Browse Topic: Selective catalytic reduction (SCR)

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Advanced Aftertreatment System Meeting Future HD CNVII Legislation II2025-01-8478To be published on 04/01/2025
With the increasing clarity of the CNVII emission legislation, it is foreseeable that CNVII will further tighten the emissions of major pollutants such as nitrogen oxide (NOx), nitrous oxide (N2O) and PN. Together with the implementation of stage IV of fuel consumption legislation in January 2025, which requires engine fuel consumption reduction or thermal efficiency improvement, it will inevitably lead to the further deterioration of its pollutant emissions and reduction of exhaust temperature, posing greater challenges to the aftertreatment system (ATS) in terms of NOx removal during engine cold start and suppressing N2O formation. This study is an extension of our earlier investigation of “Advanced Aftertreatment System Meeting Future HD CNVII Legislation” (Wang, Y., Chen, S., Zhang, J., Chen, J. et al., "Advanced Aftertreatment System Meeting Future HD CNVII Legislation," SAE Technical Paper 2024-01-2379, 2024, https://doi.org/10.4271/2024-01-2379.), a novel copper-based corrugated
Wang, Yan, Fu, Guangxia, Chen, Shuyue, Aberg, Andreas, Jiang, Shuiyan, Zhang, Jun
Technical Paper
The Role of Hydrogen in Exhaust Gas Aftertreatment Systems of Hydrogen Combustion Engines2025-01-8496To be published on 04/01/2025
Hydrogen internal combustion engines (H2-ICE) do not emit any fuel-borne carbon emission species. Nitrogen oxides are the remaining raw emission species at significant levels. However, the exhaust aftertreatment system is exposed to a different exhaust matrix, including unburned hydrogen. This raises the question of the role of hydrogen emissions for the aftertreatment system. Extensive synthetic gas bench (SGB) test campaigns address the role of hydrogen in several production catalyst components. Starting with selective catalytic reduction (SCR) systems, a systematic variation of the hydrogen concentration shows rather small effects on the NOX reduction performance. A change in selectivity results in increased secondary N2O emissions for a copper-zeolite system, whereas a vanadium-based SCR catalyst is unaffected. However, both SCR types are highly sensitive to the NO2/NOX ratio in the raw emission. Therefore, an upstream oxidation catalyst remains important for cold start performance
Sterlepper, Stefan, Lampkowski, Alexander, Himmelseher, Katrin, Özyalcin, Can, Claßen, Johannes, Pischinger, Stefan
Technical Paper
A Comparison of Stochiometric and Lean Burn Ammonia-Hydrogen Co-fuelling in a Modern Spark ignition Engine.2025-01-8432To be published on 04/01/2025
Ammonia (NH3) is emerging as a promising fuel for longer range decarbonised heavy transport, predominantly due to relative favourable characteristics as an effective hydrogen carrier. This is despite generally unfavourable combustion and toxicity attributes, restricting end use to applications where robust health and safety protocols can always be assured. In the currently reported work a spark ignited thermodynamic single cylinder research engine was equipped with separate gaseous ammonia and hydrogen port injection fuelling, with the aim of understanding the impact of varied co-fuelling upon combustion, fuel economy and engine-out emissions (and the arising implications upon future emissions after-treatment). Under stoichiometric conditions, the engine could be operated in a stable manner on pure NH3 at low-to-medium speeds and medium-to-high engine loads, with up to ~20% hydrogen (by energy) required at the lowest engine loads. Engine-out NH3 emissions remained relatively high
Ambalakatte, Ajith, Geng, Sikai, Murugan, Reese, Varaei, Amirata, Cairns, Alasdair, Harrington, Anthony, Hall, Jonathan, Bassett, Michael
Technical Paper
Comprehensive Prediction of Deposit Formation in SCR Systems Using Integrated 1D Heat Transfer Model with Empirical Data from 3D CFD Simulations2025-01-8491To be published on 04/01/2025
Urea-based selective catalytic reduction (SCR) systems are widely used to meet stringent NOx emission standards in industrial diesel engines. However, suboptimal design of the urea-water solution (UWS) mixing pipes in SCR systems can lead to the formation of urea-derived solid deposits, which may adversely affect the system performance and reliability. Although recent advancements in deposit simulation technology using three-dimensional Computational Fluid Dynamics (3D CFD) have significantly improved the performance and compactness of mixing pipes, assessing deposit formation across all operating and environmental conditions remains challenging due to high simulation costs. This study introduces a novel computational method for predicting the formation and temperature of permanent liquid films from UWS injection which are closely related to deposit formation, along with new deposit evaluation criteria based on them. This proposed method integrates a one-dimensional heat transfer model
Sugimoto, Kazuma, Kawabe, Ken
Technical Paper
Formation and Decomposition of Ammonium Sulfate Species over a Small Pore Cu/zeolite Catalyst2025-01-8493To be published on 04/01/2025
Cu/zeolite selective catalytic reduction (SCR) catalysts are used globally to reduce NOx emissions from diesel engines. These catalysts can achieve high NOx conversion efficiency, and they are hydrothermally durable under real world diesel exhaust environments. However, Cu/zeolite catalysts are susceptible to sulfur poisoning and require some type of sulfur management even when used with ultra-low sulfur diesel (ULSD). In the present study, the authors seek to better illuminate the chemical processes responsible for ammonium sulfate formation and decomposition occurring in Cu/zeolite SCR catalysts. Reactor-based experiments are first conducted with a real-world concentration of SO2 (0.5 ppmv) and a typical diesel exhaust water vapor concentration (8 vol.%) to quantify progressive effects of ammonium sulfate formation. BET surface area is used to measure the impact of ammonium sulfate on the Cu/zeolite catalysts’ physical properties. A second group of experiments probe the chemical
Ottinger, Nathan, Xi, Yuanzhou, Liu, Z. Gerald
Technical Paper
Experimental Study of DOC-on-Filter using next Generation filter solutions for Non-Road Applications2025-01-8479To be published on 04/01/2025
Upcoming California Tier 5 non-road limits mandate 90% and 75% reductions in NOx and PM respectively, from current Tier 4F emission standards. Similarly, lower NOx and PN/PM limits can be expected from a next round of European Non-Road regulations. To meet these limits, more SCR volume for greater NOx reduction, and better filtration efficiency filters for greater PN/PM reduction, may be required. The challenge is to accommodate larger SCR volume while maintaining oxidation (DOC) and filtration (DPF) functionality of the aftertreatment system within a limited packaging space on non-road machineries. Consolidating DOC and DPF into a single component as DOC-on-filter instead of separate DOC and DPF substrates to achieve space saving has been previously discussed in literature. This study expands on the current understanding and explores various functional performance characteristics of the DOC-on-filter concept in comparison with DOC + bare DPF, DOC + PGM coated DPF. The three test
