Experimental Study on the Heat Transfer Performance of Various Magnet Arrangements in a Closed Space Filled with Ferrofluid

Abstract

In this study, experiments, simulations, and optimization were performed to evaluate heat transfer performance of ferrofluids. Ferrofluids are colloidal suspensions containing magnetic-nano particles with a diameter of 5 to 15 nm in a base fluid such as oil or water. Recently, as many devices are miniaturized, the design of heat dissipation systems are being diversified to consider cost and safety, and it is becoming important to separate an ancillary device for cooling from main unit. In ferrofluids, the behavior and vortex of magnetic-nano particles are actively generated by an external magnetic field, and the cooling system can be designed in a simplified manner by using this characteristic. The main design parameter is the arrangement of permanent magnets, and the output variable is the temperature inside the magnetic nanofluid. The permanent magnet can be moved up and down, and the temperature inside the magnetic nanofluid was measured at various locations. A predictive model was created using a design of experiments (DOE) and response surface method (RSM) using selected design and temperature variables. Based on the generated regression model, an optimization was applied to find a permanent magnet arrangement that maximizes heat transfer performance. Through the optimization technique used in this study, economic efficiency in terms of time and cost was obtained by reducing the number of experiments.