Honeycomb Electrical Heater Uniform Current Distribution
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Solution Overview
Problem
Existing electrically heated catalyst systems for vehicle emissions face issues with non-uniform heating profiles, which degrade performance and increase energy inefficiency, especially during cold-start conditions when a significant proportion of emissions occur before the catalyst is fully activated.
Innovation Solution
An electrical heater design featuring a honeycomb body with intersecting conductive walls forming resistive paths of varying lengths and resistances, where insulating layers separate the paths to ensure equal current flow across the cross-section, and electrodes apply voltages proportional to path resistances to maintain uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional electrical heater design is used, then the catalyst can be heated, but the heating profile is non-uniform across the cross-section
Solution Approach 1:
The heater cross-section is divided into multiple independent resistive paths separated by insulating layers. Each path has its own current flow, allowing independent control and uniform heat distribution across different regions of the catalyst substrate.
Solution Approach 2:
Different regions of the heater are designed with varying path lengths and resistances tailored to local heating requirements. Paths in cooler regions have lower resistance to receive more current, while paths in warmer regions have higher resistance, creating locally optimized heating zones for uniform overall temperature distribution.
2Temperature
If resistive paths of varying lengths are used to achieve uniform heating, then heating uniformity improves, but path resistance varies making current control difficult
Solution Approach 1:
The design intentionally varies resistance parameters across different resistive paths to compensate for thermal gradients. By adjusting path length, width, and material composition, each path's resistance is optimized for its specific location, transforming the complexity of resistance variation into a controlled parameter for achieving uniform heating.
3Productivity
If multiple resistive paths with different lengths are created, then current distribution can be optimized, but the device structure becomes more complex
Solution Approach 1:
The heater is segmented into multiple resistive paths separated by insulating layers, allowing independent current control in each path. This segmentation enables optimized current distribution while maintaining a relatively simple overall structure that can be manufactured using conventional techniques.
Solution Approach 2:
The resistive paths serve multiple functions simultaneously: they are the heating elements, the structural framework, and the current conduction paths. The intersecting wall structure provides both mechanical support and electrical resistance, reducing the need for separate components and simplifying the overall device 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
This design achieves a uniform current distribution across the honeycomb body, enhancing heating efficiency and reducing emissions by ensuring consistent catalyst activation, even during cold-start conditions.
Implementation Method 1
electrical heater generating a substantially uniform current across a cross-section of a honeycomb body
Data Source
AI summary
An electrical heater and method for heating a catalyst. The heater includes a honeycomb body having intersecting walls forming channels extending along a longitudinal axis. A plurality of electrically resistive paths are included, each including at least a portion of the plurality of intersecting walls and extending a length across the honeycomb body transverse to the longitudinal axis. A positive electrode and a negative electrode are in electrical communication with each other via the resistive paths. The positive electrode and the negative electrode are operatively positioned to generate a respective flow of current through each resistive path. The lengths of at least two of the resistive paths differ from each other. The resistive paths are configured with respect to the at least one positive electrode and the at least one negative electrode such that the current in each of the resistive paths is substantially equal.