ABSTRACT
The continuous quest for renewable, efficient, and clean energy sources has led to significant advances in the field of biodiesel production. Hydrogenated catalytic biodiesel (HCB) seems to be a promising option among various renewable biodiesel fuels which can be obtained from waste cooking oil. However, its extreme ignitability limits its application in existing engines. Therefore, a blend of n-butanol and HCB has been proposed in the present study, aiming to explore the spray combustion and soot formation behavior of these blends as a step toward the best possible utilization of this blend in engine. The objective was to examine the impact of adding n-butanol to HCB fuel on spray combustion and soot particles. A new skeletal chemical kinetic model of HCB/n-butanol blend was introduced and validated through measured data reported in the literature. Numerical studies have been performed in a constant volume combustion chamber under reactive spray environments. The simulation results concluded that, blending 20%, 40%, and 60% n-butanol with HCB fuel increased the heat release rates by 31.6%, 47.8%, and 87%, respectively. Furthermore, introducing a 20% of n-butanol into HCB fuel resulted in a 35.7% increase in ignition delay time and a 35.3% increase in flame liftoff length. These results demonstrated the reactivity of n-butanol/HCB mixture experienced a decrease when increasing the n-butanol fraction in the blend, while the fuel atomization was improved. The simulation results also demonstrated a notable reduction in the equivalence ratio when the n-butanol addition ratio was increased, which was a result of the entrainment effect that enhanced the mixing of fuel spray and surrounding fresh air. The simulation results also demonstrated that, adding 20%, 40%, and 60% n-butanol to HCB fuel resulted in a 25%, 43%, and 50% reduction in soot mass of HCB, respectively. This was mainly attributed to the less amount of C2H2, A1, and A4 species with n-butanol addition. Consequently, this sequential reduction leads to suppression of PAHs growth, nucleation, surface growth, and soot coagulation. Besides, a longer flame length resulting from the increased blending ratio of n-butanol could also have an additional soot suppression effect by improving air-fuel mixing and thus suppressing the overall soot mass.
Acronyms
HCB | = | Hydrogenated Catalytic Biodiesel |
CI | = | Compression Ignition |
CN | = | Cetane Number |
NOX | = | Nitrogen Oxides |
UHC | = | Unburned Hydrocarbons |
SOI | = | Start of Ignition |
ASOI | = | After Start of Ignition |
A1 | = | Benzene (A3) |
A2 | = | Naphthalene |
A3 | = | Phenanthrene |
A4 | = | Pyrene |
HRR | = | Heat Release Rates |
CFD | = | Computational Fluid Dynamic |
PAHs | = | Polycyclic Aromatic Hydrocarbons |
IDT | = | Ignition Delay Time |
LOL | = | Lift-off Length |
0B | = | Pure HCB Without n-Butanol |
20B | = | 20% n-Butanol blend 80% HCB |
40B | = | 40% n-Butanol blend 60% HCB |
60B | = | 60% n-Butanol blend 40% HCB |
HACA | = | Hydrogen Abstraction Acetylene Addition |
CVCC | = | Constant Volume Combustion Chamber |
ϕ | = | Equivalence Ratio |
ICE | = | Internal Combustion Engine |
Acknowledgements
This study was supported by the National Natural Science Foundation of China (No.52076103 and 51706088). NMM acknowledges the University of Sinnar for additional support.
Disclosure statement
No potential conflict of interest was reported by the author(s).
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Notes on contributors
Nasreldin M. Mahmoud
Nasreldin M. Mahmoud received his Ph.D. in Power Machinery Engineering from Wuhan University of Technology (WUT). He spent 2 years as a postdoctoral fellow at the school of Energy and Power Engineering, Jiangsu University, Zhenjiang, China. His areas of research focus include spray and combustion, soot formation, laminar flame, and internal combustion engines. Dr. N.M.M is working as Assistant Professor at the Department of Mechanical Engineering, Faculty of Engineering, University of Sinnar, Sudan.
Wenjun Zhong
Wenjun_zhong He received his PhD Degree in mechanical engineering from Shanghai jiatong University, China. His research interests include, Spray and Combustion, soot formation and internal combustion engines He is currently working as Associate Professor at School of Energy Power Engineering, Jiangsu University, Zhenjiang 212013, China. He has published more than 76 articles, which received more than 1,153 citations.
Qian Wang
Qiang wang is a professor of mechanical engineering at School of Energy Power Engineering, Jiangsu University, Zhenjiang 212013, China. His research interests include Spray and Combustion in Diesel Engines, Micro-Combustion, Natural Gas Combustion in Marine Engine. Q wang has published more than 422 international peer-reviewed journal articles, which reveived more than 9365 citations.
Zhixia He
Zhixia He She is a professor of mechanical engineering at School of Energy Power Engineering, Jiangsu University, Zhenjiang 212013, China. Her research interests include Spray and Combustion, Cavitating Two-phase Flow, Thermal Fluid Theory in Uitilization of Energy. He, Zhixia has published more than 351 international peer-reviewed journal articles, which reveived more than 5,633 citations.