Simulation of Combustion and Smouldering of Plastics

Why are we interested in the intermediates of plastics combustion?

Goal of a project sponsored by the Swiss Federal Roads Office (FEDRO) is to identify a sensor that - similar to a dog's nose - is able to detect fire traces from an early stage of fire. This would allow for a significantly earlier alarm in favour of tunnel safety.

However, which substance should the sensor detect? Things are being complicated by the fact that a tunnel naturally contains exhaust gases from combustion engines. Common fire traces such as carbon dioxide, carbon monoxide, or methane, thus do not serve the purpose. The technical literature turns out to be incomplete.

Our Part of the Project

The chemical simulation of smouldering and combustion of a variety of plastics occurring in vehicles could bridge these gaps. Smouldering and combustion under several conditions were simulated and the occurring intermediates were meticulously monitored and recorded. Within these large lists, substances were identified that occur in all kinds of fire and under all imaginable conditions, but were absent in normal exhaust gas.

xirrus is worldwide the first commercial provider of reaction dynamics simulation. The widely automated analysis processes in the digital laboratory proved to be even faster, more efficient and more cost effective than an elaborate literature study or experimental investigation.

The Future

The concept of the gas sensor is now being evaluated further. Availability of suitable sensors will be checked, their optimum placement within a tunnel will be clarified, and the required sensitivity due to gas dilution from the fire to the sensor in turbulent air will be estimated. A real-live fire experiment in the test gallery will complement the findings with validation results.

This project is being implemented by a consortium of three companies. VSH Versuchsstollen Ha­ger­bach AG is resposible for project lead and fire experiments. Combustion Flow Solutions GmbH carries out simulation of gas spread and literature study. xirrus GmbH is responsible for the gas analytics and sensor evaluation.

Gas analytics for the very early detection of fires in road tunnels

Fine Nose for Gases

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