Multistage Open Coil Heater with Cool End Termination
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Solution Overview
Problem
Existing open coil electric heaters with multiple stages face challenges in achieving uniform heat distribution across both sides of a support plate, requiring expensive ceramic insulators and cumbersome terminal connections, which are labor-intensive and prone to deterioration due to high temperatures.
Innovation Solution
A multistage open coil electric resistance heater design where the coil stages are evenly arranged on either side of a support plate, with terminal ends located at the cool end to simplify connections and reduce the need for additional insulation, using crimp-style terminals with a hole for threaded connections that are lightweight and easy to assemble.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If coil stages are arranged on one side of the support plate, then heat distribution to one side is improved, but heat distribution uniformity across both sides deteriorates
Solution Approach 1:
The heater element is designed with asymmetric coil distribution relative to the support plate, where the majority of coil stages are positioned on one side while maintaining thermal balance through strategic placement. This asymmetric arrangement allows optimized heat distribution to both sides of the duct without requiring equal coil distribution on each side of the plate.
2Reliability
If ceramic insulators are used to support coil stages, then electrical insulation is improved, but device complexity and cost increase
Solution Approach 1:
The support plate is designed to perform multiple functions simultaneously: it provides mechanical support for the coil stages, electrical insulation between the heating element and duct, and structural mounting for the heater. By merging these functions into a single integrated component, the design eliminates the need for separate ceramic insulators while maintaining electrical isolation and structural integrity.
3Ease of operation
If terminal connections are placed at the hot end of the heater, then electrical connection accessibility is improved, but thermal stress and deterioration increase
Solution Approach 1:
The terminal connections are inverted from the conventional hot-end placement to the cool-end location of the heater element. This inversion positions the electrical terminals in the thermally stable region near the support plate, protecting them from thermal stress and deterioration while maintaining accessibility through the open coil structure design.
4Reliability
If additional insulation is added to protect terminal connections, then thermal protection is improved, but device complexity and material costs increase
Solution Approach 1:
The support plate serves as its own thermal barrier for the terminal connections by positioning them in the cool-end region where the plate itself provides thermal mass and insulation. The design utilizes the inherent thermal properties of the support plate structure to protect terminals without requiring additional insulation materials or components.
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 ensures efficient heat distribution to both sides of the air duct with reduced thermal stress on terminals, simplifying assembly and reducing labor and material costs while maintaining secure electrical connections.
Implementation Method 1
the resistance coils are energized to heat air passing over the coils
Data Source
AI summary
A multiple stage open coil electrical resistance heater uses a unique coil configuration on either side of a dividing support plate so that the air passing through the heater is heated uniformly when one or more stages of the heater are energized. The coil configuration also creates a termination zone on one side of the heater so that the terminations of the coils can be situated on the cool side of the heater. The heater coils also includes specially configured terminals to facilitate connection to power using an elongated member such as a stud or bolt.