Minneapolis, MN: U.S. Department of the Interior, Bureau of Mines, Contract P0241054, 1994 Dec; :1-151
MFIRE, written in Fortran 77, is a computer program for ventilation state simulation in the steady state or transient state condition. It can be applied for the calculation of normal ventilation system planning or the analysis of the dynamic state variation in a ventilation system under thermal or mechanical disturbance. The state simulator MFlRE is a useful tool for mine fire fighting. In the case of a mine fire, mine ventilation engineers want to get some help to obtain more information, such as what is happening in the underground mine and how to control the mine fire, for correct decision making. By use of program MF'IRE, forecasts can be made on the variation of airflow, temperature, and contaminant distribution in a ventilation system during a mine fire. The paths which the contaminant takes at each time interval can be traced. The program MFIRE can be of assistance in the preplanning of escape routes. It can also be helpful during a mine fire emergency and mine recovery operation. Besides of offering the information of state simulation during a mine fire, MFIRE can be applied for state control by pretesting the suitability of the selected state control measures. It is to simulate the effects of the state control measures on the airflow distribution of a dynamic ventilation system. The testing result can be used for fire fighting in a similar real case of a mine fire. By employing empirical methods or a qualitative analysis like Budryk approach, ventilation engineers can choose different combinations of locations and sizes of control devices as samples of state control for an underground mine fire. Program MFIRE can simulate the different combination samples, that consist of a certain mine fire, the corresponding different control measures, and obtain the control effects. After the different control results are compared, the state control measure, which creates the best effect among the different state control measures, will be chosen for that fire case. When a mine fire, which is similar to one of the pretested cases, breaks out, the corresponding choice of the state control measure is applied to the ventilation system. It means that the simulator MFIRE has the function of indirect state control. To achieve the above two functions, state simulation and state control, the mine ventilation system condition, sometimes, should be changed in a wide range to meet the requirement of the fire fighting. These wide system condition changes, such as adding operating fans, stopping or reversing fans, changing fan characteristics, adding regulators and making airflow shortcuts are represented in the time table of the input data set When the data files are changed in a wide range, however, an iteration divergence and some other computing errors in the distribution of airflow, temperature, and contaminant may occur. More serious logical programming and flexible selection on the algorithms are wanted to meet the request of the different data sets, to achieve correct state distribution simulation and improve the iteration convergence. To enhance the reliability and common suitability of program MFIRE, it is necessary to make investigation, analysis, and modification for the formal versions of MFIRE. The version 1.29, permitting dry .calculation, and versions 2.01/v2.0, permitting dry and humidity calculation, are widely applied in the mining industry today. The data sets used for the investigation have a wide range of system condition change. The investigation reveals the new computing problems on the simulation of the airflow, temperature, Or contaminant distribution, and the algorithm divergence. Programming error, improper selection of the fan curve fitting method and the treatment of the boundary region of fan curve can cause the above problems. The modification of the program may induce new problems because of the complication of the program. Avoiding new problem emergence during source code modification is a principle that was being followed by the authors of the report. This report offers the investigation on the computing results of the data sets and the existing computing problems on the state distribution, the fan c w e fitting, the handling of the boundary region of operating range of fan characteristic. The causes of the problems are analyzed and the modification of source code of MFIRE is also presented. The investigation is based on the application of MFIRE v1.29 and v2.0/v2.01. The new data file sample and modified subroutines of program MFIRE are shown in the appendix A and B respectively. The modifications have been marked to make them easily to be found.