Multi-Feed Microwave Heating 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, leading to temperature differences and hotspots, which are particularly problematic for heating and defrosting organs and foods of non-spherical shapes.
Innovation Solution
The use of multiple microwave feeds operating at different frequencies, with adjustable power levels and field adjusting elements within the cavity, to ensure uniform energy distribution and absorption across the object, while also considering changes in the object's impedance during heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional microwave ovens heat objects, then heating speed is improved, but temperature uniformity deteriorates with hotspots and thermal runaway
Solution Approach 1:
The microwave heating system is divided into multiple independent feeds (at least two), each operating at different frequencies and power levels. This segmentation allows independent control of heating zones, enabling uniform temperature distribution across the entire object while maintaining high heating speed through parallel operation of multiple feeds.
Solution Approach 2:
Each microwave feed is assigned different power levels and frequencies tailored to specific regions of the object. This local quality approach ensures that different parts of the object receive appropriate heating intensity, preventing hotspots in highly absorbent regions while ensuring adequate heating in less absorbent areas.
2Manufacturing precision
If multiple microwave feeds at different frequencies are used, then temperature uniformity is improved, but device complexity increases
Solution Approach 1:
The microwave heating system uses a universal control architecture that manages multiple feeds at different frequencies through a single integrated controller. This multi-functionality approach allows the system to handle various object types and shapes by adjusting power levels and frequencies of different feeds, reducing operational complexity despite the presence of multiple feeds.
Solution Approach 2:
The system dynamically adjusts power levels and frequencies of different microwave feeds based on real-time monitoring of temperature distribution and object characteristics. This parameter change capability allows the system to maintain temperature uniformity across different object types without requiring complex hardware modifications for each specific application.
3Manufacturing precision
If heating power is reduced to prevent hotspots, then temperature uniformity is improved, but heating time increases significantly
Solution Approach 1:
The microwave heating system employs periodic modulation of power levels for different feeds, switching between high and low power states in controlled cycles. This periodic action allows the system to deposit energy uniformly across the object over time, preventing hotspots while maintaining acceptable heating speeds through cumulative energy deposition.
Solution Approach 2:
The system maintains continuous heating operation with multiple feeds running simultaneously at different power levels, ensuring that useful heating action continues throughout the process. This continuity eliminates the need for complete heating cycles to be interrupted or repeated, reducing total heating time while maintaining temperature uniformity through coordinated feed operation.
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 the risk of thermal runaway and recrystallization, and allowing for efficient heating of irregularly shaped objects with minimal temperature variation.
Implementation Method 1
The microwave oven is a ubiquitous feature in modern society... electromagnetic heating... uniform energy distribution and absorption across the object
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.