Refrigeration unit for container
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Solution Overview
Problem
Existing container refrigeration apparatuses require large air compressors and separate carbon dioxide bottles to maintain optimal gas concentrations, leading to increased weight and cost due to the need for high-purity nitrogen production and carbon dioxide supplementation.
Innovation Solution
A container refrigeration apparatus using nitrogen-adsorbing adsorbents with a pressure swing adsorption process to produce a gas mixture with controlled oxygen and carbon dioxide concentrations, reducing the need for high-pressure compressors and separate carbon dioxide bottles by utilizing zeolite adsorbents and a vacuum pressure swing adsorption process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-purity nitrogen gas is produced using a membrane separator, then oxygen concentration control is improved, but apparatus weight increases due to large air compressor requirements
Solution Approach 1:
The invention changes the operating parameters of the adsorption process by using pressure swing adsorption instead of requiring high-pressure compression. The system operates at lower pressures by utilizing the cyclic adsorption-desorption characteristics of zeolite, where nitrogen is adsorbed during pressurization and desorbed during depressurization, eliminating the need for high-purity nitrogen production while maintaining oxygen concentration control
Solution Approach 2:
The invention replaces the mechanical high-pressure compression system with a pressure swing adsorption system using zeolite. Instead of relying on high-pressure mechanical compression to achieve nitrogen separation, the system uses the adsorption properties of zeolite material that selectively captures nitrogen at lower pressures, significantly reducing the size and weight of the air compressor required
2Manufacturing precision
If separate carbon dioxide bottles are provided to control carbon dioxide concentration, then carbon dioxide level control is improved, but apparatus weight increases
Solution Approach 1:
The invention enables the system to self-regulate carbon dioxide concentration by utilizing the natural respiration process of the stored plants. As plants respire, they consume oxygen and release carbon dioxide, naturally maintaining the required carbon dioxide levels without requiring external supplementation systems or additional weight
Solution Approach 2:
The invention extracts and eliminates the unnecessary carbon dioxide supplementation system from the apparatus. By recognizing that plant respiration naturally provides sufficient carbon dioxide, the design removes the weight burden of separate CO2 bottles and delivery mechanisms while maintaining proper atmospheric composition
3Productivity
If air heater is provided separately for membrane separator operation, then nitrogen separation efficiency is improved, but apparatus weight and complexity increase
Solution Approach 1:
The invention extracts and removes the air heater component from the system. The pressure swing adsorption process using zeolite does not require thermal energy input for nitrogen separation, unlike membrane separators that may benefit from heating. This elimination simplifies the apparatus and reduces component count while maintaining effective nitrogen removal
4Weight of moving object
If pressure swing adsorption process is used instead of high-pressure compression, then apparatus weight is reduced, but oxygen concentration control precision may be affected
Solution Approach 1:
The invention employs periodic action through cyclic pressure swing adsorption processes. The system alternates between adsorption phases (where nitrogen is captured) and desorption phases (where nitrogen is released), creating a rhythmic process that maintains consistent oxygen concentration control over time while operating at lower pressures and reducing apparatus weight
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 solution reduces the overall weight and cost of the apparatus by lowering the required pressurization pressure, eliminating the need for an air heater, and allowing plants to respire naturally, thus maintaining freshness without additional carbon dioxide supplementation.
Implementation Method 1
A container refrigeration apparatus using nitrogen-adsorbing adsorbents with a pressure swing adsorption process to produce a gas mixture with controlled oxygen and carbon dioxide concentrations
Implementation Method 2
first and second adsorbers (34) and (35) each provided with an adsorbent adsorbing nitrogen in the air
Implementation Method 3
a depressurization portion (31b) which depressurizes the other of the first and second adsorbers (34) and (35) by sucking the air from the other adsorber to perform a desorption operation of desorbing nitrogen from the associated adsorbent
Data Source
AI summary
Disclosed herein a technique for producing a gas mixture for controlling an oxygen concentration in the interior of a container while reducing the overall weight of the apparatus. For this purpose, a gas mixture supply device is provided for a container refrigeration apparatus. The gas mixture supply device is provided with adsorption columns. If one of the first and second adsorption columns is supplied with air, the adsorption columns are pressurized, and nitrogen in the air is adsorbed onto an adsorbent. If air is sucked from the other of the first and second adsorption columns, the adsorption columns are depressurized, and nitrogen adsorbed onto the adsorbent is desorbed. A gas mixture including the nitrogen desorbed from the adsorbent is supplied to the interior of a container.