Numerical Assessment of Advanced Thermo-Hydrodynamic Characteristics of Nanofluid Inside a Helically Featured Straight Pipe

Abstract

This research set out to look at the aspects of flow and convective heat transfer in this novel geometry for helically corrugated pipes. The main goal is to evaluate the thermo-hydrodynamic performance of single and hybrid nanofluids in this modified shape at various Reynolds numbers and densities of nanoparticles. With dimensional modifications, such as helical pitch and corrugation shape at the inlet, different case studies were performed for comparison in heat exchanger performance. The simulations were conducted using the ANSYS commercial program, employing the Realizable k-epsilon turbulence model. A uniform heat flux of 1000 W/m2 was assumed, and the Reynolds numbers ranged from 5000 to 20,000. The study makes use of computational techniques to evaluate the thermo-hydrodynamic capabilities of corrugation coupled with varying volume fractions (1–5 %) of single-phase nanofluids (Al2O3 and CuO) and hybrid nanofluid (1 % Al2O3/Cu) where water is kept as the conventional base fluid. The second-order upwind technique is applied for solution approximation and discretization with SIMPLE pressure-velocity coupling. Within the collection of case studies, it was observed that the most significant enhancement occurred when there was a modification in the shape of the corrugation inlet. Additionally, concerning the corrugation pitch, it was found that the tube with the smallest pitch exhibited notably improved performance. Due to the intricacy of these corrugations, which enhances heat transmission and pressure drop, a higher Nusselt number results. The heat transfer coefficient for various nanoparticle compositions for the helically corrugated pipe is demonstrated to be 20–30 % greater than for the smooth pipe. Considering the pressure drop penalty and heat transfer increment in terms of performance evaluation criterion (PEC), the 1 % Al2O3/Cu water hybrid nanofluid has been found to be the best-acquitted working fluid in the corrugated pipe flow with a maximum thermal performance improvement of 26.5 %. The study also shows that the gain in thermal efficiency steadily declined with increasing Re but increased as the nanofluid's volume concentration climbed.