The SAE MOBILUS platform will continue to be accessible and populated with high quality technical content during the coronavirus (COVID-19) pandemic. x

Your Selections

Selective catalytic reduction
Show Only

Collections

File Formats

Content Types

Dates

Sectors

Topics

Authors

Publishers

Affiliations

Committees

Events

Magazine

   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Ammonia Measurement Investigation Using Quantum Cascade Laser and Two Different Fourier Transform Infrared Spectroscopy Methods

Caterpillar UK Ltd-Richard Barrett, Jim Baxter
Loughborough university-Nilton Li, Ashraf El-Hamalawi
  • Technical Paper
  • 2020-01-0365
To be published on 2020-04-14 by SAE International in United States
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 location is some distance away from the SCR. The results reported here contradict this and show…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Evaluating the Performance of a Conventional and Hybrid Bus operating on Diesel and B20 Fuel for Emissions and Fuel Economy

US Environmental Protection Agency-Matthew Brusstar, Scott Ludlam
University of Michigan-Rinav Pillai, Andre Boehman
  • Technical Paper
  • 2020-01-1351
To be published on 2020-04-14 by SAE International in United States
With ongoing concerns about the elevated levels of ambient air pollution in urban areas and the contribution from heavy-duty diesel vehicles, hybrid electric buses are considered as a potential solution as they are perceived to be less polluting and more fuel-efficient than their conventional engine counterparts. However, recent studies have shown that real-world emissions may be substantially higher than those measured in the laboratory, mainly due to operating conditions that are not fully accounted for in dynamometer test cycles. At the U.S. EPA National Fuel and Vehicle Emissions Laboratory (NVFEL), the in-use criteria emissions and energy efficiency of heavy-duty class 8 vehicles (up to 80,000 lbs) may be evaluated under controlled conditions in the heavy-duty chassis dynamometer test. The present study evaluated the performance of a conventional bus and hybrid bus for emissions and fuel economy under representative test cycles (including cold start and hot start conditions) with Diesel (#2) and Biodiesel (B20) fuel. The conventional bus was equipped with a Cummins ISL 8.3L engine and a Diesel Particulate Filter (DPF) and Diesel Oxidation Catalyst…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Use of Nitric Acid to Control the NO2:NOX Ratio Within the Exhaust Composition Transient Operation Laboratory Exhaust Stream

Southwest Research Institute-Robert Henderson, Ryan Hartley, Cary Henry
  • Technical Paper
  • 2020-01-0371
To be published on 2020-04-14 by SAE International in United States
The Exhaust Composition Transient Operation Laboratory (ECTO-Lab) is a burner system developed at Southwest Research Institute (SwRI) for simulation of IC engine exhaust. The current system design requires metering and combustion of nitromethane in conjunction with the primary fuel source as the means of NOX generation. While this method affords highly tunable NOX concentrations even over transient cycles, no method is currently in place for dictating the speciation of nitric oxide (NO) and nitrogen dioxide (NO2) that constitute the NOX mixture. NOX generated through combustion of nitromethane is dominated by NO, and generally results in a NO2:NOX ratio of <5 %. Generation of any appreciable quantities of NO2 is therefore dependent on an oxidation catalyst to oxidize a fraction of the NO to NO2. Presented within this manuscript is a method for precise control of the NO2:NOX ratio within the ECTO-Lab exhaust stream by using nitric acid as the NOX precursor molecule in lieu of nitromethane. While decomposition of nitromethane generates NO as the dominate component of the NOX mixture, nitric acid decomposition produces primarily…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Investigation into Low-Temperature Urea-Water Solution Decomposition by Addition of Titanium-Based Isocyanic Acid Hydrolysis Catalyst and Surfactant

