Every fire starts with the ignition of a combustible material. The study of the ignition process is therefore of outmost importance. In particular, self-ignition and ignitability of fuels are relevant problematic aspects investigated by the fire group with respect to the following two research topics:
1. Self-ignition of biomass storage
When stored, biomass undergoes biological, chemical and physical material dependent processes, leading to a heating of the material. Furthermore storage of biomass implies a change in material (and formation of emissions). Hence, the storage of biomass affects the fuel efficiency and plays a role for the cost of biomass. The emitted gases and the micro-organisms cause both work environmental hazard and give a negative air-environmental contribution. The gases measured at the top of a pile (CO, methane, alcohols, carbon hydrates and terpenes) are greenhouse gases and toxic. At higher temperatures, more material is consumed. Emissions from chemical processes also contain numerous toxic gas species. Eventually this may result in spontaneous ignition. Self ignition and the following fire imply a total loss of energy and material and it is 1% of all fires in Denmark. In this process, large amounts of polluting gases and particles are emitted. The extreme situation of self ignition is poorly described. The possibilities of fire fighting are limited when the fire is detected – especially when it occurs in silos, where detection is difficult.
2. In-situ burning of crude oil under Arctic conditions
Several Arctic council reports conclude that oil spills are the most significant threat to the arctic ecosystem. With the expected increase of e.g. naval and oil drilling activities, accidents become increasingly more likely. Due to the special conditions featured in the Arctic, in-situ burning (ISB) is in many situations the most effective cleaning method. The technique has shown high burning efficiencies of over 90% and is easily deployable in ice-covered waters. However, few studies have been undertaken on the influence of ice on the ignition and burning behavior of oils and on the resulting impact on the Arctic environment. Previous research done at DTU showed there is a strict window of opportunity for ignitability of the oil, due to mixing with water. In this study, research will be continued in both the “fire science” and the “environmental science” of ISB in cold climates. The objective of the research is to obtain a better understanding, and thereby increase the potential success, of oil clean-up by ISB after an accidental spill.
The three specific goals to be reached in this study are:
- To identify the controlling mechanisms governing the ignition and burning rate of combustible liquids in ice channels - a unique situation, which has never been explored fundamentally before.
- To establish the chemical composition and the acute toxicity after the in-situ burning.
- To develop a scaling/forecasting model of the suitability of in-situ burning.
In order to achieve these goals, a three-phase plan has been setup (Fig. 1) that combines the expertise and facilities of all involved parties. The main goals are to be reached through two Ph.D. projects at WPI and DTU.
3. pace-craft fire safety
Full scale fire testing complemented by computer modelling has provided significant knowhow about the risk, prevention and suppression of fire in terrestrial systems (cars, ships, planes, buildings, mines, and tunnels). In comparison, no such testing has been carried out for manned spacecraft due to the complexity, cost and risk associated with operating a material flammability experiment of a relevant size and duration in microgravity. Therefore, there is currently a gap in knowledge of fire behaviour in spacecraft. A spacecraft fire safety research project is being developed to reduce the uncertainty and risk in the design of spacecraft fire safety systems by testing at nearly full scale in low-gravity. The large-scale material flammability demonstration will facilitate the understanding of the long-term consequences of potential spacecraft fire and provide data not only for the verification of detailed numerical models of such an event, but also for the development of models for prevention, response and mitigation of spacecraft fires.
PhD Project
In-situ burning of crude oil in the Arctic: Understanding and predicting the environmental impact, L. van Gelderen, ongoing
Research Project
Spacecraft Fire Safety, project funded by the European Space Agency (ESA), in collaboration with NASA and other 8 research institutes and universities in the world
Publications
Petersen, R.S.; Dederichs, A.S. (2010):
Self ignition of biomass: a statistical study
Proc. of International fire prevention symposium, 2010
Andersson, B.; Blomqvist, P.; Dederichs, A.S. (2007):
Thermal Breakdown of fire suppression agents
BRANDFORSK , 2007
Carlsson, J.; Husted, B.; Göransson, U.; Dederichs, A.S. (2007):
Anwendung von CFD-Programmen für Brandtechnische Berechnungen
VFDB 2006, vol. 3 p.127-131
Ruff G.A., Urban D.L., Fernandez-Pello A.C., T’ien J.S., Torero J.L., Legros G., Eigenbrod Christian, Smirnov N., Fujita O. Cowlard A.J., Rouvreau S., Minster O., Toth B. Grunde J. (2013):
Development of Large-Scale Spacecraft Fire Safety Experiments
Proc. of the 43rd Int. Conference on Environmental Systems, 2013
Legros G., Minster O., Tóth B., Fernandez-Pello A.C., T’ien, J.S., ToreroJ.L. Cowlard A.J., Eigenbrod C., Smirnov N., Fujita O.,
Rouvreau S., Jomaas G.:
Microgravity Flammability Experiments for Spacecraft Fire Safety
Proc. of the 63rd International Astronautical Congress, 2012
Contact
Anne Dederichs
Grunde Jomaas