Experimental investigation of sub-millimeter thermomagnetic pumps with temperature-sensitive magnetic fluid

Abstract

• The sub-millimeter thermomagnetic pump was successfully fabricated and operated. • Temperature-sensitive magnetic fluid was used as the working fluid. • The input heat flux and channel height affect the thermomagnetic pump flow rate. • The high Prandtl number limits the pump’s flow rate while increasing channel height. • The axial heat conduction effect was observed in the sub-millimeter thermomagnetic pump. A thermomagnetic pump represents a novel pumping system that can be operated by simply heating and applying an external magnetic field. The working fluid in the thermomagnetic pump is temperature-sensitive magnetic fluid (TSMF). The magnetization of the TSMF decreases as its temperature increases. In the present study, a set of sub-millimeter thermomagnetic pumps was fabricated in microchannel systems with channel heights of 180, 290, 350, and 420 μm. A microheater was placed underneath the microchannel to control the input heat flux. A flow meter and five thermocouples were installed to examine the performance of these thermomagnetic pumps under different heating conditions. Although the flow rate increases as the height of the microchannel rise, the highest flow rate of 81.74 μl/min was achieved under the highest heating condition of 459.8 kW/m 2 and channel height of 350 μm, instead of 420 μm, due to the high Prandtl number of the TSMF.