Simulation Based Development of Combustion Concepts for Large Diesel Engines

2011 ◽  
Author(s):  
Michael Engelmayer ◽  
Andreas Wimmer ◽  
Gerhard Pirker ◽  
Bernhard Pemp ◽  
Gernot Hirschl
Keyword(s):  
Boundary Conditions ◽  
Combustion Chamber ◽  
Diesel Engines ◽  
Cfd Simulation ◽  
Simulation Models ◽  
Injection System ◽  
Single Cylinder ◽  
Development Methodology ◽  
Cycle Simulation ◽  
Engine Cycle

The development of low-emission combustion concepts for large Diesel engines requires a specially adapted methodology. In all phases of the development process, it is essential that appropriate tools are used so that an optimized solution can be found within a short time. This paper will describe the methodology used for developing combustion concepts for large Diesel engines. In general, the development of a combustion concept for Diesel engines comprises the definition of the system (e.g. combustion chamber geometry, injection system, EGR system and charging system) and the calibration of engine parameters (e.g. injection parameters, EGR rate, charge pressure, excess air ratio and valve timing) for an application and its emission scenario. In the present case, the main objective was to develop concepts for applications to comply with emissions standards according to EU Stage III B and US EPA Tier 4. To this end, the LEC has developed the LDM method (LEC Development Methodology). This method is based on the intensive interaction of simulation with experimental investigations on single-cylinder research engines. As part of this development methodology, 3D CFD simulation as well as 0D and 1D engine cycle calculation are employed. Another approach used to handle the complexity of the systems is Design of Experiments (DoE) for simulation and experimental work. While 3D CFD simulation is used to optimize the details of the combustion and pollutant formation processes in the combustion chamber, 0D and 1D engine cycle simulation is applied to select the concepts and to pre-optimize important engine parameters. One great advantage of 0D and 1D models is their short calculation time, which allows the investigation of a great amount of variations in parameters. In order to apply the methodology, it must be guaranteed that the results from tests on the single-cylinder engine (SCE) can be transferred to the multi-cylinder engine (MCE). Therefore, it is necessary that the boundary conditions of the SCE are comparable to those of the MCE. Not only the same thermal boundary conditions but also the same conditions at the beginning of the high-pressure cycle (charge composition, pressure and temperature) must be maintained. The SCE measurement results that are generated serve to verify and calibrate the simulation models and deliver the necessary boundary conditions for further simulations. All in all, the paper comprises an evaluation of the different simulation models used and the applied development methodology in order to optimize fuel consumption and to reduce the emissions of large Diesel engines.

3D CFD Modeling and Validation of Ion Current Sensor in a Gen-Set Diesel Engine Using Chemical Kinetic Mechanism

2016 ◽  
Author(s):  
Tamer Badawy ◽  
Naeim Henein
Keyword(s):  
Diesel Engine ◽  
Combustion Chamber ◽  
Diesel Engines ◽  
Combustion Process ◽  
Ion Current ◽  
Cfd Modeling ◽  
Ionization Mechanism ◽  
Current Signal ◽  
Current Sensing ◽  
Cycle Simulation

The control of the combustion process is becoming a necessity for diesel engines in order to meet the upcoming stringent emission regulations. Ion current sensing technology has the potential to provide real-time feedback of the combustion process while using a fairly inexpensive sensor. 3D computational fluid dynamics (CFD) cycle simulation is becoming more complementary in understanding the complex combustion process in diesel engines. In this paper, a CFD study is focused on investigating the characteristics of the ion current signal produced during the combustion process of a Gen-set turbocharged diesel engine. Multiple virtual ion sensing probes are defined in different locations inside the combustion chamber to understand the influence of sensor location on signal characteristics. The n-heptane reaction mechanism and NO mechanism, combined with an ionization mechanism developed at WSU with 11 species, are used in the model to predict the chemical kinetics of combustion and the mole fraction of ionized species produced during combustion. Since the charge in diesel engines is heterogeneous and due to the sensing nature of the ion sensor, this paper explores the effect of sensor sensing diameter and its protrusion depth inside the combustion chamber on the ion current signal development. The simulation is validated by comparing in-cylinder pressure traces, the rate of heat release, and the ion current signal. Further, the model results are validated under different engine loads and injection pressures. This study utilizes the ionization mechanism to give further understanding of the complex formation of ionization species and their amplitudes, particularly at local sensing locations. This can be very vital to identify the potentials of using the ion current sensing and highlight its viability in feedback closed loop combustion control.

