Experimental Investigation of Flow and Heat Transfer Characteristics Using Thermo-Sensitive Magnetic Fluid in a Mini-Channel

Abstract

In the present study, the flow characteristics and heat transfer of a thermo-sensitive magnetic fluid, which is a multiphase-flow material, were investigated experimentally. Heat transport systems using magnetic fluids have been proposed by several researchers, but miniature devices of this type have not yet been developed. The mini-channels considered herein have a depth of 500 μm, with the nominal channel width being five times the width. The channel device was constructed from a Teflon tube. The operation of the device is based on the thermo-magnetic characteristics of the fluid, a suspension of Mn-Zn ferrite particles in kerosene, the magnetization of which is known to decrease with increasing temperature. The experimental parameters were magnetic force, the position of the magnet, and the temperature of the magnetic fluid. The experimental results indicated that force convection based on the magnetic characteristics of the fluid in the mini-channel exhibited excellent cooling performance. In particular, the observed variations in the flow patterns were compared with the results of a boundary layer of the flow velocity in the pipe, which is generally known. Furthermore, it was found that the flow characteristic of the thermo-sensitive magnetic fluid was strongly dependent on the magnetic condition, such as the force and the position.