scholarly journals Experimental Research on Distribution Characteristics of NOx Conversion Efficiency of a Diesel Engine SCR Catalyst

ACS Omega ◽  
2021 ◽  
Vol 6 (36) ◽  
pp. 23083-23089
Author(s):  
Zhancheng Wang ◽  
Huiyong Du ◽  
Ke Li ◽  
Jiaxuan Miao ◽  
Min Li ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Conversion Efficiency ◽  
Experimental Research ◽  
Distribution Characteristics ◽  
Scr Catalyst ◽  
Nox Conversion ◽  
Nox Conversion Efficiency

TWC-SCR Aftertreatment System Evaluation for a Lean Burn Gasoline Engine Operating in HCCI, SACI, and SI Combustion Modes

2016 ◽  
Author(s):  
Jordan Easter ◽  
Stanislav V. Bohac
Keyword(s):  
Conversion Efficiency ◽  
Gasoline Engine ◽  
Fuel Efficiency ◽  
Compression Ignition ◽  
Scr Catalyst ◽  
Advanced Combustion ◽  
Nox Conversion ◽  
Combustion Modes ◽  
Scr System ◽  
Nox Conversion Efficiency

Low temperature and dilute Homogenous Charge Compression Ignition (HCCI) and Spark Assisted Compression Ignition (SACI) can improve fuel economy and reduce engine-out NOx emissions to very low values, often less than 30 ppm. However, these combustion modes are unable to achieve stringent future regulations such as SULEV 30 without the use of lean aftertreatment. Though active selective catalytic reduction (SCR) with urea injection and lean NOx traps (LNT) have been investigated as options for lean gasoline engines, a passive TWC-SCR system is investigated in this work because it avoids the urea storage and dosing hardware of a urea SCR system, and the high precious metal cost of an LNT. The TWC-SCR concept uses periodic rich operation to produce NH3 over a TWC to be stored on an SCR catalyst for subsequent NOx conversion during lean operation. In this work a laboratory study was performed with a modified 2.0 L gasoline engine that was cycled between lean HCCI and rich SACI operation, or between lean and rich SI (spark ignited) combustion, to evaluate NOx conversion and reduced fuel consumption. Different lambda values during rich operation and different times held in rich operation were investigated. Results are compared to a baseline case in which the engine is always operated at stoichiometric conditions. SCR system simulations are also presented that compare system performance for different levels of stored NH3. With the configuration used in this study, lean/rich HCCI/SACI operation showed a maximum NOx conversion efficiency of 10%, while lean/rich SI operation showed a maximum NOx conversion efficiency of 60%. However, if the low conversion efficiency of lean/rich HCCI/SACI operation could be improved through higher brick temperatures or additional SCR bricks, simulation results indicate TWC-SCR aftertreatment has the potential to provide near-zero SCR-out NOx concentration and increased system fuel efficiency. In these simulations, fuel efficiency improvement relative to stoichiometric SI were 7 to15% for lean/rich HCCI/SACI with zero tailpipe NOx and −1 to 5% for lean/rich SI with zero tailpipe NOx emissions. Although previous work indicated increased time for NH3 to start forming over the TWC during rich operation, less NH3 production over the TWC per fuel amount, and increased NH3 slip over the SCR catalyst for advanced combustion systems, if NOx conversion efficiency could be enhanced, improvements in fuel economy and low engine-out NOx from advanced combustion modes would more than make up for these disadvantages.

scholarly journals Research on Optimization Design of SCR Nozzle for National VI Heavy Duty Diesel Engine

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 452 ◽  
Author(s):  
Feng Qian ◽  
Dong Ma ◽  
Neng Zhu ◽  
Peng Li ◽  
Xiaowei Xu
Keyword(s):  
Diesel Engine ◽  
Conversion Efficiency ◽  
Optimization Design ◽  
Exhaust Pipe ◽  
Heavy Duty ◽  
Deposit Formation ◽  
Nox Conversion ◽  
Heavy Duty Diesel ◽  
Scr System ◽  
Nox Conversion Efficiency

For the National VI heavy-duty diesel vehicles, NOx emission regulations are becoming more and more stringent, and the selective catalytic reduction (SCR) system has become a necessary device. The design of the adblue nozzle in the SCR system is especially critical, directly affecting the NOx conversion efficiency and deposit formation. According to the structure of a National VI diesel engine exhaust pipe and SCR system, the nozzle is optimized by computational fluid dynamics (CFD) method to avoid the collision between the urea droplets and the exhaust pipe wall, to ensure that the exhaust gas and the urea droplets are as much as possible in full contact to ensure a sufficient urea pyrolysis. With the optimized nozzle, the NH3 distribution uniformity of the inlet face of the SCR catalyst can increase from 0.58 to 0.92. Additionally, test verifications are implemented based on the spray particle size test and the engine bench tests; the results show that the Sauter mean diameter of the optimized nozzle is more decreased than the initial nozzle and that the NOx conversion efficiency of the World Harmonized Transient Cycle (WHTC) and World Harmonized Stationary Cycle (WHSC) cycle improves by nearly 3%; additionally, it can also avoid deposit formation.

