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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

HEAT TRANSFER IN AN UNBAFFLED AGITATED VAT WITH A HEATING JACKET OVER PART OF THE SIDE

Get access (open in a dialog) DOI: 10.1615/IHTC11.340
pages 199-204

Resumo

Experimental heat transfer coefficients have been obtained for heating water in an agitated unbaffled vertical vat. The heating medium was steam in a side jacket of only 0.13 of the height of liquid in the vat. The 500 litre vat was geometrically similar to vats used commercially for cooling and storing milk awaiting collection on New Zealand dairy farms. A flat blade impeller was used to provide agitation.

The experimental water-side Nusselt numbers were in the range 1750 to 2600. When the impeller Reynolds number was less than 60 000, the Nusselt number was dominated by natural convection and greatly exceeded the values from previous correlations. At higher impeller speeds, the influence of Reynolds number was found to be overstated by the published equations.

Outside the natural convection regime, the heat transfer rate was found to be higher when the impeller was at the same height as the heating jacket, rather than at the higher levels used by previous workers using full side heating jackets.

The continuous steady state measuring procedure used offered advantages over previous batch heating experiments with the same apparatus.