scholarly journals Catalyst Ammonia Storage Measurements Using Radio Frequency Sensing

2017 ◽  
Author(s):  
Jonathan Aguilar ◽  
Leslie Bromberg ◽  
Alexander Sappok ◽  
Paul Ragaller ◽  
Jean Atehortua ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Electromagnetic Waves ◽  
Catalytic Reduction ◽  
Cavity Resonator ◽  
Wide Frequency Range ◽  
Scr Catalyst ◽  
Ammonia Storage ◽  
Catalyst Temperature ◽  
Rf Antenna ◽  
Rf Signal

Motivated by increasingly strict NOx limits, engine manufactures have adopted selective catalytic reduction (SCR) technology to reduce engine-out NOx below mandated levels. In the SCR process, nitrogen oxides (NOx) react with ammonia (NH3) to form nitrogen and water vapor. The reaction is influenced by several variables, including stored ammonia on the catalyst, exhaust gas composition, and catalyst temperature. Currently, measurements from NOx and/or NH3 sensors upstream and downstream of the SCR are used with predictive models to estimate ammonia storage levels on the catalyst and control urea dosing. This study investigated a radio frequency (RF) -based method to directly monitor the ammonia storage state of the SCR catalyst. This approach utilizes the SCR catalyst as a cavity resonator, in which an RF antenna excites electromagnetic waves within the cavity to monitor changes in the catalyst state. A mmonia storage causes changes in the dielectric properties of the catalyst, which directly impacts the RF signal. Changes in the RF signal relative to stored a mmonia (NH3) were evaluated over a wide frequency range as well as temperature and exhaust conditions. The RF response to NH3 storage, desorption, and oxidation on the SCR was observed to be well-correlated with changes in the catalyst state. Calibrated RF measurements demonstrate the ability to monitor the adsorption state of the SCR to within 10 % of the sensor full scale. The results indicate direct measurement of SCR ammonia storage levels, and resulting catalyst feedback control, via RF sensing to have significant potential for optimizing the SCR system to improve NOx conversion and decrease urea consumption.

scholarly journals Catalyst Ammonia Storage Measurements Using Radio Frequency Sensing1

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Jonathan Aguilar ◽  
Leslie Bromberg ◽  
Alexander Sappok ◽  
Paul Ragaller ◽  
Jean Atehortua ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Electromagnetic Waves ◽  
Catalytic Reduction ◽  
Cavity Resonator ◽  
Wide Range ◽  
Ammonia Storage ◽  
Catalyst Temperature ◽  
Rf Antenna ◽  
Scr System ◽  
Rf Signal

Motivated by increasingly strict nitrogen oxides (NOx) limits, engine manufacturers have adopted selective catalytic reduction (SCR) technology to reduce engine-out NOx. In the SCR process, NOx react with ammonia (NH3) to form nitrogen and water vapor. The reaction is influenced by several variables, including stored ammonia on the catalyst, exhaust gas composition, and catalyst temperature. Currently, measurements from NOx and/or NH3 sensors upstream and downstream of the SCR are used with predictive models to estimate ammonia storage levels on the catalyst and control urea dosing. This study investigated a radio frequency (RF)-based method to directly monitor the ammonia storage state of the SCR. This approach utilizes the catalyst as a cavity resonator, in which an RF antenna excites electromagnetic waves within the cavity to monitor changes in the catalyst state. Ammonia storage causes changes in the dielectric properties of the catalyst, which directly impacts the RF signal. Changes in the RF signal relative to stored ammonia (NH3) were evaluated over a wide range of frequencies, temperatures, and exhaust conditions. The RF response to NH3 storage, desorption, and oxidation on the SCR was well correlated with changes in the catalyst state. Calibrated RF measurements demonstrate the ability to monitor the adsorption state of the SCR to within 10% of the sensor full scale. The results indicate direct measurement of SCR ammonia storage levels, and resulting catalyst feedback control, via RF sensing to have significant potential for optimizing the SCR system to improve NOx conversion and decrease urea consumption.

Integrated Powertrain Control to Meet Low CO2 Emissions for a Hybrid Distribution Truck With SCR-DeNOx System

2011 ◽  
Author(s):  
Frank Willems ◽  
Stefan Spronkmans ◽  
John Kessels
Keyword(s):  
Co2 Emissions ◽  
Catalytic Reduction ◽  
Average Power ◽  
Optimization Strategy ◽  
Scr Catalyst ◽  
Powertrain Control ◽  
Low Co2 ◽  
Catalyst Temperature ◽  
Hybrid Distribution ◽  
Fuel Consumption And Emissions

This article presents a cost-based optimization strategy that explicitly deals with the requirements for fuel consumption and emissions. Based on the Integrated Powertrain Control (IPC) approach, the overall powertrain performance is optimized by integrated energy and emission management. The potential of this strategy is demonstrated for a parallel hybrid diesel truck with a Selective Catalytic Reduction (SCR) de-NOx system. New results are presented for a challenging city cycle; although the average power demand is low, IPC is able to keep the SCR catalyst temperature relatively high. With this IPC approach, the CO2-NOx trade-off is optimized in a systematic way. It is demonstrated that CO2 emissions and related operating costs are reduced by 3.5% or 24.9% NOx emission reduction is achieved, depending on the applied IPC calibration.

