Ohmic Heating Auger Synchronization for Food Uniformity
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Solution Overview
Problem
Ohmic heating of food compositions, particularly soups, faces challenges due to heterogeneity in heating resulting in overcooking and degradation of organoleptic qualities, caused by differences in residence time of liquid and solid phases, exacerbated by fluid mechanics phenomena like laminar flow and slip velocity, leading to inconsistent sterilization.
Innovation Solution
An ohmic heating apparatus featuring a tubular heating pipe with an endless screw to control the flow rate and residence time of food products, where the screw is driven by a motor with a frequency variator to synchronize the movement of liquid and solid particles, ensuring uniform heating by adjusting the pitch of the screw based on the size of the largest pieces and using non-abrasive materials to minimize friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If ohmic heating is used to rapidly heat food compositions, then heating speed is improved, but heating uniformity deteriorates due to residence time differences between liquid and solid phases
Solution Approach 1:
The patent introduces a variable speed drive system that dynamically adjusts the rotation speed of the auger based on real-time monitoring of heating uniformity and residence time distribution. This allows the system to optimize the transport speed of solid particles to match the heating rate, ensuring uniform heating while maintaining rapid processing. The dynamic control of auger speed compensates for the inherent velocity differences between liquid and solid phases.
Solution Approach 2:
The patent implements a feedback control system using temperature sensors distributed throughout the heating chamber to monitor the heating process. The measured temperature distribution and residence time data are fed back to the variable speed drive, which automatically adjusts the auger rotation speed to maintain optimal heating uniformity. This closed-loop control ensures that heating speed and uniformity are simultaneously optimized based on actual process conditions.
2Productivity
If the liquid phase moves faster than solid particles through the heating column, then heating efficiency is improved, but sterilization completeness deteriorates due to insufficient heating of slowest phase
Solution Approach 1:
The variable speed drive system enables dynamic adjustment of the auger rotation speed to optimize the transport velocity of solid particles. By controlling the auger speed, the system ensures that the slowest-moving phase (solid particles) receives sufficient heating time for complete sterilization, while the liquid phase is recirculated efficiently. This dynamic control reconciles the velocity difference between phases to achieve both high productivity and reliable sterilization.
Solution Approach 2:
The patent changes the operational parameters of the heating system by introducing variable speed control of the auger, allowing optimization of residence time for different phases. The system adjusts the solid particle transport speed to match the heating rate required for sterilization, while maintaining efficient liquid phase circulation. This parameter optimization enables simultaneous achievement of heating efficiency and sterilization completeness.
3Use of energy by moving object
If preheating is performed before ohmic heating, then energy efficiency is improved, but heating heterogeneity worsens due to temperature differences between phases entering the heating tube
Solution Approach 1:
The variable speed drive system dynamically adjusts the auger rotation speed to compensate for temperature differences between preheated liquid and solid phases. By controlling the transport speed of solid particles, the system ensures that both phases spend appropriate time in the ohmic heating zone to reach uniform temperature, eliminating heating heterogeneity while maintaining the energy efficiency benefits of preheating.
Solution Approach 2:
The feedback control system monitors temperature distribution after preheating and adjusts the auger speed accordingly. The control system detects temperature differences between phases and modifies the solid particle transport velocity to ensure uniform heating in the ohmic heating zone, thereby eliminating heating heterogeneity while preserving energy efficiency.
4Stability of the object's composition
If vertical heating columns with large section are used, then sedimentation is reduced, but device complexity increases compared to horizontal columns
Solution Approach 1:
The patent introduces a variable speed drive system that dynamically controls the auger rotation to prevent sedimentation in horizontal heating columns. By adjusting the auger speed, the system maintains adequate mixing and suspension of solid particles in the liquid phase, achieving sedimentation control equivalent to vertical columns but with the space and simplicity advantages of horizontal configuration.
Solution Approach 2:
The variable speed drive system implements periodic variation in auger rotation speed to create controlled mixing cycles that prevent sedimentation. The periodic acceleration and deceleration of the auger creates turbulent flow patterns that keep solid particles suspended, achieving the sedimentation control benefit of vertical columns while maintaining the horizontal configuration's simplicity and space efficiency.
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 solution standardizes the residence time of food components, ensuring consistent heating and preserving the organoleptic qualities by minimizing differences in speed between liquid and solid phases, thereby achieving uniform sterilization and maintaining food quality.
Implementation Method 1
said heating tube comprising an endless screw made of a material not conductor, driven by a second motor controlled to ensure a flow rate in the heating chamber
Implementation Method 2
Ohmic heating allows food to be heated by the passage of an electric current. The resistance of the product to the flow of electricity causes the temperature to rise.
Data Source
Figure 1
AI summary
The present invention relates to a chemical heating system for products, particularly food compositions consisting of a heterogeneous mixture of a liquid phase and solid particles, comprising at least one tubular heating pipe (1). The heating system is supplied by a feed pump (10) that feeds directly into said heating pipe (1) and is driven by a first motor. The heating pipe (1) includes a screw conveyor (4) made of a non-conductive material and driven by a second motor (7) controlled to ensure flow in the heating chamber.