PF pin-fin ND functions
The procedure:
CHX_ND_PF_pin_fin(TypeHX$, Re: f, j_H)
provides the dimensionless performance associated with a pin fin compact heat exchanger surface. These data are from Kays and London (1994).
Inputs
TypeHX$: string identifying the geometry
AP-1: 'PF_pin-fin_AP1'
AP-2: 'PF_pin-fin_AP2'
PF-3: 'PF_pin-fin_PF3'
PF-4(F): 'PF_pin-fin_PF4F'
PF-9(F): 'PF_pin-fin_PF9F'
PF-10(F): 'PF_pin-fin_PF10F'
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.
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
$UnitSystem SI Mass J K Pa
TypeHX$='PF_pin-fin_AP-1'
Re = 2300
Call chx_nd_pf_pin_fin(TypeHX$, Re: f, j_H)
{Solution is:
f = 0.0.07189, j_H = 0.01298}
Related procedures include: