R152a-R13I1 mixture as an alternative to R1234yf for a mobile air conditioning: an estimation of flammability properties, thermodynamic and environmental performance

In response to environmental concerns, R1234yf is used in mobile air conditioning (MAC) systems, yet it can produce trifluoroacetic acid (TFA) in water bodies, a persistent pollutant with moderate phytotoxicity and high mobility. However, R152a, an alternative, faces challenges due to its flammability (classified as A2). To address this, we propose new R152a-R13I1 mixtures (M10–M50) as R1234yf replacements in MAC units. A Simscape/MATLAB model was developed to elucidate the thermodynamic performance of an MAC unit. Theoretical estimations showed a significant reduction in burning velocity (BV) and an increase in the lower flammability limit (LFL) when R13I1 was added to R152a. For instance, at 0.20 mole fraction of R13I1, BV decreased from 23.1 to 11.3 cm s⁻¹; while, LFL increased from 4.9 to 6.28 vol. %. Hence, M20 emerged as the optimal choice due to its A2L flammability classification and superior thermal properties. Simscape/MATLAB results revealed M20's 11.5–35.4% higher coefficient of performance compared to R1234yf. The model was validated against R1234yf data, showing 3.8–13.8% error. Additionally, M20's impact on MAC CO₂ emissions was evaluated, showing a potential 34.1% reduction compared to R1234yf. This highlights the environmental benefits of transitioning to R152a-R13I1 blends in MAC systems.