Finned flat tubes ND functions
The procedure:
CHX_ND_Finned_Flat_Tube(TypeHX$, Re: f, j_H)
provides the dimensionless performance associated with a finned flat tube compact heat exchanger surface. These data are from Kays and London (1994).
Inputs
TypeHX$: string identifying the geometry
FF-9.68-0.87 : 'ff_tubes_s968_087'
FF-9.1-0.737-S : 'ff_tubes_s91_0737_s'
FF-9.68-0.87-R : 'ff_tubes_s968_087_r'
FF-9.29-0.737-SR : 'ff_tubes_s929_0737_sr'
FF-11.32-0.737-SR : 'ff_tubes_s1132_0737_sr'
Re: Reynolds number (-)
Outputs
f: friction factor (-)
j_H: Colburn j function for heat transfer (-)
The Reynolds number is defined according to:
where m is the viscosity, Dh is the hydraulic diameter, and G is the mass flux. The hydraulic diameter is defined as:
where Ac is the minimum free flow area, A is the total heat transfer area, and L is the length in the flow direction (note that the length is defined from the tip of the first row to the point where the next tube would be after the last row).
The mass flux is defined as:
where 
The friction factor is defined as:
where r is the density, and to is the equivalent shear stress, defined as:
where DP is the pressure drop due to friction and form drag in the core.
Example
$UnitSystem SI Mass J K Pa
TypeHX$='ff_tubes_s968_087_R'
Re = 4000
Call chx_nd_finned_flat_tube(TypeHX$,Re: f, j_H)
{Solution:
f = 0.02159, j_H = 0.004967}
Related procedures include: