Browse Topic: Nitrogen oxides

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Calculation of Airflow through the Air Cycle Technology’s Turboexpander and Its Effects on a Diesel Engine—Part I2025-01-50233/31/2025
Abstract Amidst escalating climate change, the sustainability of internal combustion engine (ICE) vehicles, particularly in heavy transport, remains a critical challenge. Despite emission reductions from 1990 to 2020, ICEs, particularly diesel engines in Europe, continue to pose environmental challenges, notably in nitrogen oxide (NOx) emissions. This study proposes a novel solution to address the problem of NOx emissions by incorporating Air Cycle Technology’s (ACT) turboexpander into diesel engines. Acting as a second-stage compressor, intercooler, and expander, the turboexpander aims to lower intake air temperature, thereby mitigating NOx formation. The study utilizes a 4.4-l JCB-TCA-74 turbocharged diesel engine retrofitted with the ACT turboexpander as the experimental platform. The methodology involves using empirical formulae to calculate the key parameters of engine airflow for a standard turbocharged diesel engine followed by repeating the calculations for the same engine fitted with a turboexpander. Parameters including intake temperature, cylinder temperature, exhaust gas temperature, and NOx emissions are analyzed in depth and compared for both the engines. Initial calculations suggest that the turboexpander has the potential to reduce intake temperatures by up to 34°C, resulting in significant reductions in NOx emissions. These findings underscore the promising role of turboexpanders in enhancing the sustainability of diesel engines, urging further exploration across various engine types. As emissions standards tighten, the adoption of innovative solutions like turboexpanders could contribute to a cleaner and more sustainable future for the ICE.
Fayaz, Farheen, Brace, Jordan, Allport, John, Javanbakht, Gina
Engine-in-the-Loop Analysis of the Influence of Manual Gearshift Duration on Vehicle Consumption and Emissions15-16-01-00039/27/2022
Abstract The tightening of emission standards and homologation rules lead car manufacturers to rely on simulation testing in early development phases. Coupling an engine to a testbench controlled by a real-time simulation environment allows flexible, reliable, and reproducible testing for consumption and emission studies. However, interest in this method referred to as engine-in-the-loop (EiL) is relatively recent and few details can be found regarding the simulation environment. Following previous work, this study details a driver model based on the PI structure and augmented with preview and anti-windup. The focus is set on a conventional powertrain with a manual transmission for which the driver must also manage the clutch pedal during gearshift and take-off phases. Extended analysis of vehicle tests allows defining the driver’s behavior during these phases for different profiles. The driver model is then tested in the EiL environment and the impact of the gearshift profile on fuel consumption and pollutant emissions can be assessed. Besides the slight increase in fuel consumption, results show that increasing the gearshift duration degrades the regulation of the richness by the ECU, thus increasing CO engine-out emissions as well as decreasing NOx emissions. Finally, results suggest that a longer gearshift also affects the catalyst efficiency, which results in higher NOx tailpipe emissions.
Gilormini, Thomas, Chessé, Pascal, Tauzia, Xavier, Colin, Hervé
First-Principles Research on Adsorption of NOx on Pt Cluster and BaO Cluster Supported by γ-Al 2 O 3 (110) Surface2020-01-03574/14/2020
Lean NOx trap (LNT) is a great potential NOx abatement method for lean-burn gasoline engines in consideration of exhaust aftertreatment cost and installation space. NOx firstly is adsorbed on storage sites during the lean-burn period, then reduced to N2 under catalysis of the catalyst sites in the rich-burn phase. There must be a spillover of NOx species between both types of sites. For a better understanding of this spillover process of NOx species between Pt (as the catalytic center) and BaO sites (as storage components in commercial catalyst), this work focused on the vital first step of spillover, the adsorption of NOx on clean substrate surface (γ-Al2O3 (110) surface) and Ba\Pt cluster supported by the surface. Based on first principles software VASP (Vienna Ab-initio Simulation Package), the most stable adsorption structures of NO with Pt3 clusters and (BaO)3 clusters on carrier γ- Al2O3 (110) surface were confirmed and the adsorption energy of these structures were compared. Meanwhile electronic structure analysis of these adsorption systems was investigated by analyzing DOS (density of state), Bader charge, charge density difference and COHP (crystal orbital Hamilton population). From electronic structure analysis methods mentioned above, a better view of electron transfer and bond formation between gas phase NOx molecules and supported BaO or Pt cluster was obtained. This work has laid a good foundation for the further research of NOx adsorption and reduction of LNT by providing a more microscopic explanation of NOx species spillover mechanism.
Li, Shilong, Zhang, Yanke, zhao, Jin
Characteristics of Transient NOx Emissions of HEV under Real Road Driving2020-01-03804/14/2020
To meet the request of China National 6b emission regulations which will be officially implemented in China, firstly including the RDE emission test limits, the transient emissions on real road condition are paid more attention. A non-plug-in hybrid light-duty gasoline vehicles (HEV) sold in the Chinese market was selected to study real road emissions employed fast response NOx analyzer from Cambustion Ltd. with a sampling frequency of 100Hz, which can measure the missing NO peaks by standard RDE gas analyzer now. Emissions from PEMS were also recorded and compared with the results from fast response NOx analyzer. The concentration of NOx emissions before and after the Three Way Catalyst (TWC) of the hybrid vehicle were also sampled and analyzed, and the working efficiency of the TWC in real road driving process was investigated. It is found that when the engine is at high-speed and heavy-load conditions, especially when fuel is injected after fuel cut, instantaneous spikes in tailpipe NO emissions could be observed, which means that traffic positions such as crosswalks, speed bumps, expressway entrances, traffic lights, would lead to higher NOx emissions, because the instantaneous fuel cut-off occurs during the acceleration shifting process, the TWC is in an oxygen-rich state. Obvious transient effects were revealed and the results could be used for further reducing NOx emissions from automotive RDE and engine calibration of RDE.
Zhang, Yonghao, Deng, Jun, Li, Qiang, Liu, Yintong, He, Bo, Hu, Zongjie, Bo, Shi, Li, Liguang
Numerical Optimization of a SCR System Based on the Injection of Pure Gaseous Ammonia for the NOx Reduction in Light-Duty Diesel Engines2020-01-03564/14/2020
Selective Catalytic Reduction (SCR) systems are nowadays widely applied for the reduction of NOx emitted from Diesel engines. The typical process is based on the injection of aqueous urea in the exhaust gases before the SCR catalyst, which determines the production of the ammonia needed for the catalytic reduction of NOx. However, this technology is affected by two main limitations: a) the evaporation of the urea water solution (UWS) requires a sufficiently high temperature of the exhaust gases and b) the formation of solid deposits during the UWS evaporation is a frequent phenomenon which compromise the correct operation of the system. In this context, to overcome these issues, a technology based on the injection of gaseous ammonia has been recently proposed: in this case, ammonia is stored at the solid state in a cartridge containing a Strontium Chloride salt and it is desorbed by means of electrical heating. In this work, an after-treatment system based on the injection of gaseous ammonia in the SCR system is considered. Numerical 1D and 3D CFD simulations are applied in order to optimize the NOx reduction process. In particular, CFD methodology is applied to study in details the process of injection of the gaseous ammonia in the main exhaust gas stream and the effectiveness of the mixing process. Different geometrical layouts are compared to evaluate their performances in terms of uniformity of the NH3 distribution across the inlet section of the catalyst and pressure drop introduced in the exhaust line. Moreover, a 1D simulation tool is applied to evaluate the performances of the entire exhaust after-treatment system. The 1D model is calibrated on the basis of the information coming from detailed CFD simulations, in particular for what concerns the modeling of the effects of the different mixer geometries in terms on NH3 distribution. In this case, a simplified 3D catalyst is simulated, to take into account the maldistribution of ammonia at the inlet cross section and to evaluate its impact on the global deNOx performance of the system for different dosing strategies and for different levels of the ammonia maldistribution.
Della Torre, Augusto, Montenegro, Gianluca, Onorati, Angelo, Cerri, Tarcisio, Tronconi, Enrico, Nova, Isabella
Wearable Gas Sensor Enhances SensitivityTBMG-362443/1/2020
A highly sensitive wearable gas sensor for environmental and human health monitoring may soon become commercially available, according to researchers at Penn State and Northeastern University.
Research Zeroing in on Electronic Nose for Diagnosing DiseaseTBMG-362603/1/2020
Research at Oregon State University has pushed science closer to developing an electronic nose for monitoring air quality, detecting safety threats and diagnosing diseases by measuring gases in a patient’s breath.
