176
5 Main Ventilation
Figure
1
2
3
4
5
S i
Kp m
kg K
250
875
87.5
200
25
Then, the total surface S T = 1437.5
kp m
kg
K.
The coordinates of the centres of gravity of the individual surfaces are then:
Figure
1
2
3
4
5
T i (K)
8.67
12.5
15.33
8
5.67
T c =
5
i=1 S i T i
S T
= 11.26
◦ C
Then the NVP is obtained as:
P n =
S T
T c
ρ =
1437.5
kp m
kg
K
(273 + 11.26) K
1.25
kg
m 3 = 6.3
kp
m 2
(b) The centre of gravity can be also calculated for the above case by the shoelace
formula, e.g. for the decomposition of the figure as:
0
25
50
75
100
125
150
175
200
0
2
4
6
8 10 12 14 16 18
1
2
3
T ( o C)
h
(m)
5 Main Ventilation
Figure
1
2
3
4
5
S i
Kp m
kg K
250
875
87.5
200
25
Then, the total surface S T = 1437.5
kp m
kg
K.
The coordinates of the centres of gravity of the individual surfaces are then:
Figure
1
2
3
4
5
T i (K)
8.67
12.5
15.33
8
5.67
T c =
5
i=1 S i T i
S T
= 11.26
◦ C
Then the NVP is obtained as:
P n =
S T
T c
ρ =
1437.5
kp m
kg
K
(273 + 11.26) K
1.25
kg
m 3 = 6.3
kp
m 2
(b) The centre of gravity can be also calculated for the above case by the shoelace
formula, e.g. for the decomposition of the figure as:
0
25
50
75
100
125
150
175
200
0
2
4
6
8 10 12 14 16 18
1
2
3
T ( o C)
h
(m)