Indoor air-conditioning device and container refrigeration device equipped with same
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Solution Overview
Problem
Existing container refrigeration systems face challenges in maintaining a high carbon dioxide concentration while lowering oxygen levels inside containers storing plants, as introduced carbon dioxide is often released during nitrogen-enriched air supply, leading to decreased carbon dioxide concentrations.
Innovation Solution
An inside air control system with a controller that prioritizes carbon dioxide concentration by stopping gas supply when it reaches a critical level and restarting when the carbon dioxide concentration increases, ensuring the oxygen concentration is lowered to a target level while maintaining the carbon dioxide concentration around a desired target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nitrogen-enriched air is supplied into the container to lower oxygen concentration, then the oxygen concentration is reduced and plant freshness is improved, but the carbon dioxide concentration decreases due to air displacement
Solution Approach 1:
The system dynamically adjusts the gas supply operation based on real-time monitoring of both oxygen and carbon dioxide concentrations. The controller continuously modulates the nitrogen-enriched air supply to maintain oxygen concentration at target levels while preventing carbon dioxide concentration from dropping below critical thresholds, creating a dynamic balance between the two gas components.
Solution Approach 2:
The system employs feedback control by monitoring carbon dioxide concentration and using this information to regulate the gas supply operation. When carbon dioxide concentration approaches the critical level, the controller automatically adjusts or pauses the nitrogen-enriched air supply, allowing plant respiration to naturally replenish carbon dioxide levels before resuming the oxygen-reduction process.
2Quantity of substance
If carbon dioxide is introduced first to increase its concentration, then the carbon dioxide concentration is raised to desired levels, but the subsequent nitrogen-enriched air supply releases the introduced carbon dioxide
Solution Approach 1:
Rather than introducing carbon dioxide first and then risking its loss, the system takes preliminary action by continuously monitoring carbon dioxide concentration and adjusting the nitrogen-enriched air supply in advance to prevent carbon dioxide from being displaced. This proactive approach ensures carbon dioxide concentration is maintained throughout the oxygen reduction process.
Solution Approach 2:
The system maintains continuous control over the gas composition by continuously monitoring both oxygen and carbon dioxide concentrations and continuously adjusting the nitrogen-enriched air supply. This continuous action prevents interruptions in carbon dioxide concentration and ensures stable atmospheric conditions for plant freshness without requiring repeated carbon dioxide supplementation.
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 effectively keeps the carbon dioxide concentration stable, preventing its significant decrease during oxygen reduction, thereby maintaining plant freshness by ensuring optimal gas composition within the container.
Implementation Method 1
an adsorbent adsorbing a nitrogen component in the air when pressurized is used to produce nitrogen-enriched air having a higher nitrogen concentration and a lower oxygen concentration than the air
Implementation Method 2
The plants breathe by absorbing oxygen in the air and releasing carbon dioxide into the air even after they have been harvested
Data Source
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AI summary
A CA system (60) includes a gas supply device (30) which performs a gas supply operation of supplying nitrogen-enriched air into a container (11), and a controller (55) which performs the gas supply operation so that the inside air has a desired composition. The controller (55) performs carbon dioxide priority control in which the controller (55) performs the gas supply operation if an oxygen concentration of the inside air is equal to or higher than a ceiling concentration higher than a target oxygen concentration, stops the gas supply operation if a carbon dioxide concentration of the inside air is lowered to a critical concentration lower than a target carbon dioxide concentration, and restarts the gas supply operation if the carbon dioxide concentration of the inside air has reached a restart concentration higher than the target carbon dioxide concentration through breathing of the plants.