1993 Volume 36 Issue 2 Pages 351-356
The heat transfer surface used in the experiments is a chrome-plated smooth brass pipe of 28mm diameter and 1400mm length. The film Reynolds numbers are varied in the range of 40-400, which includes the range of real machines. The average absorptions mass flux is compared with the numerical results derived from the laminar flow model proposed in the previous paper. The agreement is good up to 100 in Ref, but the experimental values are far higher above 200. This may be attributed to the wave motions on the film surface. Pictures show that the film is completely smooth only at Ref below 20. Beyond 20, ring-shaped waves appear, but the surfaces between the waves are relatively smooth at Ref below 200. The measurements of the film thickness show that its minimum is constant at about 0. 38mm, but its maximum thickness increases for Ref larger than 60.