Effect of equalising ignition delay on combustion and soot emission characteristics of model fuel blends

Abstract

This paper examines the effect of equalizing ignition delay in a compression ignition engine. Two sets of tests were conducted, i.e. a set of constant injection timing tests with start of fuel injection at 10° crank angle degree (CAD) before top dead center (BTDC) and a set of constant ignition timing tests while also keeping the 10° CAD BTDC injection and adding ignition improver (2-ethylhexylnitrate-, 2-EHN) to the fuel mixtures. Soot particles were characterized using DMS-500 instrument in terms of mass, size, and number. The experimental results showed that adding 2-EHN to the model fuel blends reduced the soot surface area, soot mass concentration and soot mean size. Replacing 20 vol% of a C₇-heptane with 20 vol% methyl-decanoate (an oxygenated C₁₁ molecule) did not affect the ignition delay or rate of fuel air premixing, the peak in-cylinder pressure or heat release rates. Toluene addition (0–22.5 vol%) to heptane increased the mean size of the soot particles generated by only 3% while also resulted in a slight increase in the peak cylinder pressure and peak heat release rates. Blending toluene and methyl-decanoate into heptane without adding 2-EHN increased the premix phase fraction by at least 13%. However, by adding 2-EHN (4×10⁻⁴−1.5×10⁻³), the premixed phase fraction decreased by at least 11%.

Keywords

combustion characteristics / soot emission / compression ignition engine / ignition improver / premixed phase

References

[1] ErmanA G, HellierP, LadommatosN. The impact of ignition delay and further fuel properties on combustion and emissions in a compression ignition engine [J]. Fuel, 2020, 262: 116155

[2] ŞŀmşekS, UsluS. Analysis of the effects of cetane improver addition to diesel on engine performance and emissions [J]. International Journal of Automotive Engineering and Technologies, 2021, 10(1): 26-32

[3] DandajehH A, LadommatosN, HellierP, et al.. Effects of unsaturation of C₂ and C₃ hydrocarbons on the formation of PAHs and on the toxicity of soot particles [J]. Fuel, 2017, 194306-320

[4] DandajehH A, LadommatosN, HellierP. Influence of unsaturation of hydrocarbons on the characteristics and carcinogenicity of soot particles [J]. Journal of Analytical and Applied Pyrolysis, 2020, 151: 104900

[5] DANDAJEH H A, TALIBI M, LADOMMATOS N, et al. Polycyclic aromatic hydrocarbon and soot emissions in a diesel engine and from a tube reactor [J]. Journal of King Saud University-Engineering Sciences, 2020. DOI: https://doi.org/10.1016/j.jksues.2020.12.007.

[6] SanyalS, RochereauT, MaesanoC, et al.. Long-term effect of outdoor air pollution on mortality and morbidity: A 12-year follow-up study for metropolitan France [J]. International Journal of Environmental Research and Public Health, 2018, 15(11): 2487

[7] AgarwalA K, SinghA P, MauryaR K. Evolution, challenges and path forward for low temperature combustion engines [J]. Progress in Energy and Combustion Science, 2017, 611-56

[8] VincentM W, RichardsP, CookS LParticulates reduction in diesel engines through the combination of a particulate filter and fuel additive [C], 1998, Warrendale, PA, United States, SAE International, 982654400 Commonwealth Drive

[9] DandajehH A, TalibiM, LadommatosN, et al.. Influence of combustion characteristics and fuel composition on exhaust PAHs in a compression ignition engine [J]. Energies, 2019, 12(13): 2575

[10] DandajehH A, AhmaduT O. Engine performance of a gardener compression ignition engine using rapeseed methyl Esther [J]. FUOYE Journal of Engineering and Technology, 2019, 42126-130

[11] NingL, DuanQ-M, ChenZ-M, et al.. A comparative study on the combustion and emissions ofa non-road common rail diesel engine fueled with primary alcohol fuels (methanol, ethanol, and n-butanol)/diesel dual fuel [J]. Fuel, 2020, 266117034

[12] HuangH-Z, ZhouC-Z, LiuQ-S, et al.. An experimental study on the combustion and emission characteristics of a diesel engine under low temperature combustion of diesel/gasoline/n-butanol blends [J]. Applied Energy, 2016, 170219-231