Suppression of Soot Formation in Quasi-steady Diesel Spray Flame Produced by High-pressure Fuel Injection with Multi-orifice Nozzle2019-01-227012/19/2019
The set-off length (also referred to as the “lift-off length”) is reduced by the re-entrainment of the burned gas by the backward flow surrounding a diesel spray jet produced by a multi-hole nozzle. In the present study, to estimate the equivalence ratio at the set-off length, a means of estimating the amount of burned gas that is re-entrained into the near-nozzle region of the diesel spray jet was established. The results revealed that the suppression of soot formation in quasi-steady diesel spray flames produced by a multi-hole nozzle and a high injection pressure is not attained by reducing the equivalence ratio at the set-off length. Analysis of the amount of soot along the spray axis using a two-color method revealed that the maximum soot amount position appears in a quasi-steady spray flame, after the collapse of the head vortex in which a dense soot cloud is formed. The maximum soot amount position does not change even if the injection pressure varies. The suppression of soot formation by the application of a high injection pressure in an actual diesel engine was found to be caused by the shortening of the residence time in the soot formation region between the set-off length and the maximum soot amount position.
Fuyuto, Takayuki, Mandokoro, Yoshiyuki, Hattori, Yoshiaki, Mashida, Makoto
Investigation of Particulate Matter Formation in a Diesel Engine Using In-Cylinder Total Sampling and Thermal Desorption-GCMS/Carbon Analysis2019-01-227612/19/2019
In-cylinder total sampling technique utilizing a single-cylinder diesel engine equipped with hydraulic valve actuation system has been developed. In this study, particulate matter (PM) included in the in-cylinder sample gas was collected on a quartz filter, and the polycyclic-aromatic hydrocarbons (PAHs) component and soot were subsequently quantified by thermal desorption-gas chromatograph mass spectrometry (TD-GCMS) and a carbon analyzer, respectively. Cylinder-averaged histories of PAHs and soot were obtained by changing the sampling timing. It was found that decreasing intake oxygen concentration suppresses in-cylinder soot oxidation, and the fuel with higher aromatic and naphthenic contents accelerates soot production.
Furukawa, Shinya, Suzuki, Hirotaka, Shibata, Keiko, Saito, Hiroaki, Miyashita, Kazuya, Ishii, Yoshinori, Shimazaki, Naoki
Effects of Water Injector Spray Angle and Injector Orientation on Emission and Performance of a GDI Engine—A CFD Analysis03-13-01-000210/8/2019
Abstract Higher water evaporation and proper water vapor distribution in the cylinder are very vital for improving emission and performance characteristics of water-injected engines. The concentration of water vapor should be higher and uniform near the walls of the combustion chamber and nil at the spark plug location. In direct water-injected engines, water evaporation, vapor distribution, and spray impingement are highly dependent on injector parameters, viz., water injector orientation (WIO), location, and spray angle. Therefore, in this article, a computational fluid dynamics (CFD) investigation is conducted to study the effects of water injector spray angle (WISA), and WIO on the water evaporation, emission, and performance characteristics of a four-stroke, wall-guided gasoline direct injection (GDI) engine. The WISA is varied from 10° to 35°, whereas the WIO is varied from 15° to 35° in steps of 5°. The water is injected in the compression stroke with an optimum injection pressure of 50 bar. Water-to-fuel (W/F) ratio and spark timing are fixed at their optimum values with a compression ratio (CR) of 13.5. The engine is operated at the engine speed of 2000 rpm, with stoichiometric and naturally aspirated conditions. The CFD models used in this study are validated with the available data from the literature. Results showed that the WISA of 20° in combination with the WIO of 25° produced the maximum charge cooling, highest water evaporation, and proper water vapor distribution in the cylinder, because of which the indicated mean effective pressure (IMEP) is about 9.3% higher, whereas nitrogen oxides (NOx) and soot emissions are about 48% and 20.7% lower than that of the no_water case. This research suggests that the WISA and WIO should be chosen in such a manner that most water injection occurs around the piston periphery, without any impingement on the cylinder liner surface to achieve better water vapor distribution and evaporation characteristics.
Raut, Ankit Ashokrao, Mallikarjuna, J.M.
Diesel Vehicle with Ultra-Low NOx Emissions on the Road2019-24-01459/9/2019
The gap between diesel vehicle emissions in laboratory tests compared to those in use has been addressed by the introduction of the Real Driving Emissions (RDE) requirements. Modern diesel technology now demonstrates low emissions on the road over a wide range of driving conditions. This paper further demonstrates that consistent low nitrogen oxide (NOx) and particle number (PN) emissions can be achieved over a wide range of driving conditions beyond Euro 6d RDE requirements, with emission control technologies combined in an integrated approach. An LNT (Lean NOx Trap) is combined with a dual-dosing SCR (Selective Catalytic Reduction) system. Low-load NOx control is achieved by the LNT in combination with a close-coupled SCR coated on the Diesel Particulate Filter (SDPF). High load conditions, on the other hand, are covered by the underfloor SCR system with a second AdBlue® injector. A P0 48V mild-hybrid system is also available to support the NOx control and to ensure good driving performance and fuel efficiency. An advanced control strategy is implemented to ensure optimal interaction between all emission control functionalities. The system was implemented on a C-segment demonstrator vehicle. The paper discusses the emissions tests performed and the results achieved. A combination of tests on the road and in the lab were carried out to cover a wide range of driving conditions. Special attention was paid to the robustness of the emission performance under urban and motorway driving conditions. Results demonstrate that each aftertreatment component contributes to achieving consistently low NOx emissions under all driving conditions. Particulate emissions are effectively controlled by the DPF.
Demuynck, Joachim, Favre, Cecile, Bosteels, Dirk, Bunar, Frank, Spitta, Joachim, Kuhrt, Andreas
Oxy-Fuel HCCI Combustion in a CFR Engine with Carbon Dioxide as a Thermal Buffer2019-24-01199/9/2019
Global warming and the increasingly stringent emission regulations call for alternative combustion techniques to reduce CO2 emissions. Oxy-fuel combustion is one of those techniques since the combustion products are easily separated by condensing the water and storing CO2. A problem associated with the burning of fuel using pure oxygen as an oxidant is that it results in high adiabatic flame temperature. This high flame temperature is decreased by introducing a thermal buffer to the system. A thermal buffer in this context is any gas that does not participate in combustion but at the same time absorbs some of the released heat and thus decreases the temperature of the medium. Many experiments have been conducted to study oxy-fuel combustion in ICE using noble gases as thermal buffers. However, those experiments focused on using hydrogen as a fuel to avoid any build-up of CO2 in the system. On the contrary, the work presented in this paper investigates using CO2 as a thermal buffer for oxy-fuel combustion in HCCI engines. Experiments were performed on a standard Waukesha variable compression ratio cooperative fuel research CFR engine, modified to run in HCCI mode. Emissions were measured using an AVL SESAM-i60 FTIR spectrometer. As expected, results showed that the CO2 mixture degraded engine efficiency. The relatively lower engine temperature also decreased NOx emissions, simultaneously increasing CO and unburned hydrocarbon (UHC) emissions.
Mohammed, Abdulrahman, MASURIER, JEAN-BAPTISTE, Elkhazraji, Ali, Johansson, Bengt, Mohammed, Abdulrahman, MASURIER, JEAN-BAPTISTE, Elkhazraji, Ali, Johansson, Bengt
Message Sets for Advanced Traveler Information System (ATIS)J2354_201906 (Current)6/11/2019
This SAE Standard describes standardized medium-independent messages needed by information service providers for Advanced Traveler Information Systems (ATIS). The messages contained herein address all stages of travel (informational, pre-trip and en route), all types of travelers (drivers, passengers, personal devices, computers, other servers), all categories of information, and all platforms for delivery of information (in-vehicle, portable devices, kiosks, etc.).
V2X Core Technical Committee
Study on Improvement of NOx Reduction Performance at Low Temperature Using Urea Reforming Technology in Urea SCR System2019-01-03174/2/2019
To reduce NOx and PM emissions in exhaust gas, after-treatment systems for low NOx emissions are being developed in combination with improvements of engine combustion. In recent years, the exhaust gas temperature has been dropping because of enhanced low-fuel consumption of the engine. Therefore, it is urgent to develop NOx reduction technologies that work at a low temperature under 200degC. Since NOx is reduced by reacting with ammonia supplied to the SCR catalyst, it is necessary to make the urea solution decompose into ammonia using the heat of the exhaust gas to supply sufficient ammonia to the SCR catalyst. However, both the decomposition reaction and hydrolysis reaction of the urea have insufficient exhaust heat, thus making it difficult for urea to decompose and hydrolyze to ammonia at a low temperature. To solve this problem, it focuses on forcibly decomposing the urea solution without depending on the exhaust gas temperature. We selected a urea reforming method in which the urea is directly heated using the glow plug as the heat source. In this study, we have considered further improvement of the NOx reduction performance at a low temperature with a view to improving the ammonia generation efficiency by urea reforming.
