Radio frequency heating process with residence time control of packaged articles
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Solution Overview
Problem
Existing radio frequency (RF) energy heating systems face inefficiencies in transmitting and launching RF energy due to the wavelength, which affects the uniform heating and processing of articles, particularly in achieving desired temperature increases and uniformity.
Innovation Solution
A process and system utilizing a liquid contact zone with initial and subsequent thermal regulation zones, combined with an RF heating zone, where articles travel on a nonlinear path, ensuring temperature uniformity and efficient energy absorption, with RF energy generators capable of producing high power and specific energy-absorptive components to enhance heating efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF energy is used to heat articles, then heating speed and energy efficiency are improved, but temperature uniformity and wavelength transmission difficulties worsen
Solution Approach 1:
The heating system is divided into multiple independent RF heating zones along the convey line, each zone capable of delivering controlled RF energy to specific sections of articles. This segmentation allows different zones to target different thermal requirements, improving overall temperature uniformity while maintaining high heating speed through parallel processing.
Solution Approach 2:
Different regions of the articles receive different RF energy intensities based on their specific thermal requirements. The system applies localized heating control where certain areas receive higher energy density while others receive lower density, achieving uniform temperature distribution across the entire article surface while maintaining rapid heating.
2Manufacturing precision
If articles travel through liquid contact zone for thermal regulation, then temperature uniformity is improved, but residence time and processing duration increase
Solution Approach 1:
The liquid contact zone is designed to provide continuous thermal regulation as articles move through it, eliminating the need for discrete heating and cooling stages. The liquid medium continuously exchanges heat with articles along the entire convey path, achieving temperature uniformity in a single continuous operation rather than through multiple intermittent steps, thereby reducing total residence time.
3Productivity
If high power RF energy is applied to increase temperature rapidly, then productivity is improved, but thermal degradation and energy loss increase
Solution Approach 1:
The RF energy delivery is implemented in periodic pulses rather than continuous high-power application. Each pulse delivers sufficient energy to advance heating, followed by brief intervals allowing thermal diffusion to distribute heat uniformly. This periodic action maintains high average power for productivity while preventing localized overheating and thermal degradation through controlled rest periods.
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 effectively increases the average temperature of articles by at least 20°C, achieving uniform heating and efficient energy absorption, while maintaining a small footprint and high production rate, minimizing thermal degradation and energy loss.
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 on at least one convey line while maintaining the articles in contact with a liquid
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.