A vapor compression heat transfer system
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Solution Overview
Problem
Existing vapor compression heat transfer systems, particularly those using fluoroolefins as working fluids, face challenges in enhancing cooling capacity and energy efficiency, as they often rely on conventional methods that do not effectively utilize sub-cooling to improve refrigeration performance.
Innovation Solution
Incorporating an intermediate heat exchanger with a dual-row condenser or evaporator design, where the working fluid undergoes sub-cooling, allowing for enhanced heat transfer between hot liquid and cold gaseous phases, thereby increasing the system's coefficient of performance and cooling capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional heat transfer methods are used in vapor compression systems with fluoroolefins, then the system structure remains simple, but cooling capacity and energy efficiency are insufficient
Solution Approach 1:
The intermediate heat exchanger is integrated within the condenser structure, with the IHX coil nested inside the condenser housing. This allows the IHX to be surrounded by condensing refrigerant, enabling efficient heat transfer while maintaining a compact overall structure. The nested configuration resolves the contradiction by adding subcooling functionality without proportionally increasing system complexity.
Solution Approach 2:
The intermediate heat exchanger serves multiple functions: it subcools the liquid refrigerant, preheats the suction gas, and recovers heat from the condensing refrigerant. This multi-functionality increases cooling capacity and energy efficiency while the integrated design keeps structural complexity manageable, addressing the technical contradiction.
2Use of energy by moving object
If sub-cooling is implemented to improve cooling capacity, then refrigeration performance increases, but system complexity increases due to additional heat exchanger components
Solution Approach 1:
The intermediate heat exchanger is merged with the condenser assembly, forming an integrated unit. The IHX uses the condensing refrigerant as its heat source, eliminating the need for a separate refrigerant source. This merging reduces the number of independent components while achieving effective subcooling and improving energy efficiency.
Solution Approach 2:
The intermediate heat exchanger utilizes the condensing refrigerant itself as the heat source for subcooling the liquid refrigerant. The system serves itself by using its own operational refrigerant flow to provide the necessary cooling, rather than requiring an external or separate cooling source, thereby reducing component complexity.
3Productivity
If an intermediate heat exchanger is added for sub-cooling, then cooling capacity increases, but manufacturing cost and system complexity increase
Solution Approach 1:
The intermediate heat exchanger coil is nested within the condenser housing, utilizing the existing condenser structure and refrigerant flow paths. This nested integration allows the IHX to be manufactured as part of the condenser assembly rather than as a separate component requiring additional installation, thereby reducing manufacturing complexity and cost while achieving increased cooling capacity.
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
The implementation of an intermediate heat exchanger with sub-cooling significantly boosts the cooling capacity and energy efficiency of vapor compression systems, demonstrated by a 7.5% increase in coefficient of performance and cooling capacity when using HFC-1234yf compared to HFC-134a, showcasing improved performance with fluoroolefin working fluids.
Implementation Method 1
The first tube (30a) surrounds the second tube (50a) and a hot liquid in the first tube is in thermal contact with a cold gas in the second tube
Implementation Method 2
By 'subcooling' is meant the reduction of the temperature of a liquid below that liquid's saturation point for a given pressure
Implementation Method 3
In the evaporator, the working fluid is evaporated, which converts it into a gaseous working fluid, and the vaporization of the working fluid provides cooling
Implementation Method 4
the vaporization of the working fluid provides cooling
Implementation Method 5
The gas is compressed in the compressor, and the compressed gaseous working fluid is discharged from the compressor
Implementation Method 6
the working fluid is condensed, thus giving off heat, and the cycle then repeats
Data Source
Figure 1~1A
Figure 2~3
AI summary
The present disclosure relates to a method for exchanging heat in a vapor compression heat transfer system. In particular, it relates to use of an intermediate heat exchanger to improve performance of a vapor compression heat transfer system utilizing a working fluid comprising HFC-1234yf.