Parallel Scroll Compressor Oil Balancing Under Unequal Suction Pressure
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Solution Overview
Problem
Current multi-compressor refrigeration systems face challenges in efficiently managing oil distribution and suction gas pressure across compressors, leading to suboptimal performance and efficiency, particularly when compressors have different capacities and operational states.
Innovation Solution
The method involves connecting compressors in parallel with a common supply line that prioritizes oil distribution to a lead compressor, using restrictions in inlet supply lines to create differential suction pressures, and ensuring fluid communication between oil sumps to maintain balanced oil flow and pressure across all compressors, regardless of their operational status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common supply line is used to distribute oil to multiple compressors, then oil distribution is simplified, but oil distribution efficiency deteriorates because equal oil flow cannot be provided to compressors with different capacities
Solution Approach 1:
The patent applies local quality by providing different flow characteristics to different compressors through the common supply line. Specifically, the lead compressor receives unrestricted oil flow while non-lead compressors receive restricted flow through orifices or flow restrictors. This localized differentiation of flow properties enables each compressor to receive appropriate oil quantities according to its capacity, resolving the contradiction between system simplicity and distribution efficiency.
2Quantity of substance
If oil sumps are connected in fluid communication, then oil balance is improved, but suction pressure control deteriorates because pressure equalization prevents differential pressure management
Solution Approach 1:
The patent segments the suction pressure control function from the oil balance function. While oil sumps are connected for balance, the suction pressure control is achieved through separate means: flow restrictors in non-lead compressor lines and potential suction pressure regulation mechanisms. This segmentation allows independent optimization of both oil balance and suction pressure control, resolving the contradiction between these two functions.
3Productivity
If more oil is supplied to the lead compressor, then lead compressor performance is improved, but non-lead compressor oil supply becomes insufficient
Solution Approach 1:
The patent introduces flow restrictors (orifices) as intermediary elements in the non-lead compressor supply lines. These restrictors create a pressure differential that enables the lead compressor to receive preferential oil flow while still ensuring adequate oil supply to non-lead compressors. The restrictors act as mediators that balance the oil distribution according to compressor roles, resolving the contradiction between lead compressor performance enhancement and non-lead compressor oil supply adequacy.
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 approach enhances oil distribution efficiency, maintains balanced suction pressures, and ensures optimal performance across all compressors, even when some are not operating, by continuously supplying oil from the lead compressor to active units until oil sump pressures are equalized.
Implementation Method 1
a common supply line for supplying refrigerant and oil to each of the plurality of compressors
Implementation Method 2
configuring the common supply line to supply more oil to the lead compressor than to the non-lead compressors
Implementation Method 3
separating the oil from the refrigerant
Implementation Method 4
separating the oil from the refrigerant
Implementation Method 5
connecting the oil sumps of all of the plurality of compressors such that oil is supplied from the lead compressor to at least one non-lead compressor
Implementation Method 6
oil will flow out through the pipe connection from the lead compressor, whether or not the lead compressor is operating, to at least one of the non-lead compressors, which is operating. This flow will continue until the oil sump pressures in the oil sumps of the lead compressor and the at least one of the non-lead compressors are approximately the same
Implementation Method 7
providing, to an inlet port for each of the plurality of compressors, a separate inlet supply line, wherein configuring the common supply line to supply more oil to the lead compressor comprises restricting the inlet supply lines to each of the non-lead compressors
Implementation Method 8
the restriction of the inlet supply lines may be designed to create reduced suction pressures at the inlet ports of the non-lead compressors, as compared to the suction pressure at the inlet port of the lead compressor
Data Source
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AI summary
A method of operating a refrigeration system uses a plurality of compressors in connected parallel. The method includes returning refrigerant and oil to the compressors, the refrigerant also having oil entrained therein, separating the oil entrained in the refrigerant, and returning more of the oil entrained in the refrigerant to a lead compressor of the plurality of compressors regardless of whether the lead compressor is operating. The method also includes connecting the oil sumps of all of the plurality of compressors such that oil is supplied from the lead compressor to at least one non-lead compressor of the plurality of compressors when the at least one non-lead compressor is operating.