| Summary: | 碩士 === 國立臺北科技大學 === 能源與冷凍空調工程系碩士班 === 99 === Solidification of binary solutions is employed in industry very often. Casting of binary alloys is one of them (for example, casting of binary alloys, ice storage system). In the past, one of the main studies focused on how to eliminate or weaken double-diffusive convection during solidification because double-diffusive convection was the main reason to cause poor material quality in the final ingots. The purpose of this study is to investigate the periodic vibration in the vertical direction on the development of double-diffusive convection during solidification. A hyper-eutectic binary solution (NH4Cl-H2O) was adopted as the test sample in this project and it was put into an enclosure cooled from the bottom, known as unidirectional solidification process, to investigate the heat and mass transport phenomena during solidification. The experiments conducted in this study included flow visualization by shadowgraph, measurement of channel size and channel distribution, transient temperature distribution and movement of the solid/liquid interface. Experimental results show that the increasing of the frequency does not give any significant suppression effect on the formation of the plume-type double-diffusive convection. However the increasing of amplitude can effectively suppress formation of the plume-type double-diffusive convection.
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