Flatness-Based Control of Mode Transitions Between Conventional and Premixed Charge Compression Ignition on a Modern Diesel Engine With Variable Valve Actuation

2013 ◽  
Author(s):  
Carrie M. Hall ◽  
Dan Van Alstine ◽  
Gregory M. Shaver
Keyword(s):  
Diesel Engine ◽  
Gas Exchange ◽  
Diesel Combustion ◽  
Compression Ignition ◽  
Combustion Mode ◽  
Variable Valve Actuation ◽  
Advanced Combustion ◽  
Combustion Modes ◽  
Mode Transitions ◽  
Variable Valve

Energy needs in the transportation sector and strict emissions regulations have caused a growing focus on increasing engine efficiency while simultaneously minimizing engine out emissions. One method for accomplishing this is to leverage advanced combustion strategies which are efficient yet very clean. One such combustion mode is premixed charge compression ignition (PCCI). PCCI can lead to drastically lower emissions than conventional diesel combustion while still maintaining engine efficiencies; however, the engine operation region over which it can be utilized is limited. In order to take advantage of this advanced combustion mode, engines must be designed to move between conventional diesel combustion and PCCI. To achieve transitions between different combustion modes, a control strategy was developed which utilizes a extensively validated gas exchange model and flatness-based methods for trajectory planning and trajectory tracking to enable smooth transitions between different combustion modes on a modern diesel engine with variable valve actuation. Since the engine considered here has the ability to alter valve timings, the control method exploits both capabilities to control the gas exchange process as well as the effective compression ratio of the engine. Simulation results indicate that this flatness-based approach is effective in enabling mode transitions.

Performance and emission characteristics of conventional diesel combustion/partially premixed charge compression ignition combustion mode switching of biodiesel-fueled engine

2019 ◽  
pp. 146808741986031
Author(s):  
Akhilendra Pratap Singh ◽  
Avinash Kumar Agarwal
Keyword(s):  
Aromatic Compounds ◽  
Electronic Control Unit ◽  
Mode Switching ◽  
Particulate Emissions ◽  
Exhaust Gas ◽  
Diesel Combustion ◽  
Compression Ignition ◽  
Combustion Mode ◽  
Performance And Emission ◽  
Combustion Modes

In this experimental study, a production grade engine was modified to operate in two combustion modes, namely conventional diesel combustion (CDC) and premixed charge compression ignition (PCCI) combustion, depending on the engine load. For mode switching, an open electronic control unit was programmed to operate the engine in PCCI combustion mode up to medium engine loads and then automatically switching it to CDC mode at higher engine loads, by varying the fuel injection parameters and the exhaust gas recirculation rate. For performance and emission characterization in the entire load range (idling-to-full load) of the test engine, a test cycle of 300 s was used, which included CDC mode, PCCI combustion mode, and transition between these two modes. Results showed that both mineral diesel and B20 (20% biodiesel blended with mineral diesel, v/v) fueled PCCI combustion resulted in significantly lower NOx and particulate emissions compared to baseline CDC. Relatively lower exhaust gas temperature in PCCI combustion mode led to slightly inferior engine performance and higher concentration of unregulated emission species such as SO2, HCHO, and so on. B20-fueled engine resulted in relatively lower unregulated emission species and particulates compared to the mineral diesel–fueled engine in both the combustion modes. In CDC mode, contributions of accumulation mode particles were significantly higher compared to nucleation mode particles. Relatively lower emission of aromatic compounds in PCCI combustion mode compared to CDC mode was another important finding of this study; however, B20-fueled engines resulted in slightly higher emissions of aromatic compounds.

TWC-SCR Aftertreatment System Evaluation for a Lean Burn Gasoline Engine Operating in HCCI, SACI, and SI Combustion Modes

2016 ◽  
Author(s):  
Jordan Easter ◽  
Stanislav V. Bohac
Keyword(s):  
Conversion Efficiency ◽  
Gasoline Engine ◽  
Fuel Efficiency ◽  
Compression Ignition ◽  
Scr Catalyst ◽  
Advanced Combustion ◽  
Nox Conversion ◽  
Combustion Modes ◽  
Scr System ◽  
Nox Conversion Efficiency

