Usama Bin Khalid

Scopus Publications

Evaluation of the ducted fuel injection concept for medium duty engines and multi-hole nozzles: An optical analysis
José V. Pastor, Carlos Micó, Felipe Lewiski, Usama Bin-Khalid
Applied Energy, 2024
Ducted Fuel Injection (DFI) is a strategy still in development, which has proved to be effective in reducing soot emissions in compression ignition engines. It works by driving the spray, formed by a high-pressure fuel injection, through a small duct co-axial to the spray itself, which is expected to affect the mixture formation and combustion process, in turn leading to noticeable reduction in soot formation. This strategy has been mostly deployed in spray vessels or in some cases in heavy duty engines consisting of mostly 2-to-4-hole nozzle injectors. For this reason, the work here is aimed to study the potential of DFI in a medium-duty single-cylinder optical engine fueled with conventional diesel having an 8-hole nozzle injector. Two different optical techniques including OH* chemiluminescence and 2-color pyrometry have been utilized to perform the analysis regarding combustion evolution and soot formation. A parametric analysis regarding different geometrical parameters including stand-off distance, diameter and length of duct has been carried out regarding the DFI performance. Results indicate that DFI does decrease the soot emissions in the context of this study and the duct geometrical parameters influence combustion evolution and soot formation ultimately affecting the device's performance. However, the scale of soot reduction is not as high as reported in previous studies, which is limited by specific boundary conditions including combustion chamber design, piston geometry utilized in this study. • DFI concept applied to medium duty optical engine with 8-hole nozzle injector. • The influence of geometrical characteristics of the duct is analyzed in detail. • DFI reduces overall soot net formation with all duct geometries tested. • Soot reduction levels limited by small bore size and number of nozzle orifices.
Development of a reduced primary reference fuel – oxymethylene dimethyl ether (PRF-OMEx) mechanism for diesel engine applications
José M García-Oliver, Ricardo Novella, Carlos Micó, Usama Bin-Khalid
International Journal of Engine Research, 2024
Oxymethylene dimethyl ethers (OMEx), having a chemical formula of CH3O-(CH2O)x-CH3 where x varies from 1 to 5, have been widely considered as a promising fuel to partially replace diesel in CI engines in terms of reducing soot emissions. This work is focused on developing a reduced primary reference fuel (PRF)-OMEx chemical mechanism to better describe the combustion and emission characteristics of gasoline/diesel blends with OMEx. The novelty of this work lies in the fact that the OMEx part of the mechanism is represented not only by OME3 as done in most studies found in literature, but also with other OME chain lengths that is, OME2-4 which are considered to be optimum and better represent the commercial OMEx blends. For this purpose, a detailed OMEx mechanism is reduced by applying different reduction techniques considering a wide range of operating conditions including pressure, temperatures, equivalence ratios and fuel compositions. The result is merged with an already validated PRF mechanism to form a reduced PRF-OMEx mechanism consisting of 213 species and 840 reactions. The newly formed mechanism is validated against a wide set of experimental data including ignition delay times, laminar flame speeds and species concentration profiles. Furthermore, a rigorous set of numerical simulations for various diesel-OMEx blends in a compression ignition engine are carried out at two different operating points to validate the developed mechanism. Simulation results highlight that the developed mechanism not only replicates the experimental behavior in terms of in-cylinder pressure and heat release rate but exhibits a better combustion phasing closer to experimental data when compared with other mechanisms where only OME3 is utilized to represent OMEx. Overall, the developed PRF-OMEx mechanism proves to be realistic and suitable for application in engine combustion simulations involving gasoline/diesel and OMEx blends.
A numerical analysis of hydrotreated vegetable oil and dimethoxymethane (OME1) blends combustion and pollutant formation through the development of a reduced reaction mechanism
José M García-Oliver, Ricardo Novella, Carlos Micó, Usama Bin-Khalid, Dario Lopez-Pintor
International Journal of Engine Research, 2024
The solution to the dilemma of carbon footprint of internal combustion engines and pollutant emissions is necessary for the survival of this technology. In this context, alternative fuels have shown great potential in terms of achieving cleaner combustion and compliance with ever increasing pollutant emissions regulations. This work is focused on the study of two promising alternative fuels as Hydrotreated vegetable oil (HVO), which is a biofuel and Dimethoxymethane also termed as OME1, which is an e-fuel. A comprehensive numerical approach has been followed to study these fuels. Primarily a compact reaction mechanism having 121 species and 678 reactions has been developed which can be utilized to perform 3D CFD simulations of blends of these fuels. Secondly, a detailed numerical investigation including combustion and emissions analysis has been carried out. Results show that the developed mechanism is able to offer predictions, which match the experimental behavior observed in various combustion parameters and thus can be utilized for compression ignition engine applications involving these promising fuels. In addition, the numerical analysis also highlights that a reduction of 50% and 37% in terms soot and NOx emissions respectively can be achieved by addition of 30% OME1 in the blend containing HVO, suggesting that these blends can be utilized in unmodified CI engines to break the soot-NOx tradeoff without significantly penalizing the energy loss.
