Influence of initial temperature and pressure on the explosion behavior of n-dodecane/air mixtures

There is an increasing industrial interest towards long-chain hydrocarbons, also due to the fact that they can be obtained from renewable organic materials. These substances are flammable and, under certain conditions, can explode. Nevertheless, very few experimental data are available on their thermal and kinetic characteristics and, more specifically, on their flammability and explosion behavior under various process conditions. In the work presented in this paper, the explosion behavior of n-dodecane has been investigated through experiments performed in a closed 5-l cylindrical vessel by varying the concentration of (vaporized) fuel in air at different initial temperatures - 130 °C and 160 °C - and pressures - 1, 2 and 3 bar. From the recorded pressure-time histories, the most important parameters for the assessment of process hazards and the safe design of process equipment - maximum pressure, maximum rate of pressure rise, and deflagration index - have been quantified. It has been found that, prior to feeding air and igniting the fuel/air mixture, the n-dodecane injected into the explosion vessel undergoes pyrolysis phenomena that interfere with combustion, thus affecting the performed measurements. On the basis of these results, it can be expected that pyrolysis also affects the flammability and explosion behavior of long-chain hydrocarbons others than n-dodecane involved in industrial processes at high temperature and, thus, it should be taken into consideration when addressing safety-related issues.