Browse Topic: Selective catalytic reduction (SCR)

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Introducing a new catalyst family in gasoline aftertreatment2026-26-0231To be published on 01/16/2026
This paper is to introduce a new catalyst family in gasoline aftertreatment. Indeed, it has been shown that under certain driving conditions, three-way catalysts produce significant amounts of toxic NH3 and the strong greenhouse gas N2O, which are both very unwanted emissions. In a self-committed approach, OEMs could want to minimize these noxious pollutants, especially if this can be done with no architecture change, namely without additional underfloor catalyst. In this paper we will compare different approaches: regular underfloor TWC, SCR derived from diesel aftertreatment, gasoline dedicated Ammonia Slip Catalyst (ASC) and especially developed novel gasoline Secondary Emission Treatment (SET) catalyst, providing both ammonia abatement and underfloor three-way functionality. The data will show that SCR only reduces NH3 from a passive SCR reaction in a limited amount in the cold start including the need of oxygen presence, namely secondary air introduction. ASC is efficient in cold
Kuhn, Sebastian, Magar, Avinash, Kogel, Julius, Lahousse, Christophe
COMPUTATIONAL STUDY OF HYDROGEN BASED SCR TECHNOLOGY AS AN ALTERNATIVE TO UREA SCR IN HYDROGEN-FUELLED ENGINES2026-26-0213To be published on 01/16/2026
Air pollution from vehicle exhaust emissions is a growing issue in major cities around the world. Hydrogen is a clean and carbon-free fuel that presents a promising alternative to the fossil fuels. However, despite its environmental advantages, hydrogen internal combustion engines still produce some nitrogen oxides as a by-product due to high combustion temperatures. This study investigates the effectiveness of current exhaust after-treatment technologies designed to reduce NOx emissions in hydrogen-powered engines. A comparative analysis is conducted between the conventional urea-based selective catalytic reduction used in diesel engines and emerging hydrogen-based selective catalytic reduction technologies for hydrogen engines. The analysis is performed using CFD simulation in ANSYS Fluent, focusing on NOx reduction efficiency and other operational parameters. The results provide valuable insights into the feasibility and effectiveness of hydrogen SCR in achieving reduced NOx
KASHYAP, KESHAV, Khandagale, Anup, Petale, Mahendra
Mitigating Urea Deposits in Selective Catalytic Reduction Systems through Software Control for Improved Performance in Low Duty Cycle Operations2026-26-0424To be published on 01/16/2026
In the pursuit of achieving stringent BS VI emission standards, maintaining the efficiency of Selective Catalytic Reduction (SCR) systems is paramount, especially in vehicles operating under low duty cycles. A significant concern in such scenarios is the accumulation of urea deposits within the SCR, which can lead to detrimental push-out effects and compromised catalyst performance. This issue is particularly prevalent during low-temperature operations, where the conditions are less favorable for the effective conversion of nitrogen oxides (NOx). To address this challenge, an innovative software control system has been developed to monitor operating conditions and detect potential urea deposit faults. The software continuously evaluates parameters such as temperature and vehicle duty cycle, identifying conditions that may lead to urea crystallization within the SCR system. When unfavorable conditions are detected, the software triggers a fault alert that activates a regeneration
K, Sabareeswaran, K K, Uthira Ramya Bala, Raju, Manikandan, K J, Ramkumar, YS, Ananthkumar
Data-Driven Modeling for Hydrogen ICE Emission Prediction and ATS Performance Benchmarking2026-26-0386To be published on 01/16/2026
This study presents a novel methodology for benchmarking Hydrogen Internal Combustion Engine (H2E) emissions against diesel vehicle configurations, emphasizing Real-Drive Emission (RDE) test procedures. By leveraging Artificial Neural Networks (ANN) and Long Short-Term Memory (LSTM) models, emission profiles for legal cycles and RDE scenarios are predicted. Integrated data pipelines and physics-based modeling enable virtual evaluations of Selective Catalytic Reduction (SCR) system performance, ammonia dosing accuracy, and exhaust temperature dynamics. Key results demonstrate high prediction accuracy across models, including temperature (R² > 0.94, RMS error <25°C), air flow (92% accuracy, RMSE = 28 kg/h), upstream NOx (93% accuracy, RMSE <10 mg/s), and SCR (TP NOx accuracy = 85%, dosing accuracy = 90%). This approach significantly reduces the need for extensive on-road driving tests, as the model performs most of the work, thereby lowering development costs and supporting OEMs in
S, Manoj Kumar, Shah, Jash Vipin, Ratnaparkhi, Aditya, H, Shivaprakash
Design and evaluation of Integrated Engine-Mounted Exhaust Aftertreatment and Air Intake Filtration System with CEV/TREM Stage-5 IC engine for off-highway applications2026-26-0144To be published on 01/16/2026
Conventional exhaust aftertreatment systems (ATS) and air intake filters are typically mounted separately on the vehicle chassis, leading to complex routing, significant packaging volume, thermal management challenges for the ATS, and increased assembly complexity. This paper presents a novel system integrating the air intake filter and the complete exhaust aftertreatment system (including DOC, DPF, SCR components as applicable) into a single unit mounted directly onto the engine. This engine-mounted integrated architecture significantly reduces system footprint, minimizes exhaust and intake piping lengths, potentially improves ATS thermal efficiency through close coupling, and simplifies vehicle assembly. Design considerations, including vibration isolation, serviceability, and potential performance benefits such as reduced pressure drop and faster catalyst light-off, are discussed. This integrated approach offers a compelling solution for optimizing packaging space and system
P U, Balaji, sivasankaran, Siva, Arputharaj, Jeba, Kumar, Lingesh, Pandian, Teja, Patil, Shankar
Advanced Dual Dosing DeNOx System for Optimized NOx Reduction Under Future Emission Regulations2026-26-0230To be published on 01/16/2026
The evolution of global emission standards has imposed increasingly stringent limits on nitrogen oxide (NOx) emissions, particularly under Real Driving Emissions (RDE) testing protocols. These requirements demand effective NOx control across a wide range of operating conditions, posing a challenge for conventional single-injector Selective Catalytic Reduction (SCR) systems. This paper briefs about Dual Dosing SCR System designed to enhance NOx reduction performance by employing two Diesel Exhaust Fluid (DEF) injectors integrated within an advanced exhaust after-treatment system (EATS) configuration. The system features a close-coupled SCR on DPF (SDPF) followed by an underfloor SCR (UFSCR), enabling staged ammonia dosing. This layout promotes improved ammonia distribution and catalytic performance across both low-load and high-speed driving conditions. An Electronic Control Unit (ECU) governs the DEF injection using predefined dosing maps, with reference to real-time data from three
