Internal liquid suction heat exchanger
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Solution Overview
Problem
Refrigeration systems using low global warming potential (GWP) refrigerants face issues with low discharge superheat, leading to ineffective oil separation, oil foaming, and operational problems due to residual atomized liquid particles, as well as poor versatility in responding to fluid temperature and flowrate changes.
Innovation Solution
Incorporating a liquid suction heat exchanger within the evaporator to increase suction superheat by transferring heat from the liquid refrigerant to the refrigerant vapor, enhancing system efficiency and capacity, and using a superheat sensor to control the expansion valve for improved refrigerant flow management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low GWP refrigerants are used, then environmental impact is reduced, but discharge superheat decreases leading to poor oil separation
Solution Approach 1:
The liquid suction heat exchanger pre-heats the liquid refrigerant before it enters the evaporator by using heat from the suction vapor. This preliminary heating action ensures that sufficient superheat is achieved before the refrigerant enters the compressor, preventing oil carryover and ensuring reliable oil separation even when using low GWP refrigerants with inherently lower discharge superheat
Solution Approach 2:
The liquid suction heat exchanger acts as an intermediary component between the evaporator and condenser, facilitating heat transfer from the suction vapor to the liquid refrigerant. This intermediary heat exchange mechanism enables improved oil separation without requiring changes to the compressor or oil separator design
2Productivity
If low discharge superheat is used, then refrigerant efficiency improves, but liquid particles damage downstream components
Solution Approach 1:
The liquid suction heat exchanger performs preliminary heating of the liquid refrigerant before it enters the evaporator. This ensures that the refrigerant achieves adequate superheat before reaching the compressor, preventing liquid particle damage to downstream components while maintaining refrigerant cycle efficiency
Solution Approach 2:
The system changes the temperature parameter of the liquid refrigerant by heating it in the liquid suction heat exchanger. This parameter change transforms the refrigerant from a cold liquid state to a warmer liquid state before evaporation, ensuring proper vaporization and preventing liquid carryover that could damage downstream components
3Adaptability or versatility
If system response to fluid temperature and flowrate changes is improved, then operational versatility increases, but system complexity increases
Solution Approach 1:
The liquid suction heat exchanger is positioned inside the evaporator, merging two heat exchange functions into a single integrated component. This combination allows the system to respond more effectively to changes in fluid temperature and flowrate without adding separate external heat exchangers or complex control systems
Solution Approach 2:
The liquid suction heat exchanger performs multiple functions simultaneously: it subcools the liquid refrigerant, pre-heats it before evaporation, and increases suction superheat. This multi-functionality enables the system to adapt to various operating conditions without requiring additional specialized components
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 solution improves refrigerant cycle efficiency and capacity, enhances oil separation, reduces liquid entrainment, and extends compressor life by increasing suction superheat and subcooling, while providing better control over refrigerant flow and protecting the compressor from liquid carryover.
Implementation Method 1
heat exchange between liquid refrigerant from the condenser and refrigerant vapor in the evaporator
Implementation Method 2
transferring heat from the liquid refrigerant to the refrigerant vapor
Implementation Method 3
the expansion valve is operably coupled to the superheat sensor
Implementation Method 4
a superheat sensor disposed in the evaporator outlet
Implementation Method 5
vaporizing and superheating the cooled liquid refrigerant into the refrigerant vapor
Implementation Method 6
increasing the superheat of the refrigerant vapor through heat exchange with the liquid refrigerant
Data Source
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AI summary
In one aspect, an evaporator assembly for a refrigeration system is provided. The evaporator assembly includes a pressure vessel having an inlet and an outlet. The outlet is configured to supply refrigerant to a compressor of the refrigeration system. A liquid suction heat exchanger is disposed within the pressure vessel. The liquid suction heat exchanger is configured to receive a liquid refrigerant for heat exchange with the refrigerant in the pressure vessel.