Advanced Thermo-Hydraulic Assessment of Helical Pipes with Different Shapes of Jackets Using Single-Phase and Hybrid Nanofluids

Abstract

This study investigates the efficiency and flow characteristics of helical pipes with different jacket shapes, utilizing single and hybrid nanofluids to enhance heat transfer. The research work presented here provides a unique, coherent method to enhance heat transfer efficiency by concurrently incorporating geometrical alterations and improving operating fluid efficiency. A computational framework analyzes turbulent flow in three-dimensional helical pipes with Reynolds numbers ranging from 5000 to 30,000 and a constant heat flux of 1000 W/m2. This investigation involves evaluating the thermo-hydrodynamic performance of spiral pipes with circular, triangular, and square-shaped jackets, using various volume fractions of single-phase nanofluids (water-based Al2O3 and CuO nanofluids) and a water-based hybrid nanofluid comprising Al2O3/Cu. The results indicate that using different nanofluids significantly improves the Nusselt number value and heat transfer coefficients, ranging from 36 % to 60 % compared to water in a smooth coiled pipe. The strategic design of the jacket enhances the Nusselt number values by generating vortices and increasing turbulence. The Bejan number indicates greater irreversibility in the heat transfer process, leading to substantial energy dispersion. The performance evaluation criterion (PEC) value exceeding one suggests that the modified geometries have the potential to outperform smooth channels.