System and method for OCR control in paralleled compressors
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Solution Overview
Problem
In HVACR systems with compressors arranged in parallel, there is a challenge in reliably maintaining lubricant circulation rates, leading to lubricant loss and reduced compressor reliability due to uneven compressor capacities and operational states, where gas flow can prevent lubricant from returning to the sump.
Innovation Solution
The implementation of a flow restrictor in the lubricant transfer conduit between compressors to control refrigerant flow, reducing the lubricant circulation rate and ensuring lubricant retention in the sump, particularly by adjusting the porosity and placement of the flow restrictor to maintain desired lubricant levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If compressors are arranged in parallel with different capacities, then system flexibility and load distribution are improved, but lubricant circulation becomes uneven leading to lubricant loss
Solution Approach 1:
A flow restrictor is introduced as an intermediary component in the lubricant transfer conduit between compressors. This flow restrictor mediates the lubricant flow to prevent excessive gas flow from disrupting the lubricant return to sump, thereby resolving the uneven lubricant circulation problem while maintaining the parallel compressor configuration
Solution Approach 2:
The flow restrictor is specifically placed in the lubricant transfer conduit to create localized flow control. This local quality adjustment ensures that lubricant flow characteristics are optimized in the specific region where gas flow interference occurs, without affecting other parts of the system
2Productivity
If gas flow rate increases in parallel compressor system, then compression capacity is improved, but lubricant return to sump is prevented causing lubricant loss
Solution Approach 1:
The flow restrictor acts as a mediator that allows gas flow to pass through while restricting it enough to prevent disruption of lubricant return. This enables the system to maintain high compression capacity while preventing lubricant loss by controlling the gas flow's interfering effect on lubricant circulation
3Quantity of substance
If lubricant transfer conduit allows free flow, then lubricant distribution between compressors is improved, but gas flow disrupts lubricant return to sump
Solution Approach 1:
The flow restrictor is positioned in the lubricant transfer conduit to serve as an intermediary that permits lubricant to flow freely between compressors while simultaneously restricting gas flow that would otherwise prevent lubricant from returning to the sump
Solution Approach 2:
The flow restrictor may utilize porous material structure to achieve selective flow characteristics, allowing lubricant (liquid) to pass through while restricting gas flow, thereby maintaining lubricant distribution while ensuring lubricant retention in sump
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 effectively reduces lubricant loss and maintains reliable lubricant circulation, enhancing the operational efficiency and reliability of compressors under varying load conditions by controlling gas flow and ensuring adequate lubrication.
Implementation Method 1
A flow restrictor is disposed in the lubricant transfer conduit. The flow restrictor is configured to reduce a refrigerant flow between the first compressor and the second compressor.
Implementation Method 2
the lubricant sump is disposed at a relatively vertically lower portion of the compressor such that lubricant can be collected in the lubricant sump via gravitational force
Implementation Method 3
a suction conduit design can be deployed to allow lubricant to return to the compressor that has a lower capacity more easily
Data Source
AI summary
A heating, ventilation, air conditioning, and refrigeration (HVACR) system includes a first compressor having a first capacity, a second compressor having a second capacity, a condenser, an expansion device, and an evaporator fluidly connected. The first compressor and the second compressor are arranged in parallel. The first compressor includes a first lubricant sump. The second compressor includes a second lubricant sump. The first lubricant sump is fluidly connected to the second lubricant sump via a lubricant transfer conduit. A flow restrictor is disposed in the lubricant transfer conduit. The flow restrictor is configured to reduce a refrigerant flow between the first compressor and the second compressor.