Automatic cooling by means of thermomagnetic phenomenon of magnetic nanofluid in a toroidal loop

Flow and heat transfer characteristics of a temperature-sensitive magnetic nanofluid are numerically investigated in a toroidal loop in the presence of magnetic field using the two-phase mixture model. This system uses permanent magnet(s) and the waste heat produced from a chip or other sources to maintain the flow of coolant which transfers heat to a heat sink for dissipation. Different parameters including the amount of heat flux in the heat source, temperature of heat sink, magnet position and its magnetic strength are studied. In this system, no additional energy other than the waste heat is consumed for driving the cooling device and it is completely self-powered. Applying the heat flux causes fluid motion in the loop since magnetization of the magnetic fluid depends on the temperature, with the fluid velocity being intensified by increasing the heat flux. Meanwhile, the circulation velocity of the fluid in the loop increases by about 100% in the case of using two magnets, two heat sinks and two heat sources. Moreover, the response time of the system, i.e. the time required for reaching a desirable cooling rate in the cycle, is examined for different conditions and the obtained results are discussed. (C) 2016 Elsevier Ltd. All rights reserved.