Dam, Mrinmoy, Warkins, Jason, He, Suhao
Technical Paper
Experimental and CFD simulation study of heated and cold Diesel Exhaust Fluid Spray characteristics2025-01-8486To be published on 04/01/2025
This paper investigates heated and cold Diesel Exhaust Fluid (DEF) sprays with the aim of establishing the effect of temperature on the resulting spray characteristics. The work is motivated by the need to optimize active Selective Catalytic Reduction (SCR) systems to meet more stringent NOx emission regulations for internal combustion engines. Pre-heating DEF has the potential to improve evaporation of the injected fluid, increasing the NOx conversion efficiency of the SCR at low exhaust temperatures. Experiments are carried out using the MAHLE SmartHeat fluid heater and mounted atop a DEF injector, with an incorporated thermocouple for fluid temperature. The fluid temperature established by the heater in this configuration was about 130 °C. The fluid is injected into an atmospheric environment and Schlieren imaging is used to visualize the spray evolution. CFD Simulations are also carried out to validate the experimental observations and further shed light on the associated velocity
Liu, Zeyang, Peters, Nathan, Bunce, Mike, Pothuraju Subramanyam, Sai, Akih Kumgeh, Benjamin
Technical Paper
Efficient Modeling of SCR Urea Deposits Formation Using ANSYS Fluent2025-01-8485To be published on 04/01/2025
Selective Catalytic Reduction (SCR) systems, used for exhaust gas aftertreatment in diesel engines and newly designed H2 engines, are pushed for efficiency by strict emission regulations and requirements for fuel efficiency in road vehicles, ships and power stations. To reduce costs and time during the development process of such systems, CFD is an adequate tool to investigate and improve geometrical designs. Such CFD models require coupled physics like turbulent gas flow, liquid sprays that impinge on hot walls considering complex splashing regimes and formed wall-films driven by gas shear and gravity. All these sub-flow systems exchange momentum, energy and mass via vaporization and chemical reactions. SCR aftertreatment is prone to solid deposit formation on the walls, which hinders heat transfer and causes increased pressure losses. Therefore, it is crucial to be able to predict deposition locations and rates and optimize vaporization of water-urea droplets and mixing of gaseous
Sofialidis, Dimitrios, Mutyal, Jayesh, Faltsi, Rana, Braun, Markus, Börnhorst, Marion, Esch, Thomas
Technical Paper
Prediction and control of long-term system degradation for a light-off SCR in an ultra-low NOx aftertreatment system2025-01-8488To be published on 04/01/2025
The medium-duty low NOx program funded by CARB at Southwest Research Institute (SwRI) evaluates a combination of engine and advanced aftertreatment systems to achieve a 0.02 g/bhp-hr tailpipe NOx standard. This work emphasizes improvements to the light-off SCR (LO SCR) model used for low NOx controls. Two key mechanisms drive these improvements: the first is a real-time feedback system that utilizes the LO SCR outlet NOx sensor for short-term corrections to the model state, and the second involves adjustments to the dosing mechanism based on long-term trends in dosing signals compared to predicted NH3 consumption, derived from LO SCR inlet and outlet NOx sensors, referred to as long-term trim. An algorithm is incorporated to differentiate the LO SCR outlet NOx sensor readings into NOx and NH3 components based on cross-correlation. The integration of this speciation algorithm with both short-term and long-term trim mechanisms significantly enhances the accuracy of the model state, as
Chundru, Venkata Rajesh, Adsule, Kartik, Sharp, Christopher
Technical Paper
Study on the Impact of Arrangement of Urea Injector and Mixer in Diesel Engine Selective Catalytic Reduction System on Ammonia Uniformity02-18-02-000702/12/2025
With the continuous upgrading of emission regulations for internal combustion engines, the nitrogen oxide treatment capacity of selective catalytic reduction (SCR) aftertreatment needs to be continuously improved. In this study, based on a prototype of SCR aftertreatment, the impact of the arrangement of key components in the SCR system (urea injector, mixer, and catalyst unit) on ammonia uniformity was investigated. First, parameterized designs of the urea injector, mixer, and SCR unit were conducted. Then, using computational fluid dynamics (CFD), numerical simulations of the established aftertreatment system models with different parameter factors were performed under a high-exhaust temperature and a low-exhaust temperature conditions to study the impact of each individual parameter on ammonia uniformity. Finally, an optimized solution was designed based on the observed patterns, and the optimized samples were tested on an engine performance and emission test bench to compare their
Jie, Wang, Jin, Jianjiao, Wu, Yifan
Journal Article
Prediction of Diesel Engine NO x Transient Emissions Based on a Combined Model with Convolutional Neural Network–Efficient Channel Attention–Bidirectional Gated Recurrent Unit03-18-02-001202/06/2025
Widely used as power equipment, diesel engines emit NO x , which significantly threatens the well-being of both the ecosystem and individuals. The SCR system, which is employed to reduce NO x emissions from diesel engines, relies on precise control of the NO x emission levels. Addressing the challenge that traditional NO x emission prediction methods struggle to accurately forecast the emissions under transient operating conditions, this article introduces a deep learning model that integrates CNN, ECA, and BIGRU. The model’s necessary experimental data were collected during the hot phase of the WHTC, and input parameters were screened through correlation analysis. The model employs a CNN for feature extraction, integrates an ECA module to refine key feature processing, and utilizes BIGRU to capture temporal dynamics and dependencies, yielding predictive outcomes. Additionally, the model employs the Adam optimizer and combines it with BWO to adjust hyperparameters, thereby elevating
Peng, Yunlong, Wang, Guiyong, Wang, Yuhua, Wang, Feiyang, Wang, Zhiyuan, He, Shuchao
Journal Article
Enhanced High-Temperature Performance of NH 3 -SCR Catalysts for Lean-Burn Engines2025-01-704301/31/2025
NOx after-treatment has greatly limited the development of lean-burn technology for gasoline engines. NH3-Selective Catalytic Reduction (SCR) technology has been successfully applied to NOx conversion in diesel engines. For gasoline engines, SCR catalyst is required to maintain high activity over a higher temperature window. In this study, we utilized a turbocharged and intercooled 2.0 L petrol engine to investigate the NOx conversion of two zeolite-based SCR catalysts, Cu-SSZ-13 and Fe/Cu-SSZ-13, at exhaust flows ranging from 80 to 300 kg/h and exhaust temperatures between 550 to 600°C. The catalysts were characterized using SEM, ICP, XRD, H2-TPR, NH3-TPD, and other methods. The selected Fe/Cu-SSZ-13 catalyst showed higher NOx conversion (>80%) in the temperature range of 550~600oC and 80~300 kg/h exhaust gas flow. NOx output could be controlled below 10ppm. The characterization results showed that although the specific surface area and acidic sites decreased after the aging treatment
