Development of High-Performance Heat Transport Device Using Magnetic Fluid and Intermittent Magnetic Field

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A unique technique for the heat transfer enhancement that utilizes the interaction of a magnetic fluid and an intermittent magnetic field was proposed in the present study. It is known that the magnetic fluid shows spiky interface when the magnetic filed is imposed. The spiky interface and a flat interface will be generated alternately by putting on and off the magnetic field, and this will cause a bulk fluid motion of magnetic fluid, and thus, will result in the marked enhancement of the heat transfer. The rate of the heat transfer enhancement by the above method was investigated quantitatively in the present study. For the sake of this, the magnetic fluid was placed in a shallow container. The container was consisted with heated bottom wall and cooled top wall and air layer existed over the magnetic field. The heat transfer rates between the hot to cold walls were measured by varying the strength and frequencies of imposed magnetic field systematically. The results showed that the heat transfer rates under the intermittent magnetic field are increased by 3 to 6 times larger than those without magnetic field. In particular, the highest enhancement ratio was obtained when the water was replaced with air layer over the magnetic fluid. The optimum strength and the frequencies of the magnetic filed, the depth of the magnetic fluid on heat transfer were also discussed. The present technique will be utilized for the cooling of electronic equipment.