**4. Conclusions**

To improve the thermal performance of a square heat exchanger, four samples of nanofluids were covalently synthesized and produced. In order to start, all nano-coolants' thermophysical properties were tracked versus the temperature to perform studies on the effects of heat and momentum transfer in fully developed turbulent forced convective flow. Different conditions were implemented, such as varying temperatures, different nanofluids, and different Re numbers.

From the results of this work, the following was concluded:


**Author Contributions:** Conceptualization, M.S.A., A.H.J. and R.Z.H.; data curation, H.A.A., M.H.N., Z.H.M., M.S. and Z.M.Y.; formal analysis, H.A.A., A.M.A., A.H.J., M.H.N., R.Z.H., Z.H.M., A.H.A., M.S. and Z.M.Y.; investigation, M.H.N., A.M.A., R.Z.H., Z.H.M., A.H.A. and Z.M.Y.; methodology, M.S.A., A.H.J. and A.H.A.; resources, H.A.A., M.H.N. and R.Z.H.; software, M.S.A.; supervision, A.H.J. and M.S.; validation, H.A.A., A.M.A., M.S.A., Z.H.M., A.H.A., M.S. and Z.M.Y.; visualization, H.A.A., A.H.J., A.M.A., Z.H.M., A.H.A. and Z.M.Y.; writing–original draft, H.A.A., M.S.A., A.H.J., A.M.A., M.H.N., R.Z.H., Z.H.M., A.H.A., M.S. and Z.M.Y. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was financially supported by RainSolutions (Water JPI 2018 Joint Call project).

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

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** All the data are presented in the manuscript.

**Acknowledgments:** The authors would like to thank Al-Mustaqbal University College for providing technical support for this research.

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