Pan, Shiyi, Wang, Ruwen, Zhang, Nan, Xu, Zhiqin, Hu, Jiangtao, Liao, Xiuke, Duan, Pingping, Chen, Ruilian
Technical Paper
Machine Learning Approach to Control Thermal Strategies and Mitigate Sensor Failure Penalty on Emissions2024-28-017012/05/2024
As vehicle emission standards are becoming stringent worldwide because of the looming climate crisis, it is important to control the pollutants that vehicles emit. To achieve the stringent emission target, it has become a priority to enhance the capability of Emission Control System (ECS) which consist of Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR) sub-systems. One of the bottlenecks is the limited operating temperature range of the after-treatment system. In modern emission control systems, the temperature characteristics should always be optimized to have the best efficiency involving chemical conversions. To achieve this optimal operating temperature, different thermal control strategies are followed in the Engine and emission control unit. Temperature sensor values are one of the primary inputs for thermal management strategies. In the event of temperature sensor malfunction, the ECS performance is affected due to
Kumar, Amit, V H, Yashwanth, Kumar, Raman, Hegde, Karthik, Manojdharan, Arjungopal
Technical Paper
Novel UWS Injection Technique for SCR Performance Improvement2024-28-013312/05/2024
The present study aims to meet the Euro-VII compliance applicable for internal combustion engines (diesel and hydrogen) by improving the performance of selective catalytic reduction (SCR) system using a novel urea water solution (UWS) mist injection technique. In SCR system, the interaction of exhaust gas and UWS resulted into ammonia (NH3) species, which is mixed with harmful NOx emission and converted into harmless by-products. Despite the proven technology, there are several challenges presented in the existing system which restricts the ideal performance of SCR system especially during cold starting condition: (i) incomplete droplet evaporation (ii) solid deposit formation (iii) non uniformity of NH3 distribution at the catalyst entrance. The past studies shows that the droplet size plays a major role in this context. Further, it is noted that the smaller size droplets are desirable to overcome the impediments and enhance the efficiency of SCR application. Therefore, it is decided
Venkatachalam, Palaniappan, Shiva, Shashidhar, Govindarajan, Vaishali, Soni, Prerna, Patidar, Sachin
Technical Paper
Experimental and Numerical Investigations on the Effect of Urea Pulse Injection Strategies to Reduce NOx Emission in Urea-SCR Catalysts2024-01-430411/05/2024
A major challenge for auto industries is reducing NOx and other exhaust gas emissions to meet stringent Euro 7 emission regulations. A urea Selective Catalyst Reduction (SCR) after-treatment system (ATS) commonly uses upstream urea water injection to reduce NOx from the engine exhaust gas. The NOx emission conversion rate in ATSs is high for high exhaust gas temperatures but substantially low for temperatures below 200°C. This study aims to improve the NOx conversion rate using urea pulse injection in a mass-production 2.2 L diesel engine equipped with an SCR ATS operated under low exhaust gas temperature. The engine experimental results show that, under 200°C exhaust temperature and 3.73x104 h-1 gross hourly space velocity (SV), the NOx conversion rate can be improved by 5% using 5-sec ON and 12-sec OFF (denoted as 5/12 s) urea pulse supply compared to the constant supply under time-averaged 1.0 urea equivalence ratio. It is experimentally observed that the urea pulse supply’s
Yoshida, Fuka, Takahashi, Hideaki, Kotani, Yuya, Zu, Qiuyue, Sok, Ratnak, Kusaka, Jin
Technical Paper
The Effect Mechanism of Grain Size with Nanoscale and Microscale on Physical and Chemical Properties of Cu/SSZ-13 SCR Catalyst2024-01-430511/05/2024
Selective catalytic reduction (SCR) technology is currently one of the most effective methods to reduce NOx emissions for engine. NH3-SCR technology is also considered to be the most promising hydrogen engine after-treatment device. This paper used Cu-SSZ-13, which is widely commercially available, as the research object, and explored the relationship between micron and nanoscale grain sizes through experimental methods such as BET, XRD, NH3-TPD, UV-vis-DRS and activity testing, the influence mechanism of micron-scale and nano-scale grain size on the morphology and properties of Cu/SSZ-13 catalyst was explored. The results show that the fresh nanoscale 900F sample has higher low-temperature NOx conversion efficiency, while the micron-scale 1800F sample has poor low-temperature activity and better high-temperature activity. This is closely related to its morphological characteristics, adsorption and desorption characteristics and dual-site properties. The specific surface area and total
Chen, Yajuan, Lou, Diming, Zhang, Yunhua, Tan, Piqiang, Fang, Liang, Hu, Zhiyuan
Technical Paper
Future Emissions Following 800,000 Mile Aging Using CDA and a Low Power Electric Heater2024-01-301107/02/2024
Engine and aftertreatment solutions have been identified to meet the upcoming ultra-low NOx regulations on heavy duty vehicles in the United States. These standards will require changes to current conventional aftertreatment systems for dealing with low exhaust temperature scenarios while increasing the useful life of the engine and aftertreatment system. Previous studies have shown feasibility of meeting the US EPA and California Air Resource Board (CARB) requirements. This work includes a 15L diesel engine equipped with cylinder deactivation (CDA) and an aftertreatment system that was fully DAAAC aged to 800,000 miles. The aftertreatment system includes an e-heater (electric heater), light-off Selective Catalytic Reduction (LO-SCR) followed by a primary aftertreatment system containing a DPF and SCR. The e-heater was capable of providing up to 10 kW, however for the purpose of this project, lower power settings of 2.5 kW and 5 kW were studied in combination with CDA for lowest
Kramer, Jan, Rice, Michael, Zavala, Bryan, Sharp, Christopher, McCarthy, James, Karrer, Ben
Technical Paper
Acceleration of Fast-SCR Reaction by Eliminating “The Ammonia Blocking Effect”2024-37-000106/12/2024
