Extended Indoor Explosion Model with Vertical Concentration Profiles and Variable Ventilation Rates

摘要

For indoor processes that make use of volatile, flammable solvents there is a concern about possible explosions from accidental solvent spills. We previously developed a model that predicts the time-dependent average concentration from a solvent spill accounting for an adjustable room ventilation rate and fresh air makeup ratio. The current paper reports extending the indoor spill model to treat vertical concentration profiles and partial volume deflagration overpressures. Vertical concentration profiles occur in a lower, stratified zone for heavy vapors; a well-mixed zone occurs above that, and a lean, or fuel-free zone above that. With this extension, a flammable concentration can be found in the stratified zone even when the average concentration in the room is below flammable limits. Ignition of stratified vapors gives rise to partial volume deflagrations. A simple approach is described to predict the overpressure developed by a partial volume deflagration before explosion vents open. The predicted explosion overpressures can be plotted against time, representing various time of ignition.