CO2 Booster Cooling With Liquid Injection for Low-Temperature Load
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Solution Overview
Problem
In CO2 booster refrigeration systems, the absence of a medium temperature load leads to refrigerant temperatures that are too high for medium temperature compressors to handle safely, causing unsafe operating conditions.
Innovation Solution
A configuration that mixes refrigerant from a low temperature compressor with liquid refrigerant and flash gas from a flash tank before it reaches the medium temperature compressor, using a liquid injection line and flash gas bypass line, controlled by a controller based on temperature and pressure sensors, to reduce the temperature and pressure of the refrigerant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the medium temperature load is not present in the CO2 booster system, then the system operates with only low temperature load, but the refrigerant temperature becomes too high for the medium temperature compressor to handle safely
Solution Approach 1:
A liquid injection line is introduced as an intermediary component that injects liquid refrigerant into the refrigerant line between the low temperature compressor and medium temperature compressor. This liquid refrigerant acts as a cooling mediator that reduces the temperature of the refrigerant before it enters the medium temperature compressor, enabling safe operation when the medium temperature load is absent.
Solution Approach 2:
The system changes the temperature parameter of the refrigerant by injecting liquid refrigerant into the hot refrigerant stream from the low temperature compressor. This parameter change (temperature reduction) is controlled by a liquid injection valve that regulates the amount of liquid refrigerant injected, allowing the medium temperature compressor to operate safely within its temperature limits.
2Reliability
If liquid refrigerant is injected to cool the refrigerant, then the medium temperature compressor can operate safely, but the system complexity increases with additional components
Solution Approach 1:
The liquid injection line and valve are designed to serve multiple functions: they cool the refrigerant for compressor safety, provides controllable temperature regulation, and can be integrated into the existing refrigeration cycle infrastructure. The liquid refrigerant used for cooling is drawn from the same flash tank that already exists in the CO2 booster system, making the added component work with existing system elements.
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 allows for safe operation of the medium temperature compressor even without a medium temperature load, preventing compressor failure and ensuring system safety by cooling the refrigerant before it is compressed.
Implementation Method 1
mixes refrigerant from a low temperature compressor with liquid refrigerant and flash gas from a flash tank before it reaches the medium temperature compressor... to reduce the temperature and pressure of the refrigerant
Implementation Method 2
The high side heat exchanger removes heat from a refrigerant
Implementation Method 3
The flash tank stores the refrigerant from the high side heat exchanger
Data Source
AI summary
A system includes a flash tank, a load, a first compressor, a second compressor, and a liquid injection line. The flash tank stores a refrigerant. The load uses the refrigerant from the flash tank to remove heat from a space proximate the load. The first compressor compresses the refrigerant from the load. The second compressor compresses the refrigerant from the first compressor. The liquid injection line is coupled to the flash tank and to the second compressor and sends a liquid refrigerant from the flash tank to mix with the refrigerant from the first compressor before the refrigerant from the first compressor is received by the second compressor.