Multi-Stage Compressor Oil Balancing Using Pressure Reversal
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Solution Overview
Problem
In refrigerating cycle apparatuses with multiple compressors, oil imbalance leads to frictional losses and increased power consumption due to uneven oil distribution, causing one compressor to be over-oiled while another is under-oiled, which can result in compressor damage and reduced cooling efficiency.
Innovation Solution
An oil collection unit and controller system that utilize pressure differences between compressors to balance oil distribution by transferring oil from over-oiled to under-oiled compressors, with a refrigerant switching valve managing the flow and a determination unit monitoring oil levels to initiate balancing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple compressors are connected in series to perform multi-stage compression, then compression efficiency is improved, but oil concentrates in one compressor causing frictional loss and increased power consumption
Solution Approach 1:
An oil collection unit is introduced as an intermediary component between compressors to collect and redistribute oil. The unit includes oil collection pipes connected to each compressor, enabling oil to be transferred from compressors with excess oil to those with insufficient oil, thereby preventing frictional loss and energy waste while maintaining the multi-stage compression system's productivity
Solution Approach 2:
The system monitors and adjusts oil parameters (oil amount and distribution) dynamically. By detecting oil levels in each compressor and controlling oil transfer based on pressure differences, the system changes the oil distribution parameter to ensure each compressor operates within optimal oil parameters, preventing frictional loss and maintaining compression efficiency
2Reliability
If an oil balancing container is separately installed outside the compressors, then oil unbalance between compressors is addressed, but occupied space increases and pipe structure becomes complicated
Solution Approach 1:
The oil collection unit is merged with the existing compressor structure rather than being installed as a separate external container. The oil collection pipes are integrated into the compressor housing, combining the oil balancing function with the compressor assembly. This reduces occupied space and simplifies the overall structure while maintaining reliable oil balance between compressors
3Reliability
If complicated pipes are used to connect compressors to the oil balancing container, then oil unbalance is addressed, but flow resistance increases and cooling efficiency decreases
Solution Approach 1:
The oil collection system is segmented with dedicated oil collection pipes for each compressor, allowing direct and simple connection between compressors and the oil collection unit. This segmentation avoids the need for complicated piping networks, minimizing flow resistance and preventing energy loss that would affect cooling efficiency, while still achieving reliable oil unbalance correction
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 prevents compressor damage and frictional losses by ensuring balanced oil distribution, enhancing cooling efficiency and reducing power consumption while simplifying the apparatus structure to occupy less space and minimize flow resistance.
Implementation Method 1
an oil collection unit configured to perform an oil balancing by a pressure difference between the plurality of compressors
Data Source
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AI summary
The present disclosure relates to a refrigerating cycle apparatus and a method for operating the same. For a refrigerating cycle having a plurality of compressors connected in series for multi-stage compression, an inner space of each compressor and a pipe of the refrigerating cycle are connected via an oil collection pipe (42, 46), and oil is induced to be discharged into the refrigerating cycle by pressure reversal during pressuring balancing, so as to allow the discharged oil to be collected into a high-stage compressor (12) or a low-stage compressor (11). Accordingly, an amount of oil can be uniformly maintained in each of the plurality of compressors to prevent in advance a frictional loss of the compressors or an increase in power consumption caused due to a lack of oil, and also a device and pipes for solving oil unbalancing between the compressors can be simplified to enhance cooling efficiency of the compressors.