Dual refrigeration device
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Solution Overview
Problem
Conventional refrigerants have high global-warming potential (GWP) and pose risks of oil deterioration, sludge formation, and explosion due to the inclusion of combustible carbohydrates like propane, which are not environmentally friendly and do not effectively achieve low temperatures of -80°C.
Innovation Solution
A binary refrigerating apparatus using a refrigerant composition that combines difluoroethylene (R1132a) with carbon dioxide (R744) and hexafluoroethane (R116) in the low-temperature circuit, and a non-azeotropic mixture with a GWP of 1500 or less in the high-temperature circuit, with n-pentane or propane as an oil carrier, to achieve low temperatures while minimizing GWP and preventing oil sludge and explosion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional refrigerants like R404A or R508A are used to achieve low temperatures, then the temperature requirement of -80°C is met, but the global-warming potential (GWP) becomes extraordinarily high
Solution Approach 1:
The patent changes the chemical composition parameters of the refrigerant by using a mixture of difluoroethylene (R1132a) and carbon dioxide (R744) in specific ratios (30-70% by weight), replacing conventional high-GWP refrigerants. This parameter change achieves both the required low temperature and reduced GWP by selecting components with favorable thermodynamic properties and environmental characteristics.
Solution Approach 2:
The patent creates a composite refrigerant system by combining difluoroethylene and carbon dioxide in a non-azeotropic mixture, adding n-pentane or propane as oil carriers. This composite approach allows the system to achieve low temperatures through the refrigerant mixture while using the hydrocarbon additives to solve oil return problems, thereby reducing overall GWP compared to single-component conventional refrigerants.
2Object-affected harmful factors
If carbon dioxide (R744) is used as refrigerant to reduce GWP, then GWP becomes small (GWP=1), 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 in the refrigerant mixture. These intermediaries facilitate oil return to the compressor by dissolving in the refrigerant and being transported through the system, preventing oil deterioration and sludge formation while allowing carbon dioxide to function as the primary refrigerant with low GWP.
Solution Approach 2:
The patent modifies the refrigerant composition by adding specific amounts of n-pentane (1-10% by weight) or propane (1-10% by weight) to the carbon dioxide and difluoroethylene mixture. This parameter change adjusts the refrigerant's oil-carrying capacity and thermodynamic properties, enabling effective oil return while maintaining low GWP and achieving the required operating temperatures.
3Productivity
If carbohydrates like propane are added to carbon dioxide to improve refrigeration performance, then refrigerating capacity increases, but the risk of explosion increases due to combustible components
Solution Approach 1:
The patent optimizes the concentration parameters of combustible components by limiting propane to 1-10% by weight or n-pentane to 1-10% by weight in the refrigerant mixture. This parameter control maintains sufficient refrigerating capacity through the hydrocarbon's favorable thermodynamic properties while keeping the combustible concentration below dangerous levels, thereby reducing explosion risk.
Solution Approach 2:
The patent uses difluoroethylene (R1132a) as a primary refrigerant component that acts as an intermediary to achieve the required low temperatures without relying on high concentrations of combustible hydrocarbons. This allows the system to use small amounts of propane or n-pentane primarily for oil return functions rather than as the main refrigerant, thereby improving safety while maintaining refrigeration performance.
4Reliability
If n-pentane or propane is used as oil carrier to prevent oil deterioration, then oil return to compressor is improved, but the refrigerant composition becomes more complex
Solution Approach 1:
The patent achieves multi-functionality by selecting n-pentane or propane that serve dual purposes: as oil carriers to facilitate oil return to the compressor and as refrigerant components that contribute to the thermodynamic performance of the mixture. This eliminates the need for separate oil return additives, simplifying the overall system while improving oil management.
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, maintaining high Coefficient of Performance (COP), preventing oil deterioration and sludge, and eliminating explosion risks, making it environmentally friendly and industrially applicable.
Implementation Method 1
a refrigerant in the low-temperature-side refrigeration circuit is condensed by a refrigerant passing through a cascade condenser in the high-temperature-side refrigeration circuit
Implementation Method 2
a refrigerant in the low-temperature-side refrigeration circuit is condensed by a refrigerant passing through a cascade condenser in the high-temperature-side refrigeration circuit
Implementation Method 3
The boiling point of R407D is about -39°C, and the boiling point of R404A is about -46°C
Data Source
Figure 1
AI summary
A binary refrigerating apparatus employs a refrigerant composition that has a small global-warming potential (GWP) to be earth friendly, can be used as a refrigerant capable of achieving a low temperature of -80°C, and is excellent in refrigerating capacity and other performance. 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.