PERFORMANCE EVALUATION OF DENSE GAS DISPERSION MODELS

This paper summarizes the results of a study to evaluate the performan ce of seven dense gas dispersion models using data from three held exp eriments. Two models (DEGADIS and SLAB) are in the public domain and t he other five (AIRTOX, CHARM, FOCUS, SAFEMODE, and TRACE) are propriet ary. The field data used are the Desert Tortoise pressurized ammonia r eleases, Burro liquefied natural gas spill tests, and the Goldfish anh ydrous hydrofluoric acid spill experiments. Desert Tortoise and Goldfi sh releases were simulated as horizontal jet releases, and Burro as a liquid pool. Performance statistics were used to compare maximum obser ved concentrations and plume half-width to those predicted by each mod el. Model performance varied and no model exhibited consistently good performance across all three databases. However, when combined across the three databases, all models performed within a factor of 2. Proble ms encountered are discussed in order to help future investigators.