Okada, Yuichi, Hirabayashi, Hiroshi, Sato, Shinya, Inoue, Hiroshi
Ultra-Low NOx Emission Prediction for Heavy Duty Diesel Applications Using a Map-Based Approach2019-01-09874/2/2019
As vehicle emissions regulations become increasingly stringent, there is a growing need to accurately model aftertreatment systems to aid in the development of ultra-low NOx vehicles. Common solutions to this problem include the development of complex chemical models or expansive neural networks. This paper aims to present the development process of a simpler Selective Catalytic Reduction (SCR) conversion efficiency Simulink model for the purposes of modeling tail pipe NOx emission levels based on various inputs, temperature shifts and SCR locations, arrangements and/or sizes in the system. The main objective is to utilize this model to predict tail pipe NOx emissions of the EPA Federal Test Procedures for heavy-duty vehicles. The model presented within is focused exclusively on heavy-duty application compression ignition engines and their corresponding aftertreatment setups. The accuracy of the model depends heavily on the ability to gain precise and repeatable test cell data to calculate an expansive SCR conversion efficiency map for the given aftertreatment system. This conversion efficiency map is verifiable based on expected/known chemical and physical properties of SCR aftertreatment systems. For this application, a 2-dimensional map was created, using SCR temperature and space velocity. The model requires several inputs including engine out NOx concentrations, SCR temperature, and exhaust flow/space velocity to input into the table and thus predict the corresponding tail pipe NOx. While different engine calibrations can impact the accuracy of the model, it was found that error in average tail pipe NOx prediction (g/bhp·hr) was approximately +/- 10%. For the purposes of this model, this error was found to be sufficient in providing the proper direction for ultra-low NOx aftertreatment development.
Singh, Navtej, Adelman, Brad, Malagari, Srinivasulu, Hickey, Kyle
Should We Walk or Take a Car for Minimum Greenhouse Gas Emissions?2019-01-09964/2/2019
This paper compares the greenhouse gas (GHG) emissions attributed to driving a popular production vehicle powered by an internal combustion engine (ICE), as well as a hybrid electric vehicle (HEV), with GHG emissions associated with walking, running and bicycling. The purpose of this study is to offer a different perspective on the problem of global warming due to anthropogenic causes, specifically on transportation and eating patterns. In order to accurately estimate emissions, a full life cycle of food has been considered coupled with energy expenditures of the aforementioned activities obtained from several different sources and averaged for more reliable results. The GHG emissions were calculated for Sweden, the UK, and the US. Depending on the availability of certain data, the methodology for different countries was altered slightly. The question whether walking, running or taking a bicycle is better for the environment than driving a car cannot be answered uniquely. This study demonstrates that the answer depends on several factors, such as diet composition, the number of people commuting, vehicle powertrain, as well as the country analyzed. The conclusion is that if one has an eco-friendly diet and travels alone the preferred modes of transport would be bicycling, walking and running, the cleanest of which by far is bicycling. However, if the diet has a higher CO2 footprint, as in the case of diets containing a large amount of meat and/or imported products, then the preference shifts towards cars, among which the most environmentally friendly are hybrid electric vehicles. The same conclusion applies to the cases where the number of people commuting together exceeds two-three persons.
Babayev, Rafig, Johansson, Bengt
Numerical Modeling Study of Detailed Gas Diffusivity into Catalyst Washcoat for Lean NOx Catalyst2019-01-09934/2/2019
To evaluate the relationship between the exhaust gas purification performance and the catalyst pore properties related to gas diffusion, an elementary reaction model was combined with gas diffusion into catalyst pores, referred to as the pseudo-2D gas diffusion/reaction model. It was constructed for Pt/Al2O3 + CeO2 catalyst as lean NOx catalyst. The gas diffusion was described as macro pore diffusion between the catalyst particles and meso pore diffusion within the particle. The kinetic model was composed of 26 reactions of NO/CO/O2 chemistry including 17 Pt/Al2O3 catalyst reactions and 9 CeO2 reactions. Arrhenius parameters were optimized using activity measurement results from various catalysts with various pore properties, meso pore volume and diameter, macro pore volume and diameter, particle size, and washcoat thickness. Good agreement was achieved between the measured and calculated values. Moreover, as compared to the performance of other catalysts which was not used for reaction model calibration, the simulated results were in good agreement with this experimental data. Using the calibrated reaction model combined with detailed gas diffusion model, a sensitivity analysis for NOx concentration was performed to identify key diffusion parameters of the lean NOx catalyst. In summary, parameters with the highest sensitivity were catalyst particle size, washcoat thickness, CeO2 meso pore volume, and diameter. Also, catalyst macro pore volume and diameter showed no dependence. Consequently, to increase the NOx purification performance, the meso pore parameters and washcoat thickness should be increased, particle size should be decreased. With these changes, the gaseous NOx will easily move to the catalyst surface and into the active site of meso pore, resulting in better performance.
Yamamoto, Osami, Matsuo, Yuichi, Tosa, Shinichi, Okayama, Tatsuya, Zhang, Zhiwei, Tolsma, John
Experimental and Computational Study of DOC on CSF for Heavy Duty Diesel Applications2019-01-05864/2/2019
For diesel exhaust aftertreatment applications with space limitations, as well as to move the selective catalytic reduction system (SCR) to a warmer location closer to the engine, DOC on CSF technology can be used. This technology combines the diesel oxidation catalyst (DOC) and catalyzed soot filter (CSF) functionalities in one component, thereby enabling volume reduction. DOC on CSF maintains the abatement of hydrocarbon (HC), carbon monoxide (CO), and particulate matter (PM), and the oxidation of nitric oxide (NO) to nitrogen dioxide (NO2) for passive soot oxidation and fast SCR reaction of NOx on a downstream SCR catalyst. In this study, the performance of DOC on CSF was compared to a DOC + bare diesel particulate filter (DPF) and a DOC + CSF system, to understand the performance benefits and challenges. All the components were optimized individually for their respective functions. The DOC on CSF was optimized for NO oxidation and passive soot oxidation performance. Experimental data and simulations were used to understand the underlying mechanisms in the DOC on CSF technology. Steady state HC oxidation under active regeneration conditions showed a benefit for DOC on CSF compared to the DOC + DPF system. The soot oxidation characteristics of the DOC on CSF were evaluated in comparison to a DPF or CSF downstream of a DOC under passive and active soot oxidation conditions. In addition, the contribution of NO2 generated within the filter on the soot oxidation was assessed. The passive soot oxidation characteristics of a DOC on CSF were found to be similar, or better, compared to DOC + DPF and DOC + CSF under certain conditions. The active regeneration efficiency was lower for the DOC on CSF due to the gradual increase in temperature along the length of the part during fuel injection. This work demonstrates the differences between the DOC on CSF and DOC + bare/coated DPF systems, thus enabling a better understanding of the performance of DOC on CSF to current applications.
Sethuraman, Sharan, Sitamraju, Siddarth, Lopez-De Jesus, Yaritza M, Markatou, Penelope
Modeling of Engine Aftertreatment System Cooling for Hybrid Vehicles2019-01-09894/2/2019
Exhaust aftertreatment systems are essential components in modern powertrains, needed to reach the low legislated levels of NOx and soot emissions. A well designed diesel engine exhaust aftertreatment system can have NOx conversion rates above 95%. However, to achieve high conversion the aftertreatment system must be warm. Because of this, large parts of the total NOx emissions come from cold starts where the engine has been turned off long enough for the aftertreatment system to cool down and loose its capacity to reduce NOx. It is therefore important to understand how the aftertreatment cools down when the engine in turned off. Experimental data for a catalyst cool-down process is presented and analyzed. The analysis shows that it is important to capture the spatial distribution of temperatures both in axial and radial directions. The data and analysis are used to design a catalyst thermal model that can be used for model based catalyst temperature monitoring and control.
Holmer, Olov, Blomgren, Fredrik, Eriksson, Lars
Review of Vehicle Engine Efficiency and Emissions2019-01-03144/2/2019
This review paper covers major regulatory and technology developments in 2018 pertinent to tailpipe emissions of greenhouse gases and criteria pollutants. Europe has proposed ambitious reductions in CO2 limits for both light- and heavy-duty sectors. The challenge is compounded with changing measurement norms and a significant shift away from fuel efficient diesels in the light-duty (LD) space. Both incremental and step changes are being made to advance internal combustion. New studies show that in-use NOx emissions from diesels can be much lower than required by the Euro 6 regulation. Discussions have already started on Euro 7 regulations, and the leading regulatory concepts and proposed technical solutions are provided. In the heavy-duty (HD) sector, the progress is outlined in improving engine and vehicle fuel efficiency through the US Department of Energy’s (DOE’s) SuperTruck II program and other representative studies. Common approaches among the participants include hybridization, waste heat recovery, and both open- and closed cycle incremental improvements. Emissions control focus is on evaluating pathways to achieve California’s contemplated low-NOx standards, recently also supported by the US EPA through the Cleaner Trucks Initiative. The challenge is to reduce cold start and low load emissions, requiring innovative engine and after-treatment system solutions. Leading concepts include close-coupled SCR (selective catalytic reduction), use of passive NOx adsorbers, integration of SCR (selective catalytic reduction) on DPFs (diesel particulate filters), low temperature urea or ammonia injection, dual SCR, and active and passive thermal management to raise exhaust temperatures. Work is also underway on a new low load certification cycle. Continued advancement is made on after-treatment components. Aged three-way catalysts (TWCs) and diesel oxidation catalysts (DOCs) are nearing 90% conversion at 150 °C. SCR catalysts continue to improve both their low temperature conversion as well as high temperature durability. Particulate regulations in Europe, China and India are leading to widespread adoption of gasoline particulate filters (GPFs). Lean burn gasoline engines can offer significant fuel economy benefits. NOx control is a challenge, and passive SCR systems and new catalysts are proposed.
