Page 83 - Advanced Mine Ventilation

66 Advanced Mine Ventilation

The concentration of diesel exhaust at the end of the roadway (branch), C B is given
by:

Q dout
C B ¼ (5.8)
Q out

Eqs. (5.7) and (5.8) are referred to as roadway calculations in the computer
program.

5.1.4.2 Junction Calculation
The concentration of diesel exhaust at a junction can be solved in a similar fashion.
Fig. 5.3B shows a typical junction in a mine network. Here roadways (1), (2), and
(3) have flows into the junction; and in roadways (4) and (5), the flow is away from
the junction. Continuous mining machines can only operate at locations in a network
designed as junctions. At such places the diesel exhaust generation is quite substantial.
3
Let the quantity of diesel exhaust generated at a junction be Q djunc ft /s. The total
airflow at the junction is shown in Fig. 5.3B.

n
X
SQ ¼ Q þ Q ///Q ¼ Q i (5.9)
2
1
n
i¼1
where SQ is the summation of the air quantities flowing through a junction and n is the
total number of branches having flows into the junction.
Taking a mass balance for diesel exhaust,
SQ ¼ Q djunc þ Q þ Q d2 þ /// þ Q dn
d
dl
n (5.10)
X
¼ Q djunc þ Q di
i 1
where SQ d is the summation of all the quantity of diesel exhaust flowing into the
junction and Q di is the quantity of exhaust in branch i.
The concentration of diesel exhaust at the junction, C j , is given by:

SQ d
C j ¼ (5.11)
SQ
In the computer program, Eqs. (5.9)e(5.11) are referred to as junction calculations.
The concentration of diesel exhaust in the branches (4) and (5) as shown in
Fig. 5.3B is the same as C j ; and hence the quantity of diesel exhaust flowing in these
branches can be calculated from the following relation:

Q din ¼ C j $Q in (5.12)