Fixed Radial Anode Drum Dryer for Uniform Low-RF Heating
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Solution Overview
Problem
Conventional clothes drying methods using microwave frequencies are less efficient for dielectric heating due to higher frequencies leading to non-uniform heating and increased parasitic capacitance, which reduces energy transfer efficiency in RF dielectric heating processes.
Innovation Solution
A clothes dryer apparatus with a rotating conductive drum acting as a cathode and spatially fixed, non-rotating radial anodes that create an electric field for capacitive coupling, minimizing parasitic capacitance and using low RF frequencies for efficient dielectric heating, along with air flow for moisture removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If microwave frequencies (>800 MHz) are used for dielectric heating, then heating can be achieved, but heating uniformity deteriorates and parasitic capacitance increases reducing energy transfer efficiency
Solution Approach 1:
The patent changes the operating frequency parameter from microwave frequencies (>800 MHz) to low RF frequencies (1 MHz to 50 MHz). This parameter change reduces parasitic capacitance effects and improves energy transfer efficiency while maintaining effective dielectric heating through ion drag mechanisms in conductive liquids.
Solution Approach 2:
Instead of using the conventional microwave frequency approach for dielectric heating, the patent inverts the frequency approach by using low RF frequencies. This inversion resolves the parasitic capacitance problem that plagues high-frequency microwave systems while achieving effective heating through alternative physical mechanisms.
2Temperature
If microwave frequencies are used for dielectric heating, then heating effect is achieved, but heating uniformity deteriorates
Solution Approach 1:
The patent changes the frequency parameter from microwave to low RF range, which fundamentally alters the heating mechanism. At low RF frequencies, ion drag causes more uniform energy distribution throughout the load, eliminating the non-uniform heating problems associated with microwave frequencies.
3Use of energy by moving object
If conventional RF heating with rotating capacitive structures is used, then dielectric heating is achieved, but device complexity increases due to specialized connections required
Solution Approach 1:
The patent extracts the rotating component from the capacitive structure, leaving only fixed anodes. The drum itself serves as the moving element while the RF heating elements remain stationary, eliminating the need for complex rotating electrical connections while maintaining effective dielectric heating.
Solution Approach 2:
Instead of having rotating capacitive structures that require complex moving connections, the patent inverts the approach by using fixed anodes with a rotating conductive drum. This inversion simplifies the electrical connection system while maintaining the necessary capacitive coupling for RF heating.
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 solution enhances energy transfer efficiency by up to 10% compared to conventional methods, providing uniform heating and faster drying through optimized RF capacitive coupling and air flow management.
Implementation Method 1
Dielectric heating involves the heating of materials by dielectric loss. A changing electric field across the dielectric material (in this case, a load of clothes) causes energy to be dissipated as the molecules attempt to line up with the continuously changing electric field, creating friction.
Implementation Method 2
In conductive liquids such as salt water, 'ion drag' from using lower RF frequencies causes heating, as charged ions are 'dragged' more slowly back and forth in the liquid under influence of the electric field, striking liquid molecules in the process and transferring kinetic energy to them, which is eventually translated into molecular vibrations, and thus into thermal energy.
Implementation Method 3
This changing electric field may be caused by an electromagnetic wave propagating in free space as in a microwave oven, or it may be caused by a rapidly alternating electric field inside a capacitor, as in the present invention. In the latter case, there is no freely propagating electromagnetic wave.
Data Source
AI summary
A clothes dryer apparatus (99) comprising an electrically conductive, grounded, generally cylindrical rotatable drum (13) having a hollow interior adapted to contain a load (15) of wet clothes to be dried. The drum's (13) exterior surface (27) is partially indented to form one or more integral, generally ring-shaped insulated notches (10). An electrically conductive, generally flat arcuate anode (11) is positioned within each notch (10), with no physical contact between an anode (11) and its corresponding notch (10). Each anode (11) is spatially fixed with respect to the rotatable drum (13), and is electrically isolated from conductive portions of the drum (13). A source (21) of RF power (12), operating at a single fixed frequency, is coupled to each anode (11).