Development of experimental Nusselt number and friction factor correlations for condensation of R-1233zd(E) in plate heat exchangers

Abstract

R-1233zd(E), a kind of HCFO refrigerants, has a negligible ODP and a GWP of 1-7, and it is classified as the ASHRAE classification Al level, which means stable and safe to use in the refrigeration industry. In this study, condensation heat transfer and frictional pressure drop of R-1233zd(E) in three different plate heat exchangers, two brazed types (BPHE-30 and BPHE-60) and a shell-and-plate type (SPHE) are experimentally investigated. Condensation heat transfer coefficient and frictional pressure drop are estimated by varying heat flux from 1.5 kW/m(2) to 4.5 kW/m(2), saturation pressure from 200 kPa to 300 kPa, mass flux of refrigerant from 13.0 kg/m(2) s to 26.7 kg/m(2)s, and mean vapor quality between the inlet and outlet of heat exchanger from 0.25 to 0.9. It is confirmed that the condensation heat transfer coefficient increases with increasing heat flux, mass flux of refrigerant, and mean vapor quality while it decreases with increasing the saturation pressure of refrigerant. Frictional pressure drop increases with increasing the mass flux of refrigerant and mean vapor quality while it decreases with increasing the saturation pressure of refrigerant. On the other hand, the heat flux doesn't have significant effect on the frictional pressure drop. It was found that the BPHE has a higher Nusselt number and lower friction factor than the SPHE, so that the SPHE having excessively high friction factor against Nusselt number is not recommended as a condenser with R-1233zd(E). Finally, experimental correlations for Nusselt number and friction factor are developed with +/- 25% error range for the BPHE. (C) 2020 Elsevier Ltd. All rights reserved.