Oxygen Concentration Dynamic Model and Observer-Based Estimation Through a Diesel Engine Aftertreatment System

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Pingen Chen ◽  
Junmin Wang
Keyword(s):  
Diesel Engine ◽  
Dynamic Model ◽  
Oxygen Concentration ◽  
Catalytic Reduction ◽  
Optimization Method ◽  
Experimental Results ◽  
System Control ◽  
Exhaust Gas ◽  
Aftertreatment Systems ◽  
Oxygen Concentrations

Due to the chemical reactions occurring inside the diesel oxidation catalysts (DOCs) and diesel particulate filters (DPFs) that are commonly equipped on diesel engines, the exhaust gas oxygen concentrations considerably vary through the aftertreatment systems. Oxygen concentration in exhaust gas is important for the performance of catalysts such as the NOx conversion efficiencies of the selective catalytic reduction systems and lean NOx traps. Moreover, in the presence of a low-pressure loop exhaust gas recirculation, the exhaust gas oxygen concentration after DPF also influences the in-cylinder combustion. From system control, estimation, and analysis viewpoints, it is thus imperative to have a control-oriented model to describe the oxygen concentration dynamics across the DOC and DPF. In this paper, a physics-based, lumped-parameter, control-oriented DOC–DPF oxygen concentration dynamic model was developed with a multi-objective optimization method and validated with the experimental data obtained on a medium-duty diesel engine equipped with a full suite of aftertreatment systems. Experimental results show that the model can well capture the oxygen dynamics across the diesel engine aftertreatment systems. As an application of the experimentally validated model, an observer was designed to estimate the DOC-out and DPF-out oxygen concentrations in real time. Experimental results show that the estimated states from the proposed observer can converge to the measured signals fastly and accurately.

Oxygen Concentration Dynamic Model Through a Diesel Engine Aftertreatment System

2011 ◽  
Author(s):  
Pingen Chen ◽  
Junmin Wang
Keyword(s):  
Diesel Engine ◽  
Dynamic Model ◽  
Oxygen Concentration ◽  
Diesel Oxidation Catalyst ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Exhaust Gas ◽  
Aftertreatment System ◽  
Aftertreatment Systems ◽  
Oxygen Concentrations

This paper presents a control-oriented model describing the dynamics of oxygen concentration through a Diesel engine aftertreatment system that includes a Diesel oxidation catalyst (DOC) and a Diesel particulate filter (DPF). Exhaust gas oxygen concentration is important for catalysts such as NOx conversion efficiencies of selective catalytic reduction (SCR) systems and lean NOx traps (LNT). In the presence of low-pressure loop exhaust gas recirculation (EGR), the exhaust gas oxygen concentration after-DPF also influences combustion. Due to the chemical reactions occurring inside DOC and DPF, the exhaust gas oxygen concentration considerably varies through the aftertreatment systems. Directly measuring the exhaust gas oxygen concentrations at different locations through the exhaust gas aftertreatment system is costly and unreliable. A dynamic model is thus needed in order to design model-based observers to estimate the exhaust gas oxygen concentrations at various locations. The oxygen-related reactions within a DOC and a DPF are investigated in this study. A lumped-parameter, control-oriented DOC-DPF oxygen concentration dynamic model was developed by a multi-objective optimization method and validated with experimental data obtained on a medium-duty Diesel engine equipped with full aftertreatment systems. Experimental results show that the model can well capture the oxygen dynamics across the Diesel engine aftertreatment systems.

