scholarly journals The Influence of Cycle-to-Cycle Hydrocarbon Emissions On Cyclic NO:NO2 Ratio from a HSDI Diesel Engine

2021 ◽  
Author(s):  
Felix Leach ◽  
Varun Shankar ◽  
Martin Davy ◽  
Mark Peckham
Keyword(s):  
Diesel Engine ◽  
Fast Response ◽  
Hydrocarbon Emissions ◽  
Unburned Hydrocarbon ◽  
Crank Angle ◽  
Order Of Magnitude ◽  
Previous State ◽  
Test Points ◽  
Hsdi Diesel Engine ◽  
Aftertreatment Systems

Abstract Knowledge of the NO:NO2 ratio emitted from a diesel engine is particularly important for ensuring the highest performance of SCR NOx aftertreatment systems. As real driving emissions from vehicles increase in importance, the need to understand the NO:NO2 ratio emitted from a diesel engine during transient operation similarly increases. In this study, crank-angle resolved NO and NO2 measurements using fast response CLD (for NO) and a new fast LIF instrument (for NO2) have been taken from a single cylinder diesel engine at three different speed and load points including a point with and without EGR. In addition, crank-angle resolved unburned hydrocarbon (UHC) measurements have been taken simultaneously using a fast FID. A variation of the NO:NO2 ratio through the engine's exhaust stroke is also observed indicative of in-cylinder stratification of NO and NO2. A new link between the NO:NO2 ratio and the UHC emissions from an individual engine cycle is observed - the results show that where there are higher levels of UHC emissions in the first part of the exhaust stroke (blowdown), the proportion of NO2 emitted from that cycle is increased. This effect is observed and analysed across all test points and with and without EGR. The performance of the new fast LIF analyser has also been evaluated, in comparison with the previous state-of-the-art and standard "slow" emissions measurement apparatus showing a reduction in the noise of the measurement by an order of magnitude.

scholarly journals The Influence of Cycle-to-Cycle Hydrocarbon Emissions on Cyclic NO:NO2 Ratio From a HSDI Diesel Engine

2020 ◽  
Author(s):  
Felix Leach ◽  
Varun Shankar ◽  
Martin Davy ◽  
Mark Peckham
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Correlation Coefficients ◽  
Fast Response ◽  
Peak Cylinder Pressure ◽  
Crank Angle ◽  
Order Of Magnitude ◽  
Test Points ◽  
Hsdi Diesel Engine ◽  
Engine Cycle

Abstract Knowledge of the NO:NO2 ratio emitted from a diesel engine is particularly important for ensuring the highest performance of SCR NOx aftertreatment systems. As real driving emissions from vehicles increase in importance, the need to understand the NO:NO2 ratio emitted from a diesel engine during transient operation similarly increases. Previous work by the authors identified significant differences in NO:NO2 ratio throughout the exhaust period of a single engine cycle, with proportionally more NO2 being emitted during the blowdown period compared to the rest of the exhaust stroke. At the time it was not known what caused this effect. In this study, crank-angle resolved NO and NO2 measurements using fast response CLD (for NO) and a new fast LIF instrument (for NO2) have been taken from a single cylinder high-speed light duty diesel engine at three different speed and load points including a point with and without EGR. In addition, crank-angle resolved unburned hydrocarbon (UHC) measurements have been taken simultaneously using a fast FID. The NOx emitted per cycle and the peak cylinder pressure of that cycle have showed high correlation coefficients (R2 < 0.97 at all test points) in this work. In addition, a variation of the NO:NO2 ratio through the engine’s exhaust stroke is also observed indicative of in-cylinder stratification of NO and NO2. A new link between the NO:NO2 ratio and the UHC emissions from an individual engine cycle is observed — the results show that where there are higher levels of UHC emissions in the first part of the exhaust stroke (blowdown), perhaps caused by injector dribble or release from crevices, the proportion of NO2 emitted from that cycle is increased. This effect is observed and analysed across all test points and with and without EGR. The performance of the new fast LIF analyser has also been evaluated, in comparison with the previous state-of-the-art and standard “slow” emissions measurement apparatus showing a reduction in the noise of the measurement by an order of magnitude.

