Natural Convection Heat Transfer to Liquid Helium in a High Centrifugal Acceleration Field.

Abstract

This paper reports experimental results of natural convection heat transfer to liquid helium in a rotating field in the range of 1600 - 3700 rpm. Test surfaces are vertical plates (10 mm width, 5 mm height) with rectangular channels in a radial direction and upward- and downward-facing horizontal plates (8 mm diameter) at radial distances of 0.3 m. The results show that the heat transfer for vertical plates is approximately the same as that for horizontal ones facing upward, independent of the channel gap size in the range of 0.4 - 5 mm and direction of the Coriolis force. The heat transfer can be predicted from the conventional correlation Nu =0.13Ra1/3 in the Ra range of 1011 - 1013, if the film temperature for evaluating properties is substituted for the pseudocritical temperature only when it is above the pseudocritical temperature. The heat transfer for the horizontal plate facing downward is 1/6 - 1/7 of that for the one facing upward, and the Ra exponent of its correlation is 0.2 in the Ra range of l012 - 1014.