Joshi, Ameya
Study of Performance and Emission Characteristics of Propan-2-ol and Gasoline Fuel Blends in an Unmodified Spark Ignition Engine2019-01-07934/2/2019
In view of the rapid depletion, increasing prices and uneven distribution of conventional petroleum fuels; the interest in the use of alternative fuels has increased exponentially. Fuels such as biodiesel & alcohol have been evaluated both at experimental and commercial scale due to improved emission characteristics as compared to conventional fuels. Alcohols are oxygenated and result in improving the engine performance. As a blend with conventional gasoline, the alcohols enhance the premixed and diffusive combustion phase which improves the combustion efficiency. The present investigation evaluates studies on stability and homogeneity along with physicochemical properties like density, viscosity, calorific value, copper-strip corrosion and solubility at room temperature of Propan-2-ol and gasoline blends. Comprehensive engine trials on unmodified petrol engine fuelled with blends of Propan-2-ol and gasoline blends in the proportions of 5, 10, 15 and 20% by volume have been conducted. The performance characteristics e.g. brake-specific energy consumption, brake thermal efficiency and emissions characteristics such as NOX, CO and HC were studied and analyzed to evaluate the optimum alcohol/fuel blend for the petrol engine. The result yielded enhanced combustion and performance characteristics as compared to gasoline with reduced Carbon monoxide and un-burnt hydrocarbon emissions. However, there was an increase in the oxides of nitrogen emissions.
Kumar, Naveen, Jain, Shikhar, Bagla, Aakriti, Sharma, Shivalika, Tomar, Mukul
A Simulation Research on Emission Control Technology of Low-Speed Two-Stroke Diesel Engine Based on EGR and Miller Cycle2019-01-09454/2/2019
This paper investigates the influences of EGR and Miller cycle on NOx emission of a heavy-duty two-stroke diesel engine. The NOx emission is strictly restricted by the IMO Tier III Emission Regulations, resulting in an insufficient application of the single emission reduction technology to meet the emission requirements. It is asserted that EGR is the most effective manner to reduce NOx emission, but the fuel consumption increases simultaneously. In consideration of emission reduction with fuel economy, EGR and Miller cycle were combined and studied in this paper. Parameters like in-cylinder pressure, in-cylinder temperature, mass in the chamber, emission (NOx and soot) and fuel consumption rate were investigated based on a single-cylinder 3D model. The wet condition that happens in the engine application was considered in the model development process. The model was validated and compared with the experimental data. The simulation results show the "trade-off" relationship between NOx and soot under EGR, as well as the performance of reducing NOx in different load. This paper, subsequently, used Miller cycle (achieve by delay the closing timing of the exhaust valve with intake boosting) to optimize the fuel consumption rate base on the EGR results. Finally, the combustion conditions under different EGR ratio and different Miller cycle condition were reflected by in-cylinder pressure, the contours of in-cylinder temperatures and the generating area of NOx. According to the simulation results of EGR and Miller cycle, the optimum scheme was giving out to satisfy the IMO Tier Three with better fuel economy performance.
Zhu, Zhijie, Liang, Xingyu, Wang, Yuesen, Liu, Bo
Engine-Aftertreatment in Closed-Loop Modeling for Heavy Duty Truck Emissions Control2019-01-09864/2/2019
An engine-aftertreatment computational model was developed to support in-loop performance simulations of tailpipe emissions and fuel consumption associated with a range of heavy-duty (HD) truck drive cycles. For purposes of this study, the engine-out exhaust dynamics were simulated with a combination of steady-state engine maps and dynamic correction factors that accounted for recent engine operating history. The engine correction factors were approximated as dynamic first-order lags associated with the thermal inertia of the major engine components and the rate at which engine-out exhaust temperature and composition vary as combustion heat is absorbed or lost to the surroundings. The aftertreatment model included catalytic monolith components for diesel exhaust oxidation, particulate filtration, and selective catalytic reduction of nitrogen oxides (NOx) with urea. Both the engine and aftertreatment models have been calibrated with dynamometer measurements from a commercial 2010-certificated 15-L Cummins diesel engine. The fuel consumption engine map with the reduced data is attached in the appendix. Simulations with the combined engine and aftertreatment models above appear to reveal important trends among the fuel efficiency, emissions control, power demand for HD trucks under realistic drive cycle conditions. Thus, this type of computational simulation appears to have significant value in choosing among options for HD vehicle design and operation.
Gao, Zhiming, Deter, Dean, Smith, David, Pihl, Josh, Daw, C. Stuart, Parks, James
Material Captures and Removes Toxic Atmospheric GasTBMG-341424/1/2019
A metal-organic framework (MOF) material was developed that exhibits a selective, fully reversible, and repeatable capability to remove nitrogen dioxide gas from the atmosphere in ambient conditions. The material denoted as MFM-300 (Al) exhibited the first reversible, selective capture of nitrogen dioxide at ambient pressures and temperatures — at low concentrations — in the presence of moisture, sulfur dioxide, and carbon dioxide. Despite the highly reactive nature of nitrogen dioxide, the MFM-300(Al) material proved extremely robust, demonstrating the capability to be fully regenerated, or degassed, multiple times without loss of crystallinity or porosity. Other different porous materials often showed degraded performance in subsequent cycles by the nitrogen dioxide, or that the regeneration process was too difficult and costly.
Leading Edge Assembly Real Time Process Monitoring Using Industrial Internet of Things (IIoT)2019-01-13673/19/2019
The increasing global demand for commercial aircraft creates many new challenges in manufacturing including an increased need to maximize the automation of manufacturing processes. The purpose of this research is to develop the understanding of leading edge assembly processes using robot mounted tooling and an automated fixture with advanced process monitoring. Within this research real-time process monitoring data is acquired from an assembly operation and processed into an open cloud environment enabling advanced data analytics. Implementation of advanced analytics utilising process data could be developed for the use of machine learning algorithms which can lead to superior fault finding. The aim of this research is to improve product quality, reduce cost and increase process knowledge, enabling the potential for maximized online and offline process feedback. This paper details how an open Industrial Internet of Things (IIoT) environment can be used to interface with a number of proprietary devices to enable real-time process monitoring in aerospace manufacturing. The implementation of the software and hardware is detailed and followed by an initial evaluation of the system architecture by performing leading edge assembly operations. In addition, a baseline of current IIoT systems is discussed, with the comparison to the specific architecture used here. The system is based on a wireless integration of proprietary devices and sensors feeding real-time data to an open cloud environment. Data is analysed and visualised in real time with online access and report generation. Data is supplied from the automated fixture and Restricted Access Drilling Unit (RADU) end-effector prototype developed by the Manufacturing Technology Centre. Supplied process data includes hardware and system health, and environmental measurements during the assembly operation. Access to analysed data grants the ability to identify occurring abnormalities during the assembly process which, ultimately, will allow for advancements in increased component quality and reduce manufacturing costs.
Janik, Karol, Thompson, Ian, Walley, Gareth, Land, Patrick, Suwala, Agata
Modeling Diesel Spray, Combustion and Emission with GTEA Numerical Code2019-01-00041/15/2019
A detailed chemistry-based CFD model (GTEA, General Transport Equation Analysis) is developed to simulate the diesel spray, combustion and emission process. The numerical model incorporates an improved droplet tracking model, the Hybrid breakup model that consider the influence of turbulence inside the nozzle, the reaction mechanism of n-decane coupled with a reduced NOx mechanism, a phenomenological soot model, a modified dynamic mesh model, a spray/wall impingement model, and other improved sub models in the GTEA codes. The model is first applied to predict the diesel spray process. The computational results demonstrate that the model is capable of predicting satisfactory fuel spray process, and the improved agreement is attributed to the ability of the new Hybrid breakup model to account for the effects of turbulence inside the nozzle, which enhance the spray process. The model is also applied to investigate the ignition delay and flame lift-off length under different ambient conditions. The overall trend of ignition delay and lift-off length with the variation in different conditions is well reproduced by the model. It is found that the ignition delay and lift-off length are a function of ambient density, ambient temperature and oxygen concentration, respectively. This part of study also showed that the longest ignition delay time has the longest lift-off length. Finally, the model is employed to simulate the combustion and emission characteristics of a low-temperature combustion (LTC) engine. Good levels of agreement in cylinder pressures under different EGR conditions are obtained. Predictions of soot and NOx emission are also performed. Although the predicted results are not fully satisfactory, the general trends are still well captured by the simulation.
