High-performance magnetic thermal switch based on MnFe2O4/Ethylene Glycol:Water refrigerant dispersion

The use of magnetic nanoparticles for the remote control of heat transfer in electronic devices can overcome the current limitations of appliance engineering. In this work, we demonstrate that a thermal switch based on a low-cost and stable MnFe2O4/Ethylene Glycol:Water (MFO/EG:W) dispersion can increase the span temperatures as high as 60% in the 0.01–0.60 Hz operating frequency range under the same heat supply for different recipient filling ratios (FR). Under the optimum condition of FR = 80%, the efficiency of our new MFO/EG:W colloidal dispersion is twice the obtained for the commercial Fe3O4/paraffin oil fluid. From numerical calculation, we demonstrate that the improved heat exchange efficiency relates to the three-steps effective thermal conductivity variation during operation, expanding the contact time between the heat and cold sources. Thus, the combination of an EG:W refrigerant solution and superparamagnetic MFO nanoparticles with high saturation magnetization allows their use for heat management control of electronic systems for long operation periods.