100 likes | 254 Views
Session 10, Unit 19 Modeling Accidental Releases. Applications. Requirement by 1990 Clean Air Act Amendment – Section 112r Emergency response planning Accident investigation/assessment and litigation. Modeling Accidental Releases. Two types of accidental releases
E N D
Applications • Requirement by 1990 Clean Air Act Amendment – Section 112r • Emergency response planning • Accident investigation/assessment and litigation
Modeling Accidental Releases • Two types of accidental releases • Catastrophic rupture that lasts seconds or minutes - Puff • Leak that last a longer period of time – Continuous release • Two steps in this types of modeling projects • Modeling emission process – Source terms • Modeling dispersion process – Dispersion model
Modeling Accidental Releases • Instantaneous puff model • Equation suggested by Slade • Total exposure • With some assumptions/simplifications
Modeling Accidental Releases • Dispersion coefficients for puff model • Different from those used in the continuous models • Provided in Table 15.1 on text page 15-3 • Momentum dominated jets • Rise of the jet
Modeling Accidental Releases • Elevated dense gas releases • Richardson number • If Rio >>1.0, treat the release as dense gas release
Modeling Accidental Releases • Maximum initial rise • The downwind distance xg to touchdown
Modeling Accidental Releases • Cmax - Maximum concentration at a given downwind position Co - Initial concentration at the point of maximum rise • At the point xg
Modeling Accidental Releases • Dense gas releases at ground level • Slump and spread on the ground • Previous models not applicable • Complicating factors • Evaporation of liquid (phase and temp change) • Material seep into soil • Aerosol • Evaporation and condensation of the droplets • Heat transfer • Mass transfer • Chemical reaction