Qi, Wenliang, Ming, Pingjian, Jilani, Aisha, Peng, Ye
Influence of the Backpressure on Urea Sprays Generated by an Air-Blast Atomizer for Large-Scale SCR-Applications2019-01-00461/15/2019
In 2016, the latest step of emission standards for marine ships came into operation. As the emission limit for nitric oxides has decreased to approximately 25% of the former values, selective catalytic reduction (SCR) will play an important role to fulfil those limits. SCR is an established method in the field of trucks and heavy diesel cars, but applying it to ships requires further research and development. The demands on ship engines are different, not only due to the large scales but also because the engineering process is strongly based on numerical simulations. To allow the validation of simulations at well-defined conditions and to investigate the fundamental processes, e.g. of the injection of urea solution for marine applications, a high pressure hot gas test rig was built up at the ITV. The current work focuses on the injection of urea solution by an air-blast atomizer. The spray breakup is the initial part of the urea decomposition, which is why reliable validation data is needed for modelling and simulating the respective spray and chemical processes. Therefore, the role of the atomization air flow rate in combination with different hot gas pressures was studied. The pressure influence is of particular interest, due to the possibility to install an SCR-system upstream the turbocharger of a marine engine. High speed shadowgraphy was applied to investigate the primary breakup of the urea spray. The breakup phenomena are discussed and combined with droplet spectra, which were measured by phase-Doppler anemometry (PDA). Apart from obtaining validation data, the study gives answers to the guiding question how to obtain acceptably fine sprays by using minimal atomization air under various circumstances.
Höltermann, Markus, Wichmar, Jan, Dinkelacker, Friedrich
NOx-Conversion Comparison of a SCR-Catalyst Using a Novel Biomimetic Effervescent Injector on a Heavy-Duty Engine2019-01-00471/15/2019
NOx pollution from diesel engines has been stated as causing over 10 000 pre-mature deaths annually and predictions are showing that this level will increase [1]. In order to decrease this growing global problem, exhaust after-treatment systems for diesel engines have to be improved, this is especially so for vehicles carrying freight as their use of diesel engines is expected to carry on into the future [2]. The most common way to reduce diesel engine NOx out emissions is to use SCR. SCR operates by injecting aqueous Urea solution, 32.5% by volume (AUS-32), that evaporates prior the catalytic surface of the SCR-catalyst. Due to a catalytic reaction within the catalyst, NOx is converted nominally into Nitrogen and Water. Currently, the evaporative process is enhanced by aggressive mixer plates and long flow paths. The mixer plates create extra exhaust back pressure and cool the exhaust gases, which decreases engine and catalyst efficiency, resulting in overall poor NOx conversion (<40%) and higher CO2 production under real life drive cycle conditions. To achieve future emission legislation targets, SCR efficiency has to be improved, especially under low catalyst temperature conditions. It should also be noted that Ammonia slip has to be avoided as it is now legislated against [3]. In this study a novel biomimetic effervescent aqueous urea injector, its design inspired by the natural spray phenomenon of the Bombardier Beetle, is used to compare against a market-leading aqueous urea doser in comparable exhaust conditions with and without aggressive mixer plates being installed. The novel biomimetic effervescent injector operates by increasing the temperature of the Urea solution inside a constant volume chamber to its saturated vapour pressure. At the required time of injection an electromagnetically controlled outlet valve opens exposing the now superheated fluid to lower pressure conditions, this results in a hot, effervescent spray being ejected which rapidly breaks up into very fine droplets (<20um) projected at high velocity (60m/s) into the exhaust stream targeted at the face of the SCR catalyst. The novel biomimetic effervescent injector shows great potential with a significant higher NOx conversion rate and lower ammonia slip compared to the market-leading doser on a heavy-duty engine.
Larsson, Peter, Ravenhill, Paul, Tunestal, Per
Modeling of Aftertreatment Technologies to Meet a Future HD Low-NOx Standard2019-01-00431/15/2019
The low-NOx standard for heavy duty trucks proposed by the California Air Resources Board represents a significant challenge to the engine and aftertreatment system. In this study, exhaust thermal management requirements were quantified using a combination of engine and aftertreatment modeling. First, a 1-D engine model was used to develop a control strategy capable of increasing the exhaust enthalpy and decreasing the engine-out NOx over the initial portion of the cold FTP cycle. The outputs from this model were then used as inputs to a 1-D model of a representative HD aftertreatment system. Several different passive exhaust thermal management technologies were evaluated with this aftertreatment system model, including insulating the downpipe, close-coupling the aftertreatment system, and reducing the thermal inertia of the DOC and DPF; the last option provides the most benefit to early NOx conversion. As an example of active exhaust thermal management, a model of a mini-burner was inserted into the system model; this device is able to raise the system temperature quickly, using less fuel than the engine control strategy. Lastly, early NH3 dosing and NH3 preloading on the SCR catalyst were examined; pre-loading would appear to be much more effective.
Harris, Thomas Miller, Gardner, Timothy
Effects of Cylinder Head Geometry on Mixture Stratification, Combustion and Emissions in a GDI Engine - A CFD Analysis2019-01-00091/15/2019
Preparation of air-fuel mixture and its stratification, plays the key role to determine the combustion and emission characteristics in a gasoline direct injection (GDI) engine working in stratified conditions. The mixture stratification is mainly influenced by the in-cylinder flow structure, which mainly relies upon engine geometry i.e. cylinder head, intake port configuration, piston profile etc. Hence in the present analysis, authors have attempted to comprehend the effect of cylinder head geometry on the mixture stratification, combustion and emission characteristics of a GDI engine. The computational fluid dynamics (CFD) analysis is carried out on a single-cylinder, naturally-aspirated four-stroke GDI engine having a pentroof shaped cylinder head. The analysis is carried out at four pentroof angles (PA) viz., 80 (base case), 140, 200 and 250 with the axis of the cylinder. The entire CFD simulations are performed at the engine speed of 2000 rev/min., and the overall equivalence ratio (ER) of 0.75. Finally, it is observed that the PA of 140 produced a rise of about 10.5% in indicated thermal efficiency (ITE) and 3% rise in peak heat release rate (HRR) with a compromise of 10.7% higher NOx emissions than that of the base case.
Saw, Om Prakash, Addepalli, Srinivasa Krishna, Mallikarjuna, J M
Wide-Area Chemical SensorTBMG-3339612/1/2018
The detection and localization of gas releases, such as methane from leaking natural gas pipelines or nitrogen oxides from failing electrical equipment, require high sensitivity to the target gas and insensitivity to non-target gases. Infrared (IR) absorption spectroscopy gives highly specific characterization of the identity and amount of airborne chemicals. Traditionally, spectroscopy techniques for long-range chemical sensing separate the “sensitive to x gas” and “insensitive to x gas” atmospheric measurements by quickly switching back and forth between them to reduce errors caused by any atmospheric changes. Because the samples are not measured at the same time, it is impossible to ensure that all atmospheric conditions (e.g., contaminants or humidity) remain constant between the two measurements.
Study on the Prevention of Face-Plugging of Diesel Oxidation Catalyst (DOC)2018-32-006910/30/2018
In order to meet the reinforcement of worldwide environmental regulations, latest diesel engines for industrial machinery are required to reduce the emission of harmful gases such as carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx), and particulate matter (PM). For this reason, some of the diesel engines are equipped with exhaust gas treatment devices such as diesel particulate filter (DPF), diesel oxidation catalyst (DOC) and selective catalytic reduction (SCR) catalyst. However, applications of such industrial diesel engines bring about excessive back pressure increase and deterioration in the performance of the catalysts when continuous operation is performed at low load conditions: soot accumulates on the inlet faces of DOC and DPF, causing face plugging issues. To resolve this issue, it is necessary for the system to be equipped with certain additional devices to raise an exhaust gas temperature to a high level enough to burn out the soot [1]. In this research, in order to solve the face plugging at the inlet of DOC without using such an additional equipment, we studied the cause of the face plugging of DOC. First, in order to estimate the cause of face plugging, we grasped the engine operating conditions leading to the face plugging and analyzed the soot/coke deposits accumulating on the inlet face of DOC under specific conditions. Next, in order to identify the origin of the face plugging causative deposits, we performed a component analysis of an engine exhaust gas and also conducted catalytic reaction experiments using a model exhaust gas. Then, verification experiments using an engine were carried out. As a result, we found that the production of less combustible HC by incomplete catalytic oxidation is one of the factors of the plugging problem of DOC.
