Electrically Heated Catalyst for Compression Ignition Engines
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Solution Overview
Problem
Compression ignition engines' oxidation catalysts take a significant time to heat up to their effective operating temperature, leading to delayed emission control and increased pollutant emissions, and they also consume expensive platinum group metals.
Innovation Solution
An emissions control device comprising a first electrically heatable catalyst with a PGM and alumina-based support material, and a second catalyst without an electrically heatable substrate, where the first catalyst is upstream of the second, allowing for rapid temperature increase and reduced platinum group metal loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxidation catalyst is used to treat CO and HCs in exhaust emissions, then emission control is improved, but the catalyst takes several minutes to heat up to effective operating temperature from cold start, leading to delayed emission control and increased pollutant emissions
Solution Approach 1:
The patent applies preliminary action by incorporating an electrical heater upstream of the oxidation catalyst that activates before the catalyst reaches operating temperature. The heater preheats the exhaust gas and catalyst substrate, enabling the catalyst to reach its light-off temperature faster and begin emission control sooner after engine startup.
Solution Approach 2:
The patent uses an electrical heater as an intermediary device between the exhaust gas source and the oxidation catalyst. This mediator transfers thermal energy to the catalyst system, bridging the temperature gap during cold start conditions and enabling faster catalyst activation without modifying the catalyst itself.
2Loss of time
If an electrical heater is incorporated into the exhaust system to heat up the catalyst faster, then the time to reach operating temperature is reduced, but electrical power consumption increases
Solution Approach 1:
The patent optimizes heater parameters including positioning it upstream of the catalyst, designing it with at least 15 heated channels per square cm, and making the channels less than 1.0 cm in length. These parameter changes maximize heating efficiency and reduce the electrical power required to achieve fast catalyst light-off.
Solution Approach 2:
The electrical heater is designed with localized heated channels concentrated in specific regions upstream of the catalyst. This local quality approach focuses thermal energy where it is most needed for catalyst activation, improving heating efficiency and reducing overall power consumption compared to uniform heating approaches.
3Reliability
If platinum group metals are used in the oxidation catalyst for effective CO and HC oxidation, then catalytic activity is improved, but the cost and precious metal consumption increase
Solution Approach 1:
By preheating the catalyst with the electrical heater before exhaust gas flows through it, the catalyst reaches optimal operating temperature faster. This preliminary heating action ensures that the platinum group metals are immediately active when they begin processing exhaust, maximizing their utilization efficiency and allowing for potentially lower metal loadings while maintaining performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables faster oxidation of CO, HCs, and NOx emissions control, reducing overall pollutant emissions and lowering electrical power consumption while minimizing platinum group metal usage.
Implementation Method 1
an electrically heatable substrate and a first composition disposed on the electrically heatable substrate
Data Source
Figure 1~2
AI summary
An emissions control device for a compression ignition engine is described. The emissions control device comprises: (a) a first catalyst comprising an electrically heatable substrate and a first composition disposed on the electrically heatable substrate, wherein the first composition comprises alumina and a first platinum group metal (PGM); and (b) a second catalyst comprising a substrate and a second composition disposed on the substrate, wherein the second composition comprises alumina and a second platinum group metal (PGM); wherein the loading of the first composition is less than the loading of the second composition.