Sustainable Heat Transfer Management: Modeling of Entropy Generation Minimization and Nusselt Number Development in Internal Flows with Various Shapes of Cross-Sections Using Water and Al2O3/Water Nanofluid

In order to achieve the best performance of a thermal system, two major analyses must be carried out on the system: energy and entropy generation. The best scenario is a mechanism in which the system has minimum entropy generation and the highest Nu number. In this regard, we investigated entropy generation and Nu number of fluid flow through tubes of various cross-sections, namely circular tubes, square channels, and rectangular ducts. Additionally, the addition of nanoparticles was tested, and both analyses were carried out. The results reveal that using nanoparticles could significantly increase Nu number and, at the same time, decrease entropy generation. The results showed that the circular cross-section performs better in Nu number and entropy generation. In most cases, the rectangular cross-section performed better than the square one in terms of energy and entropy. In the best case, the average Nu for the circular cross-section was 26% greater than that of the square. The average Nu of the rectangular cross-section showed that this value is 5% greater than that of the square cross-section. Additionally, the total entropy generation of circular cross-sections, which is the minimum, was 44% and 38% lower than rectangular and square cross-sections, respectively.