Supercritical heat transfer characteristics of R1233zd(E) in vertically upward flow

The recently developed low-global-warming-potential working fluid R1233zd(E) is regarded as an alternative to R245fa in the organic Rankine cycle (ORC) considering the environmental impacts. In this study, the heat transfer characteristics of R1233zd(E) at supercritical pressures were investigated experimentally in a vertically upward flow inside a tube. The inner diameter and length of the test tube were 4 mm and 1.04 m, respectively. With the known supercritical heat transfer characteristics of R245fa, the experiment was conducted under the mass fluxes of 400 and 600 kg/m2 s, heat flux from 20 to 80 kW/m2, and pressure of 3.93 and 4.40 MPa, which were equal to the reduced pressure (P/Pcri) of 1.10 and 1.23, respectively. The effects of mass flux, heat flux, and pressure are discussed based on the experimental data. The experimental results are compared with existing correlations and the correlation proposed by Petukhov et al. shows the best predictability. Moreover, a comparison with the heat transfer coefficients of R245fa is presented. For the new R1233zd(E) working fluid, the abrupt deterioration characteristics did not occur under the experimental conditions, and a higher heat transfer coefficient was obtained in the supercritical region, in comparison to that obtained with R245fa.