Condensation heat transfer of low GWP ORC working fluids in a horizontal smooth tube

Abstract

The objective of the current study is to conduct an experimental investigation of condensation heat transfer for the ORC (organic Rankine cycle) working fluids R245fa, Novec (R) 649 and HFE-7000 over a wide range of parameters. Quasi-local condensation heat transfer coefficients are measured in a straight horizontal 7.75-mm-ID smooth tube with flow conditions at mass flux G = 150-700 kg (m(2)-s)(-1), local equilibrium quality x = 0.05-0.95, and reduced pressure, P-r = 0.05-0.15. Test data reveal that the environmentally friendly fluids have lower condensation heat transfer coefficients when compared to R245fa. The 141 measured condensation heat transfer coefficients are compared to six well-known correlations. Among the six correlations verified with test data, the Shah correlation shows the best predictive performance for the three fluids tested.