Multi-Stage Compressor Injection Switching for Liquid Compression
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Solution Overview
Problem
Multi-stage compressors face issues with liquid compression, overheating, and increased oil circulation ratio due to low dryness of refrigerant and overheating, leading to efficiency degradation in the higher stage compression mechanism.
Innovation Solution
A multi-stage compressor with a branching injection circuit and switching mechanism that adjusts the injection flow based on refrigerant dryness, injecting refrigerant through different circuits to prevent liquid compression and overheating, and maintaining lubricating oil separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refrigerant is injected into the intermediate pressure chamber to prevent liquid compression, then liquid compression is prevented, but the refrigerant may be overheated by the electric motor causing suction efficiency degradation
Solution Approach 1:
The injection circuit is divided into multiple injection ports positioned at different locations within the intermediate pressure chamber. This segmentation allows selective injection of refrigerant at optimal positions to avoid overheating by the electric motor while preventing liquid compression in the higher stage compression mechanism.
Solution Approach 2:
Different injection ports are strategically positioned in specific locations within the intermediate pressure chamber - some positioned away from the electric motor to prevent overheating, and others positioned to optimize mixing with intermediate pressure refrigerant. This local quality differentiation resolves the contradiction between preventing liquid compression and avoiding suction efficiency degradation.
2Productivity
If injection circuit is configured to improve compression efficiency, then compression efficiency is improved, but lubricating oil is raised up together with injected refrigerant increasing oil circulation ratio
Solution Approach 1:
The injection ports are positioned in specific local regions of the intermediate pressure chamber where refrigerant injection does not create upward flow that would carry lubricating oil. By controlling the local injection location and direction, the system achieves improved compression efficiency while preventing oil circulation increase.
3Device complexity
If single injection circuit is used to simplify structure, then device complexity is reduced, but cannot prevent both liquid compression and overheating simultaneously
Solution Approach 1:
The injection circuit is segmented into multiple injection ports rather than using a single injection point. This segmentation enables the system to simultaneously prevent liquid compression and overheating by distributing refrigerant injection across multiple strategic locations, resolving the contradiction between structural simplicity and compression efficiency.
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
Prevents liquid compression, improves motor efficiency by cooling the electric motor, reduces suction efficiency degradation, and lowers oil circulation ratio, enhancing overall system efficiency.
Implementation Method 1
the injection refrigerant may be overheated by the electric motor
Implementation Method 2
A lower stage rotary compression mechanism is installed below an electric motor installed at a central portion of a closed housing. The compressed gas is discharged into the closed housing
Implementation Method 3
this intermediate pressure gas is sucked into a higher stage scroll compression mechanism installed above the electric motor. Thereby, two-stage compression is performed
Data Source
Figure 1
Figure 2
AI summary
A multi-stage compressor is provided that reliably prevents liquid compression in a higher stage compression mechanism and also prevents compression efficiency degradation resulting from overheating of injection refrigerant and from the lubricating oil being raised up together with the injection refrigerant. An injection circuit (40) is branched into a plurality of circuits. A first circuit (41) thereof is communicatively connected to an inside space of a closed housing (2) that is at the same side as the higher stage compression mechanism (4) with respect to an electric motor (5), and a second circuit (42) is communicatively connected to an inside space of the closed housing (2) that is opposite from the higher stage compression mechanism (4) with respect to the electric motor (5). The first circuit (41) and the second circuit (42) are provided with a switching mechanism (43) for switching the injection circuit (40) to the first circuit (41) or the second circuit (42) according to the dryness of the injection refrigerant.