Entropy generation and exergy loss of R123-MWCNTs nanorefrigerant in flow condensation

Abstract

This experimental study examines the entropy generation due to heat transfer and frictional pressure and the exergy destruction during the condensation of an R123-MWCNTs nano-refrigerant within a horizontal tube. The effects of entropy production, Bejan number, and exergy loss are studied, together with the roles played by vapour quality, mass flux, and multi-wall carbon nanotubes (MWCNTs) concentration. The results show that the heat transfer entropy generation reduces as the vapour quality or mass flux and concentration of MWCNTs rises. In contrast, the entropy production due to frictional pressure during condensation increases with the rise in mass flux, vapour quality, and the MWCNTs fractions. The reductions in heat transfer entropy generation are high compared to the increment in frictional entropy generation, thus reducing the total entropy generation of the system. Further, nanofluid minimizes the system's Bejan number and exergy loss. The highest reduction in entropy generation and exergy loss of about 30 % and 29 %, respectively, was observed using the proposed nanofluid at a MWCNTs fraction of 0.1 % and mass velocity of 400 kg/m2s.