Hareesh, Sangaraju, Shanmugham, Balamurugan, V, Suryanarayanan
Virtual sensor modelling for ammonia slip estimation to improve SCR performance in Real Drive Emissions2024-26-016201/16/2024
Urea-NH3 dosed Selective Catalytic Reduction is powerful reaction system to ensure NOx reduction in the exhaust gases by minimizing ammonia slip. When the dosed ammonia exceeds the actual request than the required, NH3 to NOx ratio is potentially high, the unused ammonia is limited to 10ppm corresponding to experimental result of every World Harmonic Transient Cycle. The dosage estimation depends on the NOx sensors which has this drawback of high cross-sensitivity to ammonia that can affect the measurement of NOx and compromise the SCR-ASC closed loop strategies. This paper aims to resolve the complexity in prediction of ammonia slip to resolve the cross-sensitivity of tailpipe NOx sensor in the SCR system by a closed loop estimation of NOx and ammonia slip to ensure high NOx conversion efficiency. The focus is to develop a simplified model-based solution for estimating ammonia slip, because of the limitations in the real drive conditions in SCR system. This model approach is designed
K, Sabareeswaran, M, Jayashree, YS, Ananthkumar
On- Board Diagnosis of Improper Reductant Detection in BS6 SCR System Using Virtual Sensor Modelling2024-26-025601/16/2024
Selective Catalytic Reduction (SCR)is an optimized technology developed to encounter current BS6 Emission Regulations. AdBlue is the reductant used in the SCR Dosing system to eliminate NOx in the Exhaust gas. In order to ensure engine emissions compliance, insufficient or improper reductant in tank required to be detected. The right AdBlue concentration of 32.5% is highly necessary to attain the higher NOX conversion efficiency. Low concentration of the reductant will drastically reduce the NOx conversion in the system. Hence monitoring the AdBlue concentration in the tank itself is more important as per the OBD legislation. This implies on a physical quality sensor in the tank for detecting the reductant concentration. The functionalities of the quality sensor can also be instituted via a virtual software modelling called Improper Reductant Detection (IRD). IRD logic is highly robust and work competently to meet the BS6 stage 2 legislation’s NOx target. The reductant is suspected
YS, Ananthkumar, K, Sabareeswaran, M, Jayashree
After Treatment Sensors Positioning for BS6.2 Diesel Engine2024-26-003901/16/2024
BS6 emission standards were implemented in India in 2020 followed by BS6.2 which added more controls on emission limits. For BS6.2 OBD (On Board Diagnostics) and RDE (Real Driving Emission) were added on to the existing BS6 emissions. For the current 1.5L, 3 cylinder diesel engine an pSCR (Passive Selective Catalytic Reduction) brick was added for control of NOx for meeting RDE. For meeting OBD requirements PM (Particulate Matter) and NOx sensors were added in the cold end pipe along with calibration changes to meet the BS6.2 norms. In this paper we will discuss on the design aspects of sensors and pSCR only. The sensor and pSCR positioning plays vital role in meeting the legislative requirements and to ensure the ease of assembly and durability of the parts. In this paper we discuss on the various options explored for positioning, the constraints of sensor application and the importance of positioning on the emission compliance. Post the sensor positioning, parts were made and
vinaya murthy, Vijayendra, Rengaraj, Chandrasekaran, Dharan R, Bharani, Sasikumar, M
Optimized Soot Monitoring by Ammonia injection in a sDPF system for BS 6.22024-26-014101/16/2024
The BS6 norms (phase 1) were implemented in India from April 1, 2020 and replaced the previous BS4 norms. Phase 2 of the BS6 norms, which came into effect on April 1, 2023. In accordance with the regulation requirement, effective performance of after treatment systems like DPF and SCR demands critical hardware implementation and robust monitoring strategies in the extended operating zone. Effective OBD monitoring of DPF, which is common to all BSVI certified vehicles, such that the defined strategy detects the presence or absence of the component is imperative. A robust monitoring strategy is developed to detect the presence of the DPF in the real world incorporating the worst possible driving conditions including idling, and irrespective of other environmental factors subject to a location or terrain. The differential pressure sensor across the DPF is used to study the actual pressure drop across the DPF. Additional for BS 6 (phase 2) PM sensor becomes an important part to keep the
Sharma, Prashant, Hareesh, Sangaraju, V, Suryanarayanan, Palanisamy, Krishnaraj, P, Jagdesan, Rathiya, Akash
A Holistic Approach For Near Zero Emission Diesel Vehicles Using A Pre-Turbo-Catalyst-System – Ready For EU 72023-01-121106/26/2023
This work shows the newest results of a near-series Pre-Turbo-Catalyst (PTC) system reaching lowest emissions for electrified diesel passenger cars to address future emission legislation. The PTC system is developed using a state-of-the-art tool chain containing 1D & 3D simulation approaches and testing near-series exhaust gas aftertreatment systems under real-driving boundary conditions. The innovative concept of an SCR PTC and a PTC bypass path solve the challenge of a thermal handshake between PTC and underfloor SCR System as well as the challenge of a particular filter regeneration. The development of adaptive PTC bypass path operation strategies based on exhaust gas and catalyst conditions enables lowest NOx and NH3. Using this concept, near-zero emissions can be reached in a wide range of operating scenarios while sustaining full drivability and highest efficiency. Advanced catalyst technologies enable a high emission conversion and lowest secondary emissions. These results have
Conin, Michael, Beidl, Christian, Knaf, Daniel, Fiore, Luis, Kreuz, Joachim
Concept-based Evaluation and Development of Close-Coupled DOC through Model in Loop Simulation supported by Experimental Investigations on 3L Light & Medium Duty BS - VI Diesel Engine2022-01-067803/29/2022
