Experimental investigation on boiling heat transfer characteristics of R1234yf/R1336mzz(Z) in horizontal flow

Due to the inclusion of 18 HFCs, including R134a and R245fa, in the Kigali Amendment as controlled working fluids, the search for excellent alternatives to R134a and R245fa is urgent. R1234yf and R1336mzz(Z) are potential alternative working fluids to R134a and R245fa, but most studies have focused on the comparison of thermodynamic performance and boiling heat transfer capability of these pure working fluids. There is limited research on the boiling heat transfer performance of their mixed working fluids. Therefore, this study focuses on the flow boiling heat transfer characteristics of the mixed working fluid R134a/R245fa under non-azeotropic conditions. Experimental methods were employed to investigate the boiling heat transfer performance of the alternative working fluids R1234yf/R1336mzz(Z) (including R245fa/R1234yf and R1234yf/R1336mzz(Z) mixed working fluids) and evaluate the feasibility of R1234yf and R1336mzz(Z) as substitutes for R134a and R245fa. The results indicate that among the three mixed refrigerants, R134a/R245fa exhibits the highest heat transfer coefficient, while R1234yf/R1336mzz(Z) shows the lowest heat transfer coefficient. However, the differences in heat transfer coefficients among these three are relatively small, and their overall trends under different operating conditions are similar. It is evident that R134a/R245fa, with its good thermodynamic performance and stability, still holds potential as a transitional working fluid. R1234yf/R1336mzz(Z), with similar physical and thermodynamic properties, is an excellent alternative to R134a/R245fa.