Heat transport characteristics of superfluid helium in channels segmented by a spacer having holes

Heat transport characteristics of superfluid helium (He II) in channels segmented by different types of spacers having several holes have been investigated on the basis of both experimental and numerical analyses. The spacer is placed along the channel axis so that the internal flow path of the channel is divided into two rectangular portions of equal size. In the present study, the heat transport performance has been examined for the following four types of spacers; (a) FRP spacer with several holes of 2 mm diameter, (b) FRP spacer with several holes of 4 mm diameter, (c) FRP spacer with no holes, and (d) porous spacer made of fine powder of sintered Al2O3. The λ-transition heat-flux when spacers with holes of 2 mm and 4 mm in diameter are used is almost the same. This value is about 1.5 times larger than when a spacer without a hole is used. However, this value is smaller than that of the porous spacer, because the fountain defect is not induced in spacers with relatively lager holes. The temperature distribution in the He II channel and the λ-transition heat-flux, which is obtained on the basis of present two dimensional computation taking account only of the heat conduction of He II, shows satisfactory agreement with those obtained by the experiment. The results of the present study lead to the understanding that the introduction of some holes in the spacer is a very effective way to suppress a local temperature rise in the He II channel. (author)