Low GWP refrigerants condensation inside a 2.4 mm ID microfin tube

This paper explores the possible use of R1234yf and R1234ze(E) during condensation inside a microfin tube with an inner diameter at the fin tip of 2.4 mm as replacement of R134a. Having thermodynamic properties close to those of R134a, R1234yf and R1234ze(E) are some of its possible replacements for air conditioning and refrigeration systems. Experimental tests were carried out for mass velocities from 300 to 1000 kg m(-2) s(-1), vapor qualities from 0.95 to 0.2, at saturation temperatures of 30 degrees C and 40 degrees C. From the experimental measurements, it has been possible to calculate the heat transfer coefficient and to measure the frictional pressure drop. Globally speaking, R1234ze(E) shows heat transfer coefficients similar to those of R134a, whereas R1234yf shows slightly lower values. R1234ze(E) frictional pressure drops are some 30% higher than those of R134a, whereas R1234yf shows values similar to R134a. The experimental results of heat transfer coefficient and frictional pressure drop were also compared against values predicted by empirical correlations. (c) 2017 Elsevier Ltd and IIR. Allrights reserved.