Open Localization in Micro LeadFrame Package Using Space Domain Reflectometry

2013 ◽  
Author(s):  
J. Gaudestad ◽  
V. Talanov ◽  
A. Orozco ◽  
M. Marchetti
Keyword(s):  
Magnetic Field ◽  
Radio Frequency ◽  
Standing Wave ◽  
High Resistance ◽  
Space Domain ◽  
The Past ◽  
Open Defects ◽  
Rf Electronics ◽  
Rf Signal ◽  
The Magnetic Field

Abstract In the past couple years, Space Domain Reflectometry (SDR) has become a mainstream method to locate open defects among the major semiconductor manufacturers. SDR injects a radio frequency (RF) signal into the open trace creating a standing wave with a node at the open location. The magnetic field generated by the standing wave is imaged with a SQUID sensor using RF electronics. In this paper, we show that SDR can be used to non-destructively locate high resistance failures in Micro LeadFrame Packages (MLP).

Heterogeneous Mercury Reaction on a Selective Catalytic Reduction (SCR) Catalyst

2007 ◽  
Vol 121 (3-4) ◽  
pp. 219-225 ◽  
Author(s):  
Yujin Eom ◽  
Seok Ho Jeon ◽  
Thanh An Ngo ◽  
Jinsoo Kim ◽  
Tai Gyu Lee
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Scr Catalyst

Modeling of a Urea SCR Catalyst With Automotive Applications

2002 ◽  
Author(s):  
Devesh Upadhyay ◽  
Michiel Van Nieuwstadt
Keyword(s):  
Catalytic Reduction ◽  
Chemical Properties ◽  
Lumped Parameter Model ◽  
Scr Catalyst ◽  
Weighted Residuals ◽  
Method Of Weighted Residuals ◽  
Lumped Parameter ◽  
1D Model ◽  
Continuously Stirred Tank Reactor ◽  
Three State Model

A zero order lumped parameter control oriented model of a Selective Catalytic Reduction (SCR) catalyst is presented. The lumped parameter model is developed using two approaches. in the first approach it was assumed that the catalyst behaves as an Isothermal Continuously Stirred Tank Reactor (ICSTR). The second approach involved deriving the lumped parameter model from a 1D model using the method of weighted residuals. Both approaches led to a three state model, with the gas phase concentrations of NOx and NH3 and the surface coverage fraction as the states. The model depends on chemical properties specific to the SCR catalyst; consequently model validation requires knowledge of these parameters, either via laboratory-based experiments or as supplied by the catalyst supplier. We present an alternate approach that allows estimation of the essential parameters through a minimization of the l2 errors between measured and simulated results.

scholarly journals Direct Measurement of Ammonia Storage on Passive SCR Systems for Lean Gasoline NOx Reduction Using Radio Frequency Sensing

2019 ◽  
Author(s):  
Paul Ragaller ◽  
Josh Mandelbaum ◽  
Luc Lapenta ◽  
Alexander Sappok ◽  
Josh Pihl ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Real Time ◽  
Gasoline Engine ◽  
Nox Reduction ◽  
Practical Implementation ◽  
Engine Operation ◽  
Ammonia Storage ◽  
Scr System ◽  
Lean Gasoline ◽  
Passive Scr

Abstract Lean gasoline engine operation provides clear efficiency benefits relative to conventional stoichiometric combustion approaches. One of the key hurdles to the widespread, practical implementation of lean gasoline combustion remains the challenge of lean NOx control. One of the potential approaches for controlling NOx emission from lean gasoline engines is the so-called passive selective catalytic reduction (SCR) system. In such systems, periods of rich operation generate ammonia over a three-way catalyst (TWC), which is then adsorbed on the downstream SCR and consumed during lean operation. Brief periods of rich operation must occur in response to the depletion of stored ammonia on the SCR, which requires reliable measurements of the SCR ammonia inventory. Presently, lean exhaust system controls rely on a variety of gas sensors mounted up- and downstream of the catalysts, and which only provide an indirect inference of the operation state. In this study, a radio frequency (RF) sensor was used to provide a direction measurement of the amount of ammonia adsorbed on the SCR in real-time. The RF sensor was calibrated and deployed on a BMW N43B20 4-cylinder lean gasoline engine equipped with a passive SCR system. Brief periods of rich operation performed at lambda values between 0.98 and 0.99 generated the ammonia, subsequently stored on the SCR for consumption during periods of lean operation. The experiments compared real-time measurements of SCR ammonia inventory from the RF sensor with estimates of ammonia coverage derived from exhaust gas composition measurements upstream and downstream of the catalyst. The results showed a high degree of correlation between the RF measurements and SCR ammonia storage inventory, and demonstrated NOx conversion efficiencies above 98%, confirming the feasibility of the concept. Relative to stoichiometric operation, lean-gasoline operation resulted in fuel efficiency gains of up to 10%, which may be further improved through direct feedback control from the RF sensor to optimize lean–rich cycling based on actual, measured SCR ammonia levels.

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