Rotating Shaft Oil Return Passageway Reduces Heat Input
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Solution Overview
Problem
In fluid machines, surplus lubricating oil not used for lubrication in compression and expansion mechanisms contributes to increased heat transfer to the expansion mechanism, reducing refrigeration capacity, especially in air conditioners, due to its high temperature and prolonged contact with low-temperature fluids.
Innovation Solution
The fluid machine incorporates an oil supply passageway and an oil return passageway in the rotating shaft, where surplus lubricating oil is rapidly returned to the compression mechanism, reducing contact time with the expansion mechanism and utilizing heat exchange to cool the lubricating oil, thereby minimizing heat transfer to the expansion mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature lubricating oil is supplied to the expansion mechanism, then sufficient lubrication is ensured, but heat transfer to the low-temperature fluid increases, reducing refrigeration capacity
Solution Approach 1:
The oil supply system is segmented into multiple pathways: a primary oil supply passageway for essential lubrication and a secondary oil return passageway for heat removal. This segmentation allows the oil to perform both lubrication and cooling functions simultaneously, resolving the contradiction between ensuring adequate lubrication and preventing heat transfer to the refrigerant.
Solution Approach 2:
The lubricating oil acts as an intermediary substance that transfers heat from the expansion mechanism to the oil supply passageway walls. By introducing this thermal intermediary, the system can remove excess heat without directly contacting the refrigerant, thus maintaining refrigeration capacity while ensuring continuous lubrication.
2Reliability
If the flow rate of lubricating oil is increased to ensure sufficient lubrication in all operation states, then lubrication reliability is improved, but the amount of surplus oil contacting the expansion mechanism increases, enhancing heat transfer
Solution Approach 1:
The oil flow is divided into two functional streams: sufficient oil is supplied through the oil supply passageway for reliable lubrication, while surplus oil is diverted through the oil return passageway to perform heat removal. This segmentation resolves the contradiction by allowing increased total oil flow without proportionally increasing harmful heat transfer to the refrigerant.
Solution Approach 2:
The surplus lubricating oil, which would otherwise represent wasted heat transfer to the refrigerant, is converted into a beneficial cooling medium. By routing this surplus oil through the oil return passageway that contacts the expansion mechanism, the system transforms the harmful thermal energy into useful heat removal, thereby reducing the refrigeration capacity loss while maintaining adequate lubrication.
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 configuration reduces heat input to the expansion mechanism, maintaining refrigeration capacity and ensuring sufficient lubrication, while preventing lubricating oil from entering the discharge pipe, thus securing oil storage and preventing performance deterioration.
Implementation Method 1
Lubricating oil accumulated in the casing bottom is drawn into the oil supply passageway from the lower end of the rotating shaft by centrifugal pump action
Implementation Method 2
utilizing heat exchange to cool the lubricating oil, thereby minimizing heat transfer to the expansion mechanism
Data Source
AI summary
In a compression/expansion unit (30) serving as a fluid machine, both a compression mechanism (50) and an expansion mechanism (60) are housed in a single casing (31). An oil supply passageway (90) is formed in a shaft (40) by which the compression mechanism (50) and the expansion mechanism (60) are coupled together. Refrigeration oil accumulated in the bottom of the casing (31) is drawn up into the oil supply passageway (90) and is supplied to the compression mechanism (50) and to the expansion mechanism (60). Surplus refrigeration oil, which is supplied to neither of the compression and expansion mechanisms (50) and (60), is discharged out of the terminating end of the oil supply passageway (90) which opens at the upper end of the shaft (40). Thereafter, the surplus refrigeration oil flows into an oil return pipe (102) from a lead-out hole (101) and is returned back towards a second space (39). This reduces the amount of heat input to the fluid flowing through the expansion mechanism from the surplus refrigeration oil which has not been utilized to lubricate the compression and expansion mechanisms.