**5. Conclusions**

The charging process of a TES unit filled with a nonuniform metal foam was studied. The metal foam was saturated with coconut oil–CuO NEPCM, and the porosity was linearly changed from bottom to top. Hot water flowed in the heat transfer tube. Finite element method FEM was applied to solve the governing partial differential equations for momentum and phase change energy. The Taguchi optimization method was employed to find an optimum design for the TES unit. The results led to the following conclusions:


**Author Contributions:** Conceptualization, M.G., S.A.M.M., and P.T.; methodology, M.G., S.A.M.M., H.S., F.S., O.Y., K.I., G.A., and P.T.; software, S.A.M.M., H.S., and F.S.; validation, S.A.M.M. and M.G.; formal analysis, S.A.M.M., H.S., and F.S.; investigation, M.G., S.A.M.M., H.S., F.S., O.Y., K.I., G.A., and P.T.; resources, M.G. and O.Y.; writing—original draft preparation, M.G., S.A.M.M., H.S., F.S., O.Y., K.I., G.A., and P.T.; writing—review and editing, M.G., S.A.M.M., H.S., F.S., O.Y., K.I., G.A., and P.T.; visualization, S.A.M.M., H.S., and F.S.; supervision, M.G. Authorship must be limited to those who have contributed substantially to the work reported. All authors have read and agreed to the published version of the manuscript.

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

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data is contained within the article.

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

#### **References**

