RF Pasteurization Electrode Spacing for Homogeneous Food Heating
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Solution Overview
Problem
Existing food pasteurization devices face issues with high local heating leading to steam bubble formation, voltage breakdown, and non-homogeneous heating, which can result in cavitation, degeneration, and charring of food products.
Innovation Solution
The device employs co-acting electrodes with a substantial mutual axial interspace, typically 2x to 10x larger than the tube's inner dimension, to reduce field strength and ensure even heating across a longer distance, using RF energy between 10-50 MHz, and incorporates multiple tubes with separate generators to increase capacity and homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If electrodes are placed at roughly the same axial position opposite each other, then heating can be achieved in a compact space, but the mutual distance between electrodes is limited causing very high local field strength in the mass of foodstuff
Solution Approach 1:
The patent transitions from placing electrodes at the same axial position (transverse arrangement) to spacing them axially along the tube length. This dimensional change in electrode arrangement allows the electric field to extend along the tube axis rather than concentrating across the tube diameter, thereby reducing local field strength while maintaining heating effectiveness.
2Temperature
If electrodes are spaced far apart axially, then local field strength is reduced preventing steam bubbles and voltage breakdown, but the heating zone length increases requiring longer tube
Solution Approach 1:
The patent optimizes the axial spacing parameter between electrodes to achieve a balance: spacing is sufficiently large (at least 2x, preferably 5x or 10x the tube inner dimension) to reduce field strength and prevent breakdown, yet the overall heating zone length is controlled by using multiple electrode pairs rather than excessively spacing single pairs, thus managing the tube length requirement.
3Productivity
If high RF power is applied to heat the mass quickly, then productivity increases, but local overheating and charring can occur
Solution Approach 1:
The patent ensures uniform heating quality throughout the mass by spacing electrodes to create a distributed electric field that heats the mass homogeneously along the tube length. This prevents localized concentration of energy that would cause overheating and charring, while still achieving high productivity through continuous flow processing.
4Productivity
If multiple electrode pairs are used to increase heating capacity, then productivity increases, but device complexity increases
Solution Approach 1:
The patent divides the heating function into multiple discrete electrode pairs spaced along the tube. Each electrode pair acts as an independent heating unit, allowing the system to scale capacity by adding segments rather than increasing the power of single electrodes. This segmentation approach increases productivity while keeping each individual electrode pair relatively simple in design.
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 prevents local overheating, ensures homogeneous heating, and significantly increases production capacity while maintaining product quality by avoiding breakdown and charring, achieving a consistent temperature difference of less than 5°C across the heated mass.
Implementation Method 1
an arrangement of co-acting electrodes which are connected to an RF power generator which generates energy at a frequency in the range of about 10-50 MHz to the electrodes such that the mass present in the first tube can be heated during its first residence time in this first tube
Data Source
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AI summary
A device for pasteurizing a mass of foodstuff comprises : a feed; a first tube of an electrically and magnetically inert material suitable for contact with foodstuff; an arrangement of electrodes added to the first tube and connected to an RF power generator so that the mass present in the first tube can be heated in this first tube. Co-acting electrodes are disposed with a substantial mutual axial interspace.