Estimating Heat Release Rates From Large-scale Tunnel Fires

Abstract

A series of full-scale tunnel fire tests were conducted in Norway under the EUREKA EU499 firetun project, a cooperative venture involving participants from several European countries. The Channel Tunnel operators, Eurotunnel, were represented during a test designed to simulate a burning heavy goods vehicle (HGV) being conveyed on a freight shuttle train within the Channel Tunnel. The experimental tunnel was extensively instrumented to enable the progress of the fire to be monitored. In this paper, it is shown how the data on CO and C02 production rates were used to calculate the rate of heat release as a function of time and provide an estimate of the maximum heat release rate.

Full Scale Experiments On Studying Smoke Spread In A Road Tunnel

“…The Heat Release Rates were not accurate enough, the wind speeds were only measured at some certain point and it was not capable to track the smoke layer height at far away from the fire, 400m away for example, by thermocouple. Oxygen consumption way calorimetry will be improved as in the former report [12] and introduced into the Heat Release Rate estimation in the future full scale tests. The pool fires should be burned longer enough to get the smoke temperature to reach a steady state at far away from the fire, for example, +800 m or farther.…”

“…The larger velocity profile near the fire source in Test 2 is considered to be related to the air entrainment by the fire. There may be turbulent velocity near the fire source and it would be become "fully developed" only at an infinite distance downstream as pointed earlier in the former report in other full scale tests [12]. So, the wind speeds measured downstream is considered to actually represent the wind conditions in the tunnel.…”

“…Afterward, an extensive series of experiments were conducted at HSL, Buxton in a 366 m long, 2.56 m high tunnel with a cross-section of 5.4 m 2 , to provide data suitable for the validation of CFD simulation. In 1994, tests were performed in a disused Norwegian mine tunnel, nominally 5.5 m high, 6.5 m wide and 2.3 km in length under the EUREKA EU499 project [12]. The main objective of this series of tests was to determine the heat output of fire in tunnels and the velocity profile upstream of the fire.…”

“…In EUREKA EU499 tests, the walls were also rough and the cross-sectional area was significantly different with location unfortunately [13]. Although the tunnel size for the tests in Virginia was 7.9 m high and 8.8 m wide, the length of the tunnel was only 850 m while it would be desirable to get the full scale data in a tunnel as long as 1500 m. And the region for data measurement was also limited: In the HSL tests and the UREKA EU499 tests, data were only collected from 50 m upstream to 200 downstream [13] and from 100 m upstream to 100 m downstream [12] along the tunnel, respectively. It is considered to be useful to get the full scale data farther away from the fire.…”

Modelling Fire Size And Spread In Tunnels

“…Some tunnels have been built with a "design fire" of approximately 20 MW in mind (although other tunnels have been designed to withstand fires with HRRs of 50-100 MW). However, the only well documented fire test of a HGV in a tunnel, carried out in a longitudinally ventilated tunnel, exhibited a HRR well in excess of 100 MW [2]. Opinion is divided as to whether the huge difference between these two figures is due to underestimation in the first instance, or the dramatic intensifying effect of the longitudinal ventilation in the experimental results.…”