4.9 Resistances in Parallel
119
Therefore, we obtain, for the system:
Q A + Q B = 27.022
m
3
s
0.7
N s
2
m 8 Q
2
A = 234.83 Pa
Solving this we get:
Q A = 18.322
m
3
s
Q B = 8.70
m
3
s
Exercise 4.12 The figure shows the resistances of airways in a ventilation network.
R1
R2
R3
R4
R6
R7
R5
It is known that the resistances (R i ) have the values listed in the table and that the
total pressure loss in the system is 1.2 kPa.
Resistance (R i )
Value
N s 2
m 8
R 1
4
R 2
12
R 3
13
R 4
3
R 5
6.5
R 6
6
R 7
2
Determine:
(a) The equivalent resistance of the network.
(b) The total airflow rate entering the system.
(c) Pressure loss and corresponding airflow rate for each airway.