Double diffusive convection during solidification of ammonium chloride - water (NH4CL-H20) mixture in a trapezoidal cavity

• Main Author: Duggirala, Ravi Kumar
• Format: Others
• Published: FIU Digital Commons 2004
• Subjects: Mechanical Engineering
• Online Access: http://digitalcommons.fiu.edu/etd/3095; http://digitalcommons.fiu.edu/cgi/viewcontent.cgi?article=4387&context=etd

The effect of the initial concentration of ammonium chloride (sub eutectic: C < 19.8 wt. % and eutectic Ce= 19.8 wt. %) and boundary temperatures (Tcold = -30 0C to -10 0C) on the solidification process is examined. Particle Image Velocimetry (PIV) is used in this study to measure the velocity fields in the melt during the solidification process. The distributions of temperatures at discrete locations in the solution and the boundary walls were measured. This study focuses on the solidification of an ammonium chloride-water (NH4Cl- H2O) solution in a trapezoidal cavity with one and two inclined cooling walls. The thermosolutal convective flow strongly influenced the rate of freezing. An increase in thermal driving force increased the rate of freezing. Increased initial concentration retarded the freezing process and primarily affected the structure of the solid and mush regions. The results of this study will contribute in understanding the phenomena and bridge the gap between the engineering aspect and physics background for the dynamics of solid phase formation during castings, ingots, and polymerization.