Comparison of transient heat transfer from a flat plate with that from a cylinder in pressurized HeII

Experimental results of transient heat transfer caused by stepwise heat inputs on flat plates of 13.8, 10.5 and 40 mm in width were compared with those on cylinders of 0.2 0.5 and 0.7 mm in diameter. Effects of the heater shapes and dimensions were clearly observed. Major difference between the results for the flat plates and cylinders is that the transient heat transfer from flat plates can be regarded as that governed by one-dimensional heat flow perpendicular to the flat plate except for the step heights slightly above the steady-state critical heat flux. On the contrary, radial dissipation of heat flow exists in case of a cylinder. As a result, the lifetime for a cylinder is longer than that for a flat plate at the same q(s). The lifetime for a cylinder approaches that for a flat plate with the increase in q(s).