Ternary refrigerant blends for ultra-low temperature refrigeration.

• Thirteen fluids have been considered for blends in ultra-low temperature refrigeration. • Optimum blends are provided for different temperature, flammability and GWP ranges. • The highest energy performance is observed with high flammability blends. • Carbon dioxide is a refrigerant present in most blends and temperature conditions. • Ethane and ethene-based blends present the highest COP and volumetric cooling capacity. The absence of GWP limitation for refrigerants operating in vapour compression systems with a target temperature below –50 °C has caused slower market development. Therefore, while typical refrigeration applications have several mixtures offering different characteristics, a few mixtures already exist for –80 °C refrigeration (R-469A, R-472A, and R-473A). This paper explores the combination of pure fluids with varied characteristics as three-component mixtures for ultra-low temperature refrigeration. Different parameters have been considered in the theoretical screening, such as volumetric cooling capacity, coefficient of performance, global warming potential, and flammability at constant operating conditions. R-32, R-41, R-125, R-134a, R-152a, R-170, R-227ea, R-290, R-744, R-1132a, R-1150, R-1234ze(E) and RE-170 have been combined at steps of 5%. Mixtures with the lowest global warming potential and highest coefficient of performance result in high flammability, particularly at −80 °C. Environmental and energy aspects would require a lower priority in trade-off selections to reduce the flammability classification. [ABSTRACT FROM AUTHOR]