**4. Conclusions**

Magnetohydrodynamic pump-based microchannel cooling is proposed for cooling heat dissipating elements. The proposed magnetohydrodynamic pump has many advantages including vibration-free and noise-free applications. In the present study, the applied voltage and Hartmann number are varied to evaluate the effect on the MHD pump performance considering normal current density, magnetic flux density, volumetric Lorentz force, shear stress and pump flow velocity as evaluating parameters. The MHD pump-based microchannel cooling system performance with Cu-water nanofluid is evaluated considering the maximum temperature of the heat dissipating element, heat removal rate, efficiency, thermal field, flow field and Nusselt number for various applied voltages and Hartmann numbers. It is found that for a low Hartmann number, the Lorentz force increased with an increase in the applied voltage and Hartmann number. As the applied voltage increased from 0.05 V to 0.35 V at a Hartmann number of 1.41, the heat removal rate increased by 39.5%. The results revealed that for a low Hartmann number, the average Nusselt number increased with increase in the applied voltage and Hartmann number. As the applied voltage increased from 0.05 V to 0.35 V at a Hartmann number of 1.41, the average Nusselt number increased by 112.6%. In addition, the influence of various nanofluids including Cu-water, TiO2-water and Al2O3-water nanofluids on heat transfer performance of MHD pump-based microchannels is evaluated. At the Hartmann number value of 3.74 and applied voltage value of 0.35 V, average Nusselt numbers are 12.3% and 15.1% higher for Cu-water nanofluid compared to TiO2-water and Al2O3-water nanofluids, respectively. The MHD pump is more useful in cases where space and noise constraint are of particular interest. Especially in the microelectronics device cooling, the removal of heat is important and due to miniaturization, the MHD pump for cooling provides a promising option. The investigations provide an opportunity to further explore the application of MHD pumps in electronics cooling.

**Author Contributions:** Conceptualization, J.-H.S.; M.S.P. and M.-Y.L.; methodology, J.-H.S.; software, M.S.P.; validation, J.-H.S. and M.S.P.; Numerical investigation, J.-H.S. and M.S.P.; resources, M.-Y.L. and S.P.; data reduction, M.S.P. and S.P.; writing—original draft preparation, J.-H.S. and M.S.P.; writing—review and editing, M.-Y.L., and S.P.; visualization, M.S.P.; supervision, M.-Y.L.; project administration, M.-Y.L.; funding acquisition, M.-Y.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** This work was supported by the Dong-A University research fund.

**Conflicts of Interest:** The authors declare no conflict of interest.
