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Improving Heady Duty Natural Gas Engine Efficiency: A Systematic Approach to Application of Dedicated EGR

Southwest Research Institute-Michael Clifford Kocsis, Robert Mitchell, Ahmed Abdul Moiz, Vickey Kalaskar, D. Ryan Williams, Scott Sjovall
  • Technical Paper
  • 2020-01-0818
To be published on 2020-04-14 by SAE International in United States
The worldwide trend of tightening CO2 emissions standards and desire for near zero criteria pollutant emissions is driving development of high efficiency natural gas engines for a low CO2 replacement of traditional diesel engines. A Cummins Westport ISX12 G was previously converted to a Dedicated EGR ™ (D-EGR™) configuration with two out of the six cylinders acting as the EGR producing cylinders. Using a systems approach, the combustion and turbocharging systems were optimized for improved efficiency while maintaining the potential for achieving 0.02 g/bhp-hr NOX standards. A prototype variable nozzle turbocharger was selected to maintain the stock torque curve. The EGR delivery method enabled a reduction in pre-turbine pressure as the turbine was not required to be undersized to drive EGR. A high energy Dual Coil Offset (DCO®) ignition system was utilized to maintain stable combustion with increased EGR rates. High compression ratio, reduced squish pistons were designed to maintain MBT combustion phasing and fast burn rates along the torque curve. The final engine configuration was tested on the Heavy-Duty Supplemental Emissions Test (SET), a…
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Development of a Natural Gas Engine with Diesel Engine-like Efficiency Using Computational Fluid Dynamics

Southwest Research Institute-Ahmed Abdul Moiz, Zainal Abidin, Robert Mitchell, Michael Kocsis
Published 2019-04-02 by SAE International in United States
Present day natural gas engines have a significant efficiency disadvantage but benefit with low carbon-dioxide emissions and cheap three-way catalysis aftertreatment. The aim of this work is to improve the efficiency of a natural gas engine on par with a diesel engine. A Cummins-Westport ISX12-G (diesel) engine is used for the study. A baseline model is validated in three-dimensional Computational Fluid Dynamics (CFD). The challenge of this project is adapting the diesel engine for the natural gas fuel, so that the increased squish area of the diesel engine piston can be used to accomplish faster natural gas burn rates. A further increase efficiency is achieved by switching to D-EGR technology. D-EGR is a concept where one or more cylinders are run with excess fueling and its exhaust stream, containing H2 and CO, is cooled and fed into the intake stream. With D-EGR although there is an in-cylinder presence of a reactive H2-CO reformate, there is also higher levels of dilution. A new piston was designed that can match the high squish burn rates with not…
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Evaluation of Diesel Spray with Non-Circular Nozzle - Part I: Inert Spray

Southwest Research Institute-Khanh Cung, Ahmed Abdul Moiz, Bansal Shah, Vickey Kalaskar, Jason Miwa, Zainal Abidin
Published 2019-01-15 by SAE International in United States
Numerous studies have characterized the impact of high injection pressure and small nozzle holes on spray quality and the subsequent impact on combustion. Higher injection pressure or smaller nozzle diameter usually reduce soot emissions owing to better atomization quality and fuel-air mixing enhancement. The influence of nozzle geometry on spray and combustion of diesel continues to be a topic of great research interest. An alternate approach impacting spray quality is investigated in this paper, specifically the impact of non-circular nozzles. The concept was explored experimentally in an optically accessible constant-volume combustion chamber (CVCC). Non-reacting spray evaluations were conducted at various ambient densities (14.8, 22.8, 30 kg/m3) under inert gas of Nitrogen (N2) while injection pressure was kept at 100 MPa. Shadowgraph imaging was used to obtain macroscopic spray characteristics such as spray structure, spray penetration, and the spray cone angle. Analysis from image processing showed expected result of lower penetration rate and higher spray cone angle as ambient density increased. Two slot nozzles with different aspect ratios but similar flow area as compared with one…
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Advances Toward the Goal of a Genuinely Conjugate Engine Heat Transfer Analysis

