Refrigerant Mixture Composition for Sub-60°C Cooling with Low GWP
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Solution Overview
Problem
Current refrigerants with low Global Warming Potential (GWP) struggle to achieve temperatures below -60°C while being environmentally friendly and safe, as they often have reduced cooling capacity and require complex modifications to cooling devices due to zeotropic properties and high carbon dioxide concentrations, which limit temperature stability in test chambers.
Innovation Solution
A refrigerant mixture comprising 20-74% carbon dioxide, 8-65% pentafluoroethane, and 7-25% fluoromethane, which balances GWP, flammability, and freezing point to achieve low temperatures without being flammable, allowing for a non-flammable and environmentally friendly solution with improved temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a high mass fraction of carbon dioxide is used in the refrigerant mixture, then the GWP is reduced and flammability is avoided, but the freezing point increases making it difficult to achieve temperatures below -60°C
Solution Approach 1:
The patent changes the chemical composition parameters of the refrigerant mixture by introducing pentafluoroethane (R125) and fluoromethane (R41) as additional components. This modifies the phase transition characteristics and freezing point of the mixture, enabling achievement of temperatures below -60°C while maintaining low GWP and non-flammability properties through the optimized mass fractions of CO2 (20-74%), R125 (8-65%), and R41 (7-25%).
Solution Approach 2:
The patent creates a composite refrigerant mixture combining three different substances (carbon dioxide, pentafluoroethane, and fluoromethane) with complementary properties. CO2 provides low GWP and non-flammability, R125 enhances cooling capacity at low temperatures, and R41 adjusts the freezing point and temperature glide characteristics, achieving a balanced performance that none of the individual components could provide alone.
2Temperature
If zeotropic refrigerant mixtures are used to achieve low temperatures, then temperature glide occurs improving heat exchange, but temperature stability in test chambers deteriorates
Solution Approach 1:
The patent optimizes the mass fraction ratios of the three refrigerant components to control the temperature glide characteristics. By adjusting these parameters, the mixture achieves a balanced temperature glide that improves heat exchange efficiency in the evaporator while minimizing temperature fluctuations in the test chamber, resolving the contradiction between heat transfer performance and temperature stability.
3Object-affected harmful factors
If refrigerants with low GWP are used, then environmental friendliness is improved, but cooling capacity below -60°C is reduced
Solution Approach 1:
The patent develops a composite refrigerant system that combines CO2 (low GWP) with R125 and R41 to enhance cooling capacity. The synergistic interaction between these components allows the mixture to maintain excellent environmental credentials (low GWP, non-flammable) while achieving sufficient cooling power at temperatures below -60°C, overcoming the limitation of individual low-GWP refrigerants.
Solution Approach 2:
The patent utilizes the phase transition properties of the refrigerant mixture, particularly the subcooling effect and temperature glide during evaporation. The mixture's phase change characteristics are optimized to maximize heat absorption in the evaporator at low temperatures, thereby enhancing cooling capacity while maintaining low environmental impact through the dominant CO2 component.
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 refrigerant mixture effectively achieves temperatures below -60°C with reduced GWP and flammability, enabling cost-effective and safe operation of cooling devices and test chambers with improved temperature control and stability.
Implementation Method 1
a refrigerant for a cooling device with a cooling circuit with at least one heat exchanger in which the refrigerant undergoes a phase change
Data Source
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AI summary
The invention relates to a refrigerant for a cooling device with a cooling circuit with at least one heat exchanger, the refrigerant undergoes a phase change in the heat exchanger, wherein the refrigerant is a refrigerant mixture consisting of a mass fraction of carbon dioxide, a mass fraction of pentafluoroethane and a mass fraction of at least one further component, wherein the mass fraction of carbon dioxide in the refrigerant mixture is 20 to 74 mass percent, wherein the mass fraction of pentafluoroethane is 8 to 65 mass percent, and wherein the further component is fluoromethane.