Study on phase transformation characteristics of carbon dioxide in composite inert gas slurry

Abstract

To improve the current situation of mine fire in China, and to optimize the deficiency of fire extinguishing technology of the single component inert gas, a dry ice preparation system and a visual test bench for CO2 phase transformation characteristics were set up. Based on different tube types experiments, the three-phase mixture were prepared, which were composed of liquid nitrogen and dry ice particles, the formation mechanism of three-phase was discussed and the phase transformation characteristics of CO2 was analyzed by numerical simulation. The result shows that as the included angle of CO2 pipeline increases, the desublimation temperature decreases from 168 K to 157 K, dry ice desublimation increases. Dry ice particles can be accumulated on the visual inner wall by gravity to form a coating, and its thickness showed a trend of extending to the upper part of the pipeline. The simulation result shows that as the angle between LN2 and CO2 branch pipe increases from 30° to 90°, the fluid flow rate increased from 14.5 m/s to 15.8 m/s, the temperature decrease-rating increased, and the volume fraction of dry ice at the bottom of the pipe increased, which was consistent with the experiment results.

Keywords

• cryogenic inert gas-slurry
• desublimation
• phase transition
• co2
• mine fire
• spontaneous combustion