168
5 Main Ventilation
solution to this problem is to calculate the air density for the different columns (A,
B, C and D), and with them, to establish the equilibrium of pressures.
If the difference of the inverse of temperatures from Eq. 5.4 is operated obtaining
the common denominator, we have:
P n = 0.03415
N K
J
h 101,300 [Pa]
T mu − T md
T md T mu
Then T md · T mu can be replaced by its possible values, which range
4 within 273–293 K
(Eq. 5.5), therefore:
P n = 0.04
Pa
C m
(T mu − T md )h
(5.5)
For this reason, McElroy (1935) and Borisov et al. (1976), indicated that 44 Pa
of natural ventilation pressure are generated for every 10 °C difference between the
average temperature of the shafts for every 100 m of effective height. Some NVP
values depending on depth and temperature are given in Table 5.2.
Table 5.2 Natural ventilation pressure (P n ) depending on the average depth of the shafts (h m ) and
their average temperature difference (T )
T (°C)
5
10
20
30
h m (m)
200
50
100
190
280
500
120
240
500
710
1000
240
480
950
1400
Question 5.1 Pressures have been measured at each of the points indicated in the
mine in the figure. Determine an expression as the sum of the given pressures for the
calculation of the NVP of the mine.
4 Note that other temperatures within the range of possible values do not significantly vary the result.
5 Main Ventilation
solution to this problem is to calculate the air density for the different columns (A,
B, C and D), and with them, to establish the equilibrium of pressures.
If the difference of the inverse of temperatures from Eq. 5.4 is operated obtaining
the common denominator, we have:
P n = 0.03415
N K
J
h 101,300 [Pa]
T mu − T md
T md T mu
Then T md · T mu can be replaced by its possible values, which range
4 within 273–293 K
(Eq. 5.5), therefore:
P n = 0.04
Pa
C m
(T mu − T md )h
(5.5)
For this reason, McElroy (1935) and Borisov et al. (1976), indicated that 44 Pa
of natural ventilation pressure are generated for every 10 °C difference between the
average temperature of the shafts for every 100 m of effective height. Some NVP
values depending on depth and temperature are given in Table 5.2.
Table 5.2 Natural ventilation pressure (P n ) depending on the average depth of the shafts (h m ) and
their average temperature difference (T )
T (°C)
5
10
20
30
h m (m)
200
50
100
190
280
500
120
240
500
710
1000
240
480
950
1400
Question 5.1 Pressures have been measured at each of the points indicated in the
mine in the figure. Determine an expression as the sum of the given pressures for the
calculation of the NVP of the mine.
4 Note that other temperatures within the range of possible values do not significantly vary the result.