Lubricant quality management for a compressor
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Solution Overview
Problem
HVACR systems face issues with lubricant dilution and bearing viscosity problems due to the use of refrigerants with lower global warming potential, such as R1234ze(E) and R513A, leading to shortened bearing lifetimes and compressor failures, especially when operating at lower speeds.
Innovation Solution
Implementing a variable speed compressor with a minimum speed limit set based on saturated suction and discharge temperatures, and lubricant temperature, to prevent operating conditions that cause lubricant dilution and limited bearing viscosity, using a lubricant separator to manage lubricant distribution and maintain adequate lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If refrigerants with lower GWP (such as R1234ze(E) and R513A) are used to replace R-134a, then environmental performance is improved, but lubricant dilution and bearing viscosity problems occur leading to shortened bearing lifetimes
Solution Approach 1:
The patent changes the operating parameters of the compressor, specifically establishing a minimum speed limit based on saturated suction temperature, saturated discharge temperature, and lubricant temperature. This parameter change prevents the compressor from operating in conditions that cause excessive lubricant dilution and viscosity loss, thereby maintaining bearing reliability while using low-GWP refrigerants.
2Use of energy by moving object
If the compressor operates at lower speeds to meet cooling requirements, then energy efficiency is improved, but lubricant dilution and bearing viscosity problems worsen
Solution Approach 1:
The patent implements a dynamic minimum speed limit that adjusts based on operating conditions (saturated suction temperature, saturated discharge temperature, and lubricant temperature). This dynamic adjustment allows the compressor to operate at the lowest possible speed for energy efficiency while ensuring the speed remains above the threshold where lubricant dilution and viscosity loss become problematic.
Solution Approach 2:
The system uses feedback from temperature sensors (saturated suction temperature, saturated discharge temperature, and lubricant temperature) to dynamically adjust the minimum speed limit. This feedback mechanism ensures that the compressor maintains adequate lubrication by preventing operation below the calculated minimum speed while allowing maximum energy efficiency at higher speeds.
3Reliability
If a minimum speed limit is enforced to prevent lubricant dilution, then bearing reliability is improved, but operational flexibility and cooling efficiency are reduced
Solution Approach 1:
The patent changes the operational parameters by establishing a dynamic minimum speed limit rather than a fixed speed restriction. This minimum speed is calculated based on saturated suction temperature, saturated discharge temperature, and lubricant temperature, allowing the system to adapt its operational flexibility while maintaining bearing reliability through temperature-based parameter adjustments.
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
The solution effectively extends the bearing lifetime by maintaining a minimum bearing lubricant film thickness and preventing compressor failures, ensuring efficient operation and longevity of mechanical components.
Implementation Method 1
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 2
The second chamber receives a lubricant portion of the refrigerant/lubricant mixture via the conduit
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
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.