New tools for smoke residue and deposition analysis Open Access
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The physics of smoke deposition from a hot layer to a wall has been studied in a hood apparatus. The hood apparatus was specifically designed to study the smoke deposition based on thermophoresis experimentally and analytically in this work. For the first time the optical density method was used to measure the amount of smoke deposited on the surface. By using both gravimetric and optical measurement methods, the correlations between these values were determined for several fuels and test conditions. Solid phase mass specific extinction coefficient values were introduced for the first time for different fuels. Also, the optical properties of the smoke deposited on the surface were determined and compared to the smoke properties in the gas phase. An analytical thermophoretic smoke deposition model was developed using the measured smoke properties. This model is validated using experimental results from this work. This model is suitable for predicting smoke deposition due to a fire.The physics of smoke deposition from a pan fire to the gypsum wall was studied for different fire sizes and fuels. The optical density method which was developed for the hood tests was used for the wall tests. Solid phase mass specific extinction coefficients were determined for the wall tests. Fire size effect was studied for the wall tests. The effect of fire size and change in the flow regime due to the fire size has been studied in this work. It was noticed that the effect from turbulence changes the values for the solid phase mass specific extinction coefficient. The optical density measurement method was applied to the digital images taken from the smoke patterns against the wall and processed with Image J and developed Matlab code. Results from the smoke pattern predictions for the wall tests show a very good agreement between the digital images from the smoke deposition in the walls and the processed data. This can be used as a tool for fire investigation purposes to predict the smoke pattern and the amount of smoke deposited on the surface which was exposed to the fire. The analytical smoke deposition model based on thermophoresis was validated with the experimental data from the wall tests. There was good agreement between the experimental data and the results from the model.