PF wavy-fin ND functions
The procedure:
CHX_ND_PF_wavy_fin(TypeHX$, Re: f, j_H)
provides the dimensionless performance associated with a plain fin - wavy fin compact heat exchanger surface. These data are from Kays and London (1994).
Inputs
TypeHX$: string identifying the geometry
11.44-3/8W: 'PF_wavy-fin_1144_38W'
11.5-3/8W: 'PF_wavy-fin_115_38W'
17.8-3/8W: 'PF_wavy-fin_178_38W'
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 
is the mass flow rate.
The friction factor is defined as:
where r is the density, and 
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_wavy-fin_115_38W'
Re=1000
Call chx_nd_pf_wavy_fin(TypeHX$, Re: f, j_H)
{Solution is:
f = 0.08316, j_H = 0.01577}
Related procedures include: