Experimental study on heat release rate measurement in tunnel fires

Abstract

Summary Knowledge about the heat release rate (HRR) is essential for studying tunnel fires. The standard method in ISO 9705 is widely applied to calculate the HRR of combustion by measuring the consumption of oxygen in a fire. However, the studies of HRR measurement in full‐scale tunnel fires are rare because of the complication and costs of large experiments. This paper presents a system based on the principle of oxygen consumption calorimetry for the measurement of HRR and total heat release (THR) of full‐scale fires in tunnels. A total of 22 fire experiments are performed in a large‐scale ventilated testing metro tunnel with dimension of 100.0 m × 5.5 m × 5.5 m to validate the reliability and effectiveness of this system. Firstly, four oil spray fire tests are conducted with nozzle flow of 106 L/h at (1 ± 0.1) MW HRR to calibrate the instrumentation. Then, 18 full‐scale fire tests using square diesel pools at five sizes (0.5, 1.0, 2.5, and 5.0 m2) and wood cribs as fire sources are carried out for the measurement of HRR and THR. Results provided by the comparison between the measured HRR and THR values of the fire tests and the theoretically calculated ones show that our system works effectively in the HRR measurement of full‐scale fires in tunnels.

Study on the key parameters of vehicle fires for the growth stage in road tunnels

“…The main performance of the growth stage is the heat release rate (HRR) increment in a certain period of time (ranging from a few minutes to tens of minutes), 4 that is, unsteady state. The HRR is essential for studying tunnel fires, 5 and it is usually characterized by the fire growth model containing key parameters such as the growth coefficient and the growth time. In addition, different types of vehicles burning with different HRRs and combustion characteristics, 6 resulting in different performances during the growth stage.…”

A numerical study on the effects of naturally ventilated shaft and fire locations in urban tunnels

“…7,8 With the increase of tunnel mileage, the driving density of vehicles will also be increased, so the tunnel safety becomes increasingly serious. Fire is one of the disasters, which may occur in the tunnel, [9][10][11][12][13][14][15][16][17][18][19][20] as the vehicles always carry a lot of solid, liquid, and gaseous combustibles. [21][22][23] When a fire occurs in the tunnel, because of its long-narrow structure, hot smoke will quickly spread throughout the tunnel, and it will be difficult to be discharged in time.…”