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Zandie, Mohammad (2024) Investigating the thermophysical properties and ignition behaviour in CI engines of cost-effective gasoline-palm biodiesel-diesel blends. PhD thesis, University of Nottingham.

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Abstract

In this thesis a compact combined reaction mechanism for diesel-biodiesel-gasoline mixtures (CDBG) is developed. The detailed mechanisms were separately reduced prior to combining by means of directed relation graph (DRG), directed relation graphs with error propagation (DRGEP), and full species sensitivity analysis (FSSA). The reduced mechanisms were then combined and validated under closed homogenous reactor conditions at T=600-1700 K, P=1-50 atm, and equivalence ratios (Φ) of 0.25-1.5 (156 setups in total).

Cross-reaction analysis was performed to identify the important intermediate species and reactions which might have been left out. They were then integrated into the CDBG mechanism and significant improvements in ID timings of diesel, biodiesel and gasoline surrogates up to 30%, 18% and 16% were achieved, respectively. The Arrhenius rate constant optimisation was also and the dual implementation of Arrhenius rate constants optimisation and cross-reaction analysis reduced the ID timing errors considerably down to 2.13%, 1.5% and 2.9% for the diesel, biodiesel and gasoline surrogates, respectively. Moreover, the CDBG mechanism was also validated for flame speed and species mole fractions in conjunction with estimating the thermophysical properties of diesel, palm biodiesel and gasoline using temperature-dependent correlations that were found in the literature.

Also, the spray combustion, soot formation and emissions of diesel-biodiesel-gasoline mixtures are simulated in a constant volume chamber. An adaptive mesh refinement scheme and mesh independency analysis are applied. Liquid penetration length (LPL), lift-off length (LOL), ignition delay (ID) and soot formation have been validated against experimental data in the literature. The D65|BD20|G15 mixture (65%Diesel|20%Biodiesel|15%Gasoline), resulted in a lower soot mass yield than that of pure biodiesel and pure diesel for about 35% and 27%, respectively, at T=900K|O2=15%. The decrease in ambient temperature from 900K to 800K led to even greater soot mass reductions by a factor of ∼1/3. Lower nitrogen oxides (NOx) emissions were predicted for D100 by a factor of ∼1/2 at T=900K|O2=15% compared to BD100. Ternary mixtures revealed lower NOx compared to BD100 (∼20%) yet still higher than D100. Also, lower carbon dioxide (CO2) and carbon monoxide (CO) emissions were captured for D65|BD20|G15.

Also, 3D CFD simulations are conducted for a compression ignition engine fuelled with D100, D80|BD20, D75|BD20|G5, D70|BD20|G10 and D65|BD20|G15 mixtures under different blending ratios, exhaust gas recirculation (EGR) and start of injection (SOI). In brief, D65|BD20|G15 produced the least NOx and soot emissions at 6.5E-2 and 5.46E-3 g/kWh, respectively which were lower than the Euro VI limit. The least CO and unburnt hydrocarbons (UHCs) emissions were achieved for D75|BD20|G5 at 1.62 and 5.8 g/kWh, respectively. D75|BD20|G15 improved the indicated mean effective pressure (IMEP), combustion efficiency and indicated specific fuel consumption (ISFC) up to 13.9%, 12.7% and 13.9% compared to D80|BD20, respectively. Also, applying 20% EGR led to 50% reduction in NOx and soot for D65|BD20|G15, while UHCs and CO were increased up to 27% and 54%, respectively and ISFC and combustion efficiency slightly declined. Additionally, advancing SOI timing to -24 Crank Angle (˚CA) decreased the CO and UHCs emissions of D65|BD20|G15 up to 20% and 15% compared to -20 ˚CA, respectively. A multi-parameter optimisation is also performed to further suppress emissions and improve engine output and fuel efficiency. The methodology and the outcomes presented in this study pioneer the integration of ternary blends as alternative fuelling strategy, and the developed CDBG kinetic mechanism can be applied to future studies to further widen the application of this new fuelling system.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Ng, Hoon Kiat Gan, Suyin
Keywords:	diesel-biodiesel-gasoline mixtures, CDBG mechanism, reaction mechanisms, directed relation graph (DRG), directed relation graphs with error propagation (DRGEP), full species sensitivity analysis (FSSA), intermediate species
Subjects:	T Technology > TJ Mechanical engineering and machinery
Faculties/Schools:	University of Nottingham, Malaysia > Faculty of Science and Engineering — Engineering > Department of Mechanical, Materials and Manufacturing Engineering
Item ID:	76772
Depositing User:	Zandie, Mohammad
Date Deposited:	27 Jul 2024 04:40
Last Modified:	27 Jul 2024 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/76772

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