Analysis and Model/Data Comparisons of Large-Scale Releases of Nitrogen Tetroxide. Final Report June 1983 - September 1984

摘要

During the fall of 1983, the Lawrence Livermore National Laboratory (LLNL) conducted a series of large-scale (3-5 cum) nitrogen tetroxide (N2O4) spill tests of the U. S. Air Force Engineering and Service Laboratory (ESL). The purpose of the test series was to determine the source strength characteristics and heavy-gas dispersion aspects of large N2O4 spills. Six N2O4 spill tests were accomplished. Four tests were for the purpose of dispersion and source strength studies and two tests for evaluation of a Portable Foam Vapor Suppression System. The primary purpose of the Eagle test series was to demonstrate the heavy-gas dispersion aspect of large-scale releases of N2O4 vapors. The denser-than-air character of a heavy-gas cloud affects its subsequent dispersion in two main ways. The greater inertia of the heavy gas tends to reduce the rate of turbulent mixing from that of a trace gas and thereby reduces the growth of the cloud. The greater density of the cloud produces a gravity flow or slumping which tends to reduce the cloud height and increase its width. This report describes four simple dispersion models and compares model predictions with the results of two of the spill tests. The four models used in this study are the Ocean Breeze/Dry Gulch model, the Pasquill-Hanna Guassian Plume model, the Shell dispersion model, and the CHARM model. The model comparison results indicate that all of the models examined substantially underpredict the measured peak downwind gas concentration by factors ranging from 2 to 14 depending upon the various assumptions employed.