Hamdi Fathi, Agrebi Senda, Idrissi Mohamed Salah, Mondo Kambale, Labiadh Zeineb, Sadiki Amsini, Chrigui Mouldi
Research Unit of Mechanical Modeling, Energy and Materials, National School of Engineers of Gabes, University of Gabes, UR17ES47, Gabes 6029, Tunisia.
Institute of Energy and Power Plant Technology, Technical University of Darmstadt, 64287 Darmstadt, Germany.
Entropy (Basel). 2022 May 5;24(5):650. doi: 10.3390/e24050650.
The behaviors of spray, in Reactivity Controlled Combustion Ignition (RCCI) dual fuel engine and subsequent emissions formation, are numerically addressed. Five spray cone angles ranging between 5° and 25° with an advanced injection timing of 22° Before Top Dead Center (BTDC) are considered. The objective of this paper is twofold: (a) to enhance engine behaviors in terms of performances and consequent emissions by adjusting spray cone angle and (b) to outcome the exergy efficiency for each case. The simulations are conducted using the Ansys-forte tool. The turbulence model is the Renormalization Group (RNG) K-epsilon, which is selected for its effectiveness in strongly sheared flows. The spray breakup is governed by the hybrid model Kelvin-Helmholtz and Rayleigh-Taylor spray models. A surrogate of n-heptane, which contains 425 species and 3128 reactions, is used for diesel combustion modeling. The obtained results for methane/diesel engine combustion, under low load operating conditions, include the distribution of heat transfer flux, pressure, temperature, Heat Release Rate (HRR), and Sauter Mean Diameter (SMD). An exergy balance analysis is conducted to quantify the engine performances. Output emissions at the outlet of the combustion chamber are also monitored in this work. Investigations show a pressure decrease for a cone angle θ = 5° of roughly 8%, compared to experimental measurement (θ = 10°). A broader cone angle produces a higher mass of NO. The optimum spray cone angle, in terms of exergy efficiency, performance, and consequent emissions is found to lie at 15° ≤ θ ≤ 20°.
本文对反应控制燃烧点火（RCCI）双燃料发动机中的喷雾行为及其随后的排放物形成进行了数值研究。考虑了五个喷雾锥角，范围在5°至25°之间，喷油提前角为上止点前22°（BTDC）。本文的目的有两个：（a）通过调整喷雾锥角来改善发动机在性能和随之产生的排放方面的表现；（b）计算每种情况下的火用效率。使用Ansys-forte工具进行模拟。湍流模型采用重整化群（RNG）K-ε模型，因其在强剪切流中的有效性而被选用。喷雾破碎由Kelvin-Helmholtz和Rayleigh-Taylor混合喷雾模型控制。使用包含425种物质和3128个反应的正庚烷替代物进行柴油燃烧建模。在低负荷运行条件下，对甲烷/柴油发动机燃烧获得的结果包括传热通量、压力、温度、热释放率（HRR）和索特平均直径（SMD）的分布。进行了火用平衡分析以量化发动机性能。在这项工作中还监测了燃烧室出口处的排放物。研究表明，与实验测量值（θ = 10°）相比，锥角θ = 5°时压力降低约8%。更大的锥角会产生更高质量的NO。在火用效率、性能和随之产生的排放方面，最佳喷雾锥角为15°≤θ≤20°。