[13] HuangH-Z, ZhuJ-Z, ZhuZ-J, et al.. Development and validation of a new reduced diesel-n-butanol blends mechanism for engine applications [J]. Energy Conversion and Management, 2017, 149: 553-563

[14] ChenH, XieB, MaJ-Q, et al.. NO_x emission of biodiesel compared to diesel: Higher or lower? [J]. Applied Thermal Engineering, 2018, 137: 584-593

[15] ChenH, SuX, LiJ-H, et al.. Effects of gasoline and polyoxymethylene dimethyl ethers blending in diesel on the combustion and emission of a common rail diesel engine [J]. Energy, 2019, 171: 981-999

[16] ZhangP, HeJ-J, ChenH, et al.. Improved combustion and emission characteristics of ethylene glycol/diesel dual-fuel engine by port injection timing and direct injection timing [J]. Fuel Processing Technology, 2020, 199: 106289

[17] QianW-W, HuangH-Z, PanM-Z, et al.. Effects of 2-ethylhexyl nitrate and post-injection strategy on combustion and emission characterizes in a dimethyl carbonate/diesel blending engine [J]. Fuel, 2020, 263116687

[18] PuduppakkamK V, LiangL, NaikC V, et al.Combustion and emissions modeling of a gasoline HCCI engine using model fuels [C], 2009, Warrendale, PA, United States, SAE International 400 Commonwealth Drive

[19] PfahlU, AdomeitG. Self-ignition of diesel-engine model fuels at high pressures [J]. SAE Technical, 1997, 1061522-1527

[20] HellierP, LadommatosN, AllanR, et al.. Combustion and emissions characteristics of toluene/n-heptane and 1-octene/n-octane binary mixtures in a direct injection compression ignition engine [J]. Combustion and Flame, 2013, 160(10): 2141-2158

[21] MiH H, LeeW J, ChenC B, et al.. Effect of fuel aromatic content on PAH emission from a heavy-duty diesel engine [J]. Chemosphere, 2000, 41(11): 1783-1790

[22] SivaramakrishnanR, TranterR S, BrezinskyK. High-pressure, high-temperature oxidation of toluene [J]. Combustion and Flame, 2004, 139(4): 340-350

[23] WeiJ-J, SongC-L, LvG, et al.. Acomparative study of the physical properties of in-cylinder soot generated from the combustion of n-heptane and toluene/n-heptane in a diesel engine [J]. Proceedings of the Combustion Institute, 2015, 35(2): 1939-1946

[24] LuoJ, YaoM-F, LiuH-F, et al.. Experimental and numerical study on suitable diesel fuel surrogates in low temperature combustion conditions [J]. Fuel, 2012, 97: 621-629

[25] LuoJ, YaoM-F, LiuH-F, et al.. Experimental and numerical study on suitable diesel fuel surrogates in low temperature combustion conditions [J]. Fuel, 2012, 97: 621-629

[26] KnotheG. “Designer” biodiesel: Optimizing fatty ester composition to improve fuel properties [J]. Energy & Fuels, 2008, 22(2): 1358-1364

[27] AakkoP. PAH content of diesel fuels [J]. CONCAWE Review, 2005, 14(2): 18

[28] DANDAJEH H A. Effect of molecular structure of liquid and gaseous fuels on the formation and emission of PAHs and soot [D]. The University College London, 2018. https://discovery.ucl.ac.uk/id/eprint/10043389/.

