Performance Optimization of Diesel Engines with Variable Intake Valve Timing Via Genetic Algorithms

2005 ◽  
Author(s):  
Achuth Munnannur ◽  
Song-Charng Kong ◽  
Rolf D. Reitz
Keyword(s):  
Genetic Algorithms ◽  
Diesel Engines ◽  
Performance Optimization ◽  
Intake Valve ◽  
Valve Timing

Engine In-Cylinder Flow Control via Variable Intake Valve Timing

2013 ◽  
Author(s):  
Isabella Bücker ◽  
Daniel-Christian Karhoff ◽  
Michael Klaas ◽  
Wolfgang Schröder
Keyword(s):  
Flow Control ◽  
Intake Valve ◽  
Valve Timing ◽  
Cylinder Flow

Variable Intake Valve Train to Optimize the Performance of a Large Bore Gas Engine

2016 ◽  
Author(s):  
Jan Zelenka ◽  
Claudio Hoff ◽  
Andreas Wimmer ◽  
Roland Berger ◽  
Josef Thalhauser
Keyword(s):  
Valve Train ◽  
Experimental Investigations ◽  
Intake Valve ◽  
Valve Timing ◽  
Current Standard ◽  
Gas Engine ◽  
Engine Efficiency ◽  
Variable Valve Train ◽  
Operating Strategies ◽  
Variable Valve

The present paper describes the investigations made using the electro-hydraulic intake valve timing system VCM® on a large bore gas engine. The first section explains what challenges have to be faced when developing concepts for present and future applications of large bore gas engines. Following an introduction to the VCM® system, an outline is presented of expected opportunities for using variable intake valve timing in combination with modern turbocharging concepts. The second section describes 0D/1D engine cycle simulations that were carried out to assess the influence of variable valve timing on the intake side compared to a fixed intake valve profile, which is the current standard for large bore gas engines. As a result, first predictions can be made about the gain in engine efficiency achieved with different operating strategies. In order to assess the performance potentials of the variable valve train, extensive experimental investigations were carried out on a single cylinder research engine based on GE’s Type 6 gas engine. The investigations consisted of varying engine parameters including varying the geometric compression ratio as well as the engine boundary conditions. It will be shown how intake valve timing can be used to optimize engine efficiency by improving gas exchange. Furthermore, variable intake valve timing affects the overall system behavior, e.g. distances to the engine’s operating limits. Special attention was paid to analyzing combustion itself, which is necessary due to the strong influence that intake valve timing has on the thermodynamic states of the cylinder charge.

Modeling the Effects of Variable Intake Valve Timing on Diesel HCCI Combustion at Varying Load, Speed, and Boost Pressures

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
C. L. Genzale ◽  
S.-C. Kong ◽  
R. D. Reitz
Keyword(s):  
Operating Conditions ◽  
Effective Control ◽  
Intake Valve ◽  
Valve Timing ◽  
Detailed Chemical Kinetics ◽  
Hcci Combustion ◽  
Wide Range ◽  
Particulate Matter Emissions ◽  
Charge Mixture ◽  
Ignition And Combustion

Homogeneous charge compression ignition (HCCI) operated engines have the potential to provide the efficiency of a typical diesel engine, with very low NOx and particulate matter emissions. However, one of the main challenges with this type of operation in diesel engines is that it can be difficult to control the combustion phasing, especially at high loads. In diesel HCCI engines, the premixed fuel-air charge tends to ignite well before top dead center, especially as load is increased, and a method of delaying the ignition is necessary. The development of variable valve timing (VVT) technology may offer an important advantage in the ability to control diesel HCCI combustion. VVT technology can allow for late intake valve closure (IVC) times, effectively changing the compression ratio of the engine. This can decrease compression temperatures and delay ignition, thus allowing the possibility to employ HCCI operation at higher loads. Furthermore, fully flexible valve trains may offer the potential for dynamic combustion phasing control over a wide range of operating conditions. A multidimensional computational fluid dynamics model is used to evaluate combustion event phasing as both IVC times and operating conditions are varied. The use of detailed chemical kinetics, based on a reduced n-heptane mechanism, provides ignition and combustion predictions and includes low-temperature chemistry. The use of IVC delay is demonstrated to offer effective control of diesel HCCI combustion phasing over varying loads, engine speeds, and boost pressures. Additionally, as fueling levels are increased, charge mixture properties are observed to have a significant effect on combustion phasing. While increased fueling rates are generally seen to advance combustion phasing, the reduction of specific heat ratio in higher equivalence ratio mixtures can also cause noticeably slower temperature rise rates, affecting ignition timing and combustion phasing. Variable intake valve timing may offer a promising and flexible control mechanism for the phasing of diesel HCCI combustion. Over a large range of boost pressures, loads, and engine speeds, the use of delayed IVC is shown to sufficiently delay combustion in order to obtain optimal combustion phasing and increased work output, thus pointing towards the possibility of expanding the current HCCI operating range into higher load points.

