Zeotropic Refrigerant Blending for Compositional Stability
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Solution Overview
Problem
Wide-glide zeotropic refrigerant mixtures experience significant compositional shifts during handling and transfer, leading to deviations from specification, which is particularly problematic for automotive air conditioning systems where the cooling capacity change must be less than 5% across the range of compositions.
Innovation Solution
A method involving pre-blending of less volatile components and separate addition of the most volatile component by pressure or mass flow control to maintain the desired initial liquid composition, with periodic or continuous addition of the most volatile component to compensate for removal, ensuring the composition remains within specification during transfer and use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wide-glide zeotropic refrigerant mixtures are transferred from storage container to equipment, then the refrigerant can be delivered to end-use applications, but significant compositional shifts occur during handling and transfer
Solution Approach 1:
The patent applies preliminary action by pre-blending the less volatile components (R-134a and R-1234ze(E)) before adding the most volatile component (CO2). This sequential preparation ensures that the initial composition is correctly established, accounting for the fact that CO2 will preferentially evaporate during subsequent handling and transfer operations. The method also involves preliminary calculation of the required CO2 amount to compensate for expected compositional drift.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the composition parameters of the refrigerant mixture. Specifically, it compensates for compositional shifts by adding additional CO2 during or after transfer operations to maintain the desired concentration ratios. This involves monitoring and adjusting the volatile component content to counteract evaporation losses and maintain specification compliance.
2Manufacturing precision
If the most volatile component is added to achieve desired initial composition, then the target composition is attained, but compositional drift occurs during storage and transfer
Solution Approach 1:
The patent applies preliminary action by pre-blending the less volatile components (R-134a and R-1234ze(E)) before adding the most volatile component (CO2). This sequential preparation ensures that the initial composition is correctly established, accounting for the fact that CO2 will preferentially evaporate during subsequent handling and transfer operations. The method also involves preliminary calculation of the required CO2 amount to compensate for expected compositional drift.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the composition parameters of the refrigerant mixture. Specifically, it compensates for compositional shifts by adding additional CO2 during or after transfer operations to maintain the desired concentration ratios. This involves monitoring and adjusting the volatile component content to counteract evaporation losses and maintain specification compliance.
3Ease of manufacture
If conventional blending methods are used for zeotropic mixtures, then the blending process is simple, but the composition deviates from specification during handling
Solution Approach 1:
The patent applies segmentation by dividing the blending process into distinct stages: first blending the less volatile components (R-134a and R-1234ze(E)), then separately adding the most volatile component (CO2). This segmented approach allows for precise control over the initial composition while accounting for subsequent evaporation losses. The method segments the refrigerant components based on their volatility characteristics to optimize handling and composition stability.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the composition parameters of the refrigerant mixture. Specifically, it compensates for compositional shifts by adding additional CO2 during or after transfer operations to maintain the desired concentration ratios. This involves monitoring and adjusting the volatile component content to counteract evaporation losses and maintain specification compliance.
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
This method effectively maintains the composition of wide-glide zeotropic refrigerant blends within specification, ensuring consistent performance and compliance with industry standards, even for blends with large temperature glides like CO2 and hydrofluoroalkene mixtures, such as CO2, R-134a, and R-1234ze(E).
Implementation Method 1
the more volatile refrigerant component evaporates preferentially, so that the vapour space above the liquid becomes occupied with a vapour composition that becomes progressively enriched in the more volatile component
Implementation Method 2
separately adding the most volatile component to the pre-blended mixture by pressure or mass flow control so that the desired initial liquid composition is attained
Data Source
AI summary
A method for preparing a ternary or higher zeotropic refrigerant mixture comprising components of different volatilities is described. The method comprises: mixing together the less volatile components of the mixture in a pre-blending process; and separately adding the most volatile component to the pre-blended mixture by pressure or mass flow control so that the desired initial liquid composition is attained. The liquid zeotropic refrigerant mixture that is prepared may be transferred from a container in which it is held to another container or to a piece of equipment that is to use the refrigerant mixture. This method comprises the steps of: removing at least a portion of the prepared liquid zeotropic refrigerant mixture from a container in which it is held; charging the liquid zeotropic refrigerant mixture that is removed to another container or to a piece of equipment in which it is to be used; and adding at least the most volatile component of the refrigerant mixture to the holding container to compensate for the removal of liquid refrigerant mixture therefrom.