Thermosolutal convection in annular enclosure with partially conductive outer-cylinder

This study discussed the thermo-solutal natural convection phenomenon caused by temperature gradient and concentration gradient in a closed container in a geometric shape of double-cylinder through experimental method. The effect of local heat conduction of the outer-cylinder on the flow field in the double-cylinder closed container can be observed in the experiment based on the design of the geometric shape and boundary conditions. This experimental model is designed as one sixth of outer-cylinder and inner cylinder made of copper, and one and two thirds of outer-cylinder made of acrylate. The flow field pattern in a closed area is discussed according to relevant dimensionless parameters. The experimental work fluid is copper sulfate solution (CuSO₄+H₂SO₄+ H₂O) at a concentration of 0.05M. The temperature gradient is maintained by two constant temperature water tanks at different temperatures, and the concentration gradient is set up by electrochemical system. The limiting current is applied to both ends of outer cylinder and inner cylinder to make them electrodes to result in concentration gradient. The flow field in the double-cylinder closed container is observed by using shadowgraph, and photographed as record for analysis. In order to determine the structure of flow field, the temperature and concentration distributions in the flow field are measured. Finally, the relations between the mass transfer rate Sh value and Gr_m, Gr_t are analyzed.