Modeling the Effects of EGR and Injection Pressure on Soot Formation in a High-Speed Direct-Injection (HSDI) Diesel Engine Using a Multi-Step Phenomenological Soot Model

Author(s):  
Feng Tao ◽  
Yi Liu ◽  
Bret H. Rempelewert ◽  
David E. Foster ◽  
Rolf D. Reitz ◽  
...  
Author(s):  
Raouf Mobasheri ◽  
Zhijun Peng

High-Speed Direct Injection (HSDI) diesel engines are increasingly used in automotive applications due to superior fuel economy. An advanced CFD simulation has been carried out to analyze the effect of injection timing on combustion process and emission characteristics in a four valves 2.0L Ford diesel engine. The calculation was performed from intake valve closing (IVC) to exhaust valve opening (EVO) at constant speed of 1600 rpm. Since the work was concentrated on the spray injection, mixture formation and combustion process, only a 60° sector mesh was employed for the calculations. For combustion modeling, an improved version of the Coherent Flame Model (ECFM-3Z) has been applied accompanied with advanced models for emission modeling. The results of simulation were compared against experimental data. Good agreement of calculated and measured in-cylinder pressure trace and pollutant formation trends were observed for all investigated operating points. In addition, the results showed that the current CFD model can be applied as a beneficial tool for analyzing the parameters of the diesel combustion under HSDI operating condition.


Author(s):  
I P Gilbert ◽  
A R Heath ◽  
I D Johnstone

The need to increase power, to improve fuel economy and to meet stringent exhaust emissions legislation with a high level of refinement has provided a challenge for the design of a compact high-speed direct injection (HSDI) diesel engine. This paper describes various aspects of cylinder head design with particular consideration of layout and number of valves, valve actuation, port selection strategy, fuel injection systems and cylinder head construction.


Author(s):  
Vinay Nagaraju ◽  
Mufaddel Dahodwala ◽  
Kaushik Acharya ◽  
Walter Bryzik ◽  
Naeim A. Henein

Biodiesel has different physical and chemical properties than ultra low sulfur diesel fuel (ULSD). The low volatility of biodiesel is expected to affect the physical processes, mainly fuel evaporation and combustible mixture formation. The higher cetane number of biodiesel is expected to affect the rates of the chemical reactions. The combination of these two fuel properties has an impact on the auto ignition process, subsequently combustion and engine out emissions. Applying different swirl ratios and injection pressures affect both the physical and chemical processes. The focus of this paper is to investigate the effect of varying the swirl ratio and injection pressure in a single-cylinder research diesel engine using a blend of biodiesel and ULSD fuel. The engine is a High Speed Direct Injection (HSDI) equipped with a common rail injection system, EGR system and a swirl control mechanism. The engine is operated under simulated turbocharged conditions with 3 bar Indicated Mean Effective Pressure (IMEP) at 1500 rpm, using 100% ULSD and a blend of 20% biodiesel and 80% ULSD fuel. The biodiesel is developed from soy bean oil. A detailed analysis of the apparent rate of heat release (ARHR) is made to determine the role of the biodiesel component of B-20 in the combustible mixture formation, autoignition process, premixed, mixing controlled and diffusion controlled combustion fractions. The results explain the factors that cause an increase or a drop in NOx emissions reported in the literature when using biodiesel.


Author(s):  
J A Stephenson ◽  
B A Hood

The paper describes the development of a high-speed direct injection (HSDI) diesel engine suitable for passenger car applications. The evolution from a low emissions medium-speed engine, through a four-cylinder 2.3 litre research engine, into a four-cylinder 2.0 litre production engine is presented. The challenge to the engineer has been to develop the HSDI engine to operate with acceptable noise, emissions, smoke and driveability over the wide speed range (up to 5000 r/min) required for passenger cars. The key element in this task was the optimization of the combustion system and fuel injection equipment. The HSDI is shown to have a significant fuel economy advantage over the prechamber indirect injection (IDI) engine. Future developments of the fuel injection system are described which will further enhance the HSDI engine and provide additional noise and emissions control.


2001 ◽  
Author(s):  
K. J. Richards ◽  
M. N. Subramaniam ◽  
Rolf D. Reitz ◽  
Ming-Chia Lai ◽  
N. A. Henein ◽  
...  

1999 ◽  
Vol 123 (1) ◽  
pp. 167-174 ◽  
Author(s):  
P. J. Tennison ◽  
R. Reitz

An investigation of the effect of injection parameters on emissions and performance in an automotive diesel engine was conducted. A high-pressure common-rail injection system was used with a dual-guided valve covered orifice nozzle tip. The engine was a four-valve single cylinder high-speed direct-injection diesel engine with a displacement of approximately 12 liter and simulated turbocharging. The engine experiments were conducted at full load and 1004 and 1757 rev/min, and the effects of injection pressure, multiple injections (single vs pilot with main), and pilot injection timing on emissions and performance were studied. Increasing the injection pressure from 600 to 800 bar reduced the smoke emissions by over 50 percent at retarded injection timings with no penalty in oxides of nitrogen NOx or brake specific fuel consumption (BSFC). Pilot injection cases exhibited slightly higher smoke levels than single injection cases but had similar NOx levels, while the single injection cases exhibited slightly better BSFC. The start-of-injection (SOI) of the pilot was varied while holding the main SOI constant and the effect on emissions was found to be small compared to changes resulting from varying the main injection timing. Interestingly, the point of autoignition of the pilot was found to occur at a nearly constant crank angle regardless of pilot injection timing (for early injection timings) indicating that the ignition delay of the pilot is a chemical delay and not a physical (mixing) one. As the pilot timing was advanced the mixture became overmixed, and an increase of over 50 percent in the unburned hydrocarbon emissions was observed at the most advanced pilot injection timing.


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