Characteristic Response of a Production Diesel Oxidation Catalyst Exposed to Lean and Rich PCI Exhaust

2007 ◽  
Author(s):  
Timothy J. Jacobs ◽  
Dennis N. Assanis
Keyword(s):  
Low Temperature ◽  
Diesel Oxidation Catalyst ◽  
Oxidation Catalyst ◽  
Mode Switching ◽  
Lean Nox Trap ◽  
Nitric Oxides ◽  
Combustion Mode ◽  
Lean Combustion ◽  
Diesel Oxidation Catalysts ◽  
Diesel Oxidation

Although low-temperature premixed compression ignition (PCI) combustion in a light-duty diesel engine offers dramatic and simultaneous reductions in nitric oxides (NOx) and soot, associated increases in unburned hydrocarbons (HC) and carbon monoxide (CO) become unacceptable. Production diesel oxidation catalysts (DOCs) are effective in oxidizing the increased levels of HC and CO under lean combustion conditions. However, the low temperature / high CO combination under rich PCI conditions, designed as a lean NOx trap (LNT) regeneration mode, generally renders the DOC ineffective. The objectives of this study are to characterize the oxidizing efficiency of a production DOC under lean and rich PCI conditions, and attempt to identify probable causes for the observed ineffectiveness under rich PCI. The study uses several tests to characterize the behavior of the DOC under lean PCI and rich PCI combustion conditions, including: (1) steady-state feed gas characterization, (2) transient feed gas characterization, (3) air injection (4) insulated AF sweep, and (5) combustion mode switching. The DOC never becomes effective under rich PCI for any of the tests, suggesting that the platinum-based catalyst may be incorrect for use with rich PCI. Furthermore, combustion mode switching between lean PCI and rich PCI (mimicking LNT loading and regeneration) demonstrates diminishing effectiveness of the DOC during and after continuous mode transitioning.

Characteristic Response of a Production Diesel Oxidation Catalyst Exposed to Lean and Rich PCI Exhaust

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Timothy J. Jacobs ◽  
Dennis N. Assanis
Keyword(s):  
Low Temperature ◽  
Diesel Oxidation Catalyst ◽  
Oxidation Catalyst ◽  
Mode Switching ◽  
Lean Nox Trap ◽  
Nitric Oxides ◽  
Combustion Mode ◽  
Lean Combustion ◽  
Diesel Oxidation Catalysts ◽  
Diesel Oxidation

Although low-temperature premixed compression ignition (PCI) combustion in a light-duty diesel engine offers dramatic and simultaneous reductions in nitric oxides (NOx) and soot, associated increases in unburned hydrocarbons (HC) and carbon monoxide (CO) become unacceptable. Production diesel oxidation catalysts (DOCs) are effective in oxidizing the increased levels of HC and CO under lean combustion conditions. However, the low-temperature∕high CO combination under rich PCI conditions, designed as a lean NOx trap (LNT) regeneration mode, generally renders the DOC ineffective. The objectives of this study are to characterize the oxidizing efficiency of a production DOC under lean and rich PCI conditions, and attempt to identify probable causes for the observed ineffectiveness under rich PCI. The study uses several tests to characterize the behavior of the DOC under lean PCI and rich PCI combustion conditions, including (1) steady-state feed gas characterization, (2) transient feed gas characterization, (3) air injection (4) insulated air-fuel sweep, and (5) combustion mode switching. The DOC never becomes effective under rich PCI for any of the tests, suggesting that the platinum-based catalyst may be incorrect for use with rich PCI. Furthermore, combustion mode switching between lean PCI and rich PCI (mimicking LNT loading and regeneration) demonstrates diminishing effectiveness of the DOC during and after continuous mode transitioning.

scholarly journals Ceria-based nanoflake arrays integrated on 3D cordierite honeycombs for efficient low-temperature diesel oxidation catalyst

2019 ◽  
Vol 245 ◽  
pp. 623-634 ◽  
Author(s):  
Wenxiang Tang ◽  
Xingxu Lu ◽  
Fangyuan Liu ◽  
Shoucheng Du ◽  
Junfei Weng ◽  
...  
Keyword(s):  
Low Temperature ◽  
Diesel Oxidation Catalyst ◽  
Oxidation Catalyst ◽  
Diesel Oxidation

scholarly journals An on-board method to estimate the light-off temperature of diesel oxidation catalysts

2018 ◽  
Vol 21 (8) ◽  
pp. 1480-1492 ◽  
Author(s):  
Carlos Guardiola ◽  
Benjamin Pla ◽  
Pau Bares ◽  
Javier Mora
Keyword(s):  
Time Window ◽  
Diesel Oxidation Catalyst ◽  
Operating Conditions ◽  
Oxidation Catalyst ◽  
Temperature Estimation ◽  
Exhaust Temperature ◽  
Diesel Oxidation Catalysts ◽  
Diesel Oxidation ◽  
Exhaust Line ◽  
Two Temperature

Current diesel engine regulations include on-board diagnostic requirements so that after-treatment systems need on-board methods to detect their aging state through the available measurements. In a state-of-the-art diesel exhaust line, two temperature and [Formula: see text] measurements can be found upstream and downstream of the diesel oxidation catalyst. Thus, the strategy presented in this article makes use of these measurements to estimate the light-off temperature, which has been widely studied as a characteristic of diesel oxidation catalyst aging. The light-off temperature estimation potential is evaluated first under dynamic engine operating conditions, in which [Formula: see text] measurements are proved to be precise enough to detect oxidation. However, dynamic conditions make the association of a representative temperature with an oxidation event difficult. Therefore, the method makes use of more controlled conditions at idle, during which the exhaust temperature decreases avoiding dynamics of normal driving conditions. During the idle, post-injection pulses are applied to determine whether oxidation occurs at a representative temperature measured by the upstream temperature sensor. The result of each pulse is used to generate a database. Then, after a long enough time window, the database generated will allow characterizing non-oxidation and oxidation temperatures, with an intermediate interval of indefinition. This article shows how the temperatures of these ranges increase as the light-off temperature increases, thereby validating the proposed method for light-off temperature estimation.

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