Optimization and correlations development for heat transfer and fluid flow characteristics of ZnO/H₂O-ethylene glycol-based nanofluid flow through an inclined ribbed square duct

Abstract

One simple technique to improve the heat transfer rate is to roughen a square duct’s heated plate. This work is concerned with the heat transfer ($Nu$) and friction factor ($f$) of $\mathit{ZnO}$/${\mathrm{H}}_2\mathrm{O}$/ethylene glycol nanofluid flowing in ribbed square duct were optimized, and correlations have been developed. Design parameters include nanoparticle concentration (φ) 1–4%, relative angled rib pitch ${(P}_R/e_R)$2.18–3.25, relative angled rib height ${(e}_R/D_h)$0.10–0.25, flow attack angle of inclination rib $({\alpha }_{\mathit{inc}})\mathrm{ }40–{70}^0,$ and Reynolds number (Re) 4000–19,000. The response surface method (RSM) was utilized for optimization. Varying the roughness parameters improves the heat transfer performance of inclined ribbed, but it increases the pumping power of the square duct. RSM results indicated that the maximum heat transfer enhancement belongs to φ of 4%, $P_R/e_R$ of 2.50, $e_R/D_h$ of 0.20, and ${\alpha }_{\mathit{inc}}$ of 60°. In addition, a generalized quadratic correlation for Nu and f is constructed based on the analysis of variance, with percentage deviations of $\pm 12.4\mathrm{\%}$ and $\mathrm{ }\pm 9.3\mathrm{\%},$ respectively, in contrast to empirically obtained values of Nusselt number and friction factor.

Keywords:

• Heat transfer
• nanofluids
• RSM
• statistical correlation

Authors’ contributions

Conceptualization and correlation development- A.K. (Anil Kumar) and S.K. (sunil Kumar); Methodology, software, and validation- A.K., and Priyanka; Formal analysis, data curation, and result discussion- A.K., S.K.; Writing - original draft preparation – Priyanka; Writing - review and editing S.K. (Susheel Kalia). All authors have read and agreed to the published version of the manuscript.