entech. WKP Magazine Explosion Simulation – Gas Dispersal Study P a g e | 8 via Rise 1. Figure 3-4 shows the alternate path when fans are switched off. Fesh air will enter the mine via Rise 1, and contaminated air will recirculate around main travel routes, before making its way out the two haulage portals. Figure 3-4 – Explosion gas dispersal path during natural ventilation, scenario 2. Seasonal variation indicates that the winter fume path will only be reflected in sccenario 1. It appears that the minimal airflow in winter maintains Rise 1 as the primary exhaust, assuming that the diffeneces in surface and underground air densities creates a repeatable bouyancy1 effect. Air will then seek the nearest opening out of the mine, drawing cooler air in from the portals. It should be noted that challenges exist in predicting natural ventilation due to the effects of heat imposed on airflow from mining activities. During a mine emergency, such as power failure to the primary fan, the loss of activity will create a cooling effect and may see flow stagnation, and eventual reversal, over the full duration of the event. This means that predicting events according to scenario 1 and 2 as a constant, for the entire event, may be impossible and should be cross referenced with natural ventilation surveys. 1 Buoyancy in underground mines results from the density differences between underground and surface air, causing warm air to rise above the chilly intake air. This creates an upward airstream through Rise 1.
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