Film Boiling on a Horizontal Cylinder in Saturated and Subcooled Helium II

Abstract

Film boiling heat transfer coefficients on horizontal cylinders with the diameters of 0.08 and 0.5 mm were measured under saturated conditions for the liquid temperatures of 1.8, 1.9, 2.0 and 2.1 K (He IIs), and under subcooled conditions for the same liquid temperatures at atmospheric pressure (He IIp). At the maximum heat flux, q max , of Kapitza conductance regime in He IIs, the heat transfer state changes from Kapitza conductance regime to film boiling regime with a jump of the heater surface temperature. On the other hand, the heat transfer changes to film boiling with little jump of the heater surface temperature at q max in He IIp. The film boiling heat transfer coefficients under saturated conditions are dependent on the pressure at the level of the test cylinder, surface superheat and bulk liquid temperature.