Set-Point Adaptation Strategy of Air Systems of Light-Duty Diesel Engines for NOx Emission Reduction Under Acceleration Conditions

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Kyunghan Min ◽  
Haksu Kim ◽  
Manbae Han ◽  
Myoungho Sunwoo
Keyword(s):  
Diesel Engines ◽  
Performance Optimization ◽  
Control Structure ◽  
Engine Performance ◽  
Optimization Method ◽  
Driving Cycle ◽  
Operating Conditions ◽  
Nox Emission ◽  
Exhaust Gas ◽  
Set Point

Modern diesel engines equip the exhaust gas recirculation (EGR) system because it can suppress NOx emissions effectively. However, since a large amount of exhaust gas might cause the degradation of drivability, the control strategy of EGR system is crucial. The conventional control structure of the EGR system uses the mass air flow (MAF) as a control indicator, and its set-point is determined from the well-calibrated look-up table (LUT). However, this control structure cannot guarantee the optimal engine performance during acceleration operating conditions because the MAF set-point is calibrated at steady operating conditions. In order to optimize the engine performance with regard to NOx emission and drivability, an optimization algorithm in a function of the intake oxygen fraction (IOF) is proposed because the IOF directly affects the combustion and engine emissions. Using the NOx and drivability models, the cost function for the performance optimization is designed and the optimal value of the IOF is determined. Then, the MAF set-point is adjusted to trace the optimal IOF under engine acceleration conditions. The proposed algorithm is validated through scheduled engine speeds and loads to simulate the extra-urban driving cycle of the European driving cycle. As validation results, the MAF is controlled to trace the optimal IOF from the optimization method. Consequently, the NOx emission is substantially reduced during acceleration operating conditions without the degradation of drivability.

Control-Oriented Gas Exchange Model for Diesel Engines Utilizing Variable Intake Valve Actuation

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Lyle Kocher ◽  
Ed Koeberlein ◽  
Karla Stricker ◽  
D. G. Van Alstine ◽  
Greg Shaver
Keyword(s):  
Gas Exchange ◽  
Diesel Engines ◽  
Exchange Process ◽  
Exhaust Gas ◽  
Intake Valve ◽  
Physically Based ◽  
Valve Position ◽  
Gas Exchange Process ◽  
And Control ◽  
Valve Actuation

Modeling and control of the gas exchange process in modern diesel engines is critical for the promotion and control of advanced combustion strategies. However, most modeling efforts to date use complex stand-alone simulation packages that are not easily integrated into, or amenable for the synthesis of, engine control systems. Simpler control-oriented models have been developed; however, in many cases, they do not directly capture the complete dynamic interaction of air handling system components and flows in multicylinder diesel engines with variable geometry turbocharging (VGT), high pressure exhaust gas recirculation (EGR), and flexible intake valve actuation. Flexibility in the valvetrain directly impacts the gas exchange process not only through the effect on volumetric efficiency but also through the combustion process and resulting exhaust gas enthalpy utilized to drive the turbomachinery. This paper describes a low-order, five state model of the air handling system for a multicylinder variable geometry turbocharged diesel engine with cooled EGR and flexible intake valve actuation, validated against 286 steady state and 62 transient engine operating points. The model utilizes engine speed, engine fueling, EGR valve position, VGT nozzle position, and intake valve closing (IVC) time as inputs to the model. The model outputs include calculation of the engine flows as well as the exhaust temperature exiting the cylinders. The gas exchange model captures the dynamic effects of the not only the standard air handling actuators (EGR valve position and VGT position) but also IVC timing, exercised over their useful operating ranges. The model's capabilities are enabled through the use of analytical functions to describe the performance of the turbocharger, eliminating the need to use look-up maps; a physically based control-oriented exhaust gas enthalpy submodel and a physically based volumetric efficiency submodel.

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