Low temperature and dilute Homogenous Charge Compression Ignition (HCCI) and Spark Assisted Compression Ignition (SACI) can improve fuel economy and reduce engine-out NOx emissions to very low values, often less than 30 ppm. However, these combustion modes are unable to achieve stringent future regulations such as SULEV 30 without the use of lean aftertreatment. Though active selective catalytic reduction (SCR) with urea injection and lean NOx traps (LNT) have been investigated as options for lean gasoline engines, a passive TWC-SCR system is investigated in this work because it avoids the urea storage and dosing hardware of a urea SCR system, and the high precious metal cost of an LNT. The TWC-SCR concept uses periodic rich operation to produce NH3 over a TWC to be stored on an SCR catalyst for subsequent NOx conversion during lean operation. In this work a laboratory study was performed with a modified 2.0 L gasoline engine that was cycled between lean HCCI and rich SACI operation, or between lean and rich SI (spark ignited) combustion, to evaluate NOx conversion and reduced fuel consumption. Different lambda values during rich operation and different times held in rich operation were investigated. Results are compared to a baseline case in which the engine is always operated at stoichiometric conditions. SCR system simulations are also presented that compare system performance for different levels of stored NH3. With the configuration used in this study, lean/rich HCCI/SACI operation showed a maximum NOx conversion efficiency of 10%, while lean/rich SI operation showed a maximum NOx conversion efficiency of 60%. However, if the low conversion efficiency of lean/rich HCCI/SACI operation could be improved through higher brick temperatures or additional SCR bricks, simulation results indicate TWC-SCR aftertreatment has the potential to provide near-zero SCR-out NOx concentration and increased system fuel efficiency. In these simulations, fuel efficiency improvement relative to stoichiometric SI were 7 to15% for lean/rich HCCI/SACI with zero tailpipe NOx and −1 to 5% for lean/rich SI with zero tailpipe NOx emissions. Although previous work indicated increased time for NH3 to start forming over the TWC during rich operation, less NH3 production over the TWC per fuel amount, and increased NH3 slip over the SCR catalyst for advanced combustion systems, if NOx conversion efficiency could be enhanced, improvements in fuel economy and low engine-out NOx from advanced combustion modes would more than make up for these disadvantages.

Modeling the Gas Exchange Processes of a Modern Diesel Engine With an Integrated Physics-Based and Data-Driven Approach

2019 ◽  
Author(s):  
Jorge Pulpeiro Gonzalez ◽  
King Ankobea-Ansah ◽  
Elena Escuder Milian ◽  
Carrie M. Hall
Keyword(s):  
Diesel Engine ◽  
Gas Exchange ◽  
High Efficiency ◽  
Direct Injection ◽  
Data Driven ◽  
Model Framework ◽  
Variable Valve Actuation ◽  
Exchange Processes ◽  
Data Driven Approach ◽  
Using Data

Abstract The gas exchange processes of engines are becoming increasingly complex since modern engines leverage technologies including variable valve actuation, turbochargers, and exhaust gas recirculation. Control of these many devices and the underlying gas flows is essential for high efficiency engine concepts. If these processes are to be controlled and estimated using model-based techniques, accurate models are required. This work explores a model framework that leverages a data-driven model of the turbocharger along with submodels of the intercooler, intake and exhaust manifolds and engine processes to provide cylinder-specific predictions of the pressure and temperatures of the gases across the system. This model is developed and validated using data from a 2.0 liter VW turbocharged, direct-injection diesel engine and shown to provide accurate prediction of critical gas properties.

A Study of the Transition Between Lean Conventional Diesel Combustion and Lean, Premixed, Low-Temperature Diesel Combustion

2007 ◽  
Author(s):  
Stephen Busch ◽  
Stanislav V. Bohac ◽  
Dennis N. Assanis
Keyword(s):  
Diesel Engine ◽  
Low Temperature ◽  
Flow Model ◽  
Transient Behavior ◽  
Diesel Combustion ◽  
Combustion Modes ◽  
Lean Premixed ◽  
Release Analysis ◽  
Separation Behavior ◽  
No Emissions

New diesel combustion modes face difficult challenges with respect to engine-out emissions and transient behavior. Transitions between lean conventional diesel combustion and lean, premixed, low-temperature diesel combustion are investigated with an automotive diesel engine. Effects of fuel pressure on transitional cycles are investigated. Cycle-by-cycle heat release analysis is performed and an exhaust mass flow model is used to obtain cycle-averaged NO concentrations. The behavior of combustion progression and NO emissions during the transitions are discussed. Observed cool-flame separation behavior is identified and explained.

Modeling advanced combustion modes in compression ignition engines with tabulated kinetics

2019 ◽  
Vol 247 ◽  
pp. 537-548 ◽  
Author(s):  
T. Lucchini ◽  
A. Della Torre ◽  
G. D’Errico ◽  
A. Onorati
Keyword(s):  
Compression Ignition ◽  
Compression Ignition Engines ◽  
Advanced Combustion ◽  
Combustion Modes
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