Experimental research on non-azeotropic immiscible binary mixed vapors condensation mode and heat mass transfer characteristics under natural convection

The water and organic components non-azeotropic immiscible mixed vapors condensation heat transfer is important during the biomass gasification gas waste heat recovery. There is a lack of regulation methods for such mixed vapors condensation mode and a lack of empirical correlation guidance for condensation heat transfer. In this work, cyclohexane and water were used as binary mixtures. The mixed vapors condensation mode and heat mass transfer characteristics at different vapor mass fractions and wall subcooling were investigated experimentally under natural convection. The results showed that the binary mixed vapors condensation mode changed from single condensation to co-condensation as the mixed vapors mass fraction approached the eutectic fraction or as the condensation wall subcooling increased. A condensation mode map of mixed vapors was drawn based on the experimental condensation phenomenon. The mixed vapors condensation heat flux and heat transfer coefficient decreased with the water vapor condensation mass flux due to the water vapor proportion being reduced in the mixed vapors. Both two components of condensation mass flux increased with wall subcooling, while the condensation heat transfer coefficient first decreased and then increased, which was related to the change in condensation mode from single condensation to co-condensation. An empirical correlation for water and cyclohexane binary mixtures condensation heat transfer under different condensation modes was proposed, with a maximum deviation from experimental results of less than 18 %. The research results can provide reference and guidance for the mixed vapors condensation heat transfer phenomena of water and organic components in industrial environments.