NO and NO2 Concentration Modeling and Observer-Based Estimation Across a Diesel Engine Aftertreatment System

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Ming-Feng Hsieh ◽  
Junmin Wang
Keyword(s):  
Diesel Engine ◽  
Catalytic Reduction ◽  
Diesel Oxidation Catalyst ◽  
Equation Model ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Exhaust Gas ◽  
Aftertreatment System ◽  
Stirred Tank Reactors ◽  
Aftertreatment Systems

This paper presents an experimentally validated control-oriented model and an observer for diesel oxidation catalyst (DOC)-diesel particulate filter (DPF) system in the context of exhaust gas NO and NO2 concentration estimations. NO and NO2 have different reaction characteristics within DPF and selective catalytic reduction (SCR) systems, two most promising diesel engine aftertreatment systems. Although the majority of diesel engine-out NOx emissions is NO, the commonly used DOC located upstream of a DPF and a SCR can convert a considerable amount of NO to NO2. Knowledge of the NO/NO2 ratio in exhaust gas is thus meaningful for the control and diagnosis of DPF and SCR systems. Existing onboard NOx sensors cannot differentiate NO and NO2, and such a sensory deficiency makes separate considerations of NO and NO2 in SCR control design challenging. To tackle this problem, a control-oriented dynamic model, which can capture the main NO and NO2 dynamics from engine-out, through DOC, and to DPF, was developed. Due to the computational limitation concerns, DOC and DPF are assumed to be standard continuously stirred tank reactors in order to obtain a 0D ordinary differential equation model. Based on the model, an observer, with the measurement from a commercially available NOx sensor, was designed to estimate the NO and NO2 concentrations in the exhaust gas along the aftertreatment systems. The stability of the observer was shown through a Lyapunov analysis assisted by insight into the system characteristics. The control-oriented model and the observer were validated with engine experimental data and the measured NO/NO2 concentrations by a Horiba gas analyzer. Experimental results show that the model can accurately predict the main engine-out/DOC/DPF NO/NO2 dynamics very well in semisteady-state tests. For the proposed observer, the predictions converge to the model values and estimate the NO and NO2 concentrations in the aftertreatment system well.

Comparative analysis on the effects of diesel particulate filter and selective catalytic reduction systems on a wide spectrum of chemical species emissions

2018 ◽  
Author(s):  
Z. Gerald Liu ◽  
Devin R. Berg ◽  
Thaddeus A. Swor ◽  
James J. Schauer‡
Keyword(s):  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Diesel Particulate Filter ◽  
Catalytic Reduction ◽  
Wide Spectrum ◽  
Chemical Species ◽  
Pollutant Emissions ◽  
Particulate Filter ◽  
Diesel Particulate ◽  
Aftertreatment Systems

Two methods, diesel particulate filter (DPF) and selective catalytic reduction (SCR) systems, for controlling diesel emissions have become widely used, either independently or together, for meeting increasingly stringent emissions regulations world-wide. Each of these systems is designed for the reduction of primary pollutant emissions including particulate matter (PM) for the DPF and nitrogen oxides (NOx) for the SCR. However, there have been growing concerns regarding the secondary reactions that these aftertreatment systems may promote involving unregulated species emissions. This study was performed to gain an understanding of the effects that these aftertreatment systems may have on the emission levels of a wide spectrum of chemical species found in diesel engine exhaust. Samples were extracted using a source dilution sampling system designed to collect exhaust samples representative of real-world emissions. Testing was conducted on a heavy-duty diesel engine with no aftertreatment devices to establish a baseline measurement and also on the same engine equipped first with a DPF system and then a SCR system. Each of the samples was analyzed for a wide variety of chemical species, including elemental and organic carbon, metals, ions, n-alkanes, aldehydes, and polycyclic aromatic hydrocarbons, in addition to the primary pollutants, due to the potential risks they pose to the environment and public health. The results show that the DPF and SCR systems were capable of substantially reducing PM and NOx emissions, respectively. Further, each of the systems significantly reduced the emission levels of the unregulated chemical species, while the notable formation of new chemical species was not observed. It is expected that a combination of the two systems in some future engine applications would reduce both primary and secondary emissions significantly.

