RF Heating Conveyance With Nonlinear Path for Uniform Pasteurization
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Solution Overview
Problem
Existing radio frequency (RF) energy heating systems face challenges in efficiently transmitting and launching RF energy due to the wavelength, which affects the heating process of articles, leading to inefficiencies and uneven heating.
Innovation Solution
A process and system that involves passing articles through a liquid contact zone with an initial thermal regulation zone, an RF heating zone, and a subsequent thermal regulation zone, where RF energy is used to increase the temperature of the articles by at least 20°C, with a nonlinear travel path and energy-absorptive components to enhance energy absorption and uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF energy is used to heat articles, then heating speed and efficiency are improved, but wavelength transmission difficulties cause inefficiency and uneven heating
Solution Approach 1:
The heating system is divided into multiple RF applicators positioned at different locations (e.g., top, bottom, sides) that independently heat different regions of the article. Each applicator operates as a separate heating zone, allowing synchronized control to achieve uniform overall heating despite the wavelength limitations of individual RF sources.
Solution Approach 2:
Different regions of the article receive tailored RF heating treatment based on their specific thermal requirements. The system applies localized heating zones with adjusted power levels and exposure times to compensate for varying thermal conductivity and mass distribution, ensuring uniform temperature throughout the article.
2Productivity
If articles are heated rapidly with RF energy, then production rate is improved, but thermal degradation increases
Solution Approach 1:
The RF heating system employs periodic or pulsed heating cycles rather than continuous heating. Articles are exposed to RF energy in controlled intervals with brief cooling periods in between, allowing heat to distribute evenly and preventing localized overheating that causes thermal degradation while maintaining high overall heating rates.
Solution Approach 2:
The system incorporates temperature sensors and control systems that continuously monitor article temperature during RF heating. Real-time feedback allows dynamic adjustment of RF power levels to maintain optimal heating rates without exceeding temperature thresholds that would cause thermal degradation of the articles.
3Device complexity
If a linear convey line is used, then system simplicity is maintained, but heating uniformity deteriorates due to wavelength constraints
Solution Approach 1:
The convey line is configured with curved or spiral paths instead of straight linear sections. This curvature allows articles to traverse longer distances through the RF heating zones, exposing all surfaces more evenly to RF energy and compensating for the wavelength limitations that cause uneven heating in linear configurations.
Solution Approach 2:
The system transitions from two-dimensional linear conveyance to three-dimensional spatial heating patterns. Articles move through vertically stacked or multi-level RF applicators arranged in complex spatial configurations, ensuring all surfaces receive adequate RF energy exposure regardless of the convey line's horizontal path.
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
The system achieves efficient and uniform heating of articles, with the average temperature at the geometric center increased by at least 20°C, and subsequent cooling, while maintaining a small footprint and high production rate, minimizing thermal degradation and energy absorption.
Implementation Method 1
heating the articles on the convey line with RF energy in the RF heating zone to thereby increase the average temperature at the geometric center of the articles by at least 20° C.
Implementation Method 2
regulating the temperature of the articles on the convey line in the initial thermal regulation zone to promote temperature uniformity of the articles
Implementation Method 3
passing a plurality of articles through a liquid contact zone of an RF heating system
Data Source
AI summary
Heating systems utilizing radio frequency (RF) energy and methods for using the same to rapidly and uniformly heat packaged articles moving through the system on one or more convey lines. These systems may be useful for a variety of processes, including the pasteurization or sterilization of packaged foodstuffs.