Southwest Research Institute-Matthew Hoffmeyer, Ahmed Abdul Moiz, Kevin Hoag, Anthony Megel, Bansal Shah, Zainal Abidin
Published 2019-01-15 by SAE International in United States
As the design of engines advances and continues to push the capabilities of current hardware closer to their durability limits, more accurate and reliable analysis is necessary to ensure that designs are robust. This research evaluates a method of conjugate heat transfer analysis for a diesel engine that combines the combustion CFD, Engine FEA, and cooling jacket CFD with the aim of getting more accurate heat loss predictions and a more accurate temperature distribution in the engine than with current analysis methods. A 15.0 L Cummins ISX heavy duty engine operating at 1250 RPM and 15 bar BMEP load is selected for this work. Spray combustion computational fluid dynamics (CFD) simulations are performed for the diesel engine and the results are validated with experimental data. Finite Element Analysis (FEA) simulations were performed in a separate software platform. Data interchanges between CFD and FEA software codes were performed at specified sub-cycle engine intervals and the simulations ran for multiple engine cycles. A comprehensive CFD-FEA conjugate heat transfer (CHT) methodology is proposed and the accuracy of this…
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A Machine Learning-Genetic Algorithm (ML-GA) Approach for Rapid Optimization Using High-Performance Computing

SAE International Journal of Commercial Vehicles

Aramco Research Center-Yuanjiang Pei, Yu Zhang
Argonne National Laboratory-Ahmed Abdul Moiz, Pinaki Pal, Sibendu Som, Janardhan Kodavasal
  • Journal Article
  • 2018-01-0190
Published 2018-04-03 by SAE International in United States
A Machine Learning-Genetic Algorithm (ML-GA) approach was developed to virtually discover optimum designs using training data generated from multi-dimensional simulations. Machine learning (ML) presents a pathway to transform complex physical processes that occur in a combustion engine into compact informational processes. In the present work, a total of over 2000 sector-mesh computational fluid dynamics (CFD) simulations of a heavy-duty engine were performed. These were run concurrently on a supercomputer to reduce overall turnaround time. The engine being optimized was run on a low-octane (RON70) gasoline fuel under partially premixed compression ignition (PPCI) mode. A total of nine input parameters were varied, and the CFD simulation cases were generated by randomly sampling points from this nine-dimensional input space. These input parameters included fuel injection strategy, injector design, and various in-cylinder flow and thermodynamic conditions at intake valve closure (IVC). The outputs (targets) of interest from these simulations included five metrics related to engine performance and emissions. Over 2000 samples generated from CFD were then used to train an ML model that could predict these five targets…
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Proof-of-Concept Numerical Study for NOx Reduction in Diesel Engines Using Enriched Nitrogen and Enriched Oxygen

Argonne National Laboratory-Kaushik Saha, Anita Ramirez, Sibendu Som, Munidhar Biruduganti
DENSO International America Inc-Michael Bima, Patrick Powell
Published 2016-09-27 by SAE International in United States
The medium and heavy duty vehicle industry has fostered an increase in emissions research with the aim of reducing NOx while maintaining power output and thermal efficiency. This research describes a proof-of-concept numerical study conducted on a Caterpillar single-cylinder research engine. The target of the study is to reduce NOx by taking a unique approach to combustion air handling and utilizing enriched nitrogen and oxygen gas streams provided by Air Separation Membranes. A large set of test cases were initially carried out for closed-cycle situations to determine an appropriate set of operating conditions that are conducive for NOx reduction and gas diffusion properties. Several parameters - experimental and numerical, were considered. Experimental aspects, such as engine RPM, fuel injection pressure, start of injection, spray inclusion angle, and valve timings were considered for the parametric study. The numerical factors - initial swirl ratio, adaptive mesh refinement and thickness of enriched nitrogen and oxygen regions were also taken into account. Open-cycle combustion simulations were also carried out for specifically selected operating conditions to assess the potential performance…
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Investigation of Multi-Hole Impinging Jet High Pressure Spray Characteristics under Gasoline Engine-Like Conditions

Le Zhao
Michigan Technological University-Ahmed Abdul Moiz, Seong-Young Lee, Jeffrey Naber
Published 2016-04-05 by SAE International in United States
Impingement of jet-to-jet has been found to give improved spray penetration characteristics and higher vaporization rates when compared to multi-hole outwardly injecting fuel injectors which are commonly used in the gasoline engine. The current work studies a non-reacting spray by using a 5-hole impinging-jet style direct-injection injector. The jet-to-jet collision induced by the inwardly opening nozzles of the multi-hole injector produces rapid and short jet breakup which is fundamentally different from how conventional fuel injectors operate. A non-reacting spray study is performed using a 5-hole impinging jet injector and a traditional 6-hole Bosch Hochdruck-Einspritzventil (HDEV)-5 gasoline direct-injection (GDI) injector with gasoline as a fuel injected at 172 bar pressure with ambient temperature of 653 K and 490 K and ambient pressure of 37.4 bar and 12.4 bar. The engine-like thermodynamic conditions were generated in a constant-volume high pressure-temperature preburn type combustion vessel for the two corresponding SI engine conditions. In addition, Computational fluid dynamics (CFD) work has been performed using an Eulerian-Lagrangian modelling approach. Iso-octane was used as a fuel in simulation for both injectors.…
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Characteristics of Formaldehyde (CH2O) Formation in Dimethyl Ether (DME) Spray Combustion Using PLIF Imaging

