Binary refrigerating apparatus
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Solution Overview
Problem
Existing refrigerants have high global-warming potential (GWP) and pose risks of oil deterioration, sludge formation, and explosion due to the inclusion of combustible carbohydrates, making them unsuitable for achieving low temperatures while being environmentally friendly.
Innovation Solution
A binary refrigerating apparatus using a refrigerant composition of difluoroethylene (R1132a) and hexafluoroethane (R116) or carbon dioxide (R744) in the low-temperature circuit, with a non-azeotropic mixture and a predetermined amount of n-pentane or propane, and a GWP-reduced alternative mixture in the high-temperature circuit, to achieve low temperatures without oil degradation or explosion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If R508A (azeotropic mixture of R23 and R116) is used to achieve low temperature of -80°C or lower, then the refrigerating capacity is improved, but the GWP becomes extraordinarily high (13200)
Solution Approach 1:
The patent changes the chemical composition parameters of the refrigerant by replacing R23 and R116 with difluoroethylene (R1132a) and hexafluoroethane (R116) or carbon dioxide (R744), achieving both low temperature capability and reduced GWP through parameter optimization
Solution Approach 2:
The patent uses composite refrigerant formulations combining difluoroethylene with hexafluoroethane or carbon dioxide, and further composite formulations with n-pentane or propane, creating multi-component refrigerant systems that achieve both low temperature and environmental friendliness
2Object-affected harmful factors
If carbon dioxide (R744) is used as refrigerant to achieve small GWP, then the global-warming potential is reduced, but oil deterioration and sludge occur due to increase in pressure and outlet temperature
Solution Approach 1:
The patent introduces n-pentane or propane as intermediary substances that act as oil carriers, mediating between the carbon dioxide refrigerant and the compressor oil to prevent direct harmful interactions while maintaining system reliability
Solution Approach 2:
The patent creates composite refrigerant formulations combining carbon dioxide with n-pentane or propane, forming multi-component systems that mitigate the harmful effects of pure carbon dioxide on compressor oil while maintaining low GWP
3Productivity
If carbohydrates such as propane are added to carbon dioxide to improve refrigerating capacity, then the refrigerating capacity is improved, but the risk of explosion increases due to combustible components
Solution Approach 1:
The patent optimizes the concentration parameters of combustible components (n-pentane or propane) within specific ranges (1-10 mass% for n-pentane, 3-20 mass% for propane) to achieve sufficient refrigerating capacity while maintaining safety below explosion risk thresholds
Solution Approach 2:
The patent utilizes the phase transition properties of the refrigerant mixture, leveraging the different boiling points and phase behaviors of carbon dioxide, n-pentane, and propane to achieve efficient heat transfer and refrigerating capacity while controlling the amount of combustible components
4Productivity
If R404A is used to achieve suitable refrigerating performance, then the refrigerating capacity is maintained, but the GWP becomes relatively high (3920)
Solution Approach 1:
The patent changes the refrigerant composition parameters by replacing R404A's HFC components with difluoroethylene and hexafluoroethane or carbon dioxide, achieving similar refrigerating capacity with dramatically reduced GWP through parameter optimization
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 solution achieves a low temperature of −80°C with a significantly reduced GWP, preventing oil deterioration, sludge formation, and explosion risks, while maintaining high Coefficient of Performance (COP) and refrigerating capacity.
Implementation Method 1
achieves a refrigerating capacity of −80° C. or lower by condensing a refrigerant in the low-temperature-side refrigeration circuit with a refrigerant passing through a cascade condenser
Implementation Method 2
achieves a refrigerating capacity of −80° C. or lower by condensing a refrigerant in the low-temperature-side refrigeration circuit with a refrigerant passing through a cascade condenser
Data Source
AI summary
A binary refrigerating apparatus employs a refrigerant composition that has a small global-warming potential (GWP) and can be used as a refrigerant capable of achieving a low temperature of −80° C. A refrigerant composition used as a low-temperature-side refrigerant is a refrigerant mixture including a non-azeotropic mixture in which 20% by mass or less of carbon dioxide (R744) is mixed to difluoroethylene (R1132a). A refrigerant composition used as a high-temperature-side refrigerant is a combination of: a non-azeotropic mixture comprising the refrigerant group of difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a) and 1,1,3-trifluoro ethane (R143a); and 1,1,1,2,3-pentafluoropentene (HFO-1234ze), having a global-warming potential (GWP) of 1500 or less.