Electricity, e-fuel and H2 are considered important recent and future sources of energy for heavy-duty vehicles. Heavy-duty battery electric vehicles (BEV) have many technical challenges. Therefore, internal combustion engines (ICE) powered by e-fuel and hydrogen can be used as an alternative to batteries in heavy-duty trucks. Selective catalytic reduction (SCR) systems are necessary for achieving the goals of zero-emission internal combustion engines that use e-fuel or H2 as a fuel. The Japanese automotive industry mainly utilizes Cu-Zeolite-based SCR catalysts since vanadium-based catalysts have been difficult to be used to prevent the release of vanadium into the atmosphere due to the relatively low evaporation temperature. This study investigated whether improving the conversion rate by pulsing the NH3 supply was possible. Experiments were conducted in a mini-reactor with an inflow of simulated exhaust gas to examine the effect of the pulse amplitude, frequency, and duty ratio on
Morita, Daiki, Kotani, Yuya, Zu, Qiuyue, Yoshida, Fuka, Sok, Ratnak, Kusaka, Jin
Technical Paper
Development of Optimal Specification of Exhaust Purification System for Euro7 Commercial Diesel Legislation2024-01-262704/09/2024
In this study, an integrated emission prediction model was used to predict whether EURO7-compliant commercial internal combustion engine vehicles would be able to meet upcoming regulations. In particular, the optimal value of Adblue injection and EHC (Electrically Heated Catalyst) control strategy for each combination of the specifications of the close-coupled SCR system (volume, substrate spec., EHC, etc.) was derived. Through this, it was intended to derive the best specification combination in terms of control and emission performance, and to use the results as a basis for decision-making in the early stages of product concept selection.
Cho, Jiho, Choi, Sungmu, Lee, Sang Min, Hwang, Dong Min
Technical Paper
Numerical Modeling of Liquid Film Boiling, Urea Deposition and Solidification in SCR Applications2024-01-262604/09/2024
The proposed Euro 7 regulation aims to substantially reduce the NOx emissions to 0.03 g/km, a trend also seen in upcoming China 6b and US EPA regulations. Meeting these stringent requirements necessitates advancements in Urea/Selective Catalytic Reduction (SCR) aftertreatment systems, with the urea deposit formation being a key challenge to its design. It’s proven that Computational Fluid Dynamics (CFD) can be an effective tool to predict Urea deposits. Transient wall temperature prediction is crucial in Urea deposit modeling. Additionally, fully understanding the kinetics of urea decomposition and by-products solidification are also critical in predicting the deposit amount and its location. In this study, we introduce (i) a novel film boiling model (IFPEN-BRT model) and (ii) a new urea by-product solidification model in the CONVERGE CFD commercial solver, and validate the results against the recent experiments. The IFPEN-BRT model handles the spray-wall heat transfer in various
Bhatt, Mrugank P., Yang, Pengze, Habchi, Chaouki
Technical Paper
Electrically Heated Mixer for Near-Zero Urea Deposit2024-01-237704/09/2024
When used with injecting urea-water solution forming ammonia, Selective Catalytic Reduction (SCR) catalyst is a proven technology for greatly reducing tailpipe emission of nitrogen oxides (NOx) from Diesel engines. However, one major shortcoming of an SCR-based system is forming damaging urea deposits (crystals) in low temperature exhaust operations, especially exacerbated during higher injection rates. Deposits reduce SCR efficiency, damage exhaust components, and induce high concentration ammonia slips. We describe here an Electrically Heated Mixer (EHM™) demonstrated on a Diesel engine markedly inhibiting deposit formation in urea SCR systems, both in low (near 200 °C) and higher exhaust temperature operations and for both low and high urea injection rates in various, realistic engine operations. Engine test runs were conducted in long durations, 10 to 20 hours each, for a total of nearly 100 hours. In nearly all operation modes, EHM maintained deposits below 1% of the total
Vernham, Bruce, Kadam, Vaibhav, Masoudi, Mansour, Noorfeshan, Sahm, Poliakov, Nick
Technical Paper
System Level Simulation of H2 ICE after Treatment System2024-01-262504/09/2024
Hydrogen Internal Combustion Engines (H2 ICE) are gaining recognition as a nearly emission-free alternative to traditional ICE engines. However, H2 ICE systems face challenges related to thermal management, N2O emissions, and reduced SCR efficiency in high humidity conditions (15% H2O). This study assesses how hydrogen in the exhaust affects after-treatment system components for H2 ICE engines, such as Selective Catalytic Reduction (SCR), Hydrogen Oxidation Catalyst (HOC), and Ammonia Slip Catalyst (ASC). Steady-state experiments with inlet H2 inlet concentrations of 0.25% to 1% and gas stream moisture levels of up to 15% H2O were conducted to characterize the catalyst response to H2 ICE exhaust. The data was used to calibrate and validate system component models, forming the basis for a system simulation. System model validation involved comparing the model against real-world data from production diesel engine after-treatment systems for transient cycles, including Federal Test
Chundru, Venkata Rajesh, Sharp, Christopher, Rahman, Mohammed Mustafizur, Balakrishnan, Arun
Technical Paper
Reducing Emissions from Lean-Burn Hydrogen Combustion Engines Using a State-of-the-Art Oxidation Catalyst and a VWTi-Based SCR Catalyst: Potentials and Challenges2024-01-263404/09/2024
Hydrogen (H2) is commonly considered as one of the most promising carbon-free energy carriers allowing for a decarbonization of combustion applications, for instance by retrofitting of conventional diesel internal combustion engines (ICEs). Although modern H2-ICEs emit only comparably low levels of nitrogen oxides (NOx), efficient catalytic converters are mandatory for exhaust gas after-treatment in order to establish near-zero emission applications. In this context, the present study evaluates the performance of a commercial state-of-the-art oxidation catalyst (OC) and of a catalyst for selective catalytic reduction (SCR) that are typically used for emission reduction from diesel exhausts under conditions representative for H2-fueled ICEs, namely oxygen-rich exhausts with high water vapor levels, comparably low temperatures, and potentially considerable levels of unburnt H2. Herein, the OC is supposed to convert H2 slippage, which can occur due to incomplete combustion, and to oxidize
Lott, Patrick, Schäfer, Kathrin, Deutschmann, Olaf, Werner, Manuel, Weinmann, Philipp, Zimmermann, Lisa, Toebben, Heike
Technical Paper
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
M, Jayashree, K, Sabareeswaran, YS, Ananth Kumar
Technical Paper
Optimized Soot Monitoring by Ammonia Injection in a sDPF System for BS6.2 Application2024-26-014101/16/2024
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
Technical Paper
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 a 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
K, Sabareeswaran, M, Jayashree, YS, Ananthkumar
Technical Paper
After Treatment Sensors Positioning for BS6.2 Diesel Engine2024-26-003901/16/2024
BS6.1 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 BS6.1 emissions. Emission control changes usually need addition of new parts, calibration changes and durability requirements. 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. We discuss on the various options explored for positioning, the constraints of sensor application and the importance
