A new way of obtaining heat and mass transfer at flat surfaces coated with swollen polymer by measuring recession with projected fringes

Abstract

The swollen polymer mass transfer technique has been applied with surface recession measurements being made by laser generated projected fringes, thus avoiding the need for holographic equipment. The technique proved to be successful for both plane and perforated surfaces. Results have been obtained for an air jet impinging on a flat plate and also for a model of the ligament plate which supports the tube mouths at the outlet of the flow reversal chamber in a shell boiler. When using a 2 mm polymer layer, surface recessions up to 40 microns are possible which can be measured to an accuracy of ± 7 microns. Contours of equal mass transfer are produced with this technique. The technique is useful for mass transfer coefficients up to 0.01 m s −1. The results from both studies show agreement with those obtained by other methods.