An Experimental Study on Self-extinction of Methanol Fire in Tunnels with Different Wall Surfaces

Fire tests with both methanol fires ranging from 2.8 to 16.8 kW were conducted in two 1:20 reduced-scale tunnels with identical cross-section size of 0.45 m wide × 0.23 m high but different surfaces, i.e., glass and fire-resistant board respectively. The fire source is placed in the center of the tunnel and is naturally ventilated. The experiment measured the temperature and gas concentration by thermocouple and flue gas analyzer, i.e. oxygen, carbon monoxide and carbon dioxide respectively. The results showed that the heat release rate was 2.8, 5.6, 11.2 and 11.6kw, and the self-extinction (excluding the fire-resistant tunnel with a heat release rate of 2.8kw). With a lower heat release rate, the self-extinction of the glass tunnel is longer than that of the fire-resistant board tunnel, the larger heat is the release rate, and the glass tunnel and the fire-resistant tunnel have almost the same length of self-extinction. The reason why glass tunnels self-extinction faster than fire-resistant tunnels is that the glass is poorly insulated and has a large heat exchange with the outside, so that the flue gas settles quickly, blocked supply of fresh air to reach the fire seat.