Study on the Cu-ZSM-5 Catalyst for SCR System of Diesel Engine

2012 ◽  
Vol 532-533 ◽  
pp. 82-86
Author(s):  
Wei Li ◽  
Ling Shan Chen ◽  
Xiong Liu ◽  
Yi Liu
Keyword(s):  
Diesel Engine ◽  
Low Temperature ◽  
Fuzzy Sets ◽  
Conversion Efficiency ◽  
Nox Emissions ◽  
Nox Conversion ◽  
Activity Temperature ◽  
Scr System ◽  
Nox Conversion Efficiency

In this paper, we shall first briefly introduce fuzzy sets and related concepts of the reaction principle of Cu-ZSM-5 catalyst with the NO, and the preparation of Cu-ZSM-5 catalyst is also investigated. And the NOx conversion efficiency of Cu-ZSM-5 catalyst is analyzed with the experiment. Compared to V2O5/WO3/TiO2catalyst, the reaction activity of Cu-ZSM-5 catalyst at low temperature is much better, while the range of reaction activity temperature of V2O5/WO3/TiO2catalyst is relatively wide. Finally, with the diesel engine ESC test, the Cu-ZSM-5 Catalyst for SCR system can effectively reduce the NOx emissions, and the diesel engine which is installed the SCR is able to achieve the requirements of Euro Ⅳ for NOx limits.

Three Way Catalyst-Selective Catalytic Reduction Aftertreatment System Evaluation for a Lean Burn Gasoline Engine Operating in Homogenous Charge Compression Ignition, Spark-Assisted Compression Ignition, and Spark-Ignited Combustion Modes

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Jordan Easter ◽  
Stanislav V. Bohac
Keyword(s):  
Conversion Efficiency ◽  
Gasoline Engine ◽  
Catalytic Reduction ◽  
Fuel Efficiency ◽  
Compression Ignition ◽  
Scr Catalyst ◽  
Nox Conversion ◽  
Homogenous Charge Compression Ignition ◽  
Three Way Catalyst ◽  
Nox Conversion Efficiency

Low temperature and dilute homogenous charge compression ignition (HCCI) and spark-assisted compression ignition (SACI) can improve fuel efficiency and reduce engine-out NOx emissions, especially during lean operation. However, under lean operation, these combustion modes are unable to achieve Environmental Protection Agency (EPA) Tier 3 emissions standards without the use of lean aftertreatment. The three way catalyst (TWC)-SCR lean aftertreatment concept investigated in this work uses periodic-rich operation to produce NH3 over a TWC to be stored on a selective catalytic reduction (SCR) catalyst for NOx conversion during subsequent lean operation. Experiments were performed with a modified 2.0 L gasoline engine that was cycled between lean HCCI and rich SACI operation and between lean and rich spark-ignited (SI) combustion to evaluate NOx conversion and fuel efficiency benefits. Different lambda values during rich operation and different times held in rich operation were investigated. Results are compared to a baseline case in which the engine is always operated at stoichiometric conditions. SCR system calculations are also presented to allow for comparisons of system performance for different levels of stored NH3. With the configuration used in this study, lean/rich HCCI/SACI operation resulted in a maximum NOx conversion efficiency of only 10%, while lean/rich SI operation resulted in a maximum NOx conversion efficiency of 60%. If the low conversion efficiency of HCCI/SACI operation could be improved through higher brick temperatures or additional SCR bricks, calculations indicate that TWC-SCR aftertreatment has the potential to provide attractive fuel efficiency benefits and near-zero tailpipe NOx. Calculated potential fuel efficiency improvement relative to stoichiometric SI is 7–17% for lean/rich HCCI/SACI with zero tailpipe NOx and −1 to 5% for lean/rich SI with zero tailpipe NOx emissions. Although the previous work indicated that the use of HCCI/SACI increases the time for NH3 to start forming over the TWC during rich operation, reduces NH3 production over the TWC per fuel amount, and increases NH3 slip over the SCR catalyst, if NOx conversion efficiency could be enhanced, improvements in fuel efficiency could be realized while meeting stringent tailpipe NOx standards.

