4.3.3 Flow through non-circular ducts
The same co-relations as discussed in section 4.4.1 can be used for the non-circular ducts. However, the diameter of the tube has to be replaced by the hydraulic diameter or equivalent diameter for the non-circular ducts. The hydraulic diameter is defined as
Where rh is hydraulic radius.
4.3.4. Flow over a flat plate
Heat transfer in flow over a plate occurs through the boundary layer formed on the plane. Therefore at any location the heat transfer coefficient will depend on the local Reynolds and Prandtl number. For local heat transfer coefficient in laminar boundary layer flow, the following correlation can be used to find the local Nusselt number. It depends upon the distance from the leading edge (x) of the plate.
|
(4.13) |
where,
and are the local Nusselt and Reynold numbers, respectively.
An average value of the heat transfer coefficient over a distance l may be obtained by,
