Exhaust Catalyst Substrate with Phase Change Material
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Solution Overview
Problem
Exhaust gas treatment systems in hybrid vehicles face challenges in maintaining catalysis activation temperature due to frequent engine stop-start cycles, leading to prolonged ignition times and increased costs with existing solutions.
Innovation Solution
A substrate is subdivided into sectors with a phase change material placed between them, allowing for easy integration and efficient heat exchange, using a metal casing to contain the material and reduce dispersion, and incorporating insulating and damping layers to optimize heat retention and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the amount of catalytic substance on the substrate is increased to increase efficiency, then the catalytic efficiency is improved, but the cost increases significantly
Solution Approach 1:
The patent utilizes phase change material (wax) that transitions from solid to liquid at a specific temperature range (50-150°C). This phase transition absorbs and releases latent heat, maintaining the substrate temperature above the catalytic initiation temperature (300°C) during engine stop-start cycles, thereby preserving catalytic efficiency without requiring additional noble metal catalyst
2Loss of time
If the operating mode of the heat engine is modified to greatly increase the temperature of the exhaust gases to accelerate substrate temperature rise, then the ignition time is reduced, but the fuel consumption increases greatly
Solution Approach 1:
The phase change material is pre-positioned in thermal contact with the substrate before engine operation. During normal operation, it absorbs excess heat and stores it as latent heat. During stop-start cycles, this pre-stored heat is released to maintain substrate temperature, eliminating the need for preliminary heating actions that would increase fuel consumption
3Reliability
If a phase change material is integrated into the substrate to maintain temperature during stop-start cycles, then the catalysis activation is maintained, but the device complexity increases
Solution Approach 1:
The phase change material is nested within the substrate structure itself, with channels or cavities in the substrate filled with the material. This nested configuration integrates the thermal management function directly into the catalytic substrate, maintaining reliability while minimizing additional device complexity
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
This configuration reduces ignition time and maintains efficient catalysis activation by ensuring immediate heat transfer and reaction initiation, even after long shutdowns, while being cost-effective and easy to produce.
Implementation Method 1
a phase change material (3) arranged close to the substrate (2); The melting temperature is chosen to be higher than the initiation temperature, such that when the phase change material is molten, the substrate remains at a temperature above the initiation temperature
Implementation Method 2
The melting temperature is chosen to be higher than the initiation temperature, such that when the phase change material is molten, the substrate remains at a temperature above the initiation temperature
Implementation Method 3
A metal or ceramic substrate has channels coated with catalytic substances. The channels are traversed by the exhaust gases and undergo a chemical transformation facilitated by the catalytic substance
Implementation Method 4
For example, oxidation catalysts make it possible to burn off the last hydrocarbon residues contained in the gases
Implementation Method 5
when the oxidation reactions have started, they provide heat by exotherm and maintain the temperature of the substrate above the threshold
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a device (1, 1') for treating exhaust gases by catalysis, in which a phase-change material (212) is included in order to shorten the time it takes for catalysis to begin after hot starting.