Influence of water port injection on cycle-to-cycle variations in heavy-duty natural gas engine under low load

Water injection is regarded as an effective approach to decrease thermal load and suppress knock onset in heavy-duty natural gas engines. However, the cycle-to-cycle variations in heavy-duty natural gas engines via water injection has rarely been investigated. In this study, the effects of water por...

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Bibliographic Details
Published in:Fuel (Guildford) 2020-11, Vol.280, p.118678, Article 118678
Main Authors: Chen, Zhanming, Chen, Hao, Geng, Limin
Format: Article
Language:English
Subjects:
Coefficient of variation
Cycle-to-cycle variations
Cylinders
Engines
Fluctuations
Frequency distribution
Injection
Knock
Mass ratios
Natural gas
Premixed charged
Pressure
Stress concentration
Thermal analysis
Variation
Water flooding
Water injection
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Summary:Water injection is regarded as an effective approach to decrease thermal load and suppress knock onset in heavy-duty natural gas engines. However, the cycle-to-cycle variations in heavy-duty natural gas engines via water injection has rarely been investigated. In this study, the effects of water port injection on cycle-to-cycle variations in a natural gas engine were analyzed experimentally. The engine speed was fixed at 1600 r/min, and engine load was set at a low load with a brake mean effective pressure of 0.387 MPa. Three excess air-fuel ratios (λ = 1.0, 1.2, and 1.4) were defined; and four water to natural gas mass ratios (WNMRs) were set. The results demonstrated that the variations of multicycle cylinder pressure traces consistently increased with the increase in WNMR. The interdependence between the peak in-cylinder pressure (Pmax) and its corresponding crank angle became more dispersed, and the frequency distribution of Pmax covered a wider range with increasing WNMR. The obvious fluctuations and wide range of distribution of indicated mean effective pressure (IMEP) were determined by water addition. The higher the λ, the larger the fluctuations and wider the range of distribution of IMEP. The coefficient of variation of IMEP (COVIMEP) increased with the increase in WNMR and λ. However, the maximum COVIMEP among the three λs and four WNMRs did not exceed 3%. Thus, it can be concluded that no drivability problem is associated with water injection under low load.
ISSN:0016-2361
1873-7153
DOI:10.1016/j.fuel.2020.118678