Experimental measurement and theoretical modeling of liquid density and viscosity for Low-GWP azeotropic refrigerant R516A

Under the Kigali Amendment, which promotes the phase-down of refrigerants with high global warming potential (GWP), the low-GWP azeotropic mixture R516A has been considered a promising alternative to R134a. However, experimental data on its fundamental thermophysical properties remain limited. In this work, the liquid density and viscosity of R516A were systematically measured using a vibrating-wire viscometer-densimeter over the temperature range of 243.15∼363.15 K and at pressures up to 12 MPa. Treating R516A as a pseudo-pure fluid, the Tait equation and perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state were used to correlate and predict the liquid density, while the Vogel–Fulcher–Tammann (VFT) equation, extended hard-sphere (EHS) model, residual entropy scaling (RES) model, and artificial neural network (ANN) model were evaluated for viscosity prediction. The results show that the Tait equation provides an accurate representation of the liquid density, with an average absolute relative deviation (AARD) of 0.09%. For viscosity, the EHS model gives the best performance, with an AARD of 0.71%, followed by the RES model and VFT equation. In contrast, the ANN model exhibits a clear systematic deviation under the current dataset and model settings. The high-accuracy experimental data enrich the thermophysical property database of R516A and provide reliable input for property model development and the optimization of R516A-based refrigeration and heat pump systems.