Experimental study on flame behavior in under-ventilated train car

In Hong Kong, the number of parallel traders has increased quickly within these years. Passengers bring not only handbags as planned for the subway system four decades ago. There are heavy luggage put in trolleys carried by parallel traders. Goods include milk powder, electronic devices, food and drinks. The increase in fire load will enhance the fire risk. Although the subway management limits the maximum allowable luggage to 23 kg, the combustible amount is still large in train cars. Heat release rate (HRR) is the most important parameter in fire hazard assessment. A 1:15 scale modeling test was carried out to find the HRR in a train car under limited ventilation with parallel goods in this paper. The goods were simulated by a propanol pool fire. HRR for six scenarios with all closed door to all opened door were studied. Mass loss rate of fuel, oxygen consumption, air velocity and fire duration were measured. Ventilation was provided by opening different numbers of doors of the train car. The train car fire can then be ventilation-controlled or fuel-controlled. The burning phenomena of fire in the train under limited ventilation including steady burning, oscillating fire and ghosting flame were studied. It was found that the fire size and duration depended mainly on ventilation when oxygen was very limited. When the amount of oxygen supply reached a critical value (the fire at the decay period with continuous supply of oxygen), the fire tended to be fuel-controlled. Burning characteristics of train fire under limited ventilation were also observed. They were different from fires burning in open area. Oscillating flame, ghosting flame and self-extinction were observed. Results are useful to assess fire hazards associated with parallel trading activities. Three repeated experiments on the captioned subject have been done with average results of all experiments presented.