Effect of Fuel Injection Strategy on DPF Regeneration in Single Cylinder Diesel Engine

2015 ◽  
Author(s):  
Sungjun Yoon ◽  
Hongsuk Kim ◽  
Daesik Kim ◽  
Sungwook Park
Keyword(s):  
Diesel Engine ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Experimental Results ◽  
Exhaust Gas ◽  
Post Injection ◽  
Gas Temperature ◽  
Injection Strategy ◽  
Dpf Regeneration ◽  
Exhaust Gas Temperature

Stringent emission regulations (e.g., Euro-6) force automotive manufacturers to equip DPF (diesel particulate filter) on diesel cars. Generally, post injection is used as a method to regenerate DPF. However, it is known that post injection deteriorates specific fuel consumption and causes oil dilution for some operating conditions. Thus, an injection strategy for regeneration becomes one of key technologies for diesel powertrain equipped with a DPF. This paper presents correlations between fuel injection strategy and exhaust gas temperature for DPF regeneration. Experimental apparatus consists of a single cylinder diesel engine, a DC dynamometer, an emission test bench, and an engine control system. In the present study, post injection timing covers from 40 deg aTDC to 110 deg aTDC and double post injection was considered. In addition, effects of injection pressures were investigated. The engine load was varied from low-load to mid-load and fuel amount of post injection was increased up to 10mg/stk. Oil dilution during fuel injection and combustion processes were estimated by diesel loss measured by comparing two global equivalences ratios; one is measured from Lambda sensor installed at exhaust port, the other one is estimated from intake air mass and injected fuel mass. In the present study, the differences in global equivalence ratios were mainly caused from oil dilution during post injection. The experimental results of the present study suggest an optimal engine operating conditions including fuel injection strategy to get appropriate exhaust gas temperature for DPF regeneration. Experimental results of exhaust gas temperature distributions for various engine operating conditions were summarized. In addition, it was revealed that amounts of oil dilution were reduced by splitting post injection (i.e., double post injection). Effects of injection pressure on exhaust gas temperature were dependent on combustion phasing and injection strategies.

Diesel Fuel Multiple Injection Effects on Emission Characteristics of Diesel Engine Mixed Ammonia Gas Into Intake Air

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Yoichi Niki ◽  
Yoshifuru Nitta ◽  
Hidenori Sekiguchi ◽  
Koichi Hirata
Keyword(s):  
Diesel Engine ◽  
Diesel Fuel ◽  
Internal Combustion Engines ◽  
Experimental Results ◽  
Exhaust Emission ◽  
N2o Emissions ◽  
Emission Characteristics ◽  
Exhaust Gas ◽  
N2o Production ◽  
Combustion Processes

This study focuses NH3 as an alternative fuel for internal combustion engines, because NH3 is known as a H2 carrier and its combustion does not produce CO2 causing global warming. On the other hand, some reports show that unburned NH3 and N2O appear in exhaust gas, when NH3 is used as fuel for compression ignition or spark ignition engines. NH3 is toxic and N2O is one of the greenhouse gases. These emissions should not be emitted. These reports point out that exhaust gas after treatments and/or injection strategies can be effective to reduce these emissions. From our previous investigations, it was confirmed that NH3 and N2O were contained in the exhaust gas of a conventional diesel engine with NH3 gas mixed into the engine intake. In this study, NH3 combustion processes in the diesel engine were investigated from the experimental results. Based on the investigations, a pilot or postinjection was conducted to reduce emissions of NH3 and N2O. In this paper, first the experimental results of the combustion and exhaust emission characteristics on the conventional diesel engine with NH3 gas mixed into the engine intake are shown. NH3 and N2O emissions are then verified by analyzing the exhaust gas. Next, NH3 combustion processes in the diesel engine are considered from the experimental results to report on the effects of a pilot and postdiesel fuel injection on NH3 and N2O production processes. The experimental results suggest that the multiple diesel fuel injections would be one of the effective measures to reduce N2O and NH3 emissions on NH3 and diesel dual-fueled engine.

