Refrigerant Composition with Polyol Ester Oil for Low GWP Stability
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Solution Overview
Problem
Refrigeration systems face challenges with refrigerants that have high global warming potential (GWP), thermodynamic incompatibility, and poor thermal/chemical stability, particularly with difluoromethane and unsaturated hydrofluorocarbons, which affect compatibility with refrigerating machine oils and lead to lubrication failures and blockages.
Innovation Solution
A working fluid composition comprising a refrigerant with a GWP of 500 or less, including difluoromethane, tetrafluoropropene, and a hydrocarbon with 3 to 4 carbon atoms, combined with a refrigerating machine oil having a specific carbon/oxygen molar ratio, such as polyol esters, polyvinyl ethers, or polyalkylene glycols, to achieve compatibility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If difluoromethane is used as a refrigerant to achieve low GWP, then environmental performance is improved, but compatibility with refrigerating machine oil deteriorates
Solution Approach 1:
The patent uses a composite refrigerant composition containing difluoromethane (30-70 wt%), hydrocarbon (5-40 wt%), and unsaturated hydrofluorocarbon (5-40 wt%). This composite approach allows the system to benefit from difluoromethane's low GWP while the hydrocarbon and unsaturated hydrofluorocarbon components improve compatibility with refrigerating machine oil, resolving the contradiction between environmental performance and oil compatibility.
2Object-affected harmful factors
If unsaturated hydrofluorocarbons are used as refrigerant to achieve low ODP and GWP, then environmental performance is improved, but thermal/chemical stability deteriorates due to unstable double bonds
Solution Approach 1:
The patent carefully controls the composition parameters of the refrigerant mixture, limiting the unsaturated hydrofluorocarbon content to 5-40 wt% and balancing it with difluoromethane and hydrocarbon components. This parameter optimization allows the system to achieve low ODP and GWP while maintaining adequate thermal/chemical stability through the stabilizing effect of the other refrigerant components.
Solution Approach 2:
The patent creates a composite refrigerant system that combines unsaturated hydrofluorocarbon (for low ODP/GWP) with difluoromethane and hydrocarbon components (for stability). The composite nature of the mixture allows the unstable double bonds of unsaturated hydrofluorocarbons to be compensated by the stable components, resolving the contradiction between environmental performance and thermal/chemical stability.
3Productivity
If conventional HFC refrigerants are used to achieve adequate thermodynamic characteristics, then refrigeration performance is improved, but global warming potential increases
Solution Approach 1:
The patent changes the refrigerant composition parameters by replacing conventional HFC refrigerants with a new mixture containing difluoromethane (GWP 67), hydrocarbon (GWP <150), and unsaturated hydrofluorocarbon (GWP <150). This parameter change in composition achieves lower overall GWP (500 or less) while maintaining refrigeration performance through the complementary thermodynamic properties of the mixed components.
Data Source
AI summary
The working fluid composition for a refrigerating machine of the present invention comprises a refrigerant comprising a first refrigerant component and a second refrigerant component, and having a global warming potential (GWP) of 500 or less, wherein the first refrigerant component is at least one selected from difluoromethane and tetrafluoropropene, and the second refrigerant component is at least one selected from carbon dioxide and a hydrocarbon having 3 to 4 carbon atoms; and a refrigerating machine oil comprising at least one selected from a polyol ester, a polyvinyl ether and a polyalkylene glycol compound as a base oil, wherein a carbon/oxygen molar ratio of the base oil is 2.5 or more and 5.8 or less.