An Experimental Investigation of the Thermomechanics of Pipe Flow of Magnetic Fluids in Response to Heating and Applied Magnetic Fields

Book excerpt: An experimental investigation was carried out to determine the thermodynamics and fluid mechanics of the pipe flow of magnetic fluids. A water-based magnetic fluid was synthesized in the laboratory and its relative viscosity and magnetic properties were determined as a function of temperature. A "thermomagnetic pump" was built and tested in which temperature differences caused the magnetic fluid to circulate through a loop when subjected to a magnetic field. In a conceptual study, the pumping capabilities of such a flow circulation were considered for a thermal rejection system application. Pumping capabilities were observed to be directly related to the slope of the pyromagnetic curve. The sensitivity of the fluid was enhanced by the addition of zinc, manganese, and cobalt compounds. Fluid properties and flow parameters, including viscosity, magnetization, velocity, pressure, and temperature, were determined. A theoretical analysis was conducted for the prediction of values and analysis of the nature of the magnetic body forces induced in a magnetic fluid in the presence of heat and magnetic fields. A technique is introduced for the prediction of the maximum pressure difference that a "thermomagnetic pump" could produce. The advantages of a thermomagnetic pump are that it is noise free and reliable due to the absence of moving parts and control devices. At present, however, the flow rates generated by such a system are small and much research and development is needed for practical applications.