Refrigerant Mixture Composition for Low-GWP Subzero Cooling
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Solution Overview
Problem
Current refrigerants for cooling devices face challenges in achieving low temperatures while maintaining environmental sustainability, as they often have high Global Warming Potential (GWP) and flammability, leading to reduced cooling capacity and increased safety and design complexities, especially in dynamic cooling applications like test chambers.
Innovation Solution
A refrigerant mixture comprising 54 to 81 mol% carbon dioxide, 10 to 20 mol% difluoromethane, and 1 to 29 mol% 1,1,2-tetrafluoroethane, which balances GWP, flammability, and temperature stability, allowing for flexible adaptation to various applications and maintaining temperature constancy in test chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a high proportion of carbon dioxide is used in the refrigerant mixture, then the GWP is reduced and flammability is minimized, but the freezing point increases making it difficult to achieve temperatures below -56.6°C
Solution Approach 1:
The patent applies composite refrigerant mixtures combining carbon dioxide (54-81 mol%) with difluoromethane (10-20 mol%) and 1,1,1,2-tetrafluoroethane (1-29 mol%). This composite approach allows the system to achieve temperatures below -56.6°C while maintaining low GWP and acceptable flammability characteristics, as the component refrigerants have different thermal properties that complement each other.
Solution Approach 2:
The patent optimizes the compositional parameters of the refrigerant mixture by specifying precise mol% ranges for each component. By adjusting these parameters, the mixture achieves a balance between the freezing point depression needed for sub-zero temperatures and the low GWP/flammability benefits of high carbon dioxide content.
2Temperature
If a zeotropic refrigerant mixture is used to achieve low temperatures, then the temperature glide allows for broader temperature range, but the temperature stability and dew point shifts reduce control precision
Solution Approach 1:
The patent acknowledges the dynamic nature of zeotropic refrigerant mixtures with temperature glide and implements dynamic control strategies. The system adapts to temperature variations and dew point shifts through active management, allowing the refrigerant mixture to maintain both broad temperature range capability and acceptable temperature stability for test chamber applications.
3Temperature
If the proportion of 1,1,1,2-tetrafluoroethane is increased to achieve lower temperatures, then the flammability increases and safety requirements are complicated, but if it is decreased then the temperature range is limited
Solution Approach 1:
The patent establishes specific parameter ranges for 1,1,1,2-tetrafluoroethane content (1-29 mol%) in the refrigerant mixture. This parameter optimization allows the system to achieve the necessary temperature range while keeping flammability within acceptable limits, avoiding the need for complex safety measures associated with highly flammable refrigerants.
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 achieves a low GWP, reduces flammability risks, and maintains temperature stability within a wide range, enabling efficient and cost-effective operation of cooling devices, particularly in test chambers, by using an internal heat exchanger to manage temperature glide and dew point shifts.
Implementation Method 1
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 (10) with a cooling circuit (11) with at least one heat exchanger (12), wherein the refrigerant undergoes a phase change in the heat exchanger, wherein the refrigerant is a refrigerant mixture of a proportion of carbon dioxide, a proportion of difluoromethane and a proportion of 1,1,1,2-tetrafluoroethane, wherein the proportion of carbon dioxide in the refrigerant mixture is 54 to 92 mol percent, the proportion of difluoromethane is 1 to 30 mol percent and the proportion of 1,1,1,2-tetrafluoroethane is 1 to 29 mol percent.