Hunting sustainable refrigerants fulfilling technical, environmental, safety and economic requirements

Abstract

An urgent action to mitigate climate change is the replacement of hydrofluorocarbons used in refrigeration systems, for low-global warming potential (GWP) alternatives, with stringent legislations in place. However, very limited options exist for single-component low-GWP refrigerants with similar technical performance. This work presents an integrated approach for the rational design of low-GWP refrigerant blends, focused on replacing R134a (GWP 1430), and R410A (GWP 2088), used in automotive and domestic air-conditioning, and in high pressure commercial and industrial refrigeration, respectively. A 4 E analysis (energy, exergy, economic and environmental) was employed to select suitable candidates. The molecular polar soft-SAFT theory was used in a predictive manner to fill the gap in thermodynamic data required for evaluating the technical performance based on initial selection criteria including GWP, toxicity, flammability, and degree of azeotropy. Potential candidates from a pool of 432 options were narrowed down and evaluated using a drop-in analysis to replace the working fluids R134a and R410A in today's refrigeration and air conditioning cycles, resulting in seven promising blends. Environmental and cost rate evaluation (geographically dependent based on electricity cost, HFC utilization taxes, and carbon emission factors) quantified the impact associated with their use and emissions, allowing to identify suitable replacements: three blends for replacing R134a: (90/10) wt.% R1243yf + R152a, (90/10) wt.% R1243yf + R134a, and (60/40) wt.% R1243zf + R1234ze(E), and one for replacing R410A: (90/10) wt.% R1123 + R32. This work showcases the importance of using robust thermodynamic models in the search of low-GWP refrigerants blends, considering the 4 E criteria.