[29] DandajehH A, LadommatosN, HellierP, et al.. Influence of carbon number of C1–C7 hydrocarbons on PAH formation [J]. Fuel, 2018, 228: 140-151

[30] Di-SanteR. Measurements of the auto-ignition of n-heptane/toluene mixtures using a rapid compression machine [J]. Combustion and Flame, 2012, 159(1): 55-63

[31] XiaoZ, LadommatosN, ZhaoH. The effect of aromatic hydrocarbons and oxygenates on diesel engine emissions [J]. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2000, 214(3): 307-332

[32] AndraeJ, JohanssonD, BjörnbomP, et al.. Co-oxidation in the auto-ignition of primary reference fuels and n-heptane/toluene blends [J]. Combustion and Flame, 2005, 140(4): 267-286

[33] WangX-W, SongC-L, LvG, et al.. Evolution of in-cylinder polycyclic aromatic hydrocarbons in a diesel engine fueled with n-heptane and n-heptane/toluene [J]. Fuel, 2015, 158322-329

[34] WestbrookC K. Chemical kinetics of hydrocarbon ignition in practical combustion systems [J]. Proceedings of the Combustion Institute, 2000, 28(2): 1563-1577

[35] HeywoodJ PInternal combustion engine fundamentals [M], 1988, New York, McGraw-652 Hill

[36] LiR-N, WangZ, NiP-Y, et al.. Effects of cetane number improvers on the performance of diesel engine fuelled with methanol/biodiesel blend [J]. Fuel, 2014, 128: 180-187

[37] HigginsB, SiebersD, MuellerC, et al.. Effects of an ignition-enhancing, diesel-fuel additive on diesel-spray evaporation, mixing, ignition, and combustion [J]. Symposium (International) on Combustion, 1998, 27(2): 1873-1880

[38] TolandA, SimmieJ M. Ignition of alkyl nitrate/oxygen/argon mixtures in shock waves and comparisons with alkanes and amines [J]. Combustion and Flame, 2003, 132(3): 556-564

[39] GhoshP. Predicting the effect of cetane improvers on diesel fuels [J]. Energy & Fuels, 2008, 22(2): 1073-1079

[40] KidoguchiY. Effects of fuel cetane number and aromatics on combustion process and emissions of a direct-injection diesel engine [J]. JSAE Review, 2000, 21(4): 469-475

[41] Xing-CaiL, YangJ-G, ZhangW-G, et al.. Effect of cetane number improver on heat release rate and emissions of high speed diesel engine fueled with ethanol-diesel blend fuel [J]. Fuel, 2004, 83(14–15): 2013-2020

[42] KoivistoE, LadommatosN, GoldM. Systematic study of the effect of the hydroxyl functional group in alcohol molecules on compression ignition and exhaust gas emissions [J]. Fuel, 2015, 153: 650-663

[43] KoivistoE, LadommatosN, GoldM. The influence of various oxygenated functional groups in carbonyl and ether compounds on compression ignition and exhaust gas emissions [J]. Fuel, 2015, 159: 697-711

[44] DingJ-X, HeG-Z, ZhangL. Detailed temperature-dependent study of n-heptane pyrolysis at high temperature [J]. Chinese Journal of Chemical Physics, 2013, 26(3): 329-336

[45] RichterH, HowardJ B. Formation of polycyclic aromatic hydrocarbons and their growth to soot—A review of chemical reaction pathways [J]. Progress in Energy and Combustion Science, 2000, 26(4–6): 565-608

[46] AlexiouA, WilliamsA. Soot formation in shock-tube pyrolysis of toluene-n-heptane and toluene-iso-octane mixtures [J]. Fuel, 1995, 74(2): 153-158

[47] MATHIEU O, WEN J Z, DJEBAILI-CHAUMEIX N, et al. Modeling study of the soot formation process from toluene pyrolysis behind reflected [C]// Proceedings of the European Combustion Meeting. 2009: 2–7. DOI: https://doi.org/10.1.1.502.4075.

[48] ZhangL-D, CaiJ-H, ZhangT-C, et al.. Kinetic modeling study of toluene pyrolysis at low pressure [J]. Combustion and Flame, 2010, 157(9): 1686-1697

[49] ShuklaB, SusaA, MiyoshiA, et al.. Role of phenyl radicals in the growth of polycyclic aromatic hydrocarbons [J]. The Journal of Physical Chemistry A, 2008, 112(11): 2362-2369

[50] FrenklachM. Reaction mechanism of soot formation in flames [J]. Physical Chemistry Chemical Physics, 2002, 4(11): 2028-2037

[51] LadommatosN, RubensteinP, BennettP. Some effects of molecular structure of single hydrocarbons on sooting tendency [J]. Fuel, 1996, 75(2): 114-124