Suction Conduit Flow Split for Parallel Compressor Lubricant Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In HVACR systems with multiple compressors connected in parallel, existing lubricant management systems can impact temperature control by modifying compressor operations to maintain lubricant levels, leading to inefficiencies and potential insufficient lubrication.
Innovation Solution
A flow control device is used to separate the heat transfer fluid into a lubricant-rich and a lubricant-free portion, directing the lubricant-rich portion to a variable speed upstream compressor and the lubricant-free portion to a fixed speed downstream compressor, while maintaining a differential pressure to ensure lubricant transfer between the compressors via a lubricant transfer conduit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compressor operation is modified to maintain lubricant levels, then lubricant supply is improved, but temperature control deteriorates
Solution Approach 1:
The suction conduit flow is segmented into two separate streams using a flow control device: one stream directs lubricant-rich refrigerant to the first compressor while the other stream directs lubricant-poor refrigerant to the second compressor. This segmentation allows each compressor to receive appropriately conditioned refrigerant without requiring operational modifications, thus maintaining both reliable lubricant supply and temperature control.
2Productivity
If multiple compressors operate in parallel, then system capacity is improved, but lubricant distribution becomes insufficient
Solution Approach 1:
The flow control device creates local quality differences in the refrigerant streams by allowing the first compressor to receive lubricant-rich refrigerant while the second compressor receives lubricant-poor refrigerant. This local differentiation ensures that each compressor's specific lubricant needs are met, enabling multiple compressors to operate in parallel with sufficient and appropriate lubricant distribution.
3Reliability
If lubricant level is maintained by modifying compressor operation, then lubricant supply reliability is improved, but system efficiency deteriorates
Solution Approach 1:
A flow control device is introduced as an intermediary component in the suction conduit to manage lubricant distribution between compressors. This intermediary device passively separates the refrigerant flow into lubricant-rich and lubricant-poor streams without requiring active control or operational modifications to the compressors, thereby maintaining system efficiency while ensuring reliable lubricant supply.
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 ensures consistent lubricant supply to both compressors, maintaining efficient operation and temperature control by optimizing lubricant distribution and pressure differentials, thereby preventing insufficient lubrication and its associated issues.
Implementation Method 1
the lubricant sump is disposed at a relatively vertically lower portion of the compressor such that lubricant can collect in the lubricant sump via gravitational force
Implementation Method 2
the flow control device can be designed to control a differential pressure between the upstream compressor and the downstream compressor
Implementation Method 3
The lubricant is accordingly provided to the plurality of compressors via a suction conduit which provides gaseous heat transfer fluid from an evaporator of the heat transfer circuit to the plurality of compressors
Implementation Method 4
the second fluid outlet having a nozzle disposed within a flow passage of the flow control device such that a space is maintained between an outer surface of the nozzle and an inner surface of the flow passage
Data Source
AI summary
A system includes first and second compressors arranged in parallel, a condenser, expansion device, evaporator, and flow control device fluidly connected. The first compressor includes a first lubricant sump and the second compressor including a second lubricant sump. A lubricant transfer conduit fluidly connects the first lubricant sump and the second lubricant sump. The flow control device is disposed between the evaporator and the first and second compressors, and includes a fluid inlet and two fluid outlets. A first of the two fluid outlets is fluidly connected to the first compressor, a second of the two fluid outlets is fluidly connected to the second compressor. The second fluid outlet includes a nozzle disposed within a flow passage of the flow control device such that a space is maintained between an outer surface of the nozzle and an inner surface of the flow passage.