Experimental investigation of natural convection Al2O3-MWCNT/water hybrid nanofluids inside a square cavity

The use of nanofluids for convectional heat transfer has become a spry area of research in recent years with the aim of improving heat transfer efficiency. Hybrid nanofluids have attracted significant attention and are advancing research and industrial applications since they involve employing more than one type of nanoparticle(s) in a base fluid. They enhance heat transfer by combining the chemical and physical properties of several nanoparticles concurrently and providing the properties in a homogeneous state. However, few experimental studies have focused on natural convective heat transfer using hybrid nanofluids. In this study, the natural convection of alumina - multiwalled carbon nanotube/water hybrid nanofluids formulated using a two-step method at a percentage weight ratio of 10:90 Al2O3: MWCNT at various nanoparticles volume concentrations of 0.00, 0.05, 0.10, 0.15, and 0.20 vol% was studied inside a square cavity (AR = 1) with two vertical walls which are isothermal, aimed at the Rayleigh number (Ra) range of 2.81 x 10(8) to 8.58 x 10(8). The average Nusselt number (Nu(av)), heat transfer coefficient (h(av)), heat transfer (Q(av)), and Rayleigh number (Ra) were considered at varying temperature gradients of 20 degrees C - 50 degrees C. Al2O3-MWCNT