The implementation of stringent BSVI norms from April 2020 has greatly revolutionized the automobile industry. With the plan for implementation of more stringent BSVI OBD-II norms from April 2023, in place, meeting legislative limits, particularly with CI engines, will be a challenge. The major challenge is the reduction in nitrogen oxides (NOx) which necessitates a selective catalytic reduction (SCR) together with effective calibration, to maintain the conversion efficiencies at the highest possible levels. The conversion efficiency is majorly dictated by temperature and exhaust mass flow. Hence, optimization of thermal management modes would be very important for meeting legislative emission limits. This is achieved by a close-coupled diesel oxidation catalyst (DOC). This paper describes the stepwise effectiveness of model based development to perform model in the loop simulation in virtual test bed (VTB), along with, experimental testing that goes hand in hand for development of a
R, Nishant Sharma, Lakhlani, Hardik
Integrated exhaust manifold design & optimization of it through HCF and LCF simulations for a BS6 compliant Diesel engine2021-28-016810/01/2021
This paper discusses design aspects of an integrated design of exhaust manifold with turbocharger for a 3 cylinder diesel engine, simulation activities (CAE and CFD), and validation of manifold while upgrading to meet current BS6 emissions. Exhaust after-treatment system needs to be upgraded from a simple DOC (Diesel Oxidation Catalyst) to a complex DOC+sDPF (Selective catalytic reduction coated on Diesel Particulate Filter) to meet the BS6 emission norms. To avoid thermal losses and achieve a faster light-off temperature in the catalyst, the exhaust after-treatment (EATS) system needs to be placed close to the engine – exactly at the outlet of the turbocharger. This has given to challenges in packaging the EATS. The turbocharger in case of BS4 is placed near the 2nd cylinder of the engine, but this position will not allow placing the BS6 EATS. Hence, the turbocharger position must be shifted to such an extent that it is placed before the first cylinder resulting in an overhanging
vinaya murthy, vijayendra, NAMANI, Prasad, Vellandi, Vikraman, Rengaraj, Chandrasekaran
Study of Fuel in Oil Dilution Due to Aftertreatment Regeneration in Automotive Diesel Engine2021-26-018409/22/2021
The Bharat Stage VI emission norms in India is driving the use of more complex after treatment systems for diesel engines. The after-treatment system typically includes DOC, DPF and SCR to reduce the engine out hydrocarbon, particulates & NOx respectively. For a durable functioning of the after-treatment system, cleaning of these components at regular intervals is required. One such method is to burn the diesel fuel inside DOC, to clean the DPF and SCR, a process called regeneration. Regeneration involves using extra diesel fuel injected into the exhaust stream, which gets oxidized in the DOC thereby regenerating the DPF or SCR. Present technology uses the existing injectors in the diesel engine for regeneration which is cost effective and simpler compared to the external hydrocarbon dosing system. In-cylinder hydrocarbon dosing is associated with the risk of fuel getting mixed with engine oil. This happens because the regeneration fuel is injected in the exhaust stroke where the
Vinay P, Ashwyn, Verma, Utkarsh, Goswami, Imon, Suresh, Swathy
Rational design of Cu-SSZ-13 catalyst for the selective catalytic reduction of NOx to meet BS-VI emission standards2021-26-018109/22/2021
To achieve healthier and sustainable air quality and to protect human life, worldwide emission standards are being tightened for harmful vehicular air pollutants such as CO, hydrocarbon, NOx and particulate matters. Among selective catalytic reduction catalysts for NOx control in automotive after treatment system, Cu-SSZ-13 (Chabazite structure) is one of the most promising SCR catalyst, mainly used in light and heavy duty diesel vehicles. This article focuses on the development of Cu-SSZ-13 with desired properties such crystallinity, morphology, surface area and Cu loading in the catalyst. With the help of sophisticated catalyst characterization tools such as NH3-Temperature Programmed Desorption (TPD), Temperature Programmed Reduction (TPR), BET surface area, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), novel and highly active formulations of Cu-SSZ-13 are reported here. Furthermore a correlation between the physico-chemical properties and catalytic performance of
Narkhede, Vijay, Patel, Rajesh, Tinwala, Tanzeem, Sabde, Dhananjay, Kumar, Dinesh, Sidiquie, Touquire A
Experimental and Numerical Investigations of Sprays in Crossflow in Aftertreatment Systems2021-01-059604/06/2021
Selective catalytic reduction (SCR) of oxides of nitrogen (NOx) with gaseous ammonia is the leading technology used to meet on- and off-highway NOx emission standards across the world. In typical SCR systems, a low-pressure injector introduces a solution of urea and water (UWS) into hot exhaust gases leading to atomization and subsequent spray processes that finally lead to production of gaseous ammonia. Through their synergetic effect, the UWS injector and mixing enhancement devices (such as static mixers or baffles) help deliver a uniform mixture of ammonia and NOx to the SCR catalyst with minimal urea-derived solid deposits. To develop an efficient and robust aftertreatment system, it is essential to have experimental and simulation capabilities to assess the behavior of sprays under flow conditions representative of engine exhaust. The experimental part of the present work uses an optically accessible, cold- or hot-flow capable test section (called Insitu test section) that allows
Munnannur, Achuth, Blessinger, Matthew, Liu, Z. Gerald
Characterization of Physical and Chemical Properties of Particulate Emissions of a Modern Diesel-Powered Tractor under Real Driving Conditions2020-01-220409/15/2020
In this study, tailpipe-sampling was used to sample the exhaust aerosol of a Stage IV tractor equipped with Diesel Oxidation Catalyst (DOC) and Selective Catalytic Reduction (SCR) aftertreatment systems. The particle emissions were characterized in terms of number concentration (particle size of > 2.5 nm), mass concentration (particle size of 6-612 nm) BC mass concentration and chemical composition (particle size of > 30 nm). The measurements were conducted on-road by setting a mobile laboratory on a trailer and pulling it with the tractor. In addition to driving, heavy-lift work cycles were tested, where separate lifts of a 1000 kg weight were conducted with the front fork of the tractor with two minutes of idling between consecutive lifts. Both a Porous Tube Diluter (PTD) with ambient temperature dilution air as well as an ejector diluter with hot dilution air were used to sample the exhaust aerosol. Emission factors for particle number, particle mass and BC (mass) were calculated in
Martikainen, Sampsa, Karjalainen, Panu, Rönkkö, Topi, Järvinen, Anssi, Kalliokoski, Joni, Keskinen, Jorma, Ntziachristos, Leonidas, Teinilä, Kimmo, Saarikoski, Sanna, Aurela, Minna, Timonen, Hilkka, Saveljeff, Henna, Lauren, Mika
A Novel Approach for the Impingement of AdBlue-Droplets based on Smooth Regime Transitions2020-01-217909/15/2020