Nakano, Kota, Okano, Hiroaki, Inoue, Katsushi, Obuchi, Akira
Impact of Secondary Air Injection on Small Engine Motorcycle Intended for BS VI Applications2018-32-006810/30/2018
On April 2020, India will move from Bharat Stage IV to Bharat Stage VI where the combined emission limit of Total Hydrocarbons (THC) and Nitrogen oxides (NOx) of 0.79g/km will independently reduce to 0.1g/km and 0.06g/km respectively. This reduction in emission limit however may prove to be challenging for small engines (below 200 cc) with the existing generation of engines predominantly in cold operating conditions. When the vehicle is started after soaking (engine turned off for few hours), considerable amount of THC emission is generated which can be attributed to poor fuel vaporization and incomplete combustion due to flame quenching in the combustion chamber. Also, the catalyst is inactive to chemical reactions until the accumulated heat energy from the hot exhaust mass flow elevates the catalyst temperature to facilitate efficient conversion of THC, CO and NOx to H2O, CO2 and N2. This temperature point is termed as catalyst light off temperature. Hence, most of the tail pipe emissions vented out to the atmosphere in cold phase is without after-treatment. In case of two wheelers on a typical drive cycle, around 60% (fig. 3) of the total tail pipe THC emitted is before the catalyst attains light off temperature. Thus, any form of exhaust gas treatment that can lead to reduction of pre-catalyst emissions and faster catalyst light off, will prove to be beneficial in overall emission reduction. In this context, Secondary Air injection (SAI) is explored as an effective exhaust treatment method in tackling cold phase emissions. In the present study, a series of tests were conducted on a single cylinder 200cc engine fitted with a Mechanical throttle body and electronic fuel injection system. From these tests, various aspects of cold phase emissions were characterized. This paper explores in detail the impact of SAI on pre-catalytic oxidation of THC, catalyst temperatures and catalytic reactions. Present study also gives an insight into the operation of SAI such that it does not compromise the functionality of the three way catalyst (TWC). It was also observed that it is beneficial to have different modes of SAI operation such as open loop mode without oxygen sensor feedback, closed loop mode with oxygen sensor feedback and engine load specific operation of SAI. Upon application of best optimal configuration of SAI a reduction of 25% in THC and 4% of NOx was observed.
Sabu, Abhijith, Reddemreddy, Pramod, Parmar, Manojkumar
Numerical Study of the Effect of Injection Strategy and Compression Ratio on Gasoline/Diesel Fueled RCCI Engine2018-32-001710/30/2018
RCCI engine is proven to have better combustion control and to produce very low NOx and soot emissions. However, its operations is limited by HRR and PPRR as well as weak combustion efficiency which results in high levels of HC and CO emissions. Engine geometry and operation parameter such as injection strategy and compression ratio can affect the reactivity of fuels in cylinders as well as the gas temperature increase rate which are the important factors in controlling RCCI combustion. Injection strategies such as single and double injections have been previously studied but the effects are still unpredictable and the effects of compression ratio towards combustion characteristic and emissions require further analysis. This work deploys a 3D computational fluid dynamic (CFD) combustion model to study the effects on combustion characteristic and emissions with respect to single injection, double injection strategy and compression ratio. The model is validated by comparing the simulation result with a previous experimental work. The results show that double injections can produce more extensive combustion propagation than single injection. This is because the second injection of diesel fuel which is more reactive creates steeper reactivity gradient and equivalence ratio gradient throughout the combustion chamber. This also results in lower NOx, soot, HC and CO compare to single injection strategy. Single injection strategy combustion depends on the reactivity gradient and equivalence ratio gradient of injected diesel fuel which need to be at the right levels or else the combustion propagation will be retarded. The study then shifted to study the effect of compression ratio on the best parameter of double injection strategy. The results show that the increase of compression ratio can further reduce soot, HC and CO to a very low level while NOx is observed to increase. Lowering compression ratio results in worsening HC and CO emission due to incomplete combustion of gasoline, The incomplete combustion is likely to be caused by low gas temperature increase rate.
Azmi, Muhammad Asyraf Mohd, Mansor, Mohd Radzi Abu, Wan Mahmood, Wan Mohd Faizal, Mohamad, Taib Iskandar
Configuration Enables RFID Tags to Work as SensorsTBMG-3310010/1/2018
The detection and localization of gas releases, such as methane from leaking natural gas pipelines or nitrogen oxides from failing electrical equipment, require high sensitivity to the target gas and insensitivity to non-target gases. Infrared (IR) absorption spectroscopy gives highly specific characterization of the identity and amount of airborne chemicals. Traditionally, spectroscopy techniques for long-range chemical sensing separate the “sensitive to x gas” and “insensitive to x gas” atmospheric measurements by quickly switching back and forth between them to reduce errors caused by any atmospheric changes. Because the samples are not measured at the same time, it is impossible to ensure that all atmospheric conditions (e.g., contaminants or humidity) remain constant between the two measurements.
Polymer Nanofiber-Based Reversible Nano-Switch/Sensor Schottky Diode (nanoSSSD) DeviceTBMG-3311710/1/2018
Innovators at NASA's Glenn Research Center have developed a unique nano-structure device that operates as a nano-switch/sensor for detecting toxic gases and ultraviolet (UV) radiation. Conventional microsensors are limited by their short life, high cost and complexity, and unifunctional sensing task. Glenn's novel Polymer Nanofiber-Based Reversible Nano-Switch/Sensor Schottky Diode (nanoSSSD) technology offers the ability to respond to changing conditions and then revert to baseline operations when conditions return to normal. Glenn's nanoSSSD features no mechanical moving parts, and the sensors are reusable after annealing, extending their appeal for rapid-response, low-cost devices. This simple design provides an easily fabricated, mass-producible microsensor for use in numerous applications where replacement opportunities are limited.
Impact of Demanding Low Temperature Urban Operation on the Real Driving Emissions Performance of Three European Diesel Passenger Cars2018-01-18199/10/2018
In Europe, the development and implementation of new regulatory test procedures including the chassis dynamometer (CD) based World Harmonised Light Duty Test Procedure (WLTP) and the Real Driving Emissions (RDE) procedure, has been driven by the close scrutiny that real driving emissions and fuel consumption from passenger cars have come under in recent times. This is due to a divergence between stated certification performance and measured on-road performance, and has been most pointed in the case of NOx (oxides of nitrogen) emissions from diesel cars. The RDE test is certainly more relevant than CD test cycles, but currently certification RDE cycles will not necessarily include the most extreme low speed congested or low temperature conditions which are likely to be more challenging for NOx after-treatment systems. To build understanding of the emissions and fuel consumption performance of the latest available diesel passenger cars, Concawe has conducted a study of the performance of three vehicle types. Two of the vehicles featured urea-dosed Selective Catalytic Reduction (SCR) after-treatment, whilst the third was fitted with a Lean NOx Trap (LNT) and a downstream passive SCR catalyst (pSCR). For each vehicle, triplicate tests were conducted over a moderate RDE on-road cycle, as well as CD testing of the Transport for London (TfL) Urban Inter Peak (UIP) cycle, developed directly from real-driving trips in the City of London, UK. The TfL UIP is considered a severe urban cycle and was run over ambient temperatures ranging from −15 °C to 23 °C. After the initial 2-3 minute warm up period, the SCR-equipped vehicles were effective at controlling NOx, while the LNT-equipped vehicle was more effective in the initial minutes of running. The data generated provides insights into the emissions performance of Euro 6 diesel passenger cars, and their after-treatment systems, in extreme congested cold urban conditions including, and beyond, the most demanding likely to be encountered under regulatory RDE testing.
Williams, Rod, Andersson, Jon, Hamje, Heather, Ziman, Pauline, Kar, Kenneth, Fittavolini, Corrado, Pellegrini, Leonardo, Gunther, Garry, Oliva, Fermin, Van de Heijning, Paul
Effects of an On-Board Safety Device on the Emissions and Fuel Consumption of a Light Duty Vehicle2018-01-18219/10/2018
Vehicle emissions and fuel consumption are significantly affected by driving behavior. Many studies of eco-driving technology such as eco-driving training, driving simulators and on-board eco-driving devices have reported potential reductions in emissions and fuel consumption. Use of on-board safety devices is mainly for safety, but also affects vehicle emissions and fuel consumption. In this study, an on-board safety device was installed to alert the driver and provide several types of warning to the driver (e.g. headway monitoring warning, lane collision warning, speed limit warning, etc.) to improve driving behavior. A portable emissions measurement system (PEMS) was used to measure vehicle exhaust concentrations, including hydrocarbons (HC), carbon monoxide (CO), carbon dioxide (CO2) and nitrogen oxides (NOx). The driving parameters including vehicle speed, acceleration and position were also recorded. A specific test route was designed for the experiment to investigate both urban and highway conditions. The driving parameters and emissions data were compared before and after the installation of the on-board safety device with the same driver. The Vehicle Specific Power (VSP) methodology was applied to evaluate the effects of the on-board safety device on driving behavior. The results indicated that the device had a positive effect on the driver’s driving behavior. The percentage of time spent on excessive speeding and strong acceleration decreased from 22.2% to 14.7%. As a result, an average reduction of 25% in fuel consumption was observed. In addition, HC, CO2 and NOx emissions showed a reduction of 57%, 25% and 9% respectively. However, CO emission was increased and the time spent on idling showed no change with the installation of the device.
Ng, Cheuk Yin, Huang, Yuhan, Hong, Guang, Zhou, John, Surawski, Nic, Ho, Jackson, Chan, Edward
Variation in System Performance while Sorting DEF Heating Hardware Options2018-01-18139/10/2018
The desire to reduce NOx at low ambient temperatures drives the use of heating methods to make DEF available by thawing the solution in the tank. Methods to validate modelling used to design hardware options require testing to gauge the accuracy of the prediction. Using a climatic chassis dynamometer (CCD) to demonstrate the guidance procedure set by the Environmental Protection Agency (EPA) is expensive and time consuming. A method of utilizing a flow controlled cooling supply combined with a standard cold chamber is described as a precursor to running the demonstration in the CCD. Testing multiple quantities of design iterations produced unexpected variation in the results. The sources of the variation and modifications taken to minimize them are discussed and presented. Test to test control of coolant flow, coolant temperature, and specific chamber temperature inconsistencies were found to be critically important to a successful effort. Several design iterations were compared with varying degrees of success. The method was modified as variation between tanks of the same design was noted. System description details as well as modifications to the process are discussed. A design that maximizes heat transfer to the DEF pick up area while providing enough heat to melt the remainder of the volume was found to clearly out-perform the others. Test apparatus details are described. The DEF heating loop system is exposed to varying temperatures and flows in the truck. Selection of a representative coolant flow and temperature is discussed. The EPA certification test method options are referenced. Control parameters are defined with the intent of demonstrating a test practice that minimizes CCD time and ultimately accurately predicts hardware performance on the certification test.
Vermiglio, Ezio, Gilliam, Kyle, Chin, Anthony, Leonard, Treaver, Erickson, Darren
0D Modeling of Real-Driving NOx Emissions for a Diesel Passenger Vehicle2018-01-17619/10/2018
NOx emissions from diesel passenger vehicles affect the atmospheric environment. It is difficult to evaluate the NOx emissions influenced by environmental conditions such as humidity and temperature, traffic conditions, driving patterns, etc. In the authors’ previous study, real-driving experiments were performed on city and highway routes using a diesel passenger car with only an exhaust gas recirculation system. A statistical prediction model of NOx emissions was considered for simple estimations in the real world using instantaneous vehicle data measured by the portable emissions measurement system and global positioning system. The prediction model consisted of explanatory variables, such as velocity, acceleration, road gradient, and position of transmission gear. Using the explanatory variables, NOx emissions on the city and highway routes was well predicted using a diesel vehicle without NOx reduction devices. However, the prediction model had some limitations owing to the effects of NOx reduction devices. In this study, among various NOx reduction systems, a diesel vehicle with NOx storage catalyst (NSC) was chosen to predict the NOx emissions under a catalytic system. To improve the accuracy of the NOx emissions under the NSC, a catalyst model was added to the prediction model and used to predict the catalyst properties. By adding the catalyst model, the accuracy of NOx emissions of the prediction model was improved compared to the previous prediction model with individual explanatory variables. The NOx emissions were well predicted compared to the measured data.
Kim, Sangmyeong, Kuboyama, Tatsuya, Moriyoshi, Yasuo, Suzuki, Hisakazu
Effects of Environmental Parameters on Real-World NOx Emissions and Fuel Consumption for Heavy-Duty Diesel Trucks Using an OBD Approach2018-01-18179/10/2018
OBD (On-Board Diagnostic) test system is applied to research influences of environmental parameters (altitude and environment temperature) on real-world NOx emission and fuel consumption for heavy-duty diesel trucks in this paper. The research results indicate that altitude and environment temperature have great influence on NOx emission rate and fuel consumption. High altitude in range of 3000~4000 m results in NOx emission rate is lower than low and moderate temperature because of air intake amount decreasing. However the fuel consumption rate is higher than lower altitude because altitude influences real-time changes of air inflow and combustion conditions in the cylinder of the engine. NOx emission rate and fuel consumption is more stable at different vehicle speed, VSP and RPM at high altitude, and NOx emission rate fluctuate dramatically at low and moderate altitude. The fuel consumption rate is higher at 10~20 °C than that at lower and higher temperature. The environment temperature of 20~35 °C provides beneficial conditions for NOx production and deteriorates emission, and the environment temperature of −10~10 °C provides oxygen enrichment environment because of low temperature and high air density, so increases in production amount of NOx. Effects of altitude and environment temperature on NOx emission rate and fuel consumption rate show an opposite tendency. Compared with fuel consumption rate, NOx emission rate is more sensitive to vehicle speed, VSP and rotating speed.
Zhou, Hua, Zhao, Hongwei, Feng, Qian, Yin, Zenghui, Li, JIngyuan, Qin, Kongjian, Li, Mengliang, Cao, Lijuan
Dual Fuel Injection (DI + PFI) for Knock and EGR Dilution Limit Extension in a Boosted SI Engine2018-01-17359/10/2018
Combined direct and port fuel injection (i.e., dual injection) in spark ignition engines is of increasing interest due to the advantages for fuel flexibility and the individual merits of each system for improving engine performance and reducing engine-out emissions. Greater understanding of the impact of dual injection will enable deriving the maximum benefit from the two injection systems. This study investigates the effects of dual injection on combustion, especially knock propensity and tolerance to exhaust gas recirculation (EGR) dilution at different levels of EGR. A baseline for comparison with dual injection results was made using direct injection fueling only. A splash blended E20 fuel was used for the direct injection only tests. For the dual injection tests, gasoline, representing 80% by volume of the total fuel, was injected using the direct injector, and ethanol, representing 20% by volume of the total fuel, was injected using the port fuel injector. EGR mass fraction was varied from 0% to 21%, under boosted intake air pressure of 1.25 bar for both injection strategies. The results showed dual injection was beneficial to shorten the burn duration and improve combustion stability. Dual injection was more sensitive to knock than direct injection primarily due to increased unburned gas temperature. The overall thermal efficiency for the two injection types was comparable. The particulate matter emissions from dual injection showed slightly lower values, and the gaseous emissions showed lower total hydrocarbons and similar nitrogen oxides compared with only using direct injection of E20.
Han, Taehoon, Lavoie, George, Wooldridge, Margaret, Boehman, André
Real Driving NO x Emissions from Euro VI Diesel Buses2018-01-18159/10/2018
Since 2013, Euro VI heavy-duty on-road vehicles have been on the market in the Europe. Regulated exhaust emissions, including nitrogen oxides and particulate matter, have been cut down to a very low level, independent of fuel (diesel or natural gas). Multiple research papers have shown that the regulated emissions from the Euro VI and US 2010 heavy-duty on-road vehicles tested on chassis dynamometers really deliver emission levels which correspond the type approval requirements, independent of the test cycle used. In-service conformity (ISC), which is included in the Euro VI legislation, requires heavy-duty on-road engine manufacturers to test and prove their engines to comply with the emission legislation during the engine in-use period. The measurements are carried out in the field using PEMS (Portable Emission Measurement System) equipment. This kind of testing, depicting real-world emissions is the final stage to confirm low real-life emissions. Although there is evidence that the exhaust aftertreatment systems of Euro VI heavy-duty on-road engines work well on an average, there is only a limited data of city buses covering their functionality over longer operation periods, especially not at lower ambient temperatures. Especially reduction of nitrogen oxides in the SCR-system (Selective Catalytic Reduction) is sensitive to SCR catalyst operation temperature, and also to impurities transferred from engine oil or fuel. This paper present results of a unique combination of chassis dynamometer measurements, on-road PEMS measurements and continuous NOx-emission monitoring during operation in winter condition from four Euro VI diesel city buses operating in the Helsinki metropolitan area. Based on the research done, four Euro VI city buses monitored and measured during the project showed decreased NOx conversion rate and increased tailpipe NOx emissions when operating in ambient temperatures below 0 °C. Especially in ambient temperatures below −10 °C, the continuous monitoring showed dramatically increased tailpipe NOx concentrations.
Söderena, Petri, Nylund, Nils-Olof, Pettinen, Rasmus, Mäkinen, Reijo
Experimental Investigation of the Effect of Karanja Oil Biodiesel with Cerium Oxide Nano Particle Fuel Additive on Lubricating Oil Tribology and Engine Wear in a Heavy Duty 38.8L,780 HP Military CIDI Diesel Engine2018-01-17539/10/2018
Biodiesel fuels are an alternative to diesel fuel. Biodiesel is an oxygenated, sulphur free, non-toxic, biogradable and renewable fuel. It is derived from vegetable oils. Since straight vegetable oils have quite high viscosity compared to mineral diesel, they have to be modified to bring their combustion-related properties and viscosity closer to mineral diesel. This is done by modifying their molecular structure through a transesterification process. In the present study, a military heavy duty 38.8 liter, 585 kW supercharged, compression ignition diesel injection (CIDI) engine was fuelled with diesel, Karanja oil methyl ester (KOME) biodiesel, and KOME biodiesel with cerium oxide fuel additive, respectively. These were subjected to 100 hours long term endurance tests. Lubricating oil samples, drawn from the engine fuelled with these fuels after a fixed interval of 20 hours, were subjected to elemental analysis. Atomic absorption spectroscopy was done for quantification of various metal debris concentrations. Lubricating oil samples were also subjected to ferrography test which indicated lower wear debris concentrations for a biodiesel with fuel additive operated engine. Number of tests was conducted in order to evaluate the comparative performances of these fuels such as lubrication measurement, density measurement, viscosity measurement, total base number etc. The experimental result showed that engine performance with Karanja oil biodiesel with fuel additive increased by 5%, along with lower gaseous emission including 14% - 25% lower NOx emission, and lower total particulate number concentration, as compared to diesel fuel The performance of biodiesel fuel is found to be superior to that of diesel oil. Also, the lubricating oil life is found to be longer while operating the engine on biodiesel with fuel additive. Engine metals wear were found 26% lower for a KOME biodiesel with cerium oxide fuel additive operated engine.
