Air Conditioner Bypass Oil Collection for Long Gas Pipes
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Solution Overview
Problem
Conventional air conditioners face issues with refrigerating machine oil viscosity increase at low temperatures, leading to reduced flowability and accumulation in gas pipes, which limits pipe length and compressor reliability.
Innovation Solution
Incorporating a bypass unit that bypasses high-temperature, high-pressure refrigerant to the evaporator, changing the gas pipe contents to a two-phase refrigerant, reducing oil viscosity and facilitating its collection back into the compressor, thereby increasing compressor reliability and allowing longer gas pipe installations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gas pipe length is increased to provide installation freedom, then the adaptability of the air conditioner installation is improved, but the refrigerating machine oil accumulates in the gas pipe and cannot be collected into the compressor, worsening the reliability of the compressor
Solution Approach 1:
The system performs preliminary oil collection operation before normal operation begins. The control unit activates the oil collection mode where the expansion valve is closed and the four-way valve switches to bypass mode, allowing refrigerant to flow through the gas pipe in reverse direction to carry oil back to the compressor before the cooling cycle starts.
Solution Approach 2:
The system implements periodic oil collection operations during the air conditioner's operation cycle. The control unit periodically switches between oil collection mode and normal cooling mode, enabling the gas pipe to periodically flush accumulated oil back to the compressor, thus maintaining reliable operation even with long pipe lengths.
2Adaptability or versatility
If the gas pipe length is increased, then the installation flexibility is improved, but the oil viscosity increases due to temperature drop and flowability deteriorates, worsening the oil collection efficiency
Solution Approach 1:
The system changes the flow direction parameter of the refrigerant through the four-way valve. During oil collection, the four-way valve switches to bypass mode, reversing the refrigerant flow direction through the gas pipe. This parameter change enables the refrigerant to flow from the evaporator outlet toward the compressor, carrying oil droplets back against the normal operating direction.
3Reliability
If the refrigerating machine oil viscosity increases at low temperatures, then the oil remains in the gas pipe, but this limits the gas pipe length and reduces installation freedom
Solution Approach 1:
The system maintains continuous refrigerant circulation through the gas pipe during oil collection mode. The compressor continuously compresses and discharges refrigerant, which continuously flows through the gas pipe in bypass mode, creating a continuous flushing action that prevents oil accumulation and maintains oil collection efficiency regardless of pipe length.
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 enhances compressor reliability and installation flexibility by ensuring efficient oil collection and reducing pipe length constraints, preventing damage to the compressor during oil collection operations.
Implementation Method 1
changing the gas pipe contents to a two-phase refrigerant
Implementation Method 2
reducing oil viscosity and facilitating its collection back into the compressor
Implementation Method 3
a heat exchange unit that performs heat exchange between high-temperature refrigerant discharged from the compressor and refrigerant to be suctioned into the compressor
Data Source
Figure 1
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AI summary
Disclosed is an air conditioner (10) including a compressor (210), which compresses and discharges a refrigerant, a condenser (240), which condenses the refrigerant compressed in the compressor, an expansion device (22), which expands the refrigerant condensed in the condenser, an evaporator (160), which evaporates the refrigerant expanded in the expansion device, performs heat exchange between the refrigerant and indoor air, and discharges the evaporated refrigerant to the compressor, a bypass unit (31,32), which guides some of the refrigerant discharged from the condenser to an outlet end of the evaporator, a heat exchange unit (253,260), which performs heat exchange between some of the refrigerant discharged from the compressor and the refrigerant to be suctioned into the compressor, and a control unit (300), which controls overall operation of the air conditioner. The control unit controls the bypass unit so as to bypass the refrigerant, discharged from the condenser, to the outlet end of the evaporator upon an oil collection operation.