Southwest Research Institute-Ryan Hartley, Nolan Wright, Cary Henry
University of Texas-Zachary Tonzetich
  • Technical Paper
  • 2020-01-1316
To be published on 2020-04-14 by SAE International in United States
Mitigation of urea deposit formation and improved ammonia production at low exhaust temperatures continues to be one of the most significant challenges for current generation selective catalytic reduction (SCR) aftertreatment systems. Various technologies have been devised to alleviate these issues including: use of alternative reductant sources, and thermal treatment of the urea-water solution (UWS) pre-injection. The objective of this work was to expand the knowledge base of a potential third option, which entails chemical modification of UWS by addition of a titanium-based urea/isocyanic acid (HNCO) decomposition catalysts and/or surfactant to the fluid. Physical solid mixtures of urea with varying concentrations of ammonium titanyl oxalate (ATO), oxalic acid, and titanium dioxide (TiO2) were generated, and the differences in NH3 and CO2 produced upon thermal decomposition were quantified. It was found that addition of 2.0 mol % ATO to urea increased CO2 production by821 % and NH3 production by 96 % at temperatures ≤ 215 °C, indicating significantly enhanced hydrolysis of HNCO. Conversely, it was demonstrated that addition of oxalic acid or TiO2 to urea exhibited little…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A controls overview on achieving ultra-low NOx​

Southwest Research Institute-Sandesh Rao, Jayant Sarlashkar, Sankar Rengarajan, Christopher Sharp, Gary Neely
  • Technical Paper
  • 2020-01-1404
To be published on 2020-04-14 by SAE International in United States
The California Air Resources Board (CARB) funded Stage 3 Heavy-Duty Low NOx program focusses on evaluating different engine and after-treatment technologies to achieve 0.02g/bhp-hr of NOx emission over certification and low load cycles. This paper highlights the controls architecture of the engine and after-treatment systems and discusses the effects of various strategies implemented and tested in an engine test cell over heavy-duty drive cycles. A cylinder deactivation enabled engine was integrated with an after-treatment system consisting of a Light-Off Selective Catalytic Reduction (LO-SCR) system with a heated urea dosing system which was located close to the turbine outlet, a Catalyzed Soot Filter (CSF), and a main SCR system with single point urea dosing. Southwest Research Institute (SwRI) had developed a model-based controller for the main SCR system in the Stage 1 Low-NOx program. The chemical kinetics for the model-based controller were further tuned and implemented in this program to better simulate the reactions in the Stage 3 SCR system. Novel dosing, and ammonia storage management strategies created along with the model-based controls were critical in…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Review of Vehicle Engine Efficiency and Emissions

Corning, Inc.-Ameya Joshi
  • Technical Paper
  • 2020-01-0352
To be published on 2020-04-14 by SAE International in United States
This review paper covers major regulatory and technology developments in 2019 pertinent to tailpipe emissions of greenhouse gases and criteria pollutants. Europe has proposed ambitious reductions in CO2 limits for both light- and heavy-duty sectors. The challenge is compounded with changing measurement norms and a significant shift away from fuel efficient diesels in the light-duty (LD) space. Both incremental and step changes are being made to advance internal combustion. New studies show that in-use NOx emissions from diesels can be much lower than required by the Euro 6 regulation. Discussions have already started on Euro 7 regulations, and the leading regulatory concepts and proposed technical solutions are provided. In the heavy-duty (HD) sector, the progress is outlined in improving engine and vehicle fuel efficiency through the US Department of Energy’s (DOE’s) SuperTruck II program and other representative studies. Common approaches among the participants include hybridization, waste heat recovery, and both open- and closed cycle incremental improvements. Emissions control focus is on evaluating pathways to achieve California’s contemplated low-NOx standards, recently also supported by the US…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Numerical Optimization of a SCR System based on the Injection of Pure Gaseous Ammonia for the NOx Reduction in Light-duty Diesel Engines

Politecnico di Milano-Augusto Della Torre, Gianluca Montenegro, Angelo Onorati, Tarcisio Cerri, Enrico Tronconi, Isabella Nova
  • Technical Paper
  • 2020-01-0356
To be published on 2020-04-14 by SAE International in United States
Selective Catalytic Reduction (SCR) systems are nowadays widely applied for the reduction of NOx emitted from Diesel engines. The typical process is based on the injection of aqueous urea in the exhaust gases before the SCR catalyst, which determines the production of the ammonia needed for the catalytic reduction of NOx. However, this technology is affected by two main limitations: a) the evaporation of the urea water solution (UWS) requires a sufficiently high temperature of the exhaust gases and b) the formation of solid deposits during the UWS evaporation is a frequent phenomenon which compromise the correct operation of the system. In this context, to overcome these issues, a technology based on the injection of gaseous ammonia has been recently proposed: in this case, ammonia is stored at the solid state in a cartridge containing a Strontium Chloride salt and it is desorbed by means of electrical heating. In this work, an after-treatment system based on the injection of gaseous ammonia in the SCR system is considered. Numerical 1D and 3D CFD simulations are applied…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A Fast Modeling Approach for Prediction of SCR Deposits – Implementation and Validation with Advanced Optical Techniques

