Enhancement and Control of Local Heat Transfer in a Gas Flow Containing Soft Magnetic Particles

A novel technique for enhancing and controlling local heat transfer coefficients from the hot wall to the cooling gas flow using soft magnetic solid particles has been proposed in order to eliminate the disadvantages of inefficient gas-solid two-phase flow. The characteristics of the flow and local heat transfer were examined in a vertical rectangular channel flow involving ferrite particles of 145 μm in diameter. The Reynolds number of the channel flow was set at approximately 10⁴ and the particle mass loading ratio was varied up to 1.6. The result indicated 60 percent enhancement of heat transfer downstream from the location of the magnet at a mass loading ratio of about 1.6. Further enhancement in heat transfer is provided by increasing the particle mass loading ratio and the magnetic field intensity. The mechanism of heat transfer enhancement can be clarified by considering the increase in the local heat capacity near the heated plate.