Computational optimization of a combustion system for a stoichiometric DME fueled compression ignition engine

•A full optimization of a combustion system using DME has been performed.•The optimization included 21 parameters related to hardware and settings.•The non-sooting property of DME allows to work with TWC.•TWC coupled with DME allows to control NOx with low soot emissions.•The key paths to optimize t...

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Bibliographic Details
Published in:Fuel (Guildford) 2018-07, Vol.223, p.20-31
Main Authors: Benajes, Jesús, Novella, Ricardo, Pastor, Jose Manuel, Hernández-López, Alberto, Kokjohn, Sage
Format: Article
Language:English
Subjects:
Alternative energy sources
Alternative fuels
Combustion
Compression
Computational fluid dynamics
Computer applications
Configurations
Diesel
Diesel engine
Diesel engines
Dimethyl ether
Emissions
Engine efficiency
Engine optimization
Fluid dynamics
Genetic algorithms
Heat transfer
Hydrodynamics
Ignition
Nitrogen oxides
Optimization
Peak pressure
Pollutant emissions
Pressure
Research methodology
Soot
Stoichiometric combustion
Three way catalyst
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Summary:•A full optimization of a combustion system using DME has been performed.•The optimization included 21 parameters related to hardware and settings.•The non-sooting property of DME allows to work with TWC.•TWC coupled with DME allows to control NOx with low soot emissions.•The key paths to optimize the combustion system were identified.•The optimum provides a 0.6% NIE improvement and 99% NOx reduction compared to the baseline case. An optimization methodology based on a genetic algorithm coupled with the KIVA computational fluid dynamics (CFD) code is applied to the design of a combustion system of a heavy-duty diesel engine fueled with dimethyl ether (DME) and working with stoichiometric combustion in order to equip the system with a three way catalyst (TWC) to control the NOx emissions. The target of the optimization is to improve net indicated efficiency (NIE) while keeping NOx emissions, peak pressure and pressure rise rate under the reference engine levels. The results of the study provide an optimum configuration that offers a 0.6% NIE improvement while satisfying the restrictions and offering NOx values lower than 1% of the original emissions. Due to the methodology, not only the optimum combustion system configuration is presented, but also the cause-effect relation of the most relevant inputs with the optimization outputs are identified and analyzed. The new geometry shape reduced heat transfer losses by minimizing the surface area. Injection pressure and swirl proved to be key parameters necessary to overcome the increased mixing requirements of stoichiometric operation. EGR was found to simultaneously increase NIE while controlling NOx emissions. The results show the potential of stoichiometric compression ignition operation using DME as a promising pathway to maintain diesel-like efficiency, while achieving near zero NOx and soot emissions.
ISSN:0016-2361
1873-7153
DOI:10.1016/j.fuel.2018.03.022