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- Försth, Michael, et al.
(author)
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In-situ measurements of toxic gases in a tube furnace
- 2009
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Reports (peer-reviewed)abstract
- Infrared Polarization Spectroscopy (IRPS) was used to detect and quantify HCl and HCN in an 800 mm long tube furnace. Pieces of a PVC-carpet or pellets of nylon 6,6 were continuously fed into the furnace producing a heavy smoke. This constitutes a very harsh environment from a diagnostic point of view due to the high smoke density and relatively long length of the furnace. Despite this it was possible to quantify HCl and HCN concentrations in the smoke down to a levels of 50 ppm using IRPS. The explanation for this success is twofold. Firstly the IRPS method is inherently almost noise free due to the use of crossed polarisers, creating a virtually zero background. Secondly the problem with laser beam attenuation due to scattering in the smoke, especially with soot particles, decreases in importance with the fourth power of the laser wavelength. This means that infrared measurements represent a great advantage over measurements in the ultraviolet or visible wavelength range. It is concluded that IRPS shows great promise as a new diagnostics tool in fire technology for small-scale as well as for large scale experiments. Furthermore the in situ nature of the method should be emphasized since this means that valuable information is obtained that can not be extracted from sampling methods such as MS/GC or FTIR for example. This information is important, for example, in egress calculations and analysis of fire chemistry. The method can easily be adapted for other gases such as HF, NO, NO2, HBr, CO and SO2.
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- Holmstedt, Göran, et al.
(author)
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Determination of uncertainty of different CFD codes by means of comparison with experimental fire scenarios
- 2009
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In: Conference Proceedings - Fire and Materials 2009, 11th International Conference and Exhibition.
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Conference paper (peer-reviewed)abstract
- This article will summarise the evaluation of four CFD software codes (CFX, FDS4, SMAFS and SOFIE). Evaluation was performed by means of comparing the simulation data with experimental scenarios. The scenarios were chosen to represent scenarios frequently assessed using fire safety design based on performance. The greatest difficulty during validation of CFD-codes is to find well documented relevant experiments. It is true that many large scale experiments including smoke spread have been published but many of them are not described sufficiently and are therefore impossible to use for validation. It is very unusual that data on reproducibility and repeatability is available. After an extensive discussion between the participants in the project five scenarios were chosen. Scenarios 1A (large room with vents), and scenarios 1B1 and 1B2 (corridor with vents) were well documented experiments (repeatability) with ceiling vents and ceiling jets performed earlier at SP in Boras. Scenario 2 is a tunnel fire taken from an experimental study in Boston, US. Scenario 3 is an atrium fire taken from an experimental study in Japan. Lack of well documented fires in retail premises lead us to perform a series of tests in 1/2 scale, 4.1 and 4.2 at SP in Boras. Scenario 5 is an experimental study from Australia including smoke spread from a fire room to an adjacent corridor and a room. The conditions for the simulations included information about the scenarios given above. No information about experimental results was available until the results from the simulations had been sent in to the project manager. The intention was to imitate the working conditions for a consultant as far as possible when using a CFD-simulation to estimate fire safety. In this manner the simulations are dependent on many factors such as the CFD-code used, judgement of input data of the scenarios done by the operator, operator skill etc. The results from the evaluation of the CFD codes showed that the simulation results generally were a good description of the experimental fires studied, but that limitations and specific properties of the different codes, together with the operator factor, can strongly influence the results. The detailed results of all comparisons are given in the final report of the project. It was not possible to include these detailed evaluations in this conference paper but these results are available in the main report as well as in future scientific articles.
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