A technique has been developed for investigating the detailed mechanism of gas-side mass-transfer from packings. An element of packing is coated with a thin film of naphthalene of known uniform thickness. The disappearance of this film is followed as it evaporates in an air stream. This allows local mass-transfer coefficients to be determined. The method has been applied to grid packings. It was found that the details of the transfer process were controlled by the flow patterns existing around the slats. The behaviour and effectiveness of different shapes and arrangements of slats were compared. It proved possible to correlate the mass-transfer coefficients for arrays of rectangular cross-sectioned slats, and to extend the correlations over the ranges of grid dimensions and air velocity normally used in industrial practice. Experiments in a water cooling tower showed that the correlations of average mass-transfer coefficient were applicable to this system of irrigated packings. At the water rates used, no modification of the correlations was found necessary, although reported results indicate that a correction would be necessary at other water rates. The relevance of the correlations to water cooling towers was confirmed by the limited quantity of reported data thought to be reliable. Pressure-drop results obtained on the cooling tower were found to be correlated by a single equation, the form of which had been predicted by separate considerations of skin friction and form drag. The equation was found to fit reported pressure drop results with reasonable accuracy and should be applicable to all grid packed columns. The correlations of gas-film mass-transfer coefficients and the expression for pressure-drop enable the optimum grid dimensions to be chosen for any operation which is gas-film controlled and yield reliable design data for water cooling towers.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:602209 |
| Date | January 1963 |
| Creators | Anolick, Colin |
| Contributors | Danckwerts, P.V |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/13291 |
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