Summary A thermoelectric generator system is an essential component in thermal energy storage. Through the interaction of magnetic field and thermoelectric current, the thermal energy of liquid metal can be converted into kinetic energy directly, which stirs up a flow without an external hydraulic pump. The effect of the magnetic field on the flow pattern, velocity, and heat transfer efficiency of the self‐driven thermoelectric system is investigated through three‐dimensional numerical simulation. The coupling effect of the magnetic field, temperature field, and velocity field are taken into consideration using the consistent conservative scheme and partitioned iteration algorithm for multi‐region. Hartmann number (Ha) and thermoelectric number (Te) are introduced to measure the relative strength of magnetic damping effect and Seebeck effect. When the magnetic field is small (Ha/Te1/4 ≤ 0.52), the Seebeck effect dominates the flow in the bulk flow region, the velocity of rotating flow increases with the magnetic field, the direction of the Lorentz force is consistent with the flow direction. The maximum velocity of the thermoelectric system occurs when Ha/Te1/4 ∼ 0.52. Hereafter, the flow is dominated by the magnetic damping effect, the velocity decays gradually. A rotating flow in a horizontal plane is resulted from the vertical magnetic field, while a rotating flow in a vertical plane results from a horizontal magnetic field. The latter flow structure gets a larger Nusselt number and lowers the decay rate of kinetic energy because it can transport heat downward more efficiently. The rate of working of the Lorentz force depends on the magnitudes of the Seebeck coefficient and temperature difference.

In the fusion reactor, the conducting liquid metals usually work in an environment of large temperature differences and strong magnetic field. The flow driven by the interaction of the Seebeck effect and magnetic field enlightens a promising approach to enhance heat transfer under strong magnetic field. Liquid metal thermal convection affected by the Seebeck effect and magnetic field is simulated using the partitioned iteration algorithm with liquid lithium as working fluid. It is found that the Seebeck effect can change energy transport pattern and greatly improve the heat transfer efficiency under strong magnetic field. With the increase of magnetic field intensity, the flow changes from steady vertical circulation to unsteady horizontal circulation and finally to steady horizontal circulation. The flow regime diagram based on the two dimensionless parameters, Gr / Te and Ha 2 / Te , can reflect the characteristics of different energy transport patterns. The flow generated by the Seebeck effect is most remarkable when O Ha 2 / Te ≈ 1 . The Nusselt numbers at different flow regimes show that the Seebeck effect can enhance the heat transfer efficiency of liquid metal under strong magnetic field about 50% and 90%, respectively, under different Glashof numbers.

The presence of large temperature gradients in liquid metals during heat transfer can also induce thermoelectric effects, which can lead to pumping or stirring of liquid metals under the action of magnetic fields. The thermoelectric effect of liquid metals has potential application background in both nuclear fusion and metal metallurgy. In this paper, an experimental study of flow driven by the Seebeck effect, in which the temperature-dependent voltage difference at an interface between dissimilar metals, in the presence of a magnetic field, can be used to create a Lorentz force. It is proposed that this method could be used for cooling electronics, fusion reactors, and solar technologies. The working fluid is eutectic gallium–indium–tin, and flow measurements are made with ultrasound. The flow velocity tends to increase and then decrease as the magnetic field increases. Two scaling relations are developed to predict the velocity, one for weak magnetic fields and one for strong magnetic fields. Those predictions are combined to estimate the maximum velocity. Temperature gradients and wall conductance ratio have a significant effect on the Seebeck effect self-driven flow. It is found that the self-driven flow velocity caused by the Seebeck effect is positively correlated with the number of channels in the multi-channel experiments. This design idea of self-generated flow and heat transfer of liquid metal in the magnetic field will provide the possibility of pumpless self-driven liquid lithium flow in nuclear fusion reactors and provide new ideas for cooling of electronic products and related energy-saving and emission reduction applications.