Study of double-diffusive velocity during the solidification process using particle image velocimetry

This experimental study focused mainly on the solidification of a binary mixture of ammonium chloride and water (NH4Cl-H2O) in a differentially heated cavity. One vertical wall is cooled at temperature TC, and the opposite vertical wall is kept at constant temperature TH = +20°C. The effect on the solidification process of the initial concentration of ammonium chloride and cooling conditions is examined. Particle image velocimetry (PIV) is used for the visualization of the dynamic field during the solidification process. The temperature distribution at discrete locations in the solution and on the vertical cooling wall was monitored using thermocouples. The convection flow patterns, the ice thickness, and the temperature distribution were obtained for various initial concentrations of ammonium chloride ranging from 0wt% to 20wt% (sub-eutectic and near-eutectic growth). The convection patterns obtained for different initial concentrations showed significant differences. The results showed that the process of solidification is slower with an increase in the initial concentration levels of the binary solution. The ice growth rate was almost double at the bottom of the cavity.

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Experimental Study on Double-Diffusive Convection During Solidification of NH4Cl-H2O Hypereutectic Solution in Cylinder Cavity

Heat Transfer: Volume 1 ◽

10.1115/ht2008-56296 ◽

2008 ◽

Author(s):

Bofeng Bai ◽

Jun Lu ◽

Lei Zhang ◽

Heng Li

Keyword(s):

Experimental Study ◽

Cylindrical Cavity ◽

Particle Image ◽

Solidification Process ◽

Double Diffusive Convection ◽

Diffusive Convection ◽

Image Velocimetry ◽

Diffusive Interface ◽

Contrary Direction ◽

Double Diffusive

In order to reveal the law of double-diffusive convection of multi-compound solution in cylindrical cavity, experimental study on solidification of NH4Cl-H2O hypereutectic solution has been performed by using particle image velocimetry (PIV). The influencing factors of flow patterns and intensity are also analyzed. The results show that: 1) There are two approximately symmetric main convection cells in the liquid which are down along the sidewall and up along the center of the cylindrical cavity. Meanwhile, there are also two secondary cells on the bottom corner of cylindrical cavity, which flow in contrary direction to that of the main ones; 2) Due to the release of water during the solidification process, solute layers and diffusive interface are developed in the liquid and will be disappeared in the end; 3) The cooling temperature and the initial concentration have significantly effects on the flow velocity, solute layers and diffusive interface.

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The Influence of Boundary Condition on Solidification of Binary Solution in Rectangular Cavity

10.1115/imece1999-1027 ◽

1999 ◽

Author(s):

N. Pradeep ◽

H. J. Kang ◽

C. X. Lin ◽

M. A. Ebadian

Keyword(s):

Heat Transfer ◽

Boundary Condition ◽

Particle Image Velocimetry ◽

Particle Image ◽

Binary Solution ◽

Solidification Process ◽

Heat Transfer Process ◽

Bottom Surface ◽

Piv Technique ◽

Image Velocimetry

Abstract The solidification of a binary mixture of ammonium chloride and water flow cooling in rectangular cavities was investigated experimentally under different boundary conditions. Two cavities measuring 63.5 × 180 × 165 mm and 76 × 120 × 96 mm were employed in this study. For the first cavity, its three surfaces (i.e., two side surfaces and one bottom surface) were cooled. For the second cavity, however, only two side surfaces were cooled (i.e., the bottom surface was adiabatic). The influence of the change of boundary was studied. All investigations were carried out in the surface temperature range from −15 to −30°C under a constant refrigerant temperature of −22°C. The effect of cooling boundary condition had a great effect on the heat transfer process during the solidification process. The advanced Particle Image Velocimetry (PIV) technique was used to catch the velocity profiles during the solidification process.

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