Real-tme estimation of heat release rates in tunnel fires: Fid-Bau Portal

Real-tme estimation of heat release rates in tunnel fires

Nakahori, Ichiro / Sakaguchi, Toshiaki / Nakano, Ami / Mitani, Atsushi / Vardy, A.E.

In existing practice, the response to a fire in a tunnel has to be designed and implemented in the absence of knowledge of the actual heat release rate from the fire. This constraint has been regarded as inevitable, but that is no longer the case. A method of determining the heat release rate in real time has been presented herein and has been validated by reference to controlled tests in a full-scale tunnel. The availability of such real-time information has the potential to influence the method of ventilation control and many other aspects of the response to a fire incident in a tunnel. Specific conclusions from the paper include: (1) Linear temperature sensors are already used for fire detection purposes. They are capable of providing much more detailed information than is needed for this purpose alone. In particular, they can provide details of temperature change in space and time. (2) Use can be made of this capability to estimate the average temperature increase in all air/smoke that has been affected by a fire. (3) By estimating the size of the thermally stratified, heated air/smoke layer, it is possible to estimate the total energy received by air from a fire up to any particular instant. (4) This, in turn, enables an estimate to be made of the total energy emitted by the fire up to the current instant. (5) The rate of change o f the total energy is a measure of the heat release rate from the fire. The methodology yields this value at each instant during the fire. (5) The methodology has not yet been developed to its full potential. A number of limitations exist that will be relaxed in future. These limitations, and others of a more permanent nature, have been discussed in the paper.