scholarly journals Cyclic NO2:NOx ratio from a diesel engine undergoing transient load steps

2019 ◽  
Vol 22 (1) ◽  
pp. 284-294 ◽  
Author(s):  
FCP Leach ◽  
MH Davy ◽  
MS Peckham
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Formation Mechanisms ◽  
Exhaust Gas ◽  
Work Cycle ◽  
Wide Range ◽  
Gas Recirculation ◽  
Aftertreatment Systems

As the control of real driving emissions continues to increase in importance, the importance of understanding emission formation mechanisms during engine transients similarly increases. Knowledge of the NO2/NOx ratio emitted from a diesel engine is necessary, particularly for ensuring optimum performance of NOx aftertreatment systems. In this work, cycle-to-cycle NO and NOx emissions have been measured using a Cambustion CLD500, and the cyclic NO2/NOx ratio calculated as a high-speed light-duty diesel engine undergoes transient steps in load, while all other engine parameters are held constant across a wide range of operating conditions with and without exhaust gas recirculation. The results show that changes in NO and NOx, and hence NO2/NOx ratio, are instantaneous upon a step change in engine load. NO2/NOx ratios have been observed in line with previously reported results, although at the lightest engine loads and at high levels of exhaust gas recirculation, higher levels of NO2 than have been previously reported in the literature are observed.

Effects of Ammonia Gas Mixed Into Intake Air on Combustion and Emissions Characteristics in Diesel Engine

2016 ◽  
Author(s):  
Yoichi Niki ◽  
Dong-Hoon Yoo ◽  
Koichi Hirata ◽  
Hidenori Sekiguchi
Keyword(s):  
Diesel Engine ◽  
Catalytic Reduction ◽  
Gas Injection ◽  
Experimental Results ◽  
Injection System ◽  
Emission Characteristics ◽  
Diesel Injection ◽  
Injection Quantity ◽  
Carbon Dioxide Co2 ◽  
Scr System

This paper reports on the experimental results of the combustion and emission characteristics of a conventional diesel engine mixed ammonia (NH3) gas into the intake air, and discusses its usability. In the experiments, NH3 gas was injected into the intake pipe of the diesel engine by a gas injector. The diesel engine has a natural aspiration single cylinder with 7.7 kW rated power at 1500 rpm and a diesel injection system to inject diesel fuel into the cylinder. As experimental results on the combustion characteristics, it was confirmed that the compression and maximum pressures in the cylinder decreased and the ignition timing delayed with increasing the NH3 gas injection quantity. On the emission characteristics in the exhaust gas, NH3, water (H2O) and nitrous oxide (N2O) increased and carbon dioxide (CO2) decreased proportionally to the NH3 gas injection quantity. In contract, the nitrogen oxide (NO) was nearly the same. Moreover, it was confirmed that NH3 can be reduced by reacting with NO in a selective catalytic reduction (SCR) system.

scholarly journals The Experimental and Simulation Study of Selective Catalytic Reduction System in a Single Cylinder Diesel Engine Using NH3as a Reducing Agent

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Manoj Kumar Athrashalil Phaily ◽  
Sreekumar Jayachandra Sreekala ◽  
Padmanabha Mohanan
Keyword(s):  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Mass Flow ◽  
Catalytic Reduction ◽  
Pt Catalyst ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Single Cylinder ◽  
Induction Rate ◽  
Exhaust Gas Temperature

Selective catalytic reduction (SCR) technology has been widely used in automotive applications in order to meet the stringent limits on emission standards. The maximum NOxconversion efficiency of an SCR depends on temperature and mass flow rate of an exhaust gas. In order to assess the suitability of Cordierite/Pt catalyst for low temperature application, an experimental work is carried out using single cylinder diesel engine for different load conditions by varying ammonia induction rate from 0.2 kg/hr to 0.8 kg/hr. The simulation is carried out using AVL FIRE for the validation of experimental results. From the study, it has been found that for 0.6 kg/hr ammonia induction rate the maximum conversion is achieved, whereas, for 0.8 kg/hr, conversion is reduced due to desorption of ammonia. Also it has been found that, at 75% of load, for all mass flow rates of ammonia the conversion was drastically reduced due to higher exhaust gas temperature and higher emission of unburnt hydrocarbons. More than 55% of NOxconversion was achieved using Cordierite/Pt catalyst at a temperature of 320°C.

