Page 84 - Advanced Mine Ventilation

Ventilation Network Analysis 67

This process can now be repeated again till the entire network is covered. Solutions
of concentrations of diesel exhaust in a network of roadways with multiple diesel en-
gines can, now, be obtained by repeated use of Eqs. (5.7)e(5.11). It is obvious that
manual calculations are very tedious except for very small networks; and therefore,
a computer program was developed to carry out these computations.

5.2 Introduction to the Ventilation Network Analyzer

Variable definitions and program listings are given in Appendices B and C along with
a brief description of the program statements. Appendix B program uses Fortran IV
compiler, which is rather old yet workable. Appendix C gives listings for Cþþ, which
is currently popular.
Input parameters needed for the execution of ventilation network analyzer (VNA)
can be broadly classified as below:

1. System Size Parameters: These are the total number of branches, junctions, maximum num-
ber of iterations, etc. Detailed description of each parameter is given in the next section where
a hypothetical mine layout is solved using VNA.
2. Roadway Parameters: These are junction numbers, frictional factor, height, width, and length
of a roadway. One card is provided for each roadway. Roadways with special attributes, e.g.,
a fixed quantity of air, a fan, etc., are arranged in a specific manner as described in the next
section.
3. Fan Parameters: These are the values of quantities of air and corresponding pressures, which
describe a fan characteristic.
4. Emission Parameters: These are the values of emissions of various species of diesel exhaust
in cfm along with locations of such emissions. A typical illustration is given in the next
section.

5.2.1 Output Results
The program prints out the following:

1. All input parameters as detailed above.
2. The quantities of air and head loss in each branch of the network.
3. The size of the regulator, or the capacity of the booster fan as the case may be, for branches
with fixed quantities.
4. The operating point on the fan characteristics.
5. Diesel exhaust concentrations for each species in each branch and at each junction of the
network.
1
6. Mixture TLV for each branch and junction in the network.
N
1 P C j
The mixture TLV is defined as . Where C j and TLV j are the concentration and TLV, respectively,
TLV j
j¼1
for the species j, and N is the number of species in the exhaust. For a nonreacting mixture of gases, its value
should not exceed 1.0. This is recommended by the American Conference of Governmental Hygienists [6].