Page 464 - Advanced Mine Ventilation

Appendix B: Ventilation Network Analyzer in Fortran IV 433

program is available elsewhere (16, 18) and, consequently, it is described here very
briefly. Essentially, this part of the program reads in the branch characteristics, e.g.,
length, width, height, friction factor, et cetera, and forms meshes around a tree deter-
mined uniquely on the basis that the basic branch in a mesh shall have the highest resis-
tance. Natural ventilating pressures, if any, are also read in. Next, the program
approximates the fan characteristic using orthogonal polynomials. The solution for
each mesh is obtained by the well-known Hardy Cross iterative technique in conjunc-
tion with Kirchhoff’s laws for networks. The program prints out all the input param-
eters and data as well as the quantity and pressure loss in each branch of the network.
The operating point on the fan characteristic is also determined and printed out. For
branches where a fixed quantity of air is provided, the size of the regulator or the ca-
pacity of the booster fan as the case may be is printed out.
Line 352 initializes a computational switch INDIC.
Line 353 checks the value of INDIC which avoids repeated calculations when
several runs are to be made on the same mine with different sets of data.
Lines 354e361 convert all the quantity flows, originally in thousands of cubic feet
per minute into cfm and makes them positive wherever they are negative. In the latter
case, it also interchanges the junction numbers of that branch accordingly.
Lines 362e383 gather information that make it possible to follow the flow of air
and diesel exhaust from one junction to the next. There are five one-dimensional arrays
here which store the following information:
Array JCTN(I) stores all the junction numbers in the network in a sequence, com-
pacting them in the process and saving storage.
Array NBOUT(J) stores the branch number of roadways, having flow away from
junction JCTN(I).
Array JOUT(JJ) stores the location of branch J in array NBOUT(J).
Array NBIN(J) stores the branch number of roadways having flow into the junction,
JCTN(I).
Array JIN(JJ) stores the location of branch J in array NBIN(J).
Line 384 sets the value of INDIC equal to 1.
Lines 385e394 initialize the arrays of concentration of diesel exhaust components
as well as that of the mixture TLV of these components and the branch and junction
counter arrays, MB(I) and MJ(I), respectively.
Lines 395e396 identify the component of the diesel exhaust and print out the same.
Line 397 reads the outside junction, i.e., the junction representing the open atmo-
sphere. Calculations of concentrations start here.
Lines 398e403 find out the junction counter number for the outside junction. This
is labeled zero at line 403. CDJ(I) is the array which holds diesel exhaust concentration
at all junctions.
Line 404: MJ(JJ) is set equal to one to indicate that the JJ junction, i.e., outside junc-
tion, has been processed.
Lines 405e413 read the general diesel exhaust emission rate in all branches and at
all junctions. These are values of those components of diesel exhaust which are given
out by sources other than diesel engines in all roadways, e.g., hydrocarbons. Normally,
these quantities would be exceedingly small and can be set equal to zero. On the other