1. Define Kirchoff's first and second laws.
2. A mine has a total airflow requirement of 248 m3/s. If the equivalent resistance of the workings is 0.09 Ns2/m8 determine the pressure to be developed by a single mine fan to ventilate the workings.
3. A working area of a mine has diesel equipment operating within it. The maximum diesel loading is 350 kW. The same section of the mine also has a methane inflow of 0.65 m3/s flowing into it. If the maximum permissible methane concentration in the general body of the air is 1% and the design diesel air quantity is 6 m3/s per 100 kW of installed diesel power, determine the required ventilation flow rate for the working area.
Figure 1: Fan Characteristic curve
4. Determine the characteristic curves for the fan illustrated in figure 1 for the following cases:
• Two fans in series
• Two fans in parallel
5. A worker in a development drive is working at a rate of 250 W/m2. If the air velocity passing over the worker is 1.5 m/s, the air dry bulb temperature is 35°C, the air wet bulb temperature is 33°C, radiant temperature of the surroundings is 35°C, and it can be assumed that the worker's skin temperature is 34 °C, determine:
• The air cooling power
• The basic effective temperature
Is the environment safe to work in?