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The hunt for nonflammable refrigerant blends to replace R-134a.
Ian H Bell1, Piotr A Domanski2, Mark O McLinden1
1Applied Chemicals and Materials Division, National Institute of Standards and Technology, Boulder, CO, 80305, USA.
Revue Internationale Du Froid
|December 11, 2020
Summary
Researchers screened refrigerant blends for air-conditioning, seeking low global warming potential (GWP) alternatives to R-134a. While some nonflammable blends offered moderate GWP reduction, slightly flammable options achieved significant GWP decreases.
Area of Science:
- Thermodynamics and Refrigeration Engineering
- Environmental Science and Policy
Background:
- R-134a, a common refrigerant, has a high global warming potential (GWP).
- There is a critical need for environmentally friendly refrigerants in air-conditioning systems.
Purpose of the Study:
- To identify and evaluate refrigerant blends as low-GWP alternatives to R-134a.
- To assess blends based on nonflammability, GWP, coefficient of performance (COP), and volumetric capacity.
Main Methods:
- Extensive screening of binary, ternary, and four-component blends using 13 pure refrigerants (HFOs, HFCs, CO2).
- Utilized a simplified cycle model incorporating evaporator and condenser pressure drops.
- Employed a new estimation method for nonflammability assessment.
Main Results:
- Identified 16 nonflammable blends with COP and capacity comparable to R-134a, achieving up to 54% GWP reduction.
- Discovered seven "marginally flammable" (A2L) blends with GWP reductions up to 99%.
- These 23 selected blends were further analyzed using a detailed cycle model.
Conclusions:
- No single blend was ideal, but several nonflammable and marginally flammable options show promise as sustainable R-134a replacements.
- Trade-offs exist between flammability, GWP reduction, and performance metrics.
- Further detailed simulations are warranted for the most promising low-GWP refrigerant blends.
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