Dielectric Dryer Drum Using Low-Frequency RF to Avoid Metal Overheating
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Solution Overview
Problem
Conventional clothes dryers are inefficient as most energy is lost through the vent, and previous RF drying technologies face issues with non-conductive drum containers, cavity size constraints, and overheating of metal objects due to high frequency RF and microwave fields.
Innovation Solution
A low frequency RF capacitive electrical system is used to evaporate water by exciting water molecules, with a conductive drum acting as a cathode and anode, ensuring efficient energy transfer and uniform drying without overheating metal objects, using a single power source and impellers for tumbling to enhance evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high frequency RF or microwave fields are used to evaporate water, then water evaporation efficiency is improved, but metal objects in the load overheat and safety issues arise
Solution Approach 1:
The patent changes the frequency parameter of the RF field from high frequency (microwave range) to low frequency (roughly 10 MHz to 100 MHz). This parameter change allows the RF energy to be absorbed primarily by water molecules through dipole rotation without causing excessive heating of metal objects, thus resolving the contradiction between evaporation efficiency and metal safety
Solution Approach 2:
The low frequency RF field induces vibrational motion in water molecules at a frequency that matches their natural dipole relaxation frequency. This resonant vibration efficiently converts RF energy into thermal energy for water evaporation while avoiding the skin effect and eddy current heating problems that occur with high frequency fields and metal objects
2Use of energy by moving object
If non-conductive drum containers are used for RF drying, then RF energy can reach the load, but the drum cannot be made electrically conductive for efficient energy transfer
Solution Approach 1:
The patent segments the drum into two functional parts: a non-conductive outer drum structure that provides mechanical containment and allows RF penetration, and a separate conductive component (such as a mesh screen or wire elements) that is electrically connected to the RF source. This segmentation allows each part to fulfill its specific function without compromise
Solution Approach 2:
The patent introduces an intermediary conductive structure (such as a mesh screen or wire elements suspended inside the drum) that mediates between the non-conductive drum and the RF energy source. This intermediary allows efficient energy transfer to the load while the outer non-conductive drum maintains its structural and RF-transparent properties
3Productivity
If conventional forced hot air drying is used, then water is extracted from clothes by evaporation, but most energy is lost through the vent
Solution Approach 1:
The patent replaces the conventional mechanical forced hot air drying system with an electromagnetic field-based heating system. Low frequency RF energy directly heats the water molecules in the clothes through dielectric heating, eliminating the need for large volumes of heated air and the associated energy losses through ventilation
Solution Approach 2:
The patent utilizes the phase transition of water from liquid to vapor through direct RF heating. The low frequency RF energy efficiently causes water molecules to vibrate and transition to vapor phase, which is then removed by a small amount of air flow, dramatically reducing the energy required compared to conventional air drying
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 approach results in a more energy-efficient clothes drying process with uniform water removal, avoiding the inefficiencies and safety issues of conventional dryers, while maintaining a conventional drum size and preventing overheating of metal objects.
Implementation Method 1
In the present invention, water is evaporated by heat of friction of the water molecules vibrating at the RF frequency
Implementation Method 2
The wet clothes load appears as a capacitive electrical element through which the low frequency RF current flows
Implementation Method 3
causing a state change from liquid to vapor
Implementation Method 4
The resulting water vapor is carried away by forced air
Data Source
AI summary
Methods and apparatus for heating an object 9 that includes an absorbed medium. A method embodiment comprises: placing the object 9 including the medium into an enclosure 16; initiating a heating process by subjecting the object 9 and medium to a capacitive AC electrical field generated by an RF power source 2 at a single low frequency; controlling the heating process by taking real time measurements; and making real time adjustments to the RF power source 2 in response to the real time measurements. The object 9 substantially absorbs the medium in a first “cool” state, and therefore has a maximum weight in the first “cool” state. The object 9 is substantially free from the medium in a second “heated” state, due to substantial release of the medium from the object 9. The released medium is evaporated during the heating process. The heating process is completed when the object 9 is substantially transitioned into the second “heated” state. The method further comprises causing an air flow 11 inside the enclosure 16 to carry away evaporated medium out of the enclosure 16.