Refrigeration apparatus for containers
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Solution Overview
Problem
Existing container refrigeration apparatuses face difficulties in exhausting air from the container when the internal pressure is lower than the external pressure, leading to backflow issues and inefficient control of air composition.
Innovation Solution
A container refrigeration apparatus with a refrigerant circuit, internal and external fans, and an inside air control system that includes a gas supply device for nitrogen-enriched air and an exhaust passage, where the external end of the exhaust passage is open on the suction side of the external fan, allowing pressure differences to facilitate air exhaustion regardless of internal vs. external pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling operation is performed to lower the temperature of the air in the container, then the temperature control is improved, but the pressure in the container becomes lower than the outside pressure, causing backflow of air from outside to inside
Solution Approach 1:
The exhaust passage is divided into two separate passages: a first exhaust passage for exhausting air when internal pressure is higher than external pressure, and a second exhaust passage for exhausting air when internal pressure is lower than external pressure. This segmentation allows each passage to be optimized for its specific pressure condition, preventing backflow while maintaining effective exhaust functionality.
Solution Approach 2:
A pressure equalization passage is introduced as an intermediary component to equalize the pressure difference between the inside and outside of the container. This passage includes a pressure equalization hole that allows air to flow from the high-pressure side to the low-pressure side, reducing the pressure differential that causes backflow in the exhaust passage.
2Stability of the object's composition
If the oxygen concentration in the container is lowered to reduce respiration rate, then the freshness of plants is improved, but the air composition control becomes more complex
Solution Approach 1:
The system utilizes the natural respiration process of the plants themselves to control air composition. By controlling the exhaust of carbon dioxide-rich air and supplying fresh air, the system lets the plants' own metabolic processes contribute to maintaining the desired atmosphere, reducing the need for complex active composition control mechanisms.
Solution Approach 2:
The system employs sensors to detect oxygen and carbon dioxide concentrations in the container, providing feedback to the control unit. Based on this feedback, the control unit adjusts the operation of the refrigeration apparatus and exhaust system to maintain optimal air composition, creating a closed-loop control system that automatically responds to changing conditions.
3Reliability
If the carbon dioxide concentration exceeds the upper limit value, then the air quality deteriorates, but exhausting the air requires additional energy consumption
Solution Approach 1:
The exhaust system operates dynamically based on real-time pressure conditions and air quality measurements. The control unit activates the exhaust function only when carbon dioxide concentration exceeds the upper limit value and when pressure conditions are favorable, adjusting the exhaust rate according to the actual needs of the container atmosphere, thereby minimizing unnecessary energy consumption.
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
Enables efficient and accurate control of air composition within the container by ensuring air can be exhausted smoothly, maintaining desired oxygen and carbon dioxide concentrations even when internal pressure is lower than external pressure, preventing backflow and corrosion.
Implementation Method 1
a refrigerant circuit (20) in which a condenser (22) disposed in the external storage space (S1) and an evaporator (24) disposed in the internal storage space (S2) are connected together to perform a refrigeration cycle
Implementation Method 2
The air in the container guided toward the internal fan (26) is cooled when passing through the evaporator (24) by the refrigerant flowing through the refrigerant circuit (20)
Implementation Method 3
an external fan (25) which is disposed in the external storage space (S1), and guides outside air into the external storage space (S1) to form a flow of the outside air toward the condenser (22)
Implementation Method 4
an internal fan (26) which is disposed in the internal storage space (S2), and guides inside air in the container (11) into the internal storage space (S2) to form a flow of the inside air toward the evaporator (24)
Implementation Method 5
an exhaust passage (46a) which allows a space on a blowout side of the internal fan (26) in the internal storage space (S2) to communicate with the external storage space (S1), wherein an external end of the exhaust passage (46a) is open on a suction side of the external fan (25) in the external storage space (S1)
Data Source
Figure 1
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Figure 3
AI summary
A container refrigeration apparatus includes: a casing (12) which forms an external storage space (S1) communicating with the exterior of the container (11) and an internal storage space (S2) communicating with the interior of the container (11); a refrigerant circuit (20); an external fan (25); an internal fan (26); and an inside air control system (60) including an exhaust passage (46a) which allows a space on a blowout side of the internal fan (26) in the internal storage space (S2) to communicate with the external storage space (S1), and controls composition of the inside air in the container (11). An external end of the exhaust passage (46a) is open on a suction side of the external fan (25) in the external storage space