Investigation of Soot Concentration and Particle Size Distribution on a Single Cylinder Diesel Engine

2007 ◽  
Author(s):  
Markus Stumpf ◽  
Sascha Merkel ◽  
Peter Eckert ◽  
Uwe Wagner ◽  
Amin Velji ◽  
...  
Keyword(s):  
Particle Size ◽  
Diesel Engine ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Diesel Engines ◽  
Injection System ◽  
Exhaust Gas ◽  
Soot Concentration ◽  
Single Cylinder ◽  
Injection Pressures

The purpose of this study was the characterization of the size distribution and the concentration of the particles emitted by diesel engines under various speed and load points, and different injection pressures. Fine and ultrafine particles emitted by modern diesel engines, in particular those with sizes below 100 nm, are of significant importance for the human health, since the latter are respirable and may have therefore negative effects. The investigations described in this paper provide an insight into the formation of soot particles in the combustion chamber and their number concentration and size distribution in the exhaust gas pipe. The experiments were performed on a single cylinder diesel engine. For the purpose of comparability to multi cylinder engines, the crankshaft drive, the liner, the piston and the cylinder head were based on a heavy duty production engine. The engine was operated with a common rail injection system which was controlled by an electronic control device that offered several degrees of freedom regarding number, duration and timing of the single injections. During the investigations the engine was operated at several speed and load points with and without pilot injection. The in-cylinder soot concentration was measured crank angle resolved with the two-color-method. The Filter-Smoke-Number (FSN) and the NOx concentration were determined in the exhaust gas. Furthermore the particle number and the particle size distribution were measured by means of a Scanning Mobility Particle Sizer (SMPS). The main focus of the experiments was on the investigation of the in-cylinder soot concentration and the particle size distribution running the engine at several injection pressures during different engine speed/load configurations. In order to obtain a potential correlation to common exhaust gas quantification methods, the Filter-Smoke-Number was measured simultaneously. The results of the experiments provide knowledge which is of eminent importance with respect to further diesel combustion development with regard to both the soot concentration and the soot particle properties.

Model-Based Optimization and Pressure Fluctuation Control of Pressure Reservoir in Electrically Controlled Fuel Injection System for Single Cylinder Diesel Engine

2017 ◽  
Author(s):  
Ke Zhang ◽  
Zhifeng Xie ◽  
Ming Zhou
Keyword(s):  
High Pressure ◽  
Diesel Engine ◽  
Diesel Engines ◽  
Pressure Fluctuation ◽  
Fuel Injection ◽  
Common Rail ◽  
Installation Space ◽  
Injection System ◽  
Fuel Injection System ◽  
Single Cylinder

Single-cylinder diesel engines usually employ mechanically actuated or time-type electrically controlled fuel injection systems. But due to the lack of flexibility to provide high pressure and fully varying injection parameters, fuel efficiency and emissions are poor. Although modern multi-cylinder engines have employed high pressure common rail fuel injection system for a long time, this technology has not been demonstrated in single-cylinder diesel engines. Due to the small installation space and little fuel injection amount of single cylinder diesel engine, high pressure common rail fuel injection system cannot be employed directly. In this study an electrically controlled high pressure fuel injection system of time-pressure-type (PTFS) for single-cylinder diesel engine was demonstrated. PTFS integrated the fuel pump and pressure reservoir (PR) to reduce installation space, which enabled it to match various kinds of single-cylinder diesel engines. However, the volume of the PR of PTFS is still limited, leading to obvious pressure fluctuation induced by periodic fuel pumping and injection. Pressure fluctuation might affect the stability and consistency of fuel injection, deteriorating the combustion and emissions of the engine further. This work established a mathematical model for the system, and studied the effect of the main parameters of the PR to the pressure fluctuations in the PR. The structure and dimensions of the system were optimized and a damping mechanism was proposed to reduce the pressure fluctuation. The optimized pressure fluctuation of PTFS achieved an acceptable level which can support steady and effective fuel injection. As a result, the fuel consumption efficiency and emission level of single cylinder diesel engine were enhanced.

Development of Injection System for Medium-Speed Diesel Engine with Quiescent-Type Combustion Chamber

1969 ◽  
Vol 184 (10) ◽  
pp. 77-86
Author(s):  
G. Lustgarten ◽  
A. Dolenc
Keyword(s):  
Combustion Chamber ◽  
Diesel Engines ◽  
Theoretical Work ◽  
Injection System ◽  
Pressure Gradients ◽  
Injection Equipment ◽  
Fuel Distribution ◽  
Component Design ◽  
Medium Speed ◽  
Theoretical Considerations

During the development of two- and four-stroke medium-speed diesel engines at Sulzer it was realized that a minimized movement of air before and during combustion improves some of the performance characteristics of highly loaded diesel engines. The paper describes the theoretical considerations behind a new injection system giving a uniform fuel distribution and adequate atomization in an open combustion chamber with minimized air movement. The required high-pressure gradients towards the end of injection increase the danger of mechanical and cavitation attack on injection equipment components. The theoretical work and component design which helped to avoid such attack is discussed. The records obtained with new measuring equipment and some service results will also be shown.

