Electromagnetic Heater Control for Uniform Heating of Irregular Objects
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Solution Overview
Problem
Conventional microwave ovens fail to provide uniform heating for irregularly shaped objects due to limitations in frequency range, cavity structure, and coupling issues, leading to hotspots and inefficient heating processes.
Innovation Solution
The use of multiple microwave feeds with varying frequencies, adjustable field elements, and antenna arrays to distribute electromagnetic energy uniformly across irregularly shaped objects, allowing for efficient heating by sweeping frequencies and adjusting power levels based on energy absorption measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional microwave ovens use single frequency heating, then heating speed is fast, but temperature distribution becomes non-uniform with hotspots
Solution Approach 1:
The patent applies dynamics by continuously varying the operating frequency of the microwave generator and adjusting the positions of field-adjusting elements during the heating process. This dynamic adaptation allows the system to maintain uniform temperature distribution while preserving fast heating speeds, resolving the contradiction between heating speed and temperature uniformity.
Solution Approach 2:
The patent changes multiple parameters simultaneously including frequency, power level, and field-adjusting element positions during heating. By dynamically adjusting these parameters based on real-time temperature measurements, the system achieves both fast heating and uniform temperature distribution, eliminating hotspots while maintaining productivity.
2Temperature
If heating power is reduced to prevent hotspots, then temperature uniformity improves, but heating time increases significantly
Solution Approach 1:
The patent maintains continuous high-power heating by dynamically adjusting frequency and field-adjusting element positions to distribute energy uniformly throughout the object. This continuous useful action prevents hotspots while avoiding the time loss associated with reduced power heating, achieving both uniformity and speed.
Solution Approach 2:
The patent employs feedback control by continuously measuring temperature distribution and using this information to adjust frequency and field-adjusting element positions in real-time. This feedback mechanism enables the system to maintain uniform heating at high power levels, preventing hotspots without extending heating time.
3Temperature
If multiple frequency feeds are used to improve uniformity, then temperature distribution becomes more uniform, but device complexity increases
Solution Approach 1:
The patent merges multiple control functions (frequency adjustment, power control, and field-adjusting element positioning) into a single integrated control system that operates based on temperature feedback. This merging approach achieves uniform temperature distribution while managing device complexity through functional integration rather than separate independent systems.
4Productivity
If field-adjusting elements are added to improve energy distribution, then heating efficiency increases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies local quality by positioning field-adjusting elements at specific locations within the cavity where they most effectively influence energy distribution. This targeted placement optimizes heating efficiency while minimizing the number of elements required, thereby reducing manufacturing complexity compared to uniform distribution approaches.
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 achieves uniform temperature distribution within 50°C across 80-90% of the object's volume, reducing hotspots and increasing heating efficiency, as demonstrated by successful thawing and cooking of complex shapes like cow liver and eggs.
Implementation Method 1
an electromagnetic heater for heating an irregularly shaped object, comprising: a cavity within which an object is to be placed; at least one feed which feeds UHF or microwave energy into the cavity; and a controller that controls one or more characteristics of the cavity or energy to assure that the UHF or microwave energy is deposited uniformly in the object
Implementation Method 2
a controller that determines the efficiency of net transfer of energy into the cavity for each of the feeds as a function of frequency over a range of frequencies, and adjusts the frequency of the energy fed
Data Source
AI summary
An electromagnetic heater for heating an irregularly shaped object, including:a cavity within which an object is to be placed;at least one feed which feeds UHF or microwave energy into the cavity; anda controller that controls one or more characteristics of the cavity or energy to assure that the UHF or microwave energy is deposited uniformly in the object within ±30% over at least 80% of the volume of the object.