Condensation heat transfer and pressure drop of R1336mzz(Z) in a smooth horizontal tube at high saturation temperatures.

R1336mzz(Z) is a promising refrigerant for high-temperature heat pumps (HTHPs) due to its low toxicity, non-flammability, environmental friendliness, and relatively high critical temperature compared to other HFO refrigerants. However, there is no public data on the condensing heat transfer coefficient of this fluid at HTHP conditions. Thus, this study presents measurements of condensing heat transfer coefficient and pressure drop characteristics of R1336mzz(z) at high saturation temperatures in a horizontal smooth tube with an inner diameter of 4.62 mm. The test condenser is a counter-current tube-in-tube heat exchanger made of an inner copper tube and an outer stainless-steel tube. The experiments cover mass fluxes ranging from 150 to 550 kg/m²s, vapor qualities between 0.05 and 0.98, and saturation temperatures of 110, 130, and 150°C. The data are then compared to the established pressure drop and heat transfer correlations from the literature.