CO2 Two-Stage Compressor Ratio for Stable Gas-Liquid Separation
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Solution Overview
Problem
In air conditioners using a two-stage compression/two-stage expansion refrigeration cycle with CO2 refrigerant, the refrigerant at supercritical pressure in the gas-liquid separator is difficult to separate into gas and liquid phases, inhibiting intermediate pressure gas injection and reducing the coefficient of performance (COP).
Innovation Solution
The volume ratio of the high pressure side compression mechanism to the low pressure side compression mechanism is set between 0.9 and 1.1, allowing for optimal intermediate pressure gas injection and increasing the COP by ensuring the refrigerant in the gas-liquid separator remains subcritical, enabling efficient separation and compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the refrigerant is compressed to supercritical pressure in the gas-liquid separator, then the compression ratio is improved, but the refrigerant cannot be separated into gas and liquid phases, inhibiting intermediate pressure gas injection
Solution Approach 1:
The patent applies dynamics by making the compression mechanism volume ratio adjustable rather than fixed. The volume ratio of the high-pressure compression mechanism to the low-pressure compression mechanism is set within a specific range (0.9-1.1) to dynamically optimize performance. This allows the system to adapt the compression parameters to maintain refrigerant in a separable state while achieving high compression ratios, thereby enabling intermediate pressure gas injection to function properly.
Solution Approach 2:
The patent changes the critical parameter of compression mechanism volume ratio to resolve the contradiction. By setting the volume ratio of high-pressure to low-pressure compression mechanisms within 0.9-1.1, the system optimizes the compression process to prevent refrigerant from reaching supercritical pressure in the gas-liquid separator, ensuring phase separation occurs while maintaining efficient compression performance.
2Ease of manufacture
If the volume ratio of compression mechanisms is not optimized, then the compressor design is simplified, but the COP (coefficient of performance) is reduced
Solution Approach 1:
The patent identifies and optimizes the volume ratio parameter of compression mechanisms to achieve the best balance between manufacturing simplicity and energy efficiency. By setting the volume ratio of high-pressure to low-pressure compression mechanisms within 0.9-1.1, the system achieves optimal COP while maintaining relatively simple compressor design, avoiding excessive complexity in the compression mechanism configuration.
3Device complexity
If intermediate pressure gas injection is inhibited, then the gas-liquid separator operates simpler, but the power consumption increases and COP decreases
Solution Approach 1:
The patent uses dynamics by optimizing the compression mechanism volume ratio to dynamically control the refrigerant state in the gas-liquid separator. This ensures the refrigerant remains in a state that allows phase separation and enables intermediate pressure gas injection, thereby reducing power consumption and improving COP without significantly increasing the complexity of the gas-liquid separator operation.
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 configuration enhances the COP of the air conditioner by ensuring desired intermediate pressure gas injection, reducing power consumption, and allowing for cost-effective and simplified compressor design by matching the compression mechanisms' specifications.
Implementation Method 1
the gas-liquid separator separates intermediate-pressure refrigerant in a gas-liquid two-phase state into liquid refrigerant and gas refrigerant
Implementation Method 2
the refrigerant release heat to the air
Implementation Method 3
the refrigerant absorbs heat from the air to be evaporated
Implementation Method 4
the refrigerant absorbs heat from the air to be evaporated
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A refrigerant circuit (10) includes a gas-liquid separator (15) and a compressor (30) including a low pressure side compression mechanism (34) and a high pressure side compression mechanism (35) connected to each other by means of a drive shaft (33). In the refrigerant circuit (10), a two-stage compression/two-stage expansion refrigeration cycle is performed with CO2 refrigerant utilized as that at its critical pressure. In the compressor (30), a volume ratio V2/V1 of the displacement volume V2 of the second compression mechanism (35) to that V1 of the first compression mechanism is set within a range between 0.8 and 1.3, both exclusive.