**4. Conclusions**

Our experimental studies of electronic heat sinks filled with and without metal foam led to the following conclusions.

Within the specified flow rate range (10 L/h to 60 L/h), the convective heat transfer coefficients of both unfilled and filled electronic heat sinks gradually increase as the fluid flow rate increases. However, the convective heat transfer coefficient of the filled electronic heat sink is significantly higher than that of the unfilled electronic heat sink. As the number of fins in an electronic heat sink increase, the convective heat transfer coefficient tends to increase and then decrease. Additionally, the convective heat transfer coefficient is the highest when the number of fins is three.

For metal foam-filled electronic heat sinks, the rate of increase in the heat transfer coefficient gradually decreases as the flow rate increases. The rate of increase in the convective heat transfer coefficient decreases when the fluid flow rate is in the range from 10 to 30 L/h. The rate of increase in the convective heat transfer coefficient gradually increases when the fluid flow rate is between 30 and 60 L/h.

Within the specified range of the fluid flow, the pressure drop of the filled metal foam radiator gradually increases with the increase in the fluid flow. Under the same fin conditions, the greater the pore density of the filled metal foam, the greater the pressure drop. However, the effect on the pressure drop is similar when the metal foam is filled with different materials under the same fins. As the number of electronic heat sink fins increases, the pressure drop tends to rise for both the filled and unfilled metal foam.

Within the specified flow range, the Nusselt number gradually increases with the increasing Reynolds number, considering the effect of *Re*. The trend is the same for different pore densities and different radiator fins. The Nusselt number reaches its maximum value when the number of electronic heat sink fins is three. Therefore, the heat transfer capacity of the heat sink reaches its maximum when the number of fins of the electronic heat sink is three.

**Author Contributions:** Conceptualization, B.L. and R.B.; Formal analysis, B.L. and Z.Z.; Investigation, X.S. and R.W.; Writing—original draft, X.S.; Writing—review & editing, B.L., R.B. and P.E.T. All authors have read and agreed to the published version of the manuscript.

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

**Data Availability Statement:** Not applicable.

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