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Spray Characterization of Gasoline Direct Injection Sprays Under Fuel Injection Pressures up to 150 MPa with Different Nozzle Geometries

Chalmers University of Technology-Lucien Koopmans, Petter Dahlander
Denso Corp.-Akichika Yamaguchi
Published 2019-01-15 by SAE International in United States
Maximum fuel injection pressures for GDI engines is expected to increase due to positive effects on emissions and engine-efficiency. Current GDI injectors have maximum operating pressures of 35 MPa, but higher injection pressures have yielded promising reductions in particle number (PN) and improved combustion stability. However, the mechanisms responsible for these effects are poorly understood, and there have been few studies on fuel sprays formed at high injection pressures.This paper summarizes experimental studies on the properties of sprays formed at high injection pressures. The results of these experiments can be used as inputs for CFD simulations and studies on combustion behavior, emissions formation, and combustion system design. The experiments were conducted using an injection rate meter and optical methods in a constant volume spray chamber. Injection rate measurements were performed to determine the injectors’ flow characteristics. Spray imaging was performed using a high-speed video camera. Several spray properties such as the liquid spray penetration, spray plume angle, and the spray breakup point were determined as functions of the fuel injection pressure and injected fuel mass…
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Development of the Combustion System for Volvo Cars Euro6d VEA Diesel Engine

Volvo Car Corporation-Håkan Persson, Aristotelis Babajimopoulos, Arjan Helmantel, Fredrik Holst, Elin Stenmark
Published 2017-03-28 by SAE International in United States
The demands for a future diesel engine in terms of emission compliance, CO2 emissions, performance and cost effectiveness set new requirements for the development process of the combustion system.This paper focuses on the development of the next generation Volvo Cars diesel combustion system, which should comply with Euro 6d including Real Driving Emissions (RDE), with emphasis on the novel methods applied throughout the process.The foundation of a high performing combustion system is formed by first determining the requirements for the system, after which the key factors that affect system performance are selected, such as the charge motion, combustion chamber geometry and injector nozzle geometry.Based on the requirements, a robust charge motion with desired flow characteristics is defined. A new automated CFD optimization process for combustion chamber geometry and spray target is developed. From the generated Pareto front of optimal designs, the best hardware solutions are selected based on targeted attributes. An increase in knowledge is also gained by looking into the details of the simulation results for these candidates. The selected solutions are then verified…
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Combustion and Emissions in a Light-Duty Diesel Engine Using Diesel-Water Emulsion and Diesel-Ethanol Blends

Chalmers University of Technology-Xiaoqi Cui, Arjan Helmantel, Valeri Golovichev, Ingemar Denbratt
Published 2009-11-02 by SAE International in United States
The purpose of the investigation presented here was to compare the effects of fuel composition on combustion parameters, emissions and fuel consumption in engine tests and simulations with five fuels: a Diesel-water emulsion, a Diesel-ethanol blend, a Diesel-ethanol blend with EHN (cetane number improver), a Fischer-Tropsch Diesel and an ultra-low sulfur content Diesel.The engine used in the experiments was a light duty, single cylinder, direct injection, common rail Diesel engine equipped with a cylinder head and piston from a Volvo NED5 engine. In tests with each fuel the engine was operated at two load points (3 bar IMEP and 10 bar IMEP), and a pilot-main fuel injection strategy was applied under both load conditions. Data were also obtained from 3-D CFD simulations, using the KIVA code, to compare to the experimental results and to further analyze the effects of water and ethanol on combustion.The experimental data indicated that the lower aromatic content of Fischer-Tropsch Diesel fuel resulted in reduced soot emissions compared to conventional Diesel. Use of Fischer-Tropsch Diesel also gave lower NOx emissions. The…
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Injection Strategy Optimization for a Light Duty DI Diesel Engine in Medium Load Conditions with High EGR rates

Chalmers University of Technology-Arjan Helmantel, Valeri Golovitchev
Published 2009-04-20 by SAE International in United States
Further restrictions on NOx emissions and the extension of current driving cycles for passenger car emission regulations to higher load operation in the near future (such as the US06 supplement to the FTP-75 driving cycle) requires attention to low emission combustion concepts in medium to high load regimes.One possibility to reduce NOx emissions is to increase the EGR rate. The combustion temperature-reducing effects of high EGR rates can significantly reduce NO formation, to the point where engine-out NOx emissions approach zero levels. However, engine-out soot emissions typically increase at high EGR levels, due to the reduced soot oxidation rates at reduced combustion temperatures and oxygen concentrations.This paper presents an analysis of the effects of varying injection timing, fuel mass distributions in split injections and fuel rail pressure on emissions, combustion noise and fuel consumption during the medium load operation (≥10 bar IMEP) at high EGR rates (41%) of a single-cylinder test engine, with the overall objective to optimize a triple injection strategy. The results of some of the test cases are compared with those obtained…
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Reduction of NOx Emissions from a Light Duty DI Diesel Engine in Medium Load Conditions with High EGR Rates

