Experimental study on thermal efficiency improvement using nanofluids in heat sink with heated circular cylinder

Thermal efficiency is applied to research the hydraulic and thermal characteristics of nanofluids flowing around the heated circular cylinders with vertical fin in heat sink. The influences of fin heights (H = 2 mm, 3 mm, 4 mm) on the thermo-hydraulic characteristics of Fe3O4-water nanofluids are explored. Moreover, the influences of nano-particle mass fractions (ω = 0.0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%) and Reynolds numbers (Re = 491–1223) are investigated. Research shows that nanoparticle mass fraction (ω = 0.4%) and fin height (H = 3 mm) are the most suitable working conditions for the best heat exchange performance. Furthermore, the thermal efficiency and comprehensive performance index have been used to investigate the comprehensive cooling characteristics of the fin structures and nanofluids in the heat exchange system. It is discovered that thermal efficiency increases with the fin height. Comprehensive performance of the heat exchange system is significantly enhanced by the fin structure in circular cylinder.