290
8 Secondary Ventilation
Q r ≥ 0.2 A
(8.2)
In coal mining galleries the requisite minimum speed is usually set at 0.30 m s
−1
(ITC-04-07-01 [MITC 2000]), while in civil tunnels its range is 0.40–0.50 m s
−1 .
8.3.3 Airflow Rate Needed to Dilute the Exhaust Gases
from Diesel Engines (Q m )
The relevant literature (e.g. Deniau 1976) suggests that for every horsepower, a diesel
engine will emit exhaust gases at a rate (F), of about 0.07–0.09 l s
−1 . The composition
of these gases will be:
• CO: 100–400 ppm,
• NO x : 200–600 ppm, and
• CO 2 : 3–6%.
According to the approach of Bertard and Bodelle (1962), the airflow required to
ventilate these gases can be calculated as the sum of the flows necessary to lower the
concentrations of CO and NO x to admissible values as follows:
Q m = F
CO
C CO
+
NO x
C NOx
(8.3)
where
• Q m : Airflow rate required to dilute diesel equipment gases (m
3 s
−1 ).
• F: Exhaust gas flow rate (m
3 s
−1 ).
• CO: Concentration of CO in the exhaust gases.
• NO x : Concentration of NO x in exhaust gases.
• C CO : Maximum allowable concentration of CO. According to accepted values:
10
−4 (fraction).
• C NOx : Maximum permissible concentration of NO x . According to accepted values:
0.25–10
−4 (fraction).
Therefore, the above expression, if concentrations are expressed in terms of
fractions is (Eq. 8.4):
Q m = F(10,000 CO + 40,000 NO x )
(8.4)
A number of national regulations express Q m as a function of the power of the
diesel engines. Gangal (2012) offers a compilation of these:
• Australia: 0.06 m
3 s
−1 · Pw (kW),
• Canada: (0.045– 0.092) m
3 s
−1 · Pw (kW),
• Chile: 0.063 m
3 s
−1 · Pw (kW),
8 Secondary Ventilation
Q r ≥ 0.2 A
(8.2)
In coal mining galleries the requisite minimum speed is usually set at 0.30 m s
−1
(ITC-04-07-01 [MITC 2000]), while in civil tunnels its range is 0.40–0.50 m s
−1 .
8.3.3 Airflow Rate Needed to Dilute the Exhaust Gases
from Diesel Engines (Q m )
The relevant literature (e.g. Deniau 1976) suggests that for every horsepower, a diesel
engine will emit exhaust gases at a rate (F), of about 0.07–0.09 l s
−1 . The composition
of these gases will be:
• CO: 100–400 ppm,
• NO x : 200–600 ppm, and
• CO 2 : 3–6%.
According to the approach of Bertard and Bodelle (1962), the airflow required to
ventilate these gases can be calculated as the sum of the flows necessary to lower the
concentrations of CO and NO x to admissible values as follows:
Q m = F
CO
C CO
+
NO x
C NOx
(8.3)
where
• Q m : Airflow rate required to dilute diesel equipment gases (m
3 s
−1 ).
• F: Exhaust gas flow rate (m
3 s
−1 ).
• CO: Concentration of CO in the exhaust gases.
• NO x : Concentration of NO x in exhaust gases.
• C CO : Maximum allowable concentration of CO. According to accepted values:
10
−4 (fraction).
• C NOx : Maximum permissible concentration of NO x . According to accepted values:
0.25–10
−4 (fraction).
Therefore, the above expression, if concentrations are expressed in terms of
fractions is (Eq. 8.4):
Q m = F(10,000 CO + 40,000 NO x )
(8.4)
A number of national regulations express Q m as a function of the power of the
diesel engines. Gangal (2012) offers a compilation of these:
• Australia: 0.06 m
3 s
−1 · Pw (kW),
• Canada: (0.045– 0.092) m
3 s
−1 · Pw (kW),
• Chile: 0.063 m
3 s
−1 · Pw (kW),