Wednesday, 18 May

QGECE Work on Metal Foam Heat Exchangers

The QGECE seminar of this week was from Ampon Chumpia on "Improving the performance of air-cooled condensers by using metal foams."

Mr Chumpia presented the results of his work over the past year towards his PhD objectives of testing metal foam heat exchangers. Metal foam heat exchangers are being considered by the QGECE as an alternative to conventional finned tubes. Their perceived advantage over the conventional alternative is achieving the same heat transfer rate at lower pressure drop. This advantage has been identified by numerical analysis by Mostafa Odabaee, another QGECE post-graduate research student. His work has shown that the heat transfer rate from a single cylinder in cross-flow can be increased by an order of magnitude by adding a metal foam layer to its outer surface. While this increase comes at the expense of a higher pressure drop, the increase in pressure drop is small enough to promise a significant potential for this novel heat heat exchanger technology. Mostafa's numerical results for single tubes have already been published in Transport in Porous Media (86:911-923, 2011).

Ampon is now trying to validate these numerical predictions by testing metal foam wrapped tubes and tube bundles in our wind tunnel at air speeds representing the air flow over condenser tubes in natural-draft and forced-draft cooling towers. He will be testing single tubes and tube bundles and compared the results for the finned and foam-wrapped tubes between themselves and against numerical results. The following image shows examples of foam-wrapped and finned tubes being used by Ampon in his experiments.

 

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