Abstract:

A new optical method for the non-intrusive measurement of falling film thickness on the perimeter of horizontal tubes is described. The technique uses a high-speed digital video camera to capture the images of the liquid interface that are illuminated by a laser sheet, with the contrast enhanced by a fluorescent powder in the fluid. The results are compared to those predicted by the Nusselt falling film theory, showing relatively good agreement around the upper perimeter of the tube but much poorer agreement on the lower perimeter. The corresponding effects on heat transfer have also been estimated.

Document Type: Research article

DOI: 10.1080/01457630490519899

Affiliations: 1: Laboratory of Heat and Mass Transfer, Swiss Federal Institute of Technology, Lausanne, Switzerland