(254d) Multi-Phase Mathematical Modeling of Compressed CO2 Expansion through a Coanda Nozzle

Matthews, M. A., University of South Carolina
Shimpalee, S., University of South Carolina
Glenn, O. Jr., University of South Carolina
A Coanda nozzle can be used to produce a high velocity mixture of air, gaseous CO2, and dry ice particles from a supply of liquid CO2. Such a process is effective (for instance) for residue-free rapid cooling or precision cleaning. A multiphase thermodynamic and computational fluid dynamics (CFD) analysis of this flow is presented for the purpose of optimizing the process parameters, which include the temperature of the liquid CO2 supply, the flow rate, and the pressure and nozzle and air configuration.

Temperature, pressure, velocity and mass fraction profile distributions have been modeled on the spray-nozzle system. Flow characteristics have been quantified for dry ice particle sizes of 1.0x10-3m, 1.0x10-4m and 1.0x10-5m. Maximum velocity and residence time as a function of inlet temperature have been simulated and quantified. The analysis suggests that as inlet CO2 temperature increases, the maximum velocity increases and the particle residence time decreases. Decreasing dry ice particle size decreases the residence time in the nozzle channel. Overall, this study provides a basis for optimizing the temperature and velocity profiles, and thus the cooling or cleaning capacity of such Coanda devices.