A Physically-Based, Control-Oriented Diesel Particulate Filter (DPF) Model for the Applications of NO/NO2 Ratio Estimation Using a NOx Sensor

2010 ◽  
Author(s):  
Ming-Feng Hsieh ◽  
Junmin Wang
Keyword(s):  
Diesel Particulate Filter ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Diesel Oxidation Catalyst ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Exhaust Gas ◽  
Diesel Particulate ◽  
Physically Based ◽  
Aftertreatment Systems

This paper presents a physically-based, control-oriented Diesel particulate filter (DPF) model for the purposes of NO and NO2 concentration estimations in Diesel engine aftertreatment systems. The presence of NO2 in exhaust gas plays an important role in selective catalytic reduction (SCR) NOx reduction efficiency. However, current NOx cannot differentiate NO and NO2 from the total NOx concentration. A model which can be used to estimate NO and NO2concentrations in exhaust gas flowing into the SCR catalyst is thus necessary. Current aftertreatment systems for light-, medium-, and heavy-duty Diesel engines generally include Diesel oxidation catalyst (DOC), DPF, and SCR. The DPF related NO/NO2 dynamics was investigated in this study, and a control-oriented model was developed and validated with experimental data.

Ammonia Slip Estimation Based on ASC Control-Oriented Modelling And OBD NOx Sensor Cross-Sensitivity Analysis

2021 ◽  
Author(s):  
Pedro Piqueras ◽  
Benjamín Pla ◽  
Enrique José Sanchis ◽  
André Aronis
Keyword(s):  
Internal Combustion Engines ◽  
Catalytic Reduction ◽  
Injection System ◽  
Diagnostic Tools ◽  
Exhaust Gas ◽  
Passenger Cars ◽  
Cross Sensitivity ◽  
Nox Sensor ◽  
Ammonia Slip ◽  
Aftertreatment Systems

Abstract The incoming emission regulations for internal combustion engines are gradually introducing new pollutant species, which requires greater complexity of the exhaust gas aftertreatment systems concerning layout, control and diagnostics. This is the case of ammonia, which is already regulated in heavy-duty vehicles and to be included in the emissions standards applied to passenger cars. The ammonia is injected into the exhaust gas through urea injections for NOx abatement in selective catalytic reduction (SCR) systems and can be also generated in other aftertreatment systems as three-way catalysts. However, ammonia slip may require removal on a dedicated catalyst called ammonia slip catalyst (ASC). The set consisting of the urea injection system, SCR and ASC requires control and on-board diagnostic tools to ensure high NOx conversion efficiency and minimization of the ammonia slip under real driving conditions. These tasks are based on the use of NOx sensors ZrO2 pumping cell-based, which present as a drawback high cross-sensitivity to ammonia. Consequently, the presence of this species can affect the measurement of NOx and compromise SCR-ASC control strategies. In the present work, a methodology to predict ammonia and NOx tailpipe emissions is proposed. For this purpose, a control-oriented ASC model was developed to use its ammonia slip prediction to determine the cross-sensitivity correction of the NOx sensor placed downstream of the ASC. The model is based on a simplified solution of the transport equations of the species involved in the main ASC reactions. The ammonia slip model was calibrated using steady- and quasi-steady-state tests performed in a Euro 6c diesel engine. Finally, the performance of the proposed methodology to predict NOx and ammonia emissions was evaluated against experimental data corresponding to Worldwide harmonized Light vehicles Test Cycles (WLTC) applying different urea dosing strategies.

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