AnnularFlow_outer_ND
Procedure AnnularFlow_outer_ND(Re, Pr, LoverD_h, r|star, relRough: Nusselt_T,Nusselt_H, f) returns the lower and upper bounds on the Nusselt number for developing or fully-developed flow in an annulus characterized by inner and outer radii. The inner wall of the annulus is assumed to be insulated so heat transfer occurs across the outer wall. The area used for heat transfer should be the area of this outer wall. The procedure also returns the average friction factor for these conditions.
Inputs:
Re - Reynolds number based on properties evaluated at the bulk average temperature
Pr - Prandtl number of the fluid evaluated at the bulk average temperature
LoverD_h - ratio of tube length to hydraulic diameter.
r|star - ratio of the inner to the outer radius of the annulus This value should be <=1 and >0
RelRough - the ratio of the dispersions on the wall of the tube to the tube diameter (must be between 0 and 0.05)
Outputs:
Nusselt_T - lower bound on the Nusselt number assuming a constant outer annular wall temperature
Nusselt_H - upper bound on the Nusselt number assuming a constant outer annular wall heat flux
f - friction factor [-]
Notes:
This procedure is called by AnnularFlow_outer. It calls AnnularFlow_Laminar and PipeFlow_Turbulent to obtain the appropriate Nusselt numbers and the friction factor.
The procedure will determine if the flow is laminar or turbulent.
Example:
Re=1500
Pr=0.72
LoverD=20
r|star=0.5
relRough=0
Call annularflow_outer_nd(Re, Pr, LoverD, r|star, relRough: Nusselt_T,Nusselt_H, f)
{Solution:
f=0.1008 [-]
Nusselt_H=7.608
Nusselt_T=6.882 [-]}