Vinaya Murthy, Vijayendra, Rengaraj, Chandrasekaran, Dharan R, Bharani, Sasikumar, M
Technical Paper
Flexible Heating and Heat Retention Technology for Efficient Treatment of Exhaust Gases in Diesel Engines2024-26-014401/16/2024
In the Journey towards Zero Emission and decarbonization, with emerging advancement in technology form current BS6 to near future EURO7 standards of emission, these emission norms are achievable when we amalgamate with an assistive technology of Electrically Heated System for thermal management in Diesel emission control i.e., called CatVap®. With the increasingly stringent limits on vehicle pollutants- including NOx emission levels are fulfilled with Twin Urea Dosing mechanism. These comprehensive lists of advanced technology to converge lowest NOx emissions without increasing CO2 emissions. The Major effort in the existing structure is to accelerate the SCR temperature and enhance the conversion efficiency of NOx in Real Drive Emission during cold start and low load duty cycle. CatVap®system provides sufficient thermal energy to facilitate rapid heating in the course of low load cycles and cold city rides for efficient gas conversion. As they are used to accelerate the light-off
YS, Ananthkumar, K, Sabareeswaran, M, Jayashree
Technical Paper
The Effect of Different Air Path Based ATS Thermal Management Strategy on a Non- EGR Medium Duty Diesel Engine’s Performance and Emissions2024-26-003801/16/2024
The major objective of this paper is to develop thermal management strategy targeting optimum performance of Selective Catalytic Reduction (SCR) catalyst in a Medium Duty Diesel Engine performing in BS6 emission cycles. In the current scenario, the Emissions Norms are becoming more stringent and with the introduction of Real Drive Emission Test (RDE) and WHTC test comprising of both cold and hot phase, there is a need to develop techniques and strategies which are quick to respond in real time to cope with emission limit especially NOx. SCR seems to be suitable solution in reducing NOx in real time. However, there are limitations to SCR operating conditions, the major being the dosing release conditions which defines the gas temperature at which DEF (Diesel Exhaust Fluid) can be injected as DEF injection at lower gas temperatures than dosing release will lead to Urea deposit formation and will significantly hamper the SCR performance. The second factor for optimum SCR operation is to
Sharma, Ajeet Kumar, Kreuzig, Gerhard, Gupta, Ayush, Goyal, Dinesh, Garg, Varun
Technical Paper
24SIAT-0900: Heavy Duty Vehicle Aftertreatment Technologies for the Future: What May Be Required at BSVII?2024-26-014901/16/2024
This paper describes the after-treatment technology that could be used to meet a future BS-VII standard, considering close-coupled SCR (cc-SCR) to help start NOx conversion earlier. Both active (Cu/Fe-SCR based) and passive (V-SCR based) systems have the potential to meet emission limits. V-SCR may be considered in the rear position because V-SCR shows a fast response with very low N2O formation. Next-gen V-SCR technology shows significantly improved performance and durability closer to Cu-SCR. The steady-state NOx conversions over Next-Gen V-SCR were better than BS-VI V-SCR in both fresh and aged-580°C/100h conditions. High durability was also observed after engine aging of 1000h (WHTC + high load). Another big challenge in BS VII could be the PN10 requirement. With enhanced filtration coating (EFC) technology, PN emissions drop drastically in comparison to Euro VI reference without EFC to meet a future BS VII.
Singhania, Amit, Wallin, Mikaela, Edvardsson, Jonas, Chatterjee, Sougato, Vediappan, Sudhagar, Komori, Mitsuru, Phillips, Paul
Technical Paper
Experimental and Modeling Study of NH 3 -SCR on a Hydrocarbon-Poisoned Cu-CHA Catalyst2023-01-165910/31/2023
A urea-selective catalytic reduction (SCR) system is used for the reduction of NOx emitted from diesel engines. Although this SCR catalyst can reduce NOx over a wide temperature range, improvements in NOx conversion at relatively low temperatures, such as under cold-start or low-load engine conditions, are necessary. A close-coupled SCR (cc-SCR), which was set just after the engine exhaust manifold, was developed to address this issue. The temperature of the SCR catalyst increases rapidly owing to the higher exhaust temperatures, and NOx conversion is then enhanced under cold-start conditions. However, since the diesel oxidation catalyst is not installed before the SCR catalyst, hydrocarbon (HC) emissions pass directly through the SCR catalyst and poison it, leading to lower NOx conversion. Therefore, the mechanism of NOx conversion reduction on HC-poisoned SCR catalysts are required to be studied. In this study, the effects of HC poisoning on the NOx conversion of Cu-CHA catalysts
Tanaka, Kotaro, Dobashi, Ibuki, Sakaida, Satoshi, Konno, Mitsuru
Journal Article
Post-Mortem Analysis of DAAAC and Conventionally Aged Aftertreatment Systems2023-01-165610/31/2023
Upcoming regulations from CARB and EPA will require diesel engine manufacturers to validate aftertreatment durability with full useful life aged components. To this end, the Diesel Aftertreatment Accelerated Aging Cycle (DAAAC) protocol was developed to accelerate aftertreatment aging by accounting for hydrothermal aging, sulfur, and oil poisoning deterioration mechanisms. Two aftertreatment systems aged with the DAAAC protocol, one on an engine and the other on a burner system, were directly compared to a reference system that was aged to full useful life using conventional service accumulation. After on-engine emission testing of the fully aged components, DOC and SCR catalyst samples were extracted from the aftertreatment systems to compare the elemental distribution of contaminants between systems. In addition, benchtop reactor testing was conducted to measure differences in catalyst performance. Sulfur was deposited uniformly on the aftertreatment components while the oil derived
Seuser, Grant, Eakle, Scott, Rahman, Mohammed Mustafizur, Sharp, Christopher, Zavala, Bryan
Technical Paper
Product concept and design process of an SCR Mixer to solve trade-off between urea mixing uniformity and exhaust loss and to improve engineering efficiency2023-32-006309/29/2023
This study presents the development of newly proposed SCR mixer for diesel engine that improves vehicle NOx emission without rebound of the exhaust pressure loss. Unique SCR mixer structure which produces multiple vortices can realize lower NOx emission due to the highly uniform mixing of NH3 generated from the SCR spray and the exhaust gas, compared to the conventional mixer which produce a single vortex. Through its unique mixer structure constructed with some blades that generate multiple vortices. In order to study the mixer structure in a short period of time, 2 steps design process have been studied by separating parametric study in flow analysis and performance confirmation in the dual-phase flow analysis. Consequently, this newly proposed SCR mixer realize excellent mixing performance without increasing the exhaust pressure loss.
Ashida, Masaaki, Shiga, Yoshihiro, Oyanagi, Susumu
Technical Paper
Visualization of Physical / Thermal Evaporation Phenomena with Experimental and PIV-DDM Analysis in Urea-SCR Dosing System of Multi-Phase Flow2023-32-009809/29/2023
This study was visualized by experimental and numerical analysis for the unknown injected droplet phenomena with the multi-phase flow in the Urea-SCR dosing system. Visualization experiments were conducted on the droplet behavior inside the pipe with simulated urea SCR injection system. Although the total number of droplets decreases at gas temperatures of 150°C and 200°C, a significant number of injected droplets remained at the position corresponding to the SCR catalyst. That is physical kinetic energy was found to dominate over thermal evaporation. However, the impingement of droplets into the pipe wall had occurred complex behavior by physical/thermal evaporation, and these droplets weren't on gas airflow at the lower part of the pipe. Furthermore, these actual phenomena were reflected in experimental coefficients for new reduction model analysis instead of CFD.
NOHARA, Tetsuo, SUGIYAMA, Naoki, NARA, Shotaro, ONO, Jyo, ONOUE, Hiroki, OSADA, Rina, KAWAMOTO, Yuki, OCHIAI, Masayuki, TAKAHASHI, Shun, OOSUMI, Kazuo, ISHIKAWA, Naoya
Technical Paper
Influence of Heating Measures on Urea Processing2023-01-503706/26/2023
With the introduction of the emission legislation Euro VI for commercial vehicles (CVs), selective catalytic reduction (SCR) with urea water solution (UWS) as the reducing agent has become a standard to minimize the nitrogen oxides (NOx) emissions from internal combustion engines. The urea processing and mixing unit has been developed and optimized in order to avoid deposit formation and ensure a high level of urea processing over the whole operation range, especially at lower temperatures. However, there are physical limits to the conversion of urea in conventional processing units during very low engine operating conditions. With the EHC Fractal Heater, Purem by Eberspächer has developed a heating measure that, in addition to its main function of accelerating the light-off of catalytic converters, also comes with the possibility of improving the UWS processing, especially under these low-load conditions.
Többen, Heike, Weinmann, Philipp
Technical Paper
A Holistic Approach for Near Zero Emission Diesel Vehicles Using a Pre-Turbo-Catalyst-System – Ready for EU 72023-01-121106/26/2023
This study 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 a selective catalytic reduction (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, zero-impact NOx emissions, that don’t impact cities air quality, can be reached in a wide range of operating scenarios while sustaining full drivability and highest efficiency. Advanced catalyst technologies enable a
Conin, Michael, Knaf, Daniel, Fiore, Luis, Keck, Mathias, Beidl, Christian, Kreuz, Joachim, Hohenberg, Günter
Journal Article
Emission Characteristics of a Light Diesel Engine with PNA under Different Coupling Modes of EHC and Aftertreatment System2023-01-026804/11/2023
With the continuous upgrading of emission regulations, NOx emission limit is becoming more and more strict, especially in the cold start phase. Passive NOx absorber (PNA) can adsorb NOx at a relatively low exhaust temperature, electrically heated catalyst (EHC) has great potential to improve exhaust gas temperature and reduce pollutant emissions of diesel engines at cold start conditions, while experimental research on the combined use of these two kinds of catalysts and the coupling mode of the electrically heated catalyst and the aftertreatment system under the cold start condition are lacking. In this paper, under a certain cold start and medium-high temperature phase, the exhaust gas temperature and emission characteristics of PNA, EHC and aftertreatment system under different coupling modes were studied. Results showed that the average inlet temperature of diesel oxidation catalyst (DOC) and selective catalytic reduction catalyst (SCR) integrated into diesel particulate filter
Kang, Lulu, Fang, Liang, Zhao, Yunkun, Lou, Diming, Zhang, Yunhua, Luo, Chagen
Technical Paper
A Multi-Function, Heated Mixer for Rapid Heat-up, Low-Temperature Ammonia Demand, Deposit Prevention and to Meet Ultra-Low NOx Regulations2023-01-035604/11/2023
Selective Catalytic Reduction (SCR) operation depends strongly on both heat and ammonia availability (stored or incoming). These requirements make high efficiency SCR challenging in lower temperature cycles where SCR is relatively cold, and Diesel Exhaust Fluid (DEF) injection is largely absent due to deposit risks. Examples include low temperature cycles such as low-idling, stop-and-go or low-load cycles such as city driving or local delivery cycles. An Electrically Heated Mixer/ EHM™ is utilized to address these challenges in a single component. EHM simultaneously provides heat for rapid SCR heat-up during the cold phase or in other low-temperature operations, steady or transient. Second, its heating mechanism makes deposit risks nearly non-existent. Third, EHM enables DEF injection at 130 °C, markedly enhancing the low temperature SCR impact. It is shown that these capabilities collectively make EHM a promising pathway for meeting ultra-stringent NOx targets including California
Masoudi, Mansour, Poliakov, Nick, Noorfeshan, Sahm
Technical Paper
The Influences of Testing Conditions on DOC Light-Off Experiments2023-01-037204/11/2023
Diesel oxidation catalyst (DOC) is one of the critical catalyst components in modern diesel aftertreatment systems. It mainly converts unburned hydrocarbon (HC) and CO to CO2 and H2O before they are released to the environment. In addition, it also oxidizes a portion of NO to NO2, which improves the NOx conversion efficiency via fast SCR over the downstream selective catalytic reduction (SCR) catalyst. HC light-off tests, with or without the presence of NOx, has been typically used for DOC evaluation in laboratory. In this work, we aim to understand the influences of DOC light-off experimental conditions, such as initial temperature, initial holding time, HC species, with or without the presence of NOx, on the DOC HC light-off behavior. The results indicate that light-off test with lower initial temperature and longer initial holding time (at its initial temperature) leads to higher DOC light-off temperature. Depending on the types of HC used, the presence of NOx can also influence HC
Xi, Yuanzhou, Ottinger, Nathan, Kiani, Daniyal, Liu, Z. Gerald
Technical Paper
Meeting Phase-2 GHG and Ultra-Low NOx Emissions with Conventional Engine Design for Light Heavy-Duty Applications2023-01-026904/11/2023
Increasing concerns due to global warming have led to stringent regulation of greenhouse gas (GHG) emissions from diesel engines. Specifically, for GHG phase-2 regulation (2027), more than 4% improvement is needed when compared to phase-1 regulation (2017) in the light heavy-duty (LHD) diesel engine category. At the same time, California Air Resources Board (CARB) and Environmental Protection Agency (EPA) have proposed the new Low NOx standards that require up to 90% reduction in tailpipe (TP) NOx emissions in comparison to the current TP NOx standards that were implemented in 2010. In addition, CARB and EPA have proposed new certification requirements – Low Load Cycle (LLC) and revised heavy-duty in-use testing (HDIUT) based on the moving average window (MAW) method that would require rigorous thermal management. Hence, strategies for simultaneous reduction in GHG and TP NOx emissions are required to meet future regulations. This paper presents potential pathways to achieve the GHG
Kadam, Vaibhav, Mayilvaganan, Arvind, Desai, Chintan, Vernham, Bruce
Technical Paper
Impact of Second NH 3 Storage Site on SCR NO x Conversion in an Ultra-Low NO x Aftertreatment System2023-01-036704/11/2023
Typical two-site storage-based SCR plant models in literature consider NH3 stored in the first site to participate in NH3 storage, NOx conversion and second site to only participate in NH3 storage passively. This paper focuses on quantifying the impact of stored NH3 in the second site on the overall NOx conversion for an ultra-low NOx system due to intra site NH3 mass transfer. Accounting for this intra site mass transfer leads to better prediction of SCR out NH3 thus ensuring compliance with NH3 coverage targets and improved dosing characteristics of the controller that is critical to achieving ultra-low NOx standard. The stored NH3 in the second site undergoes mass transfer to the first site during temperature ramps encountered in a transient cycle that leads to increased NOx conversion in conditions where the dosing is switched off. The resultant NH3 coverage fraction prediction is critical in dosing control of SCR. This phenomenon is evaluated and quantified with different aging
Chundru, Venkata Rajesh, Desai, Chintan, Kadam, Vaibhav, Vernham, Bruce, Sharp, Christopher, Rengarajan, Sankar, Rao, Sandesh, Sarlashkar, Jayant
Journal Article
Impact of Hydrothermal and Chemical Aging on SCR Storage Characteristics and NO x Reduction Performance in an Ultra-Low NO x System2023-01-036004/11/2023
This work is a part of medium-duty Low NOx technology development project with a focus on evaluating a combination of engine and advanced aftertreatment for 0.02 g/bhp-hr NOx regulation proposed by CARB (California air resource board). In this project, a control oriented chemical kinetics model of SCR (Selective catalytic reduction) was used in the aftertreatment controller that is susceptible to performance degradation due to hydrothermal and chemical aging. This paper focuses on modeling the NOx conversion and NH3 storage characteristics using a controls oriented SCR plant model which is further used for a model-based urea dosing scheme. A set of steady state reactor tests were used to calibrate the SCR performance at degreened, hydrothermal only and hydrothermal + chemical aging conditions and also to determine inhibition factors related to aging. The resultant model is capable of simulating SCR performance deterioration such as a reduction in NOx conversion and NH3 storage. A non
Chundru, Venkata Rajesh, Desai, Chintan, Kadam, Vaibhav, Rengarajan, Sankar, Rao, Sandesh, Sharp, Christopher, Vernham, Bruce, Sarlashkar, Jayant
Journal Article
Evaluation of Indrio’s Ammonia Sensor using a Diesel Fuel Based Burner Platform2023-01-038304/11/2023
This program involved the detailed evaluation of a novel laser-based in-exhaust ammonia sensor using a diesel fuel-based burner platform integrated with an ammonia injection system. Test matrix included both steady-state modes and transient operation of the burner platform. Steady-state performance evaluation included tests that examined impact of exhaust gas temperature, gas velocity and ammonia levels on sensor response. Furthermore, cross sensitivity of the sensor was examined at different levels of NOX and water vapor. Transient tests included simulation of the FTP test cycles at different ammonia and NOX levels. A Fourier transform infrared (FTIR) spectrometer as well as NIST traceable ammonia gas bottles (introduced into the exhaust stream via a calibrated flow controller) served as references for ammonia measurement. Results suggested that Indrio’s sensor exhibits a strong linear relationship with reference ammonia measurement across the tested range of 0 ppm to 200 ppm with a
Premnath, Vinay, Balakrishnan, Arun, Sur, Ritobrata, Khalek, Imad, Eakle, Scott
Technical Paper
Application of Model-Based Controller on a Heavy-Duty Dual Selective Catalytic Reduction Aftertreatment03-16-05-004003/08/2023
Commercial vehicles require advanced engine and aftertreatment (AT) systems to meet upcoming nitrogen oxides (NOx) and carbon dioxide (CO2) regulations. This article focuses on the development and calibration of a model-based controller (MBC) for an advanced diesel AT system. The MBC was first applied to a standard AT system including a diesel particulate filter (DPF) and selective catalytic reduction (SCR) catalyst. Next, a light-off SCR (LO-SCR) was added upstream of the standard AT system. The MBC was optimized for both catalysts for a production engine where the diesel exhaust fluid (DEF) was unheated for both SCRs. This research shows that the tailpipe (TP) NOx could be reduced by using MBC on both catalysts. The net result was increased NOx conversion efficiency by one percentage point on both the LO-SCR and the primary SCR. The CO2 emissions were slightly reduced, but this effect was not significant. Finally, the MBC was used with a final setup representative of future AT
Meruva, Prathik, Matheaus, Andrew, Zavala, Bryan, Sharp, Christopher A., McCarthy Jr., James E.
