the Miller cycle on the combustion characteristics and emissions were studied to explore the feasibility of the Miller cycle coupled with EGR to meet Tier Ⅲ emission regulations for low-speed high-pressure direct injection natural gas marine engines. The results show that using 30% of EGR rate alone can meet Tier Ⅲ emission standards, but with a significant increase in the indicated fuel consumption and soot emissions; the Miller cycle is not as effective as EGR in the potential to reduce NOx emissions; excessive exhaust valve closing delay will cause increase in compressor workload, and lead to a considerable increase in fuel consumption when the same amount of NOx emissions is reduced. Coupling mild Miller cycle(delaying exhaust valve closing by 5° in crank angle) with 25% of EGR rate and the proper natural gas injection timing(advancing 2° in crank angle) can reduce NOx emissions by 77% with only a slight increase in the fuel consumption by 1.58%, which is a feasible way to meet Tier Ⅲ emission regulations. |
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