Further development of exhaust aftertreatment systems based on selective catalytic reduction (SCR) requires detailed knowledge of all involved physical and chemical processes. One major influence is the impingement of the injected urea water solution (UWS) droplets on the hot walls of the exhaust system. Due to the numerous influencing factors of this complex phenomenon, it is described by empirical impingement maps based on experimental investigations. Frequently, the impacting droplet is assigned to a single impingement regime (e.g. splash) according to surface temperature and a kinetic parameter (e.g. Bai-Gosman, Bai-ONERA, Kuhnke). A transitional range between regimes has been reported experimentally before, but was abandoned in most cases for model simplification reasons. Only rarely a smooth transition for a selected regime boundary was implemented. However, the still widespread use of hard limits is questionable for CFD, as an arbitrarily small temperature difference around a
Quissek, Max, Budziankou, Uladzimir, Lauer, Thomas
Reaction Path Analysis and Modeling of NOx Reduction in a Cu-chabazite SCR Catalyst Considering Cu Redox Chemistry and Reversible Hydrolysis of Cu Sites2020-01-218109/15/2020
In this study, reaction path analysis and modeling of NOx reduction phenomena by selective catalytic reduction (SCR) with NH3 over a Cu-chabazite catalyst were conducted considering changes in the valence state of Cu sites and local structure due to differences in ligands to the Cu sites. The analysis showed that in the Cu-chabazite catalyst, NOx was mainly reduced by adsorbed NH3 on divalent Cu sites accompanied by a change in valence state of Cu from divalent to monovalent. It is known that the activation energy of NOx reduction on a Cu-chabazite catalyst changes between low temperatures ≤ 200 °C and mid to high temperatures ≥ 300 °C. To express this phenomenon, a reversible hydrolysis reaction based on the difference in coordination state of hydroxyl groups (OH−) to Cu sites at low and high temperatures was introduced into the model. The results showed that NOx reduction phenomena can be expressed over a wide temperature range by using the activation energy specific to the Cu
Tsukamoto, Yoshihisa, Ueyama, Rikuto, Ogawa, Kenya, Seki, Keiichiro, Kunisu, Masahiro, Fukuma, Takao, Kusaka, Jin
An Experimental Facility for Rapid Testing of SCR Systems2020-01-219209/15/2020
Urea-SCR (selective catalytic reduction) has become the principal technology used to lower NOx emissions in automotive compression ignition engines. Although the technology is well known and developed, the stricter emissions’ limits force engineers to implement new approaches to reduce warm-up time and improve the mixing process of the urea-water solution with the exhaust gases while avoiding a solid deposit formation. The exhaust system’s design is optimized using 3D numerical methods, but the validation of the design’s performance requires prototype testing on an engine dynamometer, where it is difficult to decouple and adjust the exhaust gas composition and temperature as in the numerical model; and thus it is problematic to verify the model. In this study we propose an experimental facility for rapid testing of SCR systems in simulated and precisely controlled engine-relevant conditions. The experimental set-up presented here uses heated atmospheric air with an addition of nitrogen
Boruc, Łukasz, Rogoz, Rafał, Bachanek, Jakub, Kapusta, Łukasz Jan, Jaworski, Piotr, Sutkowski, Marek, Teodorczyk, Andrzej, Jarosinski, Sebastian
CO 2 Emissions Reduction through a New Multi-Functional Fluid for Simultaneous NOx and Particles Abatement2020-01-217009/15/2020
Since the Euro VI/6 regulation came into force in 2013/2014, most of the Diesel applications are equipped with both selective catalytic reduction (SCR) systems and Diesel particulate filters (DPF). On the one hand, SCR requires ammonia for the reduction of nitrogen oxides (NOx) created during the combustion process. An aqueous urea solution (AUS) containing 32.5% wt. urea, such as AdBlue® is injected into the hot exhaust gas upstream of the SCR catalyst to produce ammonia for NOx reduction. On the other hand, DPF demonstrates very high particle filtration efficiency, but requires to be periodically regenerated at high temperature to burn off accumulated soot. The regeneration temperature and duration can be significantly lowered by using fuel additives (fuel-borne catalyst or FBC) or by washcoating a catalyst into the DPF (catalyzed DPF or cDPF). However, this second technique is no longer applicable when SCR catalyst is implemented on filters); continuous combustion of soot is
Zinola, Stephane, Raux, Stephane, Pasquier, David, Trela-Baudot, Emmanuelle, Melgar, Joris, Obiols, Jerome, Callu, Cyrille, Collin, Annabelle
On the Effects of Urea and Water Injection on Particles across the SCR Catalyst in a Heavy - Duty Euro VI Diesel Engine2020-01-219609/15/2020
Particle emissions from heavy-duty engines are regulated both by mass and number by Euro VI regulation. Understanding the evolution of particle size and number from the exhaust valve to the tail pipe is of vital importance to expand the possibilities of particle reduction. In this study, experiments were carried out on a heavy-duty Euro VI engine after-treatment system consisting of diesel oxidation catalyst, diesel particulate filter and selective catalytic reduction (SCR) unit with AdBlue injection followed by ammonia slip catalyst. The present work focusses on the SCR unit with regard to total particle number with and without nucleation particles both. Experiments were conducted by varying the AdBlue injection quantity, SCR inlet temperature [to vary the reaction temperature], exhaust mass flow rate [to vary the residence time in SCR], and fuel injection pressures [to vary inlet particle number and inlet NOx]. Sampling for particle measurements was performed at the inlet, upstream
K, Arun Prasath, Bernemyr, Hanna, Erlandsson, Anders
Hydrogen Selective Catalytic Reduction of Nitrogen Oxide on Pt- and Pd-Based Catalysts for Lean-Burn Automobile Applications2020-01-217309/15/2020
The utilization of H2 to catalytically treat NO emissions under lean-burn engine exhaust conditions was studied on Pt- and Pd-containing catalysts supported on CeO2 and MgO. The catalytic performance was examined using a fixed-bed reactor whose dry effluent gas stream was analyzed by an online FTIR analyzer. The catalysts NO conversion and N2 selectivity were measured in the range of 125-3000C with a feed gas composition of 0.05%NO/1%H2/10%O2/N2. The CeO2-based catalysts exhibited higher NO conversion, and the most effective catalyst was Pd/CeO2, with a conversion of 67% and selectivity of 70% near 2300C. The prepared solids were characterized using different techniques (BET, ICP-OES, CO pulse chemisorption, STEM, EELS and EDS) to correlate the structural and morphological properties of the metallic phase and the support with the catalytic activity. CeO2 is a more effective support as it yields higher metal dispersion and better facilitates the reduction of the Pt and Pd catalysts.
