Heat Exchangers Mathematical Model

[victor27]

I derived the nusselt number for a square-shaped duct which is isolated on one side. Considerations I´ve taken into account are: Hydrodynamic - thermal fully developed regimen, Hahagen-poiseuille velocity profile, all properties are constants. Unfortunately I haven´t other result which I can compare with. So I would like to know if anyone out there has worked out the nusselt´s number for this special case?.

 

[wilg]

My best guess is:
The Nusselt number must include a shape factor,
for a standard rectangular parallelepiped shape
the equation is =
(1/Lx squared)+((1/Ly squared)+(1/Lz squared)
divided by
(1/Lx)+((1/Ly)+(1/Lz)
where:
Lx = side one (height)
Ly = side two (width)
Lz = length (length)
For your case:
the factor must be reduced by one fourth
representative of the one side that is
isolated on one side.

see:

http://kramerslab.tn.tudelft.nl/MSP-publications/WS_keypublication_bart_2_IntJRefrig.pdf

When you indicate " isolated on one side" is that
the height or an end cap position ?
wilg

 

[victor27]

Dear Wilg,
About the isolated side, I meant to refer to the height, sorry for not having specified it clearer.
On the other hand, thank´s for your the paper you provided me.