Chalmers University of Technology-Arjan Helmantel
Published 2008-04-14 by SAE International in United States
The expansion of current driving cycles for emission regulations to higher load operation in the near future (such as the US06 supplement to the FTP-75 driving cycle) requires attention to low emission combustion concepts in medium to high load regimes.One possibility to reduce NO emissions is to increase the EGR rate. The combustion-temperature reducing effects of high EGR rates can significantly reduce NO formation, to the point where engine-out NOx emissions approach zero levels. However, engine-out soot and CO emissions typically increase at high EGR levels, due to the reduced soot and CO oxidation rates at reduced combustion temperatures and oxygen concentrations.The work presented in this paper focuses on different strategies to reduce soot and CO emissions associated with EGR rates of up to 50%, at which NO formation is largely avoided, but combustion temperatures are not low enough to consider the process as Low-Temperature Combustion (LTC). The studied strategies include use of high injection pressures (up to 1800 bar), increased swirl and increased boost pressures. Using a combination of these measures, soot emission levels…
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HCCI Operation of a Passenger Car DI Diesel Engine with an Adjustable Valve Train

Chalmers University of Technology-Arjan Helmantel, Ingemar Denbratt
Published 2006-04-03 by SAE International in United States
One of the problems encountered when operating Diesel engines in HCCI mode is a too early start of combustion, due to the low ignition resistance of Diesel fuels. Correct phasing of the combustion process requires a lower in-cylinder temperature during compression. One possibility of regulating the temperature is to adjust the intake valve closing timing and thus the effective compression ratio.A single cylinder research engine, configured as a passenger car type DI Common Rail Diesel engine, was fitted with a fully adjustable hydraulic valve train, which allowed free settings of the valve timing events. Premixed combustion was achieved by injecting the fuel during the compression stroke, prior to ignition, in multiple steps. Different combinations of intake valve closing timing and external EGR were tested as well as the possibility to use internal EGR for combustion control. The results showed that accurate control of Diesel HCCI combustion phasing and rate is possible when valve timing can be freely adjusted.
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Operation of a DI Diesel Engine With Variable Effective Compression Ratio in HCCI and Conventional Diesel Mode

Chalmers University of Technology-Arjan Helmantel, Jonas Gustavsson, Ingemar Denbratt
Published 2005-04-11 by SAE International in United States
An experimental investigation was carried out in which an HSDI Common Rail Diesel engine was operated in both HCCI and conventional Diesel combustion modes, using conventional Diesel fuel in both cases. The engine used in the experiments was a single cylinder version of a modern passenger car engine with a displacement of 480 cc. In HCCI mode, the fuel was injected in multiple stages during the compression stroke, using a nozzle with a 60° included angle. To control the phasing and rate of combustion, the effective compression ratio was reduced by retarded intake valve closing. In addition, increased amounts of EGR were used. HCCI operation reduced soot and NOx emissions significantly. The use of a narrow included angle for conventional Diesel operation increased emissions significantly. The effect of a wider included angle and modifications to the piston were investigated experimentally and numerically. HCCI operation was also possible with a piezo injector with a 140° included angle. Because of the more accurate, shorter injections allowed by the piezo injector, interaction of the spray with the cylinder…
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HCCI Operation of a Passenger Car Common Rail DI Diesel Engine With Early Injection of Conventional Diesel Fuel

Chalmers University of Technology-Arjan Helmantel, Ingemar Denbratt
Published 2004-03-08 by SAE International in United States
The possibilities of operating a direct injection Diesel engine in HCCI combustion mode with early injection of conventional Diesel fuel were investigated. In order to properly phase the combustion process in the cycle and to prevent knock, the geometric compression ratio was reduced from 17.0:1 to 13.4:1 or 11.5:1. Further control of the phasing and combustion rate was achieved with high rates of cooled EGR.The engine used for the experiments was a single cylinder version of a modern passenger car type common rail engine with a displacement of 480 cc. An injector with a small included angle was used to prevent interaction of the spray and the cylinder liner. In order to create a homogeneous mixture, the fuel was injected by multiple short injections during the compression stroke.The low knock resistance of the Diesel fuel limited the operating conditions to low loads. Compared to conventional Diesel combustion, the NOx emissions were dramatically reduced. The smoke emissions also showed a significant reduction, while CO and HC emissions increased substantially. The HCCI combustion mode is characterized by…
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