Reliability of OA-ICOS for bushfire simulation studies
Customer: CSIRO Pyrotron: National Bushfire Research Facilities
Application: Wind Tunnel, bush fire monitoring
CSIRO Black Mountain (Land and Water Flagship) and CSIRO Aspendale Victoria (Oceans and Atmosphere Flagship) have set-up national bushfire research facilities testing combustion and spread of bushfires. This is towards facilitating improvements for fire safety and fire-fighting for all Australian communities. This also has health relevance via predicting smoke emissions from fires and making the choice to/not to light a prescribed fire under certain burning conditions).
The CSIRO Pyrotron is a 25 metre long fire-proof wind tunnel with a working section for conducting experiments and a glass observation area. The objective of the Pyrotron is to simulate bush fires with different fuels and burning conditions and measure gases and particulates. The Pyrotron enhances research on bushfire behaviour not possible in field experiments due to fire intensity, heat and safety concerns.
CSRIO needed to make precise measurements of GHGs (CH4/CH2/H2O) and also N2O/CO at up to 10Hz in what were normal field conditions. The trace gas measurements need to be made during a bushfire simulation (or burn) as the Pyrotron can generate a lot of heat.
The amount of heat did not allow CISRO to use traditional Cavity Ring-Down Spectroscopy (CRDS) instruments due to their reliance on precise instrument measurement conditions. CRDS was deemed unsuitable for the measurement conditions and levels of precision required at the Pyrotron.
Acoem was able to assist CSIRO by proposing the Los Gatos Research (LGR) GHG and N2O/CO (we also used the CH4/CO2 analyser as well) analysers as they utilise a patented technique called Off Axis – Integrated Cavity Output Spectroscopy (OA-ICOS), which is not dependent on precise instrument alignment.
The LGR instruments were successfully deployed around the Pyrotron. Despite the high temperatures generated around the instruments, the data measured (at up to 10Hz) was within the range and at the precision required by CSIRO.
The data accuracy was also able to be independently verified using an FTIR instrument and CSIRO was able to use this data in developing new bushfire propagation models (the FTIR/LGR comparison had more relevance for smoke forecasting (in terms of project aims) but could be used in fire spread prediction.) To be deployed to firefighting authorities for use Australia wide.
The performance of the LGR Instruments was deemed superior to CDRS in terms of accuracy, precision, sensitivity, linearity and dynamic range as well as ease of use.
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