RF Food Heating Control by Absorption Frequency Selection
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Solution Overview
Problem
Existing microwave oven technologies do not achieve optimal heating of food ingredients due to fixed heating frequencies, which can lead to inefficient heating processes.
Innovation Solution
A method and apparatus that measure the spectrum of energy absorption of food ingredients across a range of radio frequencies to identify the frequency for maximum absorption, applying an electrical field at that frequency to enhance heating efficiency, and dynamically adjust the frequency based on temperature changes and food type to optimize heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed heating frequency is used in microwave ovens, then the device complexity is reduced and operation is simplified, but the heating efficiency and energy absorption optimization deteriorate
Solution Approach 1:
The patent implements dynamic frequency adjustment by sweeping through a range of radio frequencies (e.g., 2.4 GHz to 2.5 GHz) to identify the optimal frequency for maximum energy absorption. The system continuously adapts the heating frequency based on real-time measurements of energy absorption characteristics, transforming the static fixed-frequency approach into a dynamic optimized process that maintains high heating efficiency while remaining operationally simple through automated control.
Solution Approach 2:
The patent changes the operating parameter (frequency) from a fixed value to a variable that is optimized based on measured energy absorption characteristics. By sweeping through multiple frequencies and selecting the one that maximizes energy absorption, the system achieves optimal heating efficiency without requiring complex manual intervention, as the frequency parameter is automatically adjusted based on empirical measurements.
2Adaptability or versatility
If multiple fixed frequencies are used via high-power traveling wave tubes, then heating flexibility is improved, but the device complexity and manual operation requirements increase
Solution Approach 1:
The patent implements a self-service frequency selection mechanism where the system automatically measures energy absorption characteristics at multiple frequencies and autonomously identifies the optimal frequency without requiring manual user input. The control system performs the frequency sweep, measures absorption, and selects the optimal frequency automatically, eliminating the need for manual frequency determination while maintaining heating flexibility through multiple frequency options.
Solution Approach 2:
The patent incorporates feedback by measuring the energy absorption characteristics at each frequency during the sweep process and using this measured information to determine the optimal operating frequency. The system receives feedback from the energy absorption measurements and adjusts the frequency selection accordingly, creating a closed-loop control system that optimizes heating efficiency based on actual measured performance rather than predetermined settings.
3Ease of manufacture
If the heating frequency is not optimized for maximum energy absorption, then the heating process is simpler to implement, but the heating time increases and energy efficiency deteriorates
Solution Approach 1:
The patent performs preliminary action by conducting a frequency sweep and measuring energy absorption characteristics before the actual heating process begins. This preliminary measurement phase identifies the optimal frequency in advance, ensuring that the subsequent heating process operates at maximum efficiency from the start, thereby reducing overall heating time without adding significant complexity to the implementation.
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 improves heating efficiency by using the optimal radio frequency for food absorption, reducing heating time and ensuring even energy distribution throughout the food.
Implementation Method 1
Microwave oven heats food by irradiating in the cooking chamber of the oven, an electromagnetic radiation in the microwave spectrum and causes polar molecules (e.g. water) in the food to rotate and build up thermal energy in a process known as the dielectric heating.
Implementation Method 2
measuring the ratio between the energy of the radio frequency electrical field reflected or absorbed from the food ingredients, and the energy of the radio frequency electrical field applied to the food ingredients
Data Source
AI summary
The invention relates to a method (100) and apparatus for controlling the heating of food ingredients. The method comprises the step of measuring (110) the spectrum of energy absorption of the food ingredients in a given range of radio frequencies. The method also comprises the step of identifying (120), in said given range of radio frequencies, the radio frequency for which the food ingredients have the maximum energy absorption. The method also comprises the step of applying (130) an electrical field to the food ingredients, said electrical field having a radio frequency corresponding to said radio frequency for which the food ingredients have the maximum energy absorption. The step of measuring (110) comprises, for a plurality of selected radio frequencies in said given range of radio frequencies, the steps of: applying an electrical field on the food ingredients having a radio frequency corresponding to a given selected radio frequency in said plurality of selected radio frequencies; and, measuring the ratio between the energy of the radio frequency electrical field reflected or absorbed from the food ingredients, and the energy of the radio frequency electrical field applied to the food ingredients. The plurality of selected radio frequencies are selected from said given range of radio frequencies by the steps of: for each of said given range of radio frequencies, obtaining a penetration depth of an electrical field having a radio frequency corresponding to the given radio frequency into the food ingredients, and including the given radio frequency into the plurality of selected radio frequencies if the penetration depth of the electrical field having a radio frequency corresponding to the given radio frequency is equal to or larger than the thickness of the food ingredients in the direction of the electrical field applied to the food ingredients. This invention allows reducing the heating time of food ingredients.