Potential of 2-ethylhexyl nitrate (EHN) and di-tert-butyl peroxide (DTBP) to enhance the cetane number of ethanol, a detailed chemical kinetic study
Usama Bin-Khalid, Dario Lopez-Pintor, Carlos Micó, Sanguk Lee
Fuel, 2024
A Numerical Approach for the Analysis of Hydrotreated Vegetable Oil and Dimethoxy Methane Blends as Low-Carbon Alternative Fuel in Compression Ignition Engines
Jose M Garcia-Oliver, Ricardo Novella, Dario Lopez Pintor, Carlos Micó, Usama Bin-Khalid
SAE Technical Papers, 2023
<div class="section abstract"><div class="htmlview paragraph">Despite recent advances towards powertrain electrification as a solution to mitigate pollutant emissions from road transport, synthetic fuels (especially e- fuels) still have a major role to play in applications where electrification will not be viable in short-medium term. Among e-fuels, oxymethylene ethers are getting serious interest within the scientific community and industry. Dimethoxy methane (OME<sub>1</sub>) is the smaller molecule among this group, which is of special interest due to its low soot formation. However, its application is still limited mainly due to its low lower heating value. In contrast, other fuel alternatives like hydrogenated vegetable oil (HVO) are considered as drop-in solutions thanks to their very similar properties and molecular composition to that of fossil diesel. However, their pollutant emission improvement is limited. This work proposes the combination of OME<sub>1</sub> and HVO as an alternative to fossil diesel, to achieve noticeable soot emission reductions while compensating for the different properties of the first fuel.</div><div class="htmlview paragraph">The aim of this work is to provide insight into the combustion characteristics of blends of these two fuels. For this purpose, experimental and numerical studies are combined. In this context, n-dodecane is proposed as a surrogate for HVO simulation based on the high similarities experimentally observed between both fuels. Then, a compact kinetic mechanism is developed and validated, combining individual OME<sub>1</sub> and n-dodecane mechanisms. Results confirm that the numerical approach followed was able to capture the experimental behavior of these blends in terms of heat release rate, in-cylinder pressure and soot formation. An increase of the OME<sub>1</sub> content in the blend greatly influences the combustion process. The ignition delay, as well as the premixed combustion phase peak, increase with the OME<sub>1</sub> percentage in the blend. However, HVO helps on limiting this effect while remarkable soot formation reductions are still achieved thanks to OME<sub>1</sub>.</div></div>
A Numerical Approach for the Analysis of Hydrotreated Vegetable Oil and Dimethoxy Methane Blends as Low-Carbon Alternative Fuel in Compression Ignition Engines
Jose M Garcia-Oliver, Ricardo Novella, Dario Lopez Pintor, Carlos Micó, Usama Bin-Khalid
SAE International Journal of Advances and Current Practices in Mobility, 2023
<div class="section abstract"><div class="htmlview paragraph">Despite recent advances towards powertrain electrification as a solution to mitigate pollutant emissions from road transport, synthetic fuels (especially e- fuels) still have a major role to play in applications where electrification will not be viable in short-medium term. Among e-fuels, oxymethylene ethers are getting serious interest within the scientific community and industry. Dimethoxy methane (OME<sub>1</sub>) is the smaller molecule among this group, which is of special interest due to its low soot formation. However, its application is still limited mainly due to its low lower heating value. In contrast, other fuel alternatives like hydrogenated vegetable oil (HVO) are considered as drop-in solutions thanks to their very similar properties and molecular composition to that of fossil diesel. However, their pollutant emission improvement is limited. This work proposes the combination of OME<sub>1</sub> and HVO as an alternative to fossil diesel, to achieve noticeable soot emission reductions while compensating for the different properties of the first fuel.</div><div class="htmlview paragraph">The aim of this work is to provide insight into the combustion characteristics of blends of these two fuels. For this purpose, experimental and numerical studies are combined. In this context, n-dodecane is proposed as a surrogate for HVO simulation based on the high similarities experimentally observed between both fuels. Then, a compact kinetic mechanism is developed and validated, combining individual OME<sub>1</sub> and n-dodecane mechanisms. Results confirm that the numerical approach followed was able to capture the experimental behavior of these blends in terms of heat release rate, in-cylinder pressure and soot formation. An increase of the OME<sub>1</sub> content in the blend greatly influences the combustion process. The ignition delay, as well as the premixed combustion phase peak, increase with the OME<sub>1</sub> percentage in the blend. However, HVO helps on limiting this effect while remarkable soot formation reductions are still achieved thanks to OME<sub>1</sub>.</div></div>
A numerical investigation of the performance of oxymethylene ethers blended with fossil diesel to reduce soot emissions in compression ignition engines
José M. García-Oliver, Ricardo Novella, Carlos Micó, Usama Bin-Khalid
Fuel, 2022
The reduction of the carbon footprint of internal combustion engines and the pollutant emissions is mandatory for the survival of this technology. In this sense, e-fuels are considered as a potential pathway to achieve this reduction and even remarkable carbon footprint mitigation in compression ignition engines. Among numerous e-fuels, oxymethylene ethers stand out because of their low soot formation characteristics. However, the complexity of their physical and chemical properties makes it a challenge to be used in conventional engines. The aim of the current study is to investigate the effects of the stoichiometry of oxymethylene ether on the in-cylinder combustion behaviour and the pollutant formation when blended with fossil diesel. For this purpose, numerical simulations of a medium duty optical engine fuelled with these blends were carried out using CONVERGE CFD, which were validated with experimental data. Different reaction mechanisms that can be found in the literature were evaluated, using n-heptane as to the fossil diesel surrogate and OME3 as the oxymethylene ether surrogate. Results highlight the differences in terms of equivalence ratio fields achieved when varying the e-fuel content in the blend. As a consequence, the combustion process is faster and the soot formation is drastically reduced when the oxymethylene ethers content is above 30%. This makes these blends interesting to reduce the well-known soot-NOx trade off of compression ignition engines.