Refrigerant-Lubricated Compressor with Sensor-Based Flow Control
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Solution Overview
Problem
Centrifugal compressors in chillers face challenges in operating without a dedicated oil system, requiring effective lubrication methods that do not interfere with heat transfer or machinery operations, and existing refrigerant-lubricated compressors need improved control systems for efficient lubricant distribution.
Innovation Solution
A vapor compression system with a compressor, heat rejection and absorption heat exchangers, and a controller that manages lubricant flow through shared pumps and sensors to optimize lubricant distribution based on pressure and vibration fluctuations, ensuring efficient refrigerant delivery to bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated oil system is used for compressor lubrication, then reliable bearing lubrication is achieved, but system complexity and oil interference in heat transfer increases
Solution Approach 1:
The patent combines the lubrication function with the existing refrigerant circulation system by using refrigerant as the lubricant carrier. The refrigerant picks up lubricant at the evaporator and delivers it to the compressor bearings, eliminating the need for a separate dedicated oil system while maintaining reliable bearing lubrication.
Solution Approach 2:
The refrigerant serves multiple functions: it acts as both the heat transfer medium and the lubricant delivery mechanism. This multi-functionality eliminates the need for separate oil circulation systems, reducing overall system complexity while maintaining effective lubrication.
2Reliability
If high oil concentration is used in the oil sump for bearing lubrication, then adequate lubrication is provided, but heat transfer efficiency deteriorates due to oil interference
Solution Approach 1:
The system creates different oil concentrations at different locations: high concentration in the evaporator oil reservoir for effective lubrication, and low concentration (50-500 ppm) in the condenser for minimal heat transfer interference. The refrigerant circulation system naturally transports lubricant from high-concentration to low-concentration zones.
3Loss of energy
If refrigerant-lubricated compressor is used, then oil interference in heat transfer is reduced, but control of lubricant flow to bearings becomes challenging
Solution Approach 1:
The system incorporates sensors that monitor lubricant flow conditions and provide feedback to the controller. The controller adjusts the expansion valve and compressor operation to maintain optimal lubricant delivery to bearings, ensuring reliable control despite the eliminated dedicated oil system.
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 system enables efficient lubrication of centrifugal compressors without a dedicated oil system, improving operational efficiency and reducing oil interference in heat transfer processes by dynamically controlling lubricant flow based on sensed fluctuations.
Implementation Method 1
at least one lubricant pump... A first lubricant flowpath extends from the heat rejection heat exchanger to the compressor. A second lubricant flowpath extends from the heat absorption heat exchanger to the compressor.
Implementation Method 2
the system comprises a pressure sensor positioned to measure an outlet pressure of the at least one lubricant pump... the sensed fluctuation is a sensed fluctuation in an outlet pressure of the at least one lubricant pump.
Implementation Method 3
the system comprises a vibration sensor positioned to measure a vibration of the at least one lubricant pump... the sensed fluctuation is a sensed vibration of the at least one lubricant pump.
Implementation Method 4
a compressor having a suction port and a discharge port; a heat rejection heat exchanger coupled to the discharge port to receive compressed refrigerant
Implementation Method 5
a heat rejection heat exchanger coupled to the discharge port to receive compressed refrigerant
Implementation Method 6
a heat absorption heat exchanger... A second lubricant flowpath extends from the heat absorption heat exchanger to the compressor.
Data Source
AI summary
A vapor compression system (20; 400; 420) comprises: a compressor (22) having a suction port (40) and a discharge port (42); a heat rejection heat exchanger (58) coupled to the discharge port to receive compressed refrigerant; a heat absorption heat exchanger (88); a first lubricant flowpath (120, 126) from the heat rejection heat exchanger to the compressor; a second lubricant flowpath (121, 126) from the heat absorption heat exchanger to the compressor; at least one lubricant pump (190); and a controller (900) configured to control lubricant flow along the first lubricant flowpath and the second lubricant flowpath based on a sensed fluctuation.