PTC Ceramic Honeycomb Structure for Uniform EHC Heating
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Solution Overview
Problem
Existing ceramic supports for electrically heating catalysts (EHCs) with NTC properties face challenges in temperature distribution bias due to local heat generation, and there is a need to adjust volume resistivity based on applied voltage values.
Innovation Solution
A honeycomb structure made of ceramics, comprising borosilicate and silicon particles doped with Group 13 or Group 15 elements, which allows for adjustment of volume resistivity by controlling the dopant amount and silicon particle content, enabling PTC properties and voltage-dependent resistivity adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If NTC property supports are used for electric heating, then heating speed is improved, but temperature distribution bias occurs due to local heat generation
Solution Approach 1:
The invention changes the electrical property parameter from NTC (negative temperature coefficient) to PTC (positive temperature coefficient). This fundamental parameter change allows the support to automatically regulate current distribution based on temperature, preventing local heat generation while maintaining fast heating capability through controlled resistivity changes.
Solution Approach 2:
The PTC property provides inherent feedback control: as temperature increases in any region, the electrical resistance automatically increases, reducing current flow to that region. This self-regulating mechanism prevents temperature distribution bias without requiring external control systems.
2Use of energy by moving object
If volume resistivity is adjusted for different voltage applications, then heating efficiency is improved, but support composition complexity increases
Solution Approach 1:
The invention uses dopant concentration as a controllable parameter to adjust volume resistivity. By varying the dopant amount in silicon particles, different voltage applications (200-500V range) can be optimized without changing the fundamental support structure or adding complex multi-component systems.
Solution Approach 2:
The invention introduces silicon particles with specific dopant concentrations as a localized functional component within the ceramic support matrix. This allows resistivity adjustment while maintaining the overall simplicity of the ceramic support structure.
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 proposed solution allows for effective temperature distribution and resistivity adjustment in EHCs, enhancing the heating efficiency and oxidation resistance of the honeycomb structure.
Implementation Method 1
a support having a PTC property (a property in which electric resistance increases as a temperature increases)
Implementation Method 2
heating by current conduction
Implementation Method 3
silicon particles doped with at least one dopant, wherein the dopant is a Group 13 element or a Group 15 element
Data Source
AI summary
A honeycomb structure made of ceramics, wherein the honeycomb structure includes: a borosilicate; and silicon particles doped with at least one dopant, the dopant is a Group 13 element or a Group 15 element, the silicon particles have a dopant amount (A) of 1×1016 to 5×1020/cm3, and the honeycomb structure has a silicon particle content (B) of 30 to 80% by mass.