Retrograde condensation of carbon dioxide - n-decane mixtures on horizontal cylinders

Measurements of heat transfer coefficients are reported for a horizontal cylinder in a mixture of 97 mode % CO2, 3.0 mole % n-decane at pressures of 10.4 and 12.2 MPa. The measurements were made in both crossflow and natural convection. These measurements were in the retrograde region of the dew point curve and show enhancement due to the formation of a condensate film on the surface. When wall temperatures were about 50 K above bulk fluid temperatures, they became unstable and multiple steady states were observed by first increasing and then decreasing the heat flux. Associated wall temperatures approximate those of the dew point extremum of the x-T phase diagram. It is conjectured that this behavior is accompanied by the drying out of the surface in analogy with the transition from nucleate to film boiling