Page 96 - Industrial Ventilation Design Guidebook
P. 96
4,1 FLUID FLOW 61
FIGURE 4.6 The system to be dimensioned.
The following values are known:
3
Volume flow = 10 m s" 1
Diameter d 0 = 79.8 mm
Pressure p () = 600 kPa
p2=p4 = 250 kPa
Temperature T = 283 K
Length L = 50 m
Roughness k — 0.03 mm
Water properties can be found from tables, such as the VDI-Wasser-
dampftafeln; The NBS/NRC Steam Tables; the ASHRAE and CIBSE Guides; or
Thermodynamic and Transport Properties of Fluids by Mayhew and Rodgers.
First we dimension c/ 4, and now Eq. (4.65} is
2
3
Taking z 0 = 0, when T = 283 K, p = 999.7 kg/rrr , v = 1.3 x 1(H m s and
=
1
=
tfv< <?!/ 10 m3 s ~*' Thus the flow velocity WQ = 2 ms" . From Eq. (4.67) we re-
ceive
The formula for the pressure loss is now
The Reynolds number is
Hence the flow is turbulent.