Alghamdi, Nawaf M., Restrepo Cano, Juan, Anjum, Dalaver H., Im, Hong G., Kalamaras, Christos, Gascon, Jorge, Sarathy, S. Mani
On-Road Emissions of Euro 6d-TEMP Vehicles: Consequences of the Entry into Force of the RDE Regulation in Europe2020-01-221909/15/2020
Human health and the environment are heavily impacted by air pollution. Air quality standards for Nitrogen dioxide (NO2) and particulate matter (PM) are commonly exceeded in Europe, particularly in urban areas with high density of traffic. Road transport contributed to 39% of NOx emissions, and 11% of PM emissions in the European Union (EU) in 2017. Measurements with Portable Emissions Measurement Systems (PEMS) showed that most Euro 5 and Euro 6b diesel vehicles emitted significantly more NOx on the road than their permissible limit in the laboratory type-approval test. In that context, EU Real Driving Emissions (EU-RDE) regulation aims at securing low on-road emissions of light duty vehicles under normal conditions of use. This paper assesses the tailpipe emissions performance of Euro 6d-TEMP gasoline and diesel passenger cars, type-approved after the entry into force of the RDE regulation in September 2017. Vehicles were tested by the Joint Research Centre (JRC), the in-house
Valverde Morales, Victor, Clairotte, Michael, Pavlovic, Jelica, Giechaskiel, Barouch, Bonnel, Pierre
The Variation of Functional Characteristics of a Euro VI Selective Catalytic Reduction Reactor after Ageing2020-01-220509/15/2020
The selective catalytic reduction (SCR) of nitrogen oxides by ammonia is commonly applied as a method of exhaust aftertreatment for lean burn compression ignition (CI) engines. The catalytic reactor of an SCR system, like all catalytic emission control devices, is susceptible to partial deactivation as its operating time progresses. Long-term exposure of an SCR reactor to exhaust gas of fluctuating temperature and composition results in variations of the characteristics of its catalytically active layer. The aim of this study was to observe and investigate the variation of parameters characterizing the SCR reactor as a result of its ageing. Attention was paid to changes in ammonia storage capacity, selectivity of chemical reactions and maximum achievable NOx conversion efficiency. The experimental setup was a heavy duty (HD) Euro VI-compliant engine and its aftertreatment system (ATS). The setup was installed on a transient engine dyno instrumented with emission measurement devices
Dzida, Jakub, Bielaczyc, Piotr, Brzeżański, Marek
An Analysis of Emissions at Low Ambient Temperature from Diesel Passenger Cars Using the WLTP Test Procedure2020-01-218609/15/2020
The aim of this paper is to analyse the results of regulated and unregulated emissions and carbon dioxide (CO2) emissions of passenger cars equipped with compression-ignition engines that meet the emission Euro 6d standards. Both test vehicles featured selective catalytic reduction (SCR) systems for control of oxides of nitrogen (NOx) and one vehicle also featured a passive NOx absorber (PNA). Research was performed using the current European Union exhaust emission test methods for passenger cars (Worldwide harmonized Light vehicles Test Procedures (WLTP)). Emission testing was performed on a chassis dynamometer, within a climatic chamber, at two different ambient temperatures: 23°C (i.e. Type I test) and -7°C (known as a Type VI test - currently not required for this engine type according to EU legislative requirements). Gaseous and particulate emissions limited in the Euro 6 standard were measured using the applicable legislative procedures and the additional components CO2, NH3
Adamiak, Borys, Puchalka, Bartosz, Woodburn, Joseph, Szczotka, Andrzej, Bielaczyc, Piotr
Fuel Dosing on a Diesel Oxidation Catalyst for After-Treatment System Heating on a Heavy-Duty Engine Powered by Polyoxymethylene Dimethyl Ethers2020-01-215709/15/2020
Polyoxymethylene dimethyl ethers (OME) are synthetic fuels, which offer the property of sustainability because the reactants of production base on hydrogen and carbon dioxide on the one hand, and the air pollution control in consequence of a soot-free combustion in a diesel engine on the other hand. High exhaust gas recirculation (EGR) rates are a promising measure for nitrogen oxide (NOx) reduction without increasing particle emissions because of the resolved soot-NOx trade-off. However, EGR rates towards stoichiometric combustion in OME operation reveals other trade-offs such as methane and formaldehyde emissions. To avoid these, a lean mixture with a combination of EGR and exhaust after-treatment with selective catalytic reduction (SCR) is useful. The limitation of urea dosing due to the light-off temperature of SCR systems requires heating measures. Besides electrical heating, fuel injection into the diesel oxidation catalyst (DOC) for an exothermic reaction is an effective method
Gelner, Alexander D., Pastoetter, Christian, Beck, Harald A., Härtl, Martin, Wachtmeister, Georg
Numerical Optimization of a SCR System Based on the Injection of Pure Gaseous Ammonia for the NOx Reduction in Light-Duty Diesel Engines2020-01-035604/14/2020
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
Della Torre, Augusto, Montenegro, Gianluca, Onorati, Angelo, Cerri, Tarcisio, Tronconi, Enrico, Nova, Isabella
Probabilistic Analysis of Bimodal State Distributions in SCR Aftertreatment Systems2020-01-035504/14/2020
Sensor selection for the control of modern powertrains is a recognised technical challenge. The key question is which set of sensors is best suited for an effective control strategy? This paper addresses the question through probabilistic modelling and Bayesian analysis. By quantifying uncertainties in the model, the propagation of sensor information throughout the model can be observed. The specific example is an abstract model of the slip behaviour of Selective Catalytic Reduction (SCR) DeNOx aftertreatment systems. Due to the ambiguity of the sensor reading, linearization-based approaches including the Extended Kalman Filter, or the Unscented Kalman Filter are not successful in resolving this problem. The stochastic literature suggests approximating these nonlinear distributions using methods such as Markov Chain Monte Carlo (MCMC), which is able in principle to resolve bimodal or multimodal results. However, the most effective methods are Hamiltonian solvers, which again struggle
Comissiong, Rhys, Steffen, Thomas, Shead, Leo
Simulation of Aftertreatment Thermal Management Strategies for Low-Load Operation2020-01-035904/14/2020
The low-NOx regulation for heavy duty trucks proposed by California’s Air Resources Board (CARB) will present a significant challenge to truck, engine and aftertreatment system manufacturers. This regulation will include a new test cycle representative of low-load operation. With low-load cycles, NOx conversion by the SCR (selective catalytic reduction) system is limited primarily by the exhaust temperature; thus, thermal management will dominate development. Simulation can be used to examine different thermal management strategies, and to define high-level requirements for new components. In this study, modeling was used to investigate SCR performance on two different low-load cycles, including the one selected by CARB for the low-NOx regulation. First, the “thermal deficit” of the cycle was quantified using a constant heat input. Next, direct heating of the exhaust with a fuel mini-burner or an electric heater, using realistic controls, was simulated to determine their capability to
Harris, Thomas
Optimal Aftertreatment Pre-Heat Strategy for Minimum Tailpipe NO x Around Green Zones2020-01-036104/14/2020
Green zones are challenging problems for the thermal management systems of hybrid vehicles. This is because within the green zone the engine is turned off, and the only way to keep the aftertreatment system warm is lost. This means that there is a risk of leaving the green zone with a cold and ineffective aftertreatment system, resulting in high emissions. A thermal management strategy that heats the aftertreatment system prior to turning off the engine, in an optimal way, to reduce the NOx emissions when the engine is restarted, is developed. The strategy is also used to evaluate under what conditions pre-heating is a suitable strategy, by evaluating the performance in simulations using a model of a heavy-duty diesel powertrain and scenario designed for this purpose. The results show that, for the studied vehicle, pre-heating of the aftertreatment system is an effective strategy to reduce NOx for engine-off events shorter than two hours, and is most effective for engine off events of
Holmer, Olov, Willems, Frank, Blomgren, Fredrik, Eriksson, Lars
Ammonia Measurement Investigation Using Quantum Cascade Laser and Two Different Fourier Transform Infrared Spectroscopy Methods2020-01-036504/14/2020
Most diesel engine exhausts have been fitted with SCR (Selective Catalyst Reduction) in order to reduce NOX (Oxides of Nitrogen) by using NH3 (ammonia). However, both NOX and NH3 have been classified as compounds hazardous for the environment and human health. If the reaction between NOX and NH3 is unbalanced during treatment, it can lead to either NOX or NH3 being released into the environment. Accurate measurement is thus necessary. QCL (Quantum Cascade Laser) and FTIR (Fourier Transform InfraRed) are two methods that have been used to measure NH3 and NOX directly in diesel engine exhausts. However, only a few studies have compared those two methods of NH3 measurement, mainly from diesel engine exhausts. The aim of this paper is to compare the QCL and 2 different FTIR specifications for NH3 measurement directly from diesel engine exhausts under well-controlled laboratory conditions. Researchers have found that as NH3 is reactive, it is absorbed inside the exhaust pipe if the probe
Li, Nilton, El-Hamalawi, Ashraf, Barrett, Richard, Baxter, Jim
Design, Development and Analysis of Mullite Catalytic Converter for CI Engines2019-28-001710/11/2019
Emissions of Hydrocarbon (HC), Carbon Monoxide (CO) and Oxides of Nitrogen (NOx) are the largest concerns for fossil fuel driven automotive vehicles. Catalytic converter is an important component in the selective catalytic reduction process. It oxidizes harmful CO and HC emission to CO2 and H2O in the exhaust system and thus the emission is controlled. Different kinds of problems are associated with noble metal based catalytic converter. A catalytic converter with a new catalyst for compression ignition engine is considered in this study. The catalytic converter is designed and developed with a new catalyst. Due to better durable characteristics and poison resistant nature, non-noble metal based material limestone (mullite) is selected as a catalyst for catalytic convertor and the emission characteristics are studied on four stroke single cylinder CI engine by using mullite based catalytic converter. The results are compared without catalytic converter in the same engine. In the design
Pandiaraj, Selvakumar, Subbaiyan, Dhamotharan, Ayyasamy, Tamilvanan, Nagarajan, Sathishkumar
Analysis of TWC Characteristics in a Euro6 Gasoline Light Duty Vehicle2019-24-016209/09/2019
A Euro6 gasoline light duty vehicle has been tested at the engine dynamometer and the emissions have been analyzed upstream and downstream the Three-Way-Catalyst (TWC) during a WLTC cycle. Catalyst simulations have been used for assessing the processes inside the catalytic converter using a reaction scheme based on 19 brutto reactions (direct oxidation and reduction, selective catalytic reductions with CO, C3H6 and H2, steam reforming, water-gas shift and bulk ceria as well as surface ceria reactions). The reactions have been parameterized in order to best approximate the measurements. Based on the reactions taken into account, the real vehicle emissions can be predicted with good accuracy. The simulations show that the cycle emissions comprise mainly the cold start contribution as well as discrete emission break-through events during transients. During cold start no reactions are evident in the catalyst before the temperature of the gas entering the catalyst reaches 270°C. Following
Papetti, Viola, Dimopoulos Eggenschwiler, Panayotis, Emmanouil, Vasiliki, Koltsakis, Grigorios
