Conductive Ceramic Honeycomb Structure for Exhaust Gas Heater
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Solution Overview
Problem
Existing honeycomb structures used as catalyst supports and heaters in exhaust gas treatment systems face issues with excessive current flow when high-voltage power sources are used, damage to metal heaters, and deterioration of electrodes in conductive ceramic materials due to exposure to exhaust gases, leading to inadequate heat distribution and mechanical stress.
Innovation Solution
A honeycomb structure with a tubular design featuring porous partition walls and band-like electrode parts arranged on the side surfaces, with controlled electrical resistivity, heat capacity, and porosity, allowing for even current flow and heat distribution while withstanding rapid temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a metal heater with low electric resistance is used with a high-voltage power source, then heating function is achieved, but excessive current flows and damages the power source circuit
Solution Approach 1:
The invention changes the electrical resistance parameter by using conductive ceramic material instead of metal, and by controlling the porosity and composition of the ceramic to achieve an appropriate resistance value that limits current flow while maintaining heating capability
Solution Approach 2:
The invention uses composite ceramic materials with specific porosity and composition to achieve the desired electrical resistance characteristics, combining insulating and conductive properties in a single structured material
2Power
If a metal heater is processed into a honeycomb constitution, then heater function is achieved, but catalyst is not easily loaded onto the heater
Solution Approach 1:
The invention uses conductive ceramic material that inherently provides both heating capability and catalyst support functionality, eliminating the need for separate metal heater and catalyst components
Solution Approach 2:
The honeycomb structure serves multiple functions simultaneously: it acts as the heater body, provides surface for catalyst loading, and maintains structural integrity, replacing the need for separate components
3Ease of operation
If electrodes are directly exposed to exhaust gas in a catalyst support with heater, then electrical connection is achieved, but electrodes easily deteriorate and resistance value increases
Solution Approach 1:
The invention introduces the conductive ceramic honeycomb structure as an intermediary between the electrodes and the exhaust gas, providing electrical conductivity while protecting the electrodes from direct exposure to corrosive exhaust gases
Solution Approach 2:
The ceramic material creates a chemically inert environment around the electrodes, preventing direct reaction between the electrodes and exhaust gas components, thereby reducing deterioration
4Device complexity
If a honeycomb structure is used as both catalyst support and heater, then integration is achieved, but heat shock resistance is compromised
Solution Approach 1:
The invention changes the thermal parameters of the honeycomb structure by controlling the porosity and material composition, enabling the structure to withstand rapid temperature changes while maintaining integration of heating and catalyst support functions
Solution Approach 2:
The porous ceramic structure provides thermal management capabilities, allowing controlled heat distribution and reducing thermal stress during rapid temperature changes, thereby improving heat shock resistance
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 honeycomb structure effectively manages current flow and heat distribution, preventing damage and mechanical stress, ensuring efficient heat generation and purification of exhaust gases without excessive power consumption or electrode deterioration.
Implementation Method 1
a honeycomb structure which is a catalyst support and also functions as a heater when a voltage is applied thereto and which has an excellent heat shock resistance
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
There is disclosed a honeycomb structure 100 including: a tubular honeycomb structure part 4 having porous partition walls 1 with which a plurality of cells 2 are formed, and an outer peripheral wall 3; and a pair of electrode parts 21 arranged on a side surface 5 of the honeycomb structure part 4, an electrical resistivity of the honeycomb structure part 4 is from 1 to 200 Ωcm, each of the pair of electrode parts 21 is formed into a band-like shape extending in a direction in which the cells 2 extend, in a cross section perpendicular to the extending direction of the cells 2, the one electrode part 21 is disposed opposite to the other electrode part 21 via the center of the honeycomb structure part 4, and a total of heat capacities of the pair of electrode parts 21 is from 2 to 150% of a heat capacity of the whole outer peripheral wall 3. There is provided the honeycomb structure which is a catalyst support and also functions as a heater when a voltage is applied thereto and which has an excellent heat shock resistance.