SAE International Journal of Fuels and Lubricants

Michigan Technological Univ.-Khanh Cung, Xiucheng Zhu, Ahmed Abdul Moiz, Seong-Young Lee
WM International Engineering-William De Ojeda
  • Journal Article
  • 2016-01-0864
Published 2016-04-05 by SAE International in United States
Recognition of Dimethyl Ether (DME) as an alternative fuel has been growing recently due to its fast evaporation and ignition in application of compression-ignition engine. Most importantly, combustion of DME produces almost no particulate matter (PM). The current study provides a further understanding of the combustion process in DME reacting spray via experiment done in a constant volume combustion chamber. Formaldehyde (CH2O), an important intermediate species in hydrocarbon combustion, has received much attention in research due to its unique contribution in chemical pathway that leads to the combustion and emission of fuels. Studies in other literature considered CH2O as a marker for UHC species since it is formed prior to diffusion flame. In this study, the formation of CH2O was highlighted both temporally and spatially through planar laser induced fluorescence (PLIF) imaging at wavelength of 355-nm of an Nd:YAG laser at various time after start of injection (ASOI). The injection pressure was kept at 750 bar using a single-hole injector with diameter of 180 μm. The formation of CH2O is also correlated with time of…
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Experimental and Numerical Studies on Combustion Model Selection for Split Injection Spray Combustion

Argonne National Laboratory-Sibendu Som
Army Research Laboratory-Luis Bravo
Published 2015-04-14 by SAE International in United States
A wide variety of spray models and their associated sub-models exist to assist with numerical spray development studies in the many applicable areas viz., turbines, internal combustion engines etc. The accuracy of a simulation when compared to the experiments varies, as these models chosen are varied. Also, the computational grid plays a crucial role in model correctness; a grid-converged CFD study is more valuable and assists in proper validation at later stages. Of primary relevance to this paper are the combustion models for a grid-converged Lagrangian spray modeling scenario. CONVERGE CFD code is used for simulation of split injection diesel (n-heptane) sprays and a structured methodology, using RNG k-ε turbulence model, is followed to obtain a grid-converged solution for the key Computational Fluid Dynamics (CFD) parameters viz., grid size, injected parcels and spray break-up time constant. Four combustion models namely the SAGE model, the Representative Interactive Flamelet model, the 3-Zone Extended Coherent Flamelet model, and SHELL+Characteristic Time Combustion model will be examined using the grid-converged CFD settings and validation against experimental flame luminosity data will…
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High-Speed Spray-to-Spray Collision Study on Two-Hole Impinging Jet Nozzles

Michigan Technological Univ-Le (Emma) Zhao, Ahmed Abdul Moiz, Jeffrey Naber, Seong-Young Lee
Nostrum Energy LLC-Sam Barros, William Atkinson
Published 2015-04-14 by SAE International in United States
High-speed spray-to-spray liquid impingement could be an effective phenomenon for the spray propagation and droplet vaporization. To achieve higher vaporization efficiency, impingement from two-hole nozzles is analyzed in this paper. This paper focuses on investigating vaporization mechanism as a function of the impingement location and the collision breakup process provided by two-hole impinging jet nozzles. CFD (Computational Fluid Dynamics) is adopted to do simulation. Lagrangian model is used to predict jet-to-jet impingement and droplet breakup conditions while KH-RT breakup and O'Rourke collision models are implemented for the simulation. The paper includes three parts: First, a single spray injected into an initially quiescent constant volume chamber using the Lagrangian approach is simulated to identify the breakup region, which will be considered as a reference to study two-hole impinging jet nozzles. Lagrangian simulation results would be validated via experimental results. Second, collision mechanism is analyzed to obtain probability distribution of collision efficiency and study the jet-to-jet impingement. Finally, the paper examines the collision phenomenon under engine-like conditions, to examine impingement at pre (case 1), exact (case 2),…
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