Pandey, Anand Kumar, Nandgaonkar, Milankumar, Pandey, Umang, Suresh, S
The Effect of Cerium Oxide Nano Particles Fuel Additive on Performance and Emission of Karanja Biodiesel Fueled Compression Ignition Military 585kW Heavy Duty Diesel Engine2018-01-18189/10/2018
Global warming with stringent emission legislation along with the depletion of fossil fuel has given us an opportunity to find biodiesel as alternative to diesel fuel. Biodiesel has been widely accepted as comparable fuel to diesel in diesel engine. This is due to its renewable property, better lubricity, along with lesser gaseous emission as compared to diesel fuel. However, there is a major disadvantage in the use of biodiesel as it increases NOx emission. Fuel additive becomes one of the essential tools to overcome the drawback of biodiesel required to meet the international standard of performance and emission. In this study, the performance, combustion, and gaseous emission of CO, CO2, HC, NOx and PM including particle size number distribution characteristics, were compared for diesel, Karanja oil biodiesel, and Karanja oil biodiesel with Cerium Oxide Nano particles fuel additive, in a 12 cylinder, 585 kW, CIDI military diesel engine. The experimental result showed that engine performance with Karanja oil biodiesel with fuel additive increased by 5%, along with lower gaseous emission including 14% - 26% lower NOx emission, lower particulate size number distribution, lower particle size surface area distribution, and lower total particulate number concentration, as compared to diesel fuel.
Pandey, Anand Kumar, Nandgaonkar, Milankumar, Pandey, Umang, Suresh, S, Varghese, Anil
Polycyclic Aromatic Hydrocarbons in Diesel Engine Exhaust Both with and without Aftertreatment2018-01-18129/10/2018
Since the conception of the internal combustion engine, smoky and ill-smelling exhaust was prevalent. Over the last century, significant improvements have been made in improving combustion and in treating the exhaust to reduce these effects. One group of compounds typically found in exhaust, polycyclic aromatic hydrocarbons (PAH), usually occurs at very low concentrations in diesel engine exhaust. Some of these compounds are considered carcinogenic, and most are considered hazardous air pollutants (HAP). Many methods have been developed for sampling, handling, and analyzing PAH. For this study, an improved method for dilute exhaust sampling was selected for sampling the PAH in diesel engine exhaust. This sampling method was used during transient engine operation both with and without aftertreatment to show the effect of aftertreatment. A total of 23 different PAH were measured using a 2012 medium-duty diesel engine equipped with a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic reduction (SCR) catalyst in series. The PAH were then analyzed by gas chromatography/mass (GC/MS) spectrometry to determine the individual concentrations for engine-out (without aftertreatment) and aftertreatment-out emissions. Concentrations for the engine-out PAH were significantly higher than when the aftertreatment was present. PAH in the exhaust were then compared to the PAH in the fuel.
Fanick, E. Robert, Kroll, Svitlana
Holistic Development of Future Low NO x Emission Concepts for Heavy-Duty Applications2018-01-17009/10/2018
Further tightening of NOx emission standards as well as CO2 emission limits for commercial vehicles are currently under discussion. In the on-road market, lowering NOx emissions up to 90%, down to 0.02 g/bhp-hr, has been proposed by CARB and is evaluated by US EPA. Testing for in-service conformity using a portable emission measurement system (PEMS) is currently under review in the US. In Europe, CO2 emission limits are anticipated and a CO2 monitoring program is ongoing. PEMS legislation has been recently tightened and further restrictions can be expected. Stage V legislation has been introduced in Europe and it is foreseeable that further tightening of off-road standards will take place in the future. This study deals with virtual development and evaluation of future engine and exhaust aftertreatment (EAT) technology solutions to fulfill the diverse future emission requirements with emphasis on off-road applications. Considering a future emission standard scenario, first the NOx reduction efficiency of different exhaust aftertreatment layouts is analyzed. Multiple EAT concepts and possible technology solutions combining different technologies are considered. It has been recognized that the future solutions require an integrated approach, combining both novel aftertreatment technology and engine related emission reduction measures. Using a phenomenological combustion model and predictive emission models, the engine model is virtually developed. The full-size physical engine model is coupled to the EAT model to enable a holistic system development. Technology packages for emission reduction and requirements to thermal management of the exhaust gas are defined accordingly. Evaluation of future EAT concepts, multiple emission reduction and advanced heating strategies are performed for a heavy-duty off-road application. Standard certification and a typical real cycle are considered and evaluated.
Rauch, Hendrik, Rezaei, Reza, Weber, Martin, Kovacs, David, Strots, Vadim, Bertram, Christoph
Investigation of Late Stage Conventional Diesel Combustion - Effect of Additives2018-01-17879/10/2018
The accepted model of conventional diesel combustion [1] assumes a rich premixed flame slightly downstream of the maximum liquid penetration. The soot generated by this rich premixed flame is burnt out by a subsequent diffusion flame at the head of the jet. Even in situations in which the centre of combustion (CA50) is phased optimally to maximize efficiency, slow late stage combustion can still have a significant detrimental impact on thermal efficiency. Data is presented on potential late-stage combustion improvers in a EURO VI compliant HD engine at a range of speed and load points. The operating conditions (e.g. injection timings, EGR levels) were based on a EURO VI calibration which targets 3 g/kWh of engine-out NOx. Rates of heat release were determined from the pressure sensor data. To investigate late stage combustion, focus was made on the position in the cycle at which 90% of the fuel had combusted (CA90). An EN590 compliant fuel was tested. To this fuel was added an organic compound, commonly encountered in sunscreen products, that was designed to absorb ultraviolet light. Such a material is postulated to speed up the late stage combustion and thereby improve the thermal efficiency. It was found that both the CA90 and the CA50 were advanced by addition of this material. There is evidence to suggest that addition of the material particularly effects the late stages of combustion, and that it works in a different way to a conventional diesel ignition improver.
Bakker, P.C., Willems, Robbert, Dam, Nico, Somers, Bart, Wakefield, Caroline, Brewer, Mark, Cracknell, Roger
Kinetic Measurements of HNCO Hydrolysis over SCR Catalyst2018-01-17649/10/2018
To meet the strict emission regulations for diesel engines, an advanced processing device such as a Urea-SCR (selective catalytic reduction) system is used to reduce NOx emissions. The Real Driving Emissions (RDE) test, which is implemented in the European Union, will expand the range of conditions under which the engine has to operate [1], which will lead to the construction of a Urea-SCR system capable of reducing NOx emissions at lower and higher temperature conditions, and at higher space velocity conditions than existing systems. Simulations are useful in improving the performance of the urea-SCR system. However, it is necessary to construct a reliable NOx reduction model to use for system design, which covers the expanded engine operation conditions. In the urea-SCR system, the mechanism of ammonia (NH3) formation from injected aqueous urea solution is not clear. Thus, it is important to clarify this mechanism to improve the NOx reduction model. In particular, the investigation of the hydrolysis of isocyanic acid (HNCO), which is formed as an intermediate product in the process of NH3 formation from urea-water solution, is required. Although previous studies have reported the rate constant of HNCO hydrolysis, these were obtained from indirect rather than direct measurements of HNCO. In this study, the reaction rate of HNCO hydrolysis over Cu-ZSM5 catalyst was measured by generating high-purity HNCO and conducting high-precision HNCO measurements. The reaction rate of HNCO hydrolysis is used in the simulation of the urea-SCR system in order to construct a reliable NOx reduction model for system design.
Matsuoka, Masahiro, Kitamura, Takaaki, Obuchi, Akira, Tsuchida, Jun, Tanaka, Kotaro, Konno, Mitsuru
Fuel Stratification Using Twin-Tumble Intake Flows to Extend Lean Limit in Super-Lean Gasoline Combustion2018-01-16649/10/2018
To drastically improve thermal efficiency of a gasoline spark-ignited engine, super-lean burn is a promising solution. Although, studies of lean burn have been made by so many researchers, the realization is blocked by a cycle-to-cycle combustion variation. In this study, based on the causes of cycle-to-cycle variation clarified by the authors’ previous study, a unique method to reduce the cycle-to-cycle variation is proposed and evaluated. That is, a bulk quench at early expansion stroke could be reduced by making slight fuel stratification inside the cylinder using the twin-tumble of intake flows. As a result, the lean limit was extended with keeping low NOx and moderate THC emissions, leading to higher thermal efficiency.
Moriyoshi, Yasuo, Kuboyama, Tatsuya, Kaneko, Makoto, Yamada, Toshio, Sato, Hironao
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