Effect of Physical Parameters on DeNOx Conversion in Selective Catalytic Converter Used in Diesel Vehicles

2013 ◽  
Vol 376 ◽  
pp. 13-16
Author(s):  
A.P. Manoj Kumar ◽  
P. Mohanan
Keyword(s):  
Cell Density ◽  
Conversion Efficiency ◽  
Catalytic Converter ◽  
Frontal Area ◽  
Physical Parameters ◽  
Cell Geometry ◽  
Diesel Vehicles ◽  
Nox Conversion ◽  
Nox Conversion Efficiency ◽  
Denox Efficiency

The Urea SCR system is a promising approach to reduce NOx in order to meet stringent limits on Euro 1V and Euro V standards. Apart from thermodynamic properties (temperature, pressure,heat and mass transfer), the cell geometry of SCR also got significant role in reduction of NOx. The current study focuses on the calculation of NOx conversion by varying the Open Frontal area of monolith, volume of monolith, cell density thereby to choose best cell geometry which will result in maximum DeNOx efficiency. It has been found that as the cell density increases the NOx conversion efficiency also increases. In the current analysis, a cell density varying from 200 CPSI to 400 CPSI is considered. One dimensional steady state and transient kinetic analysis are carried out using AVL BOOST software. The monolith volume is varied from 0.002m3 to 0.008m3 and the effects on DeNOx efficiency are discussed. The Open frontal area of SCR catalyst also been varied, and the effects on NOx conversion is studied. It has been found that as the cell density, monolith volume increases, the NOx conversion efficiency also increases, where as it decreases with increase in Open frontal area. The results are validated through experimental results obtained from the literature.

The effect of surface reactions on the prediction of NOX conversion efficiency in a porous burner

2013 ◽  
Vol 160 (10) ◽  
pp. 2169-2181 ◽  
Author(s):  
Shahrooz Afsharvahid ◽  
Pedro N. Alvarado ◽  
Peter J. Ashman ◽  
Bassam B. Dally
Keyword(s):  
Conversion Efficiency ◽  
Surface Reactions ◽  
Nox Conversion ◽  
Porous Burner ◽  
Effect Of Surface ◽  
Nox Conversion Efficiency

Effect of Hydrocarbon Emissions From PCCI-Type Combustion on the Performance of Selective Catalytic Reduction Catalysts

2011 ◽  
Author(s):  
Vitaly Y. Prikhodko ◽  
Josh A. Pihl ◽  
Samuel A. Lewis ◽  
James E. Parks
Keyword(s):  
Conversion Efficiency ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Hydrocarbon Emissions ◽  
Engine Exhaust ◽  
Nox Conversion ◽  
Combustion Modes ◽  
Performance Trends ◽  
Scr Catalysts ◽  
Nox Conversion Efficiency

Core samples cut from full size commercial Fe- and Cu-zeolite SCR catalysts were exposed to a slipstream of raw engine exhaust from a 1.9-liter 4-cylinder diesel engine operating in conventional and PCCI combustion modes. Subsequently, the NOx reduction performance of the exposed catalysts was evaluated on a laboratory bench-reactor fed with simulated exhaust. The Fe-zeolite NOx conversion efficiency was significantly degraded, especially at low temperatures (<250°C), after the catalyst was exposed to the engine exhaust. The degradation of the Fe-zeolite performance was similar for both combustion modes. The Cu-zeolite was much more resistant to HC fouling than the Fe-zeolite catalyst. In the case of the Cu-zeolite, PCCI exhaust had a more significant impact than the exhaust from conventional combustion on the NOx conversion efficiency. For all cases, the clean catalyst performance was recovered after heating to 600°C. GC-MS analysis of the HCs adsorbed to the catalyst surface provided insights into the observed NOx reduction performance trends.

Evaluation of In-Situ Synthesized Monolithic Metal-MFI/Cordierite Catalysts to Remove NOx From Lean Exhaust

2005 ◽  
Author(s):  
Tianyou Wang ◽  
Shuliang Liu ◽  
Hongjun Xu ◽  
Xing Li ◽  
Maolin Fu ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Gasoline Engine ◽  
Catalytic Reduction ◽  
Space Velocity ◽  
Test Results ◽  
Lean Burn ◽  
Exhaust Temperature ◽  
Nox Conversion ◽  
Nox Conversion Efficiency

In this study, ZSM-5 zeolites were successfully in situ synthesized on the surface of honeycomb cordierite substrate and certified by XRD and SEM techniques. Strong interaction between zeolite and substrate has been found during in-situ synthesis, and hydrothermal stabilities of the zeolites was improved by entailing. The in-situ synthesized monolithic ZSM-5/cordierite showed superior thermal and hydrothermal stabilities. Cu-ZSM-5/cordierite was prepared by ion-exchange and impregnation methods were studied as catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NOx) in a lean-burn gasoline engine. Engine test results show that NOx emission was decreased by reductants of HC and CO in the exhaust gas without any other extra reducing agents. It also exhibited high activities. Using Cu-ZSM-5/cordierite, the maximum NOx conversion efficiency to N2 reached to 64% at the exhaust temperature of 400 °C and the gas hourly space velocity (GHTV) of 25 000/h. Meanwhile, the HC conversion efficiency was about 60%, while CO was little converted. Cu-ZSM-5/cordierite also showed good duration and anti-poison properties. Furthermore, the activated temperature of the Cu-ZSM-5/cordierite was decreased and the NOx conversion was increased via addition of iridium as a modifier.

Sign in / Sign up

Export Citation Format

Share Document