Cycle-to-Cycle NO and NOx Emissions From a HSDI Diesel Engine

2018 ◽  
Author(s):  
Felix Leach ◽  
Martin Davy ◽  
Mark Peckham
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Nox Emissions ◽  
Nox Formation ◽  
Reduction Techniques ◽  
Light Duty ◽  
Peak Cylinder Pressure ◽  
Crank Angle ◽  
The Difference ◽  
Hsdi Diesel Engine

Engine-out NOx emissions from diesel engines continue to be a major topic of research interest. While substantial understanding has been obtained of engine-out (i.e. before any aftertreatment) NOx formation and reduction techniques, not least EGR which is now well established and fitted to production vehicles, much less data are available on cycle resolved NOx emissions. In this work, crank-angle resolved NO and NOx measurements have been taken from a high-speed light duty diesel engine at test conditions both with and without EGR. These have been combined with 1D data of exhaust flow and this used to form a mass average of NO and NOx emissions per cycle. These results have been compared with combustion data and other emissions. The results show that there is a very strong correlation (R2 > 0.95) between the NOx emitted per cycle and the peak cylinder pressure of that cycle. In addition, the crank-angle resolved NO and NOx measurements also reveal that there is a difference in NO : NO2 ratio (where NO2 is assumed to be the difference between NO and NOx) during the exhaust period, with proportionally more NO2 being emitted during the blowdown period compared to the rest of the exhaust stroke.

Cycle-to-Cycle NO and NOx Emissions From a HSDI Diesel Engine

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Felix Leach ◽  
Martin Davy ◽  
Mark Peckham
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Nox Emissions ◽  
Nox Formation ◽  
Reduction Techniques ◽  
Peak Cylinder Pressure ◽  
Crank Angle ◽  
The Difference ◽  
Hsdi Diesel Engine ◽  
Gas Recirculation

Engine-out NOx emissions from diesel engines continue to be a major topic of research interest. While substantial understanding has been obtained of engine-out (i.e., before any aftertreatment) NOx formation and reduction techniques, not least exhaust gas recirculation (EGR) which is now well established and fitted to production vehicles, much less data are available on cycle resolved NOx emissions. In this work, crank-angle resolved NO and NOx measurements have been taken from a high-speed light duty diesel engine at test conditions both with and without EGR. These have been combined with 1D data of exhaust flow, and this used to form a mass average of NO and NOx emissions per cycle. These results have been compared with combustion data and other emissions. The results show that there is a very strong correlation (R2 > 0.95) between the NOx emitted per cycle and the peak cylinder pressure of that cycle. In addition, the crank-angle resolved NO and NOx measurements also reveal that there is a difference in NO : NO2 ratio (where NO2 is assumed to be the difference between NO and NOx) during the exhaust period, with proportionally more NO2 being emitted during the blowdown period compared to the rest of the exhaust stroke.

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.

High-output diesel engine heat transfer: Part 1 - comparison between piston heat flux and global energy balance

2021 ◽  
pp. 146808742110170
Author(s):  
Eric Gingrich ◽  
Michael Tess ◽  
Vamshi Korivi ◽  
Jaal Ghandhi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Diesel Engine ◽  
Surface Temperature ◽  
Fast Response ◽  
Temperature Data ◽  
Start Of Injection ◽  
Local Measurements ◽  
Surface Temperature Data ◽  
High Output

High-output diesel engine heat transfer measurements are presented in this paper, which is the first of a two-part series of papers. Local piston heat transfer, based on fast-response piston surface temperature data, is compared to global engine heat transfer based on thermodynamic data. A single-cylinder research engine was operated at multiple conditions, including very high-output cases – 30 bar IMEPg and 250 bar in-cylinder pressure. A wireless telemetry system was used to acquire fast-response piston surface temperature data, from which heat flux was calculated. An interpolation and averaging procedure was developed and a method to recover the steady-state portion of the heat flux based on the in-cylinder thermodynamic state was applied. The local measurements were spatially integrated to find total heat transfer, which was found to agree well with the global thermodynamic measurements. A delayed onset of the rise of spatially averaged heat flux was observed for later start of injection timings. The dataset is internally consistent, for example, the local measurements match the global values, which makes it well suited for heat transfer correlation development; this development is pursued in the second part of this paper.

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