Thermo-hydraulic Analysis of Helically corrugated geometry using Single phase and Hybrid Nanofluids

Abstract

This research set out to look at the aspects of flow and convective heat transfer in helically corrugated pipes. The main goal is to evaluate the thermo-hydrodynamic performance of single and hybrid nanofluids in this modified shape at different Reynolds numbers and nanoparticle volume concentrations. With dimensional modifications as in helical pitch, corrugation shape at the inlet, different case studies were performed for comparison in heat exchanger performance. Assuming a uniform heat flux of 1000 W/m2, Realizable k-epsilon turbulence model was used in ANSYS-FLUENT-2020 R1 commercial software to carry out the simulations at Reynolds numbers ranging 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). For solution approximation and discretization with SIMPLE pressure-velocity coupling, the second-order upwind technique is applied. Among the case studies, a change in corrugation inlet shape depicted the maximum augmentation whereas in terms of corrugation pitch, the lowest pitch corrugated tube had a considerably superior performance. Due to the intricacy of the corrugations, which enhances heat transmission and pressure drop with large volume fractions, a higher Nusselt number results. The heat transfer coefficient for various nanoparticle compositions for the helically corrugated pipe was demonstrated to be 20–30% greater than for the smooth pipe. Considering the pressure drop penalty and the heat transfer increase in terms of performance evaluation criterion (PEC), the 1% Al2O3/Cu water hybrid nanofluid was 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 as the Re rose, but it increased with an increase in the volume concentration of the nanofluid.