Pre-cooling Radiators for Cardboard Package Sterilization

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Solution Overview

Problem

Fragile packaging materials like cardboard-based containers are damaged during heat treatment due to excessive humidification and thermal shock, leading to irreversible degradation of adhesive properties and mechanical weaknesses, especially during the cooling phase after sterilization.

Innovation Solution

A method involving a pre-cooling step using radiators to lower the ambient temperature outside the packaging without direct water contact, followed by a rapid drying process through indirect heat exchange, and subsequent water injection or spraying to cool the packages, ensuring the binders regain mechanical and adhesive strength before further cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If water is injected or sprayed on packaging during cooling after sterilization, then rapid cooling is achieved, but cardboard packaging is damaged due to excessive humidification at high temperature

Engineering Contradiction:
Improvecooling speedVSAvoidhumidification damage to packaging
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by introducing a pre-cooling phase before the water spray cooling phase. During this pre-cooling phase, the packaging is cooled indirectly through heat exchange with the sterilization water itself, reducing the packaging temperature from sterilization temperature (e.g., 121°C) to a lower temperature (e.g., 80-90°C) before water spray is applied. This preliminary temperature reduction prevents the harmful interaction between high-temperature packaging and moisture, thereby avoiding adhesive degradation while still enabling subsequent rapid cooling through water spray.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If water is sprayed on hot packaging, then cooling efficiency is improved, but adhesive properties of cardboard binders are irreparably degraded

Engineering Contradiction:
Improvecooling efficiencyVSAvoidadhesive strength of packaging
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The pre-cooling phase serves as a preliminary action that reduces packaging temperature before water spray application. By lowering the packaging temperature in advance through indirect heat exchange, the conditions for water spray cooling are optimized - the packaging is cool enough to avoid adhesive degradation but still hot enough to maintain condensation-driven cooling efficiency. This sequential approach preserves adhesive strength while maintaining high cooling productivity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the temperature parameter of the packaging progressively through two distinct phases. The pre-cooling phase reduces temperature from sterilization level (121°C) to a intermediate level (80-90°C), and the subsequent water spray phase completes the cooling to ambient temperature. This parameter change strategy ensures that water spray is applied only when the packaging temperature is below the critical threshold for adhesive degradation, thereby maintaining both cooling efficiency and packaging strength.

Inventive Principle:
Principle #35Parameter changes

3Loss of time

If conventional water spray cooling is used, then cooling time is reduced, but mechanical properties of packaging are not restored after drying

Engineering Contradiction:
Improvecooling timeVSAvoidmechanical integrity of packaging
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The pre-cooling phase acts as a protective preliminary action that prepares the packaging for the water spray cooling phase by reducing its temperature to a safe level. This preliminary temperature reduction ensures that when water spray is applied, the packaging will cool rapidly without suffering adhesive degradation. The result is that both cooling time is reduced and mechanical properties are preserved, as the adhesive never experiences the harmful combination of high temperature and moisture that would prevent recovery of mechanical integrity.

Inventive Principle:
Principle #10Preliminary action

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 damage to cardboard packaging by maintaining the packaging in a dry state during high temperatures, allowing the binders to recover their properties and withstand subsequent humidification, enabling efficient and safe cooling without thermal shock.

Implementation Method 1

lowering of the temperature on the outside of said packaging and drying of said packaging by circulation of cold water inside pipes forming radiators passing close to said packages inside said autoclave

Methodology Applied
Scientific EffectIndirect heat exchange: Heat Exchanger

Implementation Method 2

radiators forming a said ventilation channel

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 3

pre-cooling is carried out by circulating water to an intermediate temperature inside the autoclave but without bringing the water into contact with the containers

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

injection of hot steam on said packaging

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 5

heating step by injection of steam into the autoclave and ventilation of the steam between said packages

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP1820410B1Process of heat treatment of products in a package comprising paper or cardboard and device for carrying out said process
Publication Date: 2010.01.06 LAGARDE
  • EP1820410B1 patent drawingFigure 1
  • EP1820410B1 patent drawingFigure 2~3
  • EP1820410B1 patent drawingFigure 4

AI summary

The present invention relates to a device and method for heat treatment of product(s), in particular food(s), in hermetically sealed packaging, in particular for their sterilization, in which a heating step is carried out followed by a cooling step, characterized in that, after the heating step, it includes at least one pre-cooling step in which a lowering of the temperature of the ambient atmosphere outside the packaging is carried out by circulation of cold water inside pipes forming radiators (2a, 2b, 2c) passing near said packaging inside said autoclave (1), without direct contact of water with said packaging.