Method of controlling atmosphere in a refrigerated container

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Solution Overview

Problem

Existing atmosphere control systems in refrigerated containers are inadequate in regulating oxygen and carbon dioxide levels to extend the shelf life and quality of perishables, as they fail to effectively manage gas concentrations to prevent ripening and damage caused by high CO2 levels.

Innovation Solution

An atmosphere control system that operates in a start-up phase to adjust oxygen levels by adding nitrogen and a control phase to regulate both oxygen and carbon dioxide levels by adding outside air or nitrogen, using sensors and valves to maintain specific control limits, ensuring optimal gas concentrations within the container.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If nitrogen is continuously added to control oxygen levels, then oxygen concentration is reduced to prevent ripening, but carbon dioxide concentration may increase to harmful levels

Engineering Contradiction:

Improveoxygen concentrationVSAvoidcarbon dioxide accumulation

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The system uses sensors to continuously monitor both oxygen and carbon dioxide concentrations, and the controller adjusts nitrogen addition based on feedback from both gas levels. When CO2 exceeds the upper threshold, the controller reduces or stops nitrogen addition, and when CO2 drops below the lower threshold, normal oxygen control resumes. This feedback mechanism resolves the contradiction by dynamically adjusting nitrogen addition to maintain both oxygen and carbon dioxide within acceptable ranges.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system changes the operating parameters of gas addition based on real-time concentration measurements. By adjusting the flow rate and duration of nitrogen addition according to monitored CO2 and O2 levels, the system maintains optimal atmospheric composition without allowing CO2 to accumulate to harmful levels while still preventing excessive oxygen that causes ripening.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of stationary object

If atmosphere control is implemented to extend shelf life, then produce quality is maintained, but system complexity increases with multiple sensors and control phases

Engineering Contradiction:

Improveshelf lifeVSAvoidcontrol system structure

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The control process is segmented into distinct phases: a startup phase for initial atmosphere establishment and a control phase for maintenance. This segmentation allows the system to handle different operational requirements separately, simplifying the control logic within each phase while achieving comprehensive atmosphere management that extends shelf life.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The startup phase performs preliminary action by establishing the target atmospheric composition before the control phase begins. During this phase, the system pre-adjusts gas concentrations to desired levels, which simplifies subsequent maintenance control and reduces the complexity of real-time adjustments during the extended storage period.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If precise gas concentration control is maintained throughout storage, then produce quality is preserved, but energy consumption increases from continuous monitoring and adjustment

Engineering Contradiction:

Improveatmosphere control precisionVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system employs periodic monitoring and control actions rather than continuous operation. Gas concentrations are monitored at specific intervals, and adjustments are made periodically based on these measurements. This periodic approach maintains reliable atmosphere control while significantly reducing energy consumption compared to continuous monitoring and adjustment systems.

Inventive Principle:

Principle #19Periodic 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

The system effectively controls the atmosphere within the refrigerated container, preventing over-ripening of produce and damage from high CO2 levels, thereby maintaining the quality and extending the shelf life of perishables.

Implementation Method 1

adding nitrogen to the container until the oxygen level in the container is equal to an oxygen pulldown limit

Methodology Applied

Scientific EffectGas displacement:

Implementation Method 2

adding outside air to the container until the carbon dioxide level in the container equals a carbon dioxide lower control limit

Methodology Applied

Scientific EffectGas mixing:

Data Source

PatentUS11846463B2Method of controlling atmosphere in a refrigerated container

Publication Date: 2023.12.19 CARRIER CORP

AI summary

A method of operating an atmosphere control system to control an atmosphere in a refrigerated container includes operating the atmosphere control system in a start up phase to control an oxygen level in the container; ending the start up phase; and operating the atmosphere control system in a control phase to control the oxygen level and a carbon dioxide level in the container.