Journal Article
Improvement of SCR Thermal Management System and Emissions Reduction through Combustion Optimization2022-28-048212/23/2022
Achieving higher emission norms involves various techniques and it has always been a challenging task on meeting the same. Improving the exhaust temperature is indispensable in order to enhance better conversion efficiency on the after-treatment systems. This paper clearly investigates on the various strategies involved to improve the exhaust temperatures of selective catalytic reduction and post injection strategies to meet the emission norms. On the basis of MIDC operation, key load points were selected and split injections with three pulses were implemented. The variation of both the post injection timing and quantity were performed in this paper in order to evaluate the optimum output. The effect of post injection timing and quantity variation on hydrocarbon emissions, carbon monoxide, diesel oxidation catalyst temperatures was observed on all load points. The above strategy was also evaluated on generating the pressure crank angle data. SCR efficiency improvement was investigated
Anbarasu, Muthusamy, Shangar Ramani, Vagesh
Technical Paper
Influence of Rail Grinding Operations on the World's Largest Multimodal Network2022-28-056012/23/2022
Rail-wheel interaction plays a key role in determining the life of railway tracks. An increase in the speed and axle load leads to significant wear and fatigue damage on materials resulting in a safety concern for the Indian Railway network. In response to the above context, rail grinding technology is introduced to maintain the stability and safety of the railway system. In the present work, three (3) Zones named South-Central Railway (SCR), North Central Railway (NCR) and Northern Railway (NR) of Indian Railways (IR) were prone to severe problems pertaining to wear and fatigue damage were selected for the rail grinding performance studies. From the collected data, the performance features in terms of rail wear, width and position of contact band, length and pitch of crack, attainment of target profile, defect generation rate and rail/weld fracture analysis were evaluated. Average wear rates per 100 Gross Million Tonnes (GMT) at SCR, NCR and NR for the tangent track were found to be
Verma, Sachin, Joseph Selvi, Binoj, Yogesh Shah, Vijesh
Technical Paper
Case Study of Water Condensation and Evaporation Effects on Tailpipe Continuous Mass Emission Calculations in a Gasoline Powertrain03-16-04-002910/11/2022
Emissions development work for gasoline aftertreatment systems is often conducted in a laboratory on a chassis dynamometer. In this situation, extractive sample lines are frequently connected to the aftertreatment system before and after various components, such as a three-way catalyst, selective catalytic reduction substrate, and the like. This is done to measure the conversion efficiency of the aftertreatment system components as a function of time. The time series exhaust component concentration data, also referred to as continuous data, are combined with a measure of exhaust volumetric flowrate and used to calculate mass-based emissions. As gasoline powertrains become cleaner and produce lower levels of criteria emissions, the proximity (i.e., colocated or not colocated) of the volumetric flowrate and concentration measurements may affect the accuracy of the overall mass emission calculation. In this work, we investigate the effect of water condensation and evaporation on
Kempema, Nathan J., Lown, Anne, Kralik, Lora, Loos, Mike
Journal Article
Design Optimizations of Static Dual-Stage Mixer for SCR Layout to Improve UWS Conversion Efficiency2022-28-032510/05/2022
Aftertreatment system meeting BS-VI emission regulations for diesel engines led to a decrease in NOx emissions to a low level. Selective catalyst reduction (SCR) is the most prominent and mature technology used to reduce NOx emissions. Initially, the UWS injection layout was designed without any mixer which resulted in low NH3 uniformity on SCR monolith with reduced UWS conversion efficiency, leading to concentrated wall spray loads. A dual-stage static mixer was designed and introduced to enhance the proper mixing of UWS droplets with exhaust gas upstream, to accelerate UWS breakup and evaporation of droplets. The mixer blades enhance the local turbulence, which resulted in a high mixing degree of droplets with the exhaust gas stream, thus reducing the crystallization risk at the mixer and the surrounding area. Mixers also extend the evaporation path, residence time, and thermal decomposition for droplets. Mixer shape was optimized with various design parameters with good structural
Benny, Bineesh, Bala, Harinivas, S, Veera Vishnu, M, Dayananda, B, Sriram
Technical Paper
Another Look at the Diagnostics for Exhaust Systems with Dual Urea1333910/05/2022
To meet the low NOx standard for heavy duty engines deployed by CARB for 27MY and 31MY, many manufacturers are resorting to an exhaust layout with 2 SCR catalysts and 2 urea injectors, where the 2 SCR catalysts are separated by another non-NOx converting catalyst. The first SCR allows for best NOx conversion in cold start and low load conditions, whereas the second SCR addresses NOx conversion at full load. The regulation allows monitoring the SCR catalysts as individual components or as a system, where CARB staff has indicated that monitoring the individual catalysts entails some further requirements. In this presentation we will evaluate the benefits and drawbacks of both options under some realistic aging assumptions. The findings will be supported by simulations of various aging scenarios.
Van, Michiel
Video
Challenges with On Board Monitoring1331610/04/2022
The upcoming Euro 7 regulation includes a proposal for On Board Monitoring, or OBM, to continuously monitor vehicles for emissions conformance. OBM relies on feedback from sensors and models to identify high emitting vehicles, which poses many challenges. Sensors are not commercially available for all emissions constituents, and the accuracy of commercially available sensors is not capable enough for in use compliance determination. On board emissions models also do not currently have enough fidelity to determine in use compliance and implementation of models is complicated. The stack up of multi-component deterioration leading to an emissions exceedance is possible but also infeasible to detect using available sensors and models. The presentation will review what is being promulgated elsewhere in regard to using on-board sensors to directly measure pollutants such as CARB�s �REAL NOx Tracking� system. Meanwhile US EPA�s proposed �Health Monitors� seek to provide vehicle owners warning
Pruski, Erica
Video
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