Oil Feed Path Valve Control for Liquid Refrigerant Detection
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Solution Overview
Problem
In refrigerating apparatuses, the variation in oil retention in the oil separator can lead to liquid refrigerant flowing into the oil return pipe and being sent to the compressor, reducing the refrigerant supply to the evaporator and cooling capacity.
Innovation Solution
A refrigerant flow limiting section is implemented, including an oil separator and an oil feed path with a refrigerant detection system that prevents liquid refrigerant from being sucked into the compressor by limiting the flow through the oil feed path, using mechanisms like pressure reduction, temperature detection, and opening adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the oil separator retains less oil, then the oil can be sent to the compressor through the oil return pipe, but liquid refrigerant may flow into the oil return pipe and reduce cooling capacity
Solution Approach 1:
The refrigerant flow limiting section is installed in advance in the oil return pipe to prevent liquid refrigerant from being sucked into the compressor. This preliminary protective measure blocks the harmful flow path before liquid refrigerant can enter the compressor, thereby preventing cooling capacity reduction while still allowing oil to be returned to the compressor.
2Productivity
If the oil separator retains more oil, then liquid refrigerant flow is prevented, but the oil cannot be sent to the compressor for lubrication
Solution Approach 1:
The refrigerant flow limiting section acts as an intermediary device in the oil return pipe. It selectively allows oil to pass through to the compressor while blocking liquid refrigerant. This intermediary component resolves the contradiction by mediating between the need to retain oil for lubrication and the need to prevent liquid refrigerant from reducing cooling capacity.
3Quantity of substance
If liquid refrigerant is sucked into the compressor, then the refrigerant supply to the evaporator is reduced, but the compressor may suffer from liquid compression damage
Solution Approach 1:
The refrigerant flow limiting section provides preliminary protection by blocking the path of liquid refrigerant before it can enter the compressor. This prevents both the reduction of refrigerant supply to the evaporator and the potential liquid compression damage to the compressor, thereby maintaining both cooling performance and compressor reliability.
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 ensures a sufficient refrigerant supply to the evaporator, prevents liquid compression damage to the compressor, and maintains optimal cooling performance by accurately managing the oil and refrigerant flow.
Implementation Method 1
In the oil separator, the oil is separated from the two-phase gas/liquid refrigerant, and is retained in the bottom of the oil separator
Implementation Method 2
using mechanisms like pressure reduction, temperature detection, and opening adjustment
Data Source
AI summary
An on-off valve (70) is provided in an oil feed path (43). When liquid refrigerant enters the oil feed pipe (43) from the oil separator (22), the temperature of the liquid refrigerant whose pressure has been reduced in the on-off valve (70) dramatically decreases. When the amount of such a decrease in temperature detected by a temperature sensor (73) exceeds a specified amount, it is determined that the liquid refrigerant enters the oil feed pipe (43), and the on-off valve (70) is closed.