Abstract
Free-convection heat-transfer coefficients have been measured on a horizontal circular cylinder to Freon 12 near the critical-state conditions as a function of the temperature difference between the test cylinder and the Freon environment. Experimental heat-transfer coefficients have been determined for constant Freon temperatures of 233, 244, and 259 F, and for a constant pressure of 580 psia, the critical pressure of Freon 12. In all cases the heat-transfer coefficients have been determined as functions of the temperature difference between the test cylinder and the Freon for densities varying from supercritical to subcritical. In the region near the critical state the experimental heat-transfer coefficients are shown to increase tenfold over the typical values in the superheated-vapor region. Satisfactory correlation of the present results with the work of other investigators in the field of free-convection heat transfer has been made for state conditions removed from the critical.