Vienna University of Technology-Uladzimir Budziankou, Max Quissek, Thomas Lauer
  • Technical Paper
  • 2020-01-0358
To be published on 2020-04-14 by SAE International in United States
The permanently tightening emission regulations for NOx pollutants force further development of automotive exhaust aftertreatment systems with selective catalytic reduction (SCR). Of particular interest is the long-term reliability of SCR-systems with regard to unfavorable operating conditions, such as high injection rates of urea water solution (UWS) or a low exhaust gas temperature. Both of them may lead to formation of solid deposits which decrease system efficiency by increasing backpressure and impairing ammonia uniformity. A fast modeling approach for numerical prediction of deposit formation in urea SCR systems is desired for optimization of system design. This paper presents a modified Smith´s methodology for the modeling of deposit formation risk. A new criterion for determination of the initial foot print of the spray, where the deposit formation is inhibited, is proposed. The threshold values for the evaluation of the liquid film dynamic were validated based on experimental results. Furthermore, for a better prediction of the liquid film pathways, a new approach for realistic modeling of the film viscosity was developed. To achieve a more realistic simulation in…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Evaluation of Cylinder Deactivation on a Class 8 Truck over Light Load Cycles

Jacob Vehicle Systems-Robb Janak
Navistar, Inc.-Jasmeet Singh
  • Technical Paper
  • 2020-01-0800
To be published on 2020-04-14 by SAE International in United States
Selective Catalytic Reduction (SCR) systems provide excellent NOx control for diesel engines provided the exhaust inlet temperature remains 200 degrees C or higher. Since diesel engines run lean, extended light load operation typically causes exhaust temperatures to fall below 200 degrees C and SCR conversion efficiency diminishes. Heated urea dosing systems are being developed to allow dosing below 190 degrees C. However, catalyst face plugging remains a concern. Close coupled SCR systems and lower temperature formulation of SCR systems are also being developed. Current strategies of post fuel injection and retarded injection timing increases fuel consumption. One viable keep-warm strategy examined in this paper is cylinder deactivation (CDA) which can increase exhaust temperature and reduce fuel consumption. Cycles such as the heavy-duty federal test procedure (HD FTP) which have long idle periods can benefit from CDA by increasing temperature, lowering exhaust flow, and reducing catalyst cooling. This technology could become even more important if future regulations include low load cycles. For this paper, CDA was utilized at loads below 6 bar brake mean effective pressure…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A Case Study of a Cu-SSZ-13 SCR Catalyst Poisoned by Real-World High Sulfur Diesel Fuel

Cummins Emission Solutions-Yuanzhou Xi, Nathan Ottinger, Christopher Keturakis, Z. Gerald Liu
  • Technical Paper
  • 2020-01-1319
To be published on 2020-04-14 by SAE International in United States
To meet increasingly stringent diesel engine emission regulations, diesel engines are required to use ultra-low sulfur diesel (ULSD) and are equipped with advanced aftertreatment systems. Cu-SSZ-13 zeolite catalysts are widely used as selective catalytic reduction (SCR) catalysts due to their high NOx reduction and excellent hydrothermal stability. However, active Cu sites of Cu-SSZ-13 catalysts can be poisoned by exposure to engine exhaust sulfur species. This poison effect can be mitigated with the use of ULSD and high temperature exposure from engine operation. On the other hand, ULSD is still not universally available where regulations require it, and vehicles may inadvertently operate with high sulfur diesel fuel (HSD) in some locations. The high concentration of exhaust sulfur species resulting from HSD combustion may rapidly poison the Cu-SSZ-13 SCR catalyst. In this study, the catalytic performance of a sulfur poisoned Cu-SSZ-13 SCR catalyst is analyzed. Results show that the as received SCR catalyst displays substantially low NOx conversion below 350 °C. A thermal treatment at 550 °C can recover most of its lost performance. Temperature programmed desorption…