An experimental investigation was conducted to examine the effects of convection currents in nucleate pool boiling and to determine the changes in critical heat flux caused by varying the diameter of horizontal flat plate heating surfaces. Trichlorotrifluoroethane (Freon 113) was boiled from flat circular copper surfaces at one atmosphere absolute pressure. Convection currents across the heating surface were produced by auxiliary heaters located to the side of the main healer. Bubbles escaping from the auxiliary heaters caused a circular flow pattern across the test surface. It was shown that increasing this flow over the surface increased the critical flux.Three test surface diameters were studied: 2.0, 3.3, and 5.0 cm. Critical fluxes were obtained independent of auxiliary heater effects. These fluxes decreased from approximately 74,800 Btu/hr/sqft (236,000 W/sqm) for the 2.0 cm surfaces to 69,500 Btu/hr/sqft (219,000 W/sqm) for the 5.0 cm. Critical flux was correlated in an exponential relationship and approached an asymptotic value of about 65,000 Btu/hr/sqft (205,000 W/sqm) at a diameter of about 20.0 cm.
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