Two‐phase ammonia plume behavior in a still room: Jack Rabbit III chamber studies

This paper describes a new set of 45 laboratory experiments where about 180 g of ammonia was released from pressurized liquefied storage in a still 51.3 m 3 chamber (i.e., a small room) and the variations of the ammonia gas concentrations and liquid deposition over a 60 min time period were investigated. Chamber temperatures ranged from −18 to 40°C, and relative humidities from 11% to 90%. A liquid collection (catch) tray was placed so that the 45° downwards‐directed two‐phase jet would strike its center, and a scale under the tray measured the liquid mass. In three trials, the tray was inverted; in six trials, a water spray system was operated; and, in four trials, CO 2 gas was introduced. The initial ammonia deposition to the tray ranged from about 10%–50% of the released mass, with the larger fractions occurring during colder conditions. The strong ammonia jet generated eddies lasting for many minutes. The addition of CO 2 gas produced only minor differences in the concentrations. The addition of water spray resulted in about a 50% reduction in ammonia vapor. These results should be helpful in planning emergency response to ammonia accidents in confined locations.