Hi Tunc,
I do not know about the channels.
With regards to the cables: do you have forced fluid flow around them? If not, you will have to look at the Rayleigh number to see if you get significant natural convection. If you do and you want to do it correctly I think it is best to build a full multiphysics model with heat transfer and fluid dynamics to model the heat flux in and outside the cables, together with the fluid flow around the cables. Otherwise you might be able to find a nice analytical model which you can translate into a heat transfer coeficient.
I do not know about the channels.
With regards to the cables: do you have forced fluid flow around them? If not, you will have to look at the Rayleigh number to see if you get significant natural convection. If you do and you want to do it correctly I think it is best to build a full multiphysics model with heat transfer and fluid dynamics to model the heat flux in and outside the cables, together with the fluid flow around the cables. Otherwise you might be able to find a nice analytical model which you can translate into a heat transfer coeficient.
