Abstract
Measurements of the ion current between two electrodes have been conducted in order to assess whether the ion current can be used for the detection of ignition in a cone calorimeter, and for fire dynamics investigations in general. The measured ion current clearly indicates when ignition occurs, in agreement with traditional results based on visual inspection. It was also seen that soot deposits on the electrodes do not adversely affect the ability of the ion current to indicate ignition. However, short circuiting may occur if the electrodes are kept in a sooty flame long enough for the soot to completely bridge the gap between the electrodes. The latter scenario is not a problem from an ignition detection point of view since soot growth occurs after ignition has taken place.
Measurement of the ion current between the electrodes was also conducted in a premixed propane flame in order to characterize the dependence of the current on applied voltage and on combustion conditions. The ion current obeys Ohm's law since the current increases linearly with applied voltage in the investigated voltage range. It was also seen that the ion current gave unique results based on its position in a propane flame and the fuel/air ratio of the flame. Copyright © 2010 John Wiley & Sons, Ltd.