Review of Vehicle Engine Efficiency and Emissions2019-01-031404/02/2019
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
Joshi, Ameya
Accelerating Accurate Urea/SCR Film Temperature Simulations to Time-Scales Needed for Urea Deposit Predictions2019-01-098204/02/2019
Urea water solution-based Selective Catalytic Reduction (SCR) of NOx emissions from vehicular diesel engines is now widely used world-wide to meet strict health and environmental protection regulations. While urea-based SCR is proven effective, urea-derived deposits often form near injectors, on mixers and pipes, and on the SCR catalyst face. Further understanding of these deposit-formation processes is needed to design aftertreatment system hardware and control systems capable of avoiding severe urea-derived deposits. Computational Fluid Dynamics (CFD) is widely used in SCR aftertreatment design. Film formation, movement, solid wall cooling and deposit initiation/growth time-scales are in the range of minutes to hours, but traditional CFD simulations take too long to reach these time-scales. Here, we propose and demonstrate the frozen flow approach for pulsed sprays and conjugate heat transfer to reduce computation time while maintaining accuracy of key physics. The motivation and
Maciejewski, Daniel, Sukheswalla, Parvez, Wang, Chu, Drennan, Scott A., Chai, Xiaochuan
Optimization of a Diesel Engine with Variable Exhaust Valve Phasing for Fast SCR System Warm-Up2019-01-058404/02/2019
Early exhaust valve opening (eEVO) increases the exhaust gas temperature by faster termination of the power stroke and is considered as a potential warm up strategy for diesel engines aftertreatment thermal management. In this study, first, it is shown that when eEVO is applied, the engine main variables such as the boost pressure, exhaust gas recirculation (EGR) and injection (timing and quantity) must be re-calibrated to develop the required torque, avoid exceeding the exhaust temperature limits and keep the air fuel ratio sufficiently high. Then, a two-step procedure is presented to optimize the engine operation after the eEVO system is introduced, using a validated diesel engine model. In the first step, the engine variables are optimized at a constant eEVO shift. In the second step, optimal eEVO trajectories are calculated using Dynamic Programming (DP) for a transient test cycle. The optimized results indicate that with early EVO, the boost pressure should be increased to provide
Srinivas, Pavan Kumar, Salehi, Rasoul
Identification of Film Breakup for a Liquid Urea-Water-Solution and Application to CFD2019-01-098304/02/2019
The reduction of NOx-emissions from diesel engines is crucial for the fulfilment of environmental standards. Selective catalytic reduction (SCR) is an effective way to achieve very low tailpipe NOx-emission levels. For an efficient after treatment system, a homogeneous distribution of gaseous ammonia across the catalytic surface is essential. Therefore, a detailed understanding of the impingement of the injected urea water solution (UWS), its evaporation and transformation to gaseous ammonia is of vital importance. Due to the complex physics of the impingement process, the simulation of SCR systems with computational fluid dynamics (CFD) relies upon empirical models known as impingement maps. In the current study a droplet chain generator was used to investigate single droplet impingement of UWS. The impingement events were filmed with a high speed camera and then analysed with respect to impingement velocity and droplet diameter as well as droplet Weber-number. Together with the
Quissek, Max, Lauer, Thomas, García-Afonso, Oscar, Fowles, Stewart
Deposit Reduction in SCR Aftertreatment Systems by Addition of Ti-Based Coordination Complex to UWS2019-01-031304/02/2019
Formation of urea-derived deposits in selective catalytic reduction (SCR) aftertreatment systems continues to be problematic at temperatures at and below 215 °C. Several consequences of deposit formation include: NOx and NH3 slip, exhaust flow maldistribution, increased engine backpressure, and corrosion of aftertreatment components. Numerous methods have been developed to reduce deposit formation, but to date, there has been no solution for continuous low-temperature dosing of Urea-Water Solution (UWS). This manuscript presents a novel methodology for reducing low-temperature deposit formation in SCR aftertreatment systems. The methodology described herein involves incorporation and dissolution of an HNCO hydrolysis catalyst directly into the UWS. HNCO is a transient species formed by the thermolysis of urea upon injection of UWS into the aftertreatment system. Ideally HNCO undergoes hydrolysis to form NH3 and CO2, but under certain conditions HNCO may polymerize or react with other
Hartley, Ryan, Henry, Cary, Eakle, Scott, Tonzetich, Zachary
Towards Quantitative Prediction of Urea Thermo-Hydrolysis and Deposits Formation in Exhaust Selective Catalytic Reduction (SCR) Systems2019-01-099204/02/2019
In order to assist in fast design cycle of Diesel engines selective catalytic reduction (SCR) exhaust systems, significant endeavor is currently being made to improve numerical simulation accuracy of urea thermo-hydrolysis. In this article, the achievements of a recently developed urea semi-detailed decomposition chemical scheme are assessed using three available databases from the literature. First, evaporation and thermo-hydrolysis of urea-water solution (UWS) single-droplets hanged on a thin thermocouple ring (127 μm) as well as on a thick quartz (275 μm), have been simulated at ambient temperature conditions ranging from 473K to 773K. It has been shown that the numerical results, in terms of evaporation rate and urea gasification, as well as droplet temperature history are very close to the experiments if the heat flux coming from the droplet support is properly accounted for. Indeed, an additional conduction flux has proved to be necessary in the evaporation model in order to
Habchi, Chaouki, Quan, Shaoping, Drennan, Scott, Bohbot, Julien
Engine-Aftertreatment in Closed-Loop Modeling for Heavy Duty Truck Emissions Control2019-01-098604/02/2019
