Two-Level Ribbon Heater Assembly to Prevent Overheating and Shorting
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Solution Overview
Problem
Existing electrical resistance heaters for clothes dryers face issues such as short circuiting, excessive temperatures, and high costs, particularly due to the helical coil design which leads to inefficient heat distribution and material stress.
Innovation Solution
A two-level electrical resistance heater assembly with mica board assemblies supporting heater ribbons in a looped configuration, featuring unique 180-degree turn openings that minimize stress and allow parallel operation, reducing the height and weight of the ribbons while maintaining efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a helical coil heater design is used, then heating capability is provided, but the heater causes excessive temperatures and short circuiting problems
Solution Approach 1:
The heater is divided into two separate levels with distinct heating zones. The first level has heating ribbons that heat air, and the second level has heating ribbons that heat the already warmed air from the first level. This segmentation prevents excessive temperature concentration at any single location and eliminates short circuiting between overlapping heating elements.
Solution Approach 2:
The invention transitions from a single-plane helical coil design to a two-level vertical arrangement. The first level heating ribbons are positioned above the second level heating ribbons, creating a vertical dimension for heat distribution. This dimensional change allows air to flow horizontally through both levels without contacting multiple hot surfaces simultaneously, preventing overheating and short circuits.
2Power
If traditional heater configurations are used, then heating function is achieved, but material stress and construction costs increase
Solution Approach 1:
Each level is designed with specific local characteristics: the first level heating ribbons are positioned to maximize initial heating efficiency, while the second level ribbons are arranged to optimize secondary heating. The mica board assemblies at each level provide localized insulation and support tailored to the specific thermal requirements of that zone, reducing overall material stress.
Solution Approach 2:
The heater employs composite construction with mica board assemblies combining insulating mica material with structural support elements. This composite approach provides both thermal insulation and mechanical support, reducing material stress and simplifying construction compared to traditional single-material heater designs.
3Device complexity
If heater ribbons are positioned in a single level, then construction is simplified, but heat distribution efficiency decreases
Solution Approach 1:
The invention adds a vertical dimension by positioning heating ribbons on two different levels. Air enters the housing and flows horizontally through channels that pass beneath the first level ribbons and over the second level ribbons. This two-level arrangement doubles the effective heating surface area in contact with the air stream, significantly improving heat distribution efficiency while maintaining relatively simple construction through modular mica board assemblies.
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 solution provides a safer, more efficient, and cost-effective heating solution by operating at lower temperatures, reducing material stress, and allowing the use of less expensive resistance materials, while also simplifying the dryer design and reducing weight and labor costs.
Implementation Method 1
electrical resistance heater assembly
Data Source
AI summary
An electrical resistance heater assembly includes a heater housing forming a channel having a longitudinal axis for a fluid such as air to pass through and a heater support plate forming first and second levels in the heater housing. A first mica board assembly supporting a ribbon heater is mounted to the heater support plate at the first level and a second mica board assembly supporting a ribbon heater is mounted to the heater support plate at the second level. The first level is positioned adjacent an inlet of the heater housing and the second level is positioned adjacent an outlet of the heater housing. The first level and a side of the heater housing form a passageway for air to enter the heater housing and be directed to the ribbons of the second level, thereby allowing air to bypass the heater ribbons of the first level.