Abstract
As pressure increases and approaches the critical pressure, density difference between liquid and vapor becomes small, latent heat of condensation approaches zero and other physical properties show remarkably different behaviors from those at lower pressure. Therefore it is expected that condensation heat transfer near the critical pressure differs from that at lower pressure.
An experimental study of natural convection condensation on a vertical cylinder surface was carried out using Carbon Dioxide as a working fluid in the pressure range of 5.0 to 7.1 MPa. Filmwise condensation was observed, and heat transfer coefficients were obtained from measuring condensate volume and compared with Nusselt's theory and with experimental results under usual pressure conditions.
