Page 85 - Advanced Mine Ventilation

68 Advanced Mine Ventilation

Diagnostic messages, whenever the TLV is exceeded, are also printed out. Further
details of output results are given in the next section where a hypothetical mine layout
is solved using VNA.

5.2.2 Program Testing on a Hypothetical Case
To illustrate the use of this program, the hypothetical mine shown in Fig. 5.1A is
analyzed. A small network such as this provides an opportunity for exact solution
providing a check on machine computations. It is assumed here that branches (4)
and (6) and junction (4) have diesel exhaust emissions.
The Input: The description of the input deck and numerical values of parameters are
given in Appendix D.
The Output: The program prints out all the input data for all the branches in the
network, the mesh tables, data on fan characteristics, coefficient of the polynomials
approximating the fan curves, and final solutions of quantity of air and head loss in
each branch in order as given here. It also prints out the operating point on the fan
characteristic. Output of concentrations of carbon monoxide, nitric oxide, etc., follow
in sequence. TLV of all gases except hydrocarbons is the same as given in American
Conference of Governmental Industrial Hygienists [6]. For hydrocarbons, a TLV of
15 ppm is assumed to force the computer program to print diagnostic messages. As
can be seen from the Table, the TLV is exceeded by carbon monoxide concentration
in branch (6). A message to this effect is printed by the computer. Similar diagnostic
messages are printed out for NO, NO 2 , and hydrocarbon (HC). Finally, it prints out
the mixture TLV. Whenever it exceeds the value 1.0, a message is printed to that
effect.
To keep the concentration of diesel exhaust components, and mixtures thereof
below their respective TLV, increased quantities of air should be assigned to branches
wherein these are exceeded. In general, for a given equipment deployment, several
runs of the simulator will provide enough information to decide on the ventilation
requirements.
Table 5.1 shows a typical output from the VNA. Emission sources and concentra-
tions of CO, NO, NO 2 , and HC are listed. A complete list of all inputs and output print-
outs are listed in Appendix D. The results were verified by hand calculations.

5.3 Verification of the Ventilation Network Analyzer in a
Working Mine

The VNA was used to simulate a working mine with several diesel equipment in oper-
ation. Only CO was tracked by actual measurement in designated branches. Drager-
handheld instrument (with test tubes) and an ecolyzer instrument were used for actual
CO measurements in the mine. The mine line diagram is shown in Fig. 5.4.
The input data for this problem are listed in Table 5.2.