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
Gao, Zhiming, Deter, Dean, Smith, David, Pihl, Josh, Daw, C. Stuart, Parks, James
Modeling of Close-Coupled SCR Concepts to Meet Future Cold Start Requirements for Heavy-Duty Engines2019-01-098404/02/2019
The low-NOx standard for heavy-duty trucks proposed by the California Air Resources Board will require rapid warm-up of the aftertreatment system (ATS). Several different aftertreatment architectures and technologies, all based on selective catalytic reduction (SCR), are being considered to meet this need. One of these architectures, the close-coupled SCR (ccSCR), was evaluated in this study using two different physics-based, 1D models; the simulations focused on the first 300 seconds of the cold-start Federal Test Procedure (FTP). The first model, describing a real, EuroVI-compliant engine equipped with series turbochargers, was used to evaluate a ccSCR located either i) immediately downstream of the low-pressure turbine, ii) in between the two turbines, or iii) in a by-pass around the high pressure turbine. These simulations indicate that the location downstream of the low-pressure turbine offers nearly the best NOx conversion, and that the optimal volume of the ccSCR in this
Harris, Thomas Miller, Mc Pherson, Kristoffer, Rezaei, Reza, Kovacs, David, Rauch, Hendrik, Huang, Yinyan
Experimental and Computational Study of DOC on CSF for Heavy Duty Diesel Applications2019-01-058604/02/2019
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
Sethuraman, Sharan, Sitamraju, Siddarth, Lopez-De Jesus, Yaritza M, Markatou, Penelope
Study on Improvement of NOx Reduction Performance at Low Temperature Using Urea Reforming Technology in Urea SCR System2019-01-031704/02/2019
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
Okada, Yuichi, Hirabayashi, Hiroshi, Sato, Shinya, Inoue, Hiroshi
Low Pressure-Driven Injection Characterization for SCR Applications2019-01-099404/02/2019
Aqueous Urea is a non-toxic and stable ammonia carrier and its injection and mixing represent the basis for the most common de-NOx technology for mobile applications. The reactant feed preparation process is defined by evaporation, thermolysis and hydrolysis of the liquid mixture upstream the Selective Catalytic Reduction reactor, and it is strongly dependent on the interaction between spray and gaseous flow. Low-pressure driven injectors are the common industrial standard for these applications, and their behavior in almost-ambient pressure cross flows is significantly different from any in-cylinder application. For this reason, two substantially different injectors in terms of geometry and design are experimentally studied, characterizing drop sizes and velocities through Phase Doppler Anemometry (PDA) and liquid mass spatial distribution through Shadow Imaging (SI). The measurements involve the analysis of the spray in quiescent air conditions, gathering information at the closest
Nocivelli, Lorenzo, Montenegro, Gianluca, Dimopoulos Eggenschwiler, Panayotis
Model-Based Approaches in Developing an Advanced Aftertreatment System: An Overview2019-01-002601/15/2019
Cummins has recently launched next-generation aftertreatment technology, the Single ModuleTM aftertreatment system, for medium-duty and heavy-duty engines used in on-highway and off-highway applications. Besides meeting EPA 2010+ and Euro VI regulations, the Single ModuleTM aftertreatment system offers 60% volume and 40% weight reductions compared to current aftertreatment systems. In this work, we present model-based approaches that were systematically adopted in the design and development of the Cummins Single ModuleTM aftertreatment system. Particularly, a variety of analytical and experimental component-level and system-level validation tools have been used to optimize DOC, DPF, SCR/ASC, as well as the DEF decomposition device. The highlights of this work can be summarized as follows: a). internal dosing is more efficient than external dosing to control HC slip; High CPSI DOCs show better HC oxidation performance at high SV due to enhanced mass transfer; b). the adopted advanced
Su, Changsheng, Brault, Joseph, Munnannur, Achuth, Liu, Z. Gerald, Milloy, Sean, Harinath, Arvind, Dunnuck, David, Federle, Ken
NOx-Conversion Comparison of a SCR-Catalyst Using a Novel Biomimetic Effervescent Injector on a Heavy-Duty Engine2019-01-004701/15/2019
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
Larsson, Peter, Ravenhill, Paul, Tunestal, Per
Influence of the Backpressure on Urea Sprays Generated by an Air-Blast Atomizer for Large-Scale SCR-Applications2019-01-004601/15/2019
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
Höltermann, Markus, Wichmar, Jan, Dinkelacker, Friedrich
Kinetic Modeling of Ammonia-SCR and Experimental Studies over Monolithic Cu-ZSM-5 Catalyst2019-01-002401/15/2019
Ammonia-selective catalytic reduction (SCR) systems have been introduced commercially in diesel vehicles, however catalyst systems with higher conversion efficiency and better control characteristics are required to know the actual emissions during operation and the emissions in random test cycles. Computational fluid dynamics (CFD) is an effective approach when applied to SCR catalyst development, and many models have been proposed, but these models need experimental verification and are limited in the situations they apply to. Further, taking account of redox cycle is important to have better accuracy in transient operation, however there are few models considering the cycle. Model development considering the redox reactions in a zeolite catalyst, Cu-ZSM-5, is the object of the research here, and the effects of exhaust gas composition on the SCR reaction and NH3 oxidation at high temperatures are investigated. The simulations are compared with the experimental results of a surrogate
Eijima, Wataru, Shibata, Gen, Kobashi, Yoshimitsu, Koiwai, Ryutaro, Ogawa, Hideyuki, Shimizu, Kenichi, Kusaka, Jin
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
Nakano, Kota, Okano, Hiroaki, Inoue, Katsushi, Obuchi, Akira
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