High-Pressure Electronic Fuel Injection for Small-Displacement Single-Cylinder Diesel Engine

2015 ◽  
Author(s):  
Andrew L. Carpenter ◽  
Robert E. Mayo ◽  
Jerald G. Wagner ◽  
Paul E. Yelvington
Keyword(s):  
High Pressure ◽  
Diesel Engines ◽  
Fuel Injection ◽  
Injection Pressure ◽  
Injection System ◽  
Orifice Diameter ◽  
Small Displacement ◽  
Fuel System ◽  
Single Cylinder ◽  
Injection Parameters

Small-displacement, single-cylinder, diesel engines employ mechanically actuated fuel injection systems. These mechanically governed systems, while robust and low-cost, lack the ability to fully vary injection parameters, such as timing, pulse duration, and injection pressure. The ability of a particular injection system to vary these injection parameters impacts engine efficiency, power, noise, and emissions. Modern, multi-cylinder automotive engines employ some form of electronically controlled injection to take advantage of the benefits of fully variable injection, including advanced strategies such as multi-pulse injections and rate shaping. Modern diesel electronic fuel injection systems also operate at considerably higher injection pressures than mechanical fuel systems used in small-bore industrial engines. As the cost of electronic fuel systems continues to decrease and the demand for high-efficiency engines increases, electronic fuel injection becomes a more viable option for incorporation into small industrial diesel engines. In particular, this technology may be well-suited for demanding and critical applications such as military power generation. In this study, a small-bore, single-cylinder diesel was retrofit with a custom, four-hole, high-pressure electronic fuel system. Compared to the mechanical injector, the electronic, common-rail injector had a 50% smaller orifice diameter and was designed for a 4x higher injection pressure. The mechanical governor was also replaced with an electronic speed controller. The baseline and modified engines were installed on a dynamometer, and measurements of exhaust emissions, fuel consumption, brake torque, and in-cylinder pressure were made. The electronic injector led to lower smoke opacity and NOx emissions, while CO and hydrocarbon emissions were observed to increase slightly, likely due to some wall wetting of fuel with the initial prototype injector. Testing with low ignition quality fuels was also performed, and the electronic fuel system enabled the engine to operate with fuel having a cetane number as low as 30.

High-Pressure Electronic Fuel Injection for Small-Displacement Single-Cylinder Diesel Engines

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Andrew L. Carpenter ◽  
Robert E. Mayo ◽  
Jerald G. Wagner ◽  
Paul E. Yelvington
Keyword(s):  
High Pressure ◽  
Diesel Engines ◽  
Fuel Injection ◽  
Cetane Number ◽  
Injection Pressure ◽  
Injection System ◽  
Orifice Diameter ◽  
Small Displacement ◽  
Single Cylinder ◽  
Injection Parameters

Small-displacement single-cylinder diesel engines employ mechanically actuated fuel injection systems. These mechanically governed systems, while robust and low cost, lack the ability to fully vary injection parameters, such as timing, pulse duration, and injection pressure. The ability of a particular injection system to vary these injection parameters impacts engine efficiency, power, noise, and emissions. Modern, multicylinder automotive engines employ some form of electronically controlled injection to take advantage of the benefits of fully variable injection, including advanced strategies such as multipulse injections and rate shaping. Modern diesel electronic fuel injection (EFI) systems also operate at considerably higher injection pressures than mechanical fuel systems used in small-bore industrial engines. As the cost of electronic fuel systems continues to decrease and the demand for high-efficiency engines increases, EFI becomes a more viable option for incorporation into small industrial diesel engines. In particular, this technology may be well-suited for demanding and critical applications, such as military power generation. In this study, a small-bore single-cylinder diesel was retrofit with a custom high-pressure EFI system. Compared to the mechanical injector, the electronic, common-rail injector had a 50% smaller orifice diameter and was designed for a fourfold higher injection pressure. The mechanical governor was also replaced with an electronic speed controller. The baseline and modified engines were installed on a dynamometer, and measurements of exhaust emissions, fuel consumption, brake torque, and in-cylinder pressure were made. The electronic injector leads to lower smoke opacity and NOx emissions, while CO and hydrocarbon emissions were observed to increase slightly, likely due to some wall wetting of fuel with the initial prototype injector. Testing with low ignition quality fuels was also performed, and the electronic fuel system enabled the engine to operate with fuel having a cetane number as low as 30.

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