Gas-Liquid Separator Pressure Control for Supercritical Refrigeration
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Solution Overview
Problem
In refrigeration apparatuses with supercritical refrigeration cycles, pressure abnormalities can occur in the gas-liquid separator when the outside air temperature exceeds the critical point, leading to refrigerant evaporation and increased pressure.
Innovation Solution
The refrigeration apparatus includes a heat source unit with a gas-liquid separator, a compression unit, and an opening and closing device that controls a gas passage. When the pressure in the gas-liquid separator exceeds a predetermined value, the opening and closing device opens, allowing refrigerant to flow into heat exchangers, thereby reducing pressure abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gas-liquid separator is designed with larger internal volume to accommodate refrigerant expansion, then pressure abnormality can be suppressed, but device complexity and cost increase
Solution Approach 1:
The gas-liquid separator is divided into a liquid storage chamber and a gas storage chamber separated by a partition wall. This segmentation allows independent volume optimization for each phase, enabling the liquid chamber to be compact while the gas chamber provides sufficient expansion space, thus maintaining pressure stability without increasing overall device complexity
Solution Approach 2:
The partition wall with refrigerant communication hole is nested within the separator structure, creating a compact integrated design where the gas and liquid storage chambers share the same physical space through vertical or horizontal nesting, reducing the overall footprint while maintaining adequate volume for pressure regulation
2Reliability
If a dedicated pressure relief container is added to the system, then pressure abnormality can be suppressed, but device complexity increases
Solution Approach 1:
The gas-liquid separator performs multiple functions: it separates gas and liquid refrigerant during normal operation, stores expanded refrigerant during temperature changes, and regulates pressure through the communication hole mechanism. This multi-functionality eliminates the need for dedicated pressure relief containers, maintaining system simplicity while ensuring pressure control
Solution Approach 2:
The pressure regulation function is merged into the gas-liquid separator structure itself through the refrigerant communication hole between chambers. When pressure rises in the liquid chamber, refrigerant automatically flows to the gas chamber, combining storage and pressure relief functions in a single integrated component rather than adding separate devices
3Volume of moving object
If the separator is made compact to reduce device size, then space efficiency improves, but pressure abnormality risk increases
Solution Approach 1:
The partition wall includes a refrigerant communication hole that dynamically adjusts refrigerant flow between chambers based on pressure differential. This dynamic response allows the compact separator to automatically expand its effective storage capacity when pressure rises, maintaining pressure stability despite the reduced overall size
Solution Approach 2:
The separator utilizes changes in refrigerant density and pressure parameters to regulate flow through the communication hole. When temperature increases cause pressure rise, the density change drives refrigerant from the liquid to gas chamber, allowing the compact design to adapt to varying conditions and maintain pressure stability
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 solution effectively suppresses pressure abnormalities in the gas-liquid separator by allowing refrigerant to be released to heat exchangers, maintaining system stability without the need for increased internal volume or dedicated containers.
Implementation Method 1
When the pressure in the gas-liquid separator (15) is higher than a predetermined value, the opening and closing device (71) opens, allowing refrigerant to flow into heat exchangers, thereby reducing pressure abnormalities
Implementation Method 2
when an outside air temperature becomes higher than a critical point temperature in a state where a compressor is stopped, the refrigerant in the gas-liquid separator may evaporate and the pressure in the gas-liquid separator may increase
Data Source
Figure 1
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AI summary
A refrigeration apparatus (1) includes a gas-liquid separator (15) on a downstream side of a radiator, and a refrigerant circuit (6) in which a high pressure of a refrigeration cycle is equal to or higher than a critical pressure. The refrigeration apparatus (1) includes a gas passage (70) that communicates with the gas-liquid separator (15) and at least one of a plurality of heat exchangers provided in the refrigerant circuit (6), and an opening and closing device (71) that opens and closes the gas passage (70). There is provided a controller (100) that opens the opening and closing device (71) when a pressure in the gas-liquid separator (15) is equal to or higher than a predetermined value in a state where a compression unit (20) of the refrigerant circuit (6) is stopped to suppress occurrence of pressure abnormality inside the gas-liquid separator (15) in a state where a compressor (20) is stopped.