Ejector Refrigerant Separation for Lower Compressor Power
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Solution Overview
Problem
Ejector refrigeration systems face inefficiencies due to the direct feeding of superheated refrigerant to the compressor, which increases power consumption and limits evaporator performance, as they require a superheated zone for optimal operation.
Innovation Solution
The system introduces a two-phase mixture with a controlled quality of 1-10% liquid and 90-99% vapor to the heat absorption heat exchanger and compressor, utilizing a modified accumulator to manage the refrigerant flow, allowing for improved heat transfer and reduced compressor power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If superheated refrigerant is fed directly to the compressor, then the evaporator can operate with optimal superheated zone, but compressor power consumption increases
Solution Approach 1:
The system segments the refrigerant flow into two separate streams: a first stream (superheated vapor) directed to the compressor and a second stream (two-phase mixture) directed to the suction line heat exchanger. This segmentation allows each stream to serve its specific function optimally while reducing overall compressor power consumption.
Solution Approach 2:
The suction line heat exchanger acts as an intermediary device that pre-cools the refrigerant before it enters the compressor. By positioning this heat exchanger in the refrigerant circuit between the evaporator and compressor, it recovers heat from the discharge line refrigerant and transfers it to the suction line refrigerant, reducing the temperature differential the compressor must handle.
2Productivity
If superheated refrigerant is fed to the compressor, then the evaporator can maintain optimal operation, but heat transfer efficiency in the suction line decreases
Solution Approach 1:
The system changes the thermodynamic parameters of the refrigerant by introducing a two-phase mixture (1-10% quality) to the suction line heat exchanger instead of superheated vapor. This parameter change enables more effective heat transfer in the suction line while maintaining adequate evaporator performance through the separated first stream.
3Use of energy by moving object
If two-phase mixture with low quality is provided to the heat absorption heat exchanger, then compressor power consumption is reduced, but the refrigerant quality distribution becomes more complex to control
Solution Approach 1:
The accumulator is designed to perform multiple functions simultaneously: it separates the refrigerant into two streams with different qualities, controls the distribution of these streams to different parts of the system, and maintains proper refrigerant levels. This multi-functionality reduces the need for additional complex control devices.
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 approach reduces compressor power consumption, enhances evaporator performance, and extends the operating range of the compressor by cooling the motor and improving heat transfer efficiency in the suction line heat exchanger.
Implementation Method 1
The primary refrigerant flow 103 enters the inlet 40 and then passes into a convergent section 104 of the motive nozzle 100. It then passes through a throat section 106 and an expansion (divergent) section 108 through an outlet 110 of the motive nozzle 100. The motive nozzle 100 accelerates the flow 103 and decreases the pressure of the flow.
Implementation Method 2
The outer member includes a mixer having a convergent section 114 and an elongate throat or mixing section 116. The motive nozzle outlet 110 is positioned within the secondary nozzle convergent section 114. As the flow 103 exits the outlet 110, it begins to mix with the flow 112 with further mixing occurring through the mixing section 116 which provides a mixing zone.
Implementation Method 3
The outer member also has a divergent section or diffuser 118 downstream of the elongate throat or mixing section 116. The resulting combined flow 120 is a liquid/vapor mixture and decelerates and recovers pressure in the diffuser 118 while remaining a mixture.
Implementation Method 4
Upon entering the separator, the flow 120 is separated back into the flows 103 and 112. The flow 103 passes as a gas through the compressor suction line as discussed above. The flow 112 passes as a liquid to the expansion valve 70.
Implementation Method 5
The flow 112 may be expanded by the valve 70 (e.g., to a low quality (two-phase with small amount of vapor)) and passed to the evaporator 64.
Implementation Method 6
Within the evaporator 64, the refrigerant absorbs heat from a heat transfer fluid (e.g., from a fan-forced air flow or water or other liquid) and is discharged from the outlet 68 to the line 74 as the aforementioned gas.
Implementation Method 7
In the heat rejection heat exchanger, the refrigerant loses/rejects heat to a heat transfer fluid (e.g., fan-forced air or water or other liquid).
Data Source
AI summary
A system has a compressor. A heat rejection heat exchanger is coupled to the compressor to receive refrigerant compressed by the compressor. An ejector has a primary inlet coupled with heat rejection heat exchanger to receive refrigerant, a secondary inlet, and an outlet. The system has a heat absorption heat exchanger. The system includes means for providing at least of a 1-10% quality refrigerant to the heat absorption heat exchanger and an 85-99% quality refrigerant to at least one of the compressor and, if present, a suction line heat exchanger.