[Gareth85]

Hi all,

I am currently working on a heat transfer problem for a galvanizing process. I would like to determine the time it takes wire to saturate to the temperature of the molten lead it is pulled through. The problem I have is in calculating the heat transfer coefficient h. The wire is pulled slowly (<1m/s) through the molten lead such that the flow is axially along the wire (horizontal cylinder with parallel flow). I have attempted to approximate h by assuming the Nu relation for flow of liquid metal over a flat plate (Nu = 0.564*Pr^0.5*Re^0.5). However i'm unsure on the validity of this assumption.

Is there any relation for Nusselt number or heat transfer coefficient for laminar flow axially over a cylinder? I can only seem to find correlations for flow across a cylinder (e.g.: In a tube bank system). I'm at a complete loss at the moment.

Any help would be greatly appreciated. Thanks.