Compressor Lubricant Control for Low-GWP Refrigerant Operation
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Solution Overview
Problem
Current HVACR systems face issues with lubricant dilution and reduced bearing viscosity due to the use of refrigerants with lower global warming potential, leading to premature bearing failure and compressor inefficiencies, especially when operating at variable speeds.
Innovation Solution
Implementing a variable speed compressor with a minimum speed limit set based on saturated suction and discharge temperatures, combined with a lubricant separator to manage lubricant distribution and prevent lubricant dilution, using environmentally suitable refrigerants like R1234ze(E) or R513A, and incorporating a controller to override speed settings if they fall below the minimum limit to maintain adequate lubricant film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If refrigerants with lower global warming potential (e.g., R1234ze(E), R513A) are used to replace R-134a, then environmental performance is improved, but lubricant dilution increases and bearing viscosity decreases leading to premature bearing failure
Solution Approach 1:
The patent changes the operating parameters of the compressor by establishing a minimum speed limit based on saturated suction and discharge temperatures. This parameter change prevents the compressor from operating at speeds that would cause excessive lubricant dilution and bearing viscosity loss, thereby resolving the reliability issue while maintaining environmental benefits
Solution Approach 2:
The patent introduces a lubricant separator as an intermediary component between the compressor and condenser. This separator manages lubricant distribution and prevents lubricant dilution in the refrigerant circuit, addressing the harmful effects of low-GWP refrigerants on bearing lubrication
2Use of energy by moving object
If the compressor operates at variable speeds to meet cooling requirements, then energy efficiency is improved, but bearing lubrication deteriorates when operating below minimum speed limit
Solution Approach 1:
The patent modifies the speed parameter by implementing a minimum speed limit that varies with saturated suction and discharge temperatures. This ensures adequate bearing lubrication is maintained while still allowing variable speed operation for energy efficiency, resolving the contradiction between energy savings and lubrication quality
Solution Approach 2:
The controller uses feedback from temperature measurements (saturated suction and discharge temperatures) to dynamically adjust the minimum speed limit. This feedback mechanism ensures the compressor maintains adequate lubrication while operating efficiently across different cooling conditions
3Reliability
If a minimum speed limit is enforced to prevent lubricant dilution, then bearing reliability is improved, but compressor flexibility and adaptability are reduced
Solution Approach 1:
The patent makes the minimum speed limit dynamic rather than fixed. The limit varies with saturated suction and discharge temperatures, allowing the compressor to adapt its operating constraints based on actual thermal conditions. This dynamic approach maintains bearing reliability while preserving compressor flexibility for different operating conditions
4Reliability
If a lubricant separator is added to manage lubricant distribution, then lubricant dilution is prevented, but system complexity increases
Solution Approach 1:
The lubricant separator is designed to perform multiple functions: separating lubricant from refrigerant, managing lubricant distribution, and preventing lubricant dilution. By consolidating these functions into a single component, the patent reduces the overall system complexity while improving lubricant management reliability
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 extends the lifespan of mechanical components by maintaining optimal lubricant viscosity and preventing premature compressor failures, while also adhering to environmental standards by using refrigerants with lower global warming potential.
Implementation Method 1
A lubricant separator has an inlet fluidly connected between the compressor and the condenser and a plurality of outlets
Implementation Method 2
A lubricant separator has an inlet fluidly connected between the compressor and the condenser and a plurality of outlets. A first of the plurality of outlets is fluidly connected to the condenser. A second of the plurality of outlets is fluidly connected to one or more components of the compressor to provide a lubricant to the one or more components
Implementation Method 3
Compressors, such as, but not limited to, screw compressors and scroll compressors, utilize bearings to support a rotating shaft. The bearings generally include a lubricant system. If the bearings are not properly lubricated, the bearings, and ultimately the compressor, may fail prior to an expected lifetime of the bearing
Data Source
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AI summary
A heating, ventilation, air conditioning, and refrigeration (HVACR) system is disclosed. The HVACR system includes a refrigerant circuit. The refrigerant circuit includes a compressor, a condenser, an expansion device, and an evaporator fluidly connected. A controller is electronically connected to the compressor. The controller is configured to prevent the compressor from operating at a speed that is less than a minimum speed limit. A lubricant separator has an inlet fluidly connected between the compressor and the condenser and a plurality of outlets. A first of the plurality of outlets is fluidly connected to the condenser. A second of the plurality of outlets is fluidly connected to one or more components of the compressor to provide a lubricant to the one or more components.