Compressor Oil Concentration Control in Refrigeration Cycles
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Solution Overview
Problem
The reliability of compressors in refrigeration cycle apparatuses is reduced due to poor lubrication caused by inadequate concentration and oil level of refrigerating machine oil, leading to increased wear and decreased heat transfer performance.
Innovation Solution
A refrigeration cycle apparatus equipped with temperature and pressure detectors that control the compressor frequency and expansion device opening to maintain the concentration and oil level of refrigerating machine oil within predetermined ranges, ensuring proper lubrication of the compression mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compressor operates at high frequency, then productivity increases, but oil concentration decreases due to increased liquid back
Solution Approach 1:
The patent uses oil concentration detection to provide feedback control. The detection unit monitors oil concentration, and the control unit adjusts the suction line valve opening degree based on this feedback to maintain oil concentration within the appropriate range while allowing high-frequency operation.
Solution Approach 2:
The system dynamically adjusts the suction line valve opening degree in response to changing operating conditions including compressor frequency. This dynamic control allows the system to maintain oil concentration even when operating at high frequencies that would otherwise cause liquid back and dilution.
Data Source
AI summary
A refrigeration cycle apparatus includes: a refrigerant circuit including a compressor, a condenser, an expansion device, and an evaporator; a first detector provided to the compressor, and configured to detect a temperature of the compressor; a second detector provided between the compressor and the expansion device in the refrigerant circuit, and configured to detect one of a temperature of refrigerant and a pressure of the refrigerant; and a controller configured to control at least one of frequency of the compressor and an opening degree of the expansion device based on the temperature detected by the first detector and one of the temperature and the pressure detected by the second detector so as to maintain a concentration of a refrigerating machine oil dissolved in the refrigerant in the compressor and an oil level of the refrigerating machine oil in the compressor within respective predetermined ranges.