Method for filling mixed refrigerant containing 2,3,3,3-tetrafluoropropene
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Solution Overview
Problem
Non-azeotropic refrigerant mixtures, such as those comprising difluoromethane (HFC-32) and 2,3,3-tetrafluoropropene (HFO-1234yf), experience significant composition changes during transfer due to differences in boiling points, leading to performance degradation and safety concerns related to flammability, particularly when transferred from one container to another.
Innovation Solution
A method for filling refrigerant mixtures that involves adjusting the initial composition of HFC-32 in the liquid phase of the refrigerant mixture before transfer to specific ranges, using equations to calculate optimal proportions to maintain a set tolerance of ±a wt% of the target composition, thereby minimizing composition changes and ensuring consistent performance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-azeotropic refrigerant mixtures with large boiling point differences are transferred from liquid phase, then transfer efficiency is improved, but composition changes occur leading to performance degradation
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the initial composition of HFC-32 in the liquid phase before transfer begins. The composition is set to a higher value than the target composition, anticipating the evaporation loss of low-boiling-point components during transfer. This advance adjustment ensures that despite composition changes during transfer, the final composition remains within acceptable tolerances, maintaining refrigerant performance.
2Ease of operation
If non-azeotropic refrigerant mixtures are transferred, then refrigerant distribution is improved, but flammability safety is compromised due to composition changes
Solution Approach 1:
The patent implements feedback control by continuously monitoring the composition changes during transfer and adjusting the initial composition setting based on the desired final composition and acceptable tolerance ranges. The method calculates the appropriate initial HFC-32 concentration considering the expected evaporation losses, ensuring that the final composition remains within safety limits for flammability while achieving proper refrigerant distribution.
3Object-affected harmful factors
If HFO-1234yf is used as alternative refrigerant, then GWP is reduced, but vapor pressure is insufficient leading to performance degradation
Solution Approach 1:
The patent applies composite materials principle by creating a non-azeotropic mixture of HFO-1234yf and HFC-32. HFO-1234yf provides low GWP (global warming potential), while HFC-32 supplements the vapor pressure and refrigerating capacity. The specific composition ratio is optimized to achieve both environmental benefits and sufficient thermodynamic performance, combining the advantages of both refrigerants while mitigating their individual weaknesses.
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 method effectively controls composition changes within acceptable limits, maintaining refrigerant performance and safety by adjusting the initial composition of HFC-32 in the refrigerant mixture before transfer, ensuring consistent refrigerant capacity and reduced flammability risks.
Implementation Method 1
low-boiling-point components are more likely to be evaporated, and high-boiling-point components are more likely to be condensed
Implementation Method 2
undergo composition changes during phase changes, such as evaporation and condensation
Implementation Method 3
low-boiling-point components are more likely to be evaporated, and high-boiling-point components are more likely to be condensed
Data Source
AI summary
A principal object of the present invention is to provide a method for filling a refrigerant mixture. According to this method, when a non-azeotropic refrigerant mixture comprising HFC-32 and HFO-1234yf is transferred, changes in the composition that occur during the transfer can be made to fall within an acceptable range in terms of refrigerant properties.