Rotaru Silviu, Pana Constantin, Negurescu Niculae, Cernat Alexandru, Nutu Cristian, Fuiorescu Dinu, Lazaroiu Gheorghe
National University of Science and Technology Politehnica Bucharest, Department of Thermotechnics, Engines, Thermal and Frigorific Equipment, Romania.
National University of Science and Technology Politehnica Bucharest, Department of Energy Generation and Use, Romania.
Heliyon. 2024 Jul 23;10(15):e35010. doi: 10.1016/j.heliyon.2024.e35010. eCollection 2024 Aug 15.
The main objective of the paper is to reveal a few aspects related to combustion quality of a diesel engine fueled in diesel-gas mode with diesel fuel and compressed natural gas. The total amount of heat released per cycle will be higher when the engine is fueled in dual-fuel mode due to higher LHV and because of the gaseous state of CNG. For low and medium loads the total quality of heat released per cycle will increase with 10 % and for higher loads it will reach levels with 25 % higher. The heat release rate of the preformed mixture will double its value for low and medium loads and will reach thresholds up to 3.5 times higher (interval -15; -5°CA); admitting CNG into cylinder will help the preformed mixture to reach stoichiometric values and thus improving the fast combustion phase. Fueling the engine in dual fuel mode with diesel fuel and CNG will have a negative effect on the maximum heat release rate; there will be a 10 % drop in maximum HRR for low loads when the energetic substitution coefficient reaches 36 % and 14 % at high loads when the xc is 26 %. The gaseous state and a higher LHV of CNG will have a good impact on indicated mean effective pressure for all studied regimes when the engine is fueled in DG mode: for low and medium loads 30 % and for high loads 20 % increase will be recorded. Gaseous state of CNG will lead to a higher percentage of preformed mixture and thus the fast combustion phase will extend for longer periods for all studied regimes when the engine is fueled in DG mode (20 % longer for low and medium loads and 30 % for high loads). The diffusive combustion phase will become shorter due to a lower quantity of the main dose when CNG is injected into the intake manifold (10-15 % shorter for low loads and 7 % at high loads).
本文的主要目的是揭示与以柴油和压缩天然气为燃料的柴油 - 气体模式下柴油发动机燃烧质量相关的几个方面。由于更高的低热值以及压缩天然气的气态状态，当发动机以双燃料模式运行时，每个循环释放的总热量会更高。对于低负荷和中等负荷，每个循环释放的总热量质量将增加10%，对于高负荷，其将达到高25%的水平。对于低负荷和中等负荷，预混合混合气的放热率将翻倍，并且在 - 15至 - 5°CA区间内将达到高达3.5倍的阈值；将压缩天然气引入气缸有助于预混合混合气达到化学计量比，从而改善快速燃烧阶段。以柴油和压缩天然气双燃料模式为发动机供油会对最大放热率产生负面影响；当能量替代系数达到36%时，低负荷下最大放热率会下降10%，当xc为26%时，高负荷下最大放热率会下降14%。当发动机以柴油 - 气体模式运行时压缩天然气的气态状态和更高的低热值对所有研究工况下的指示平均有效压力都有良好影响：低负荷和中等负荷下增加30%以及高负荷下增加20%。压缩天然气的气态状态将导致更高比例的预混合混合气含量，因此当发动机以柴油 - 气体模式运行时，对于所有研究工况，快速燃烧阶段将延长更长时间（低负荷和中等负荷下延长20%，高负荷下延长30%）。当压缩天然气被注入进气歧管时由于主剂量减少，扩散燃烧阶段将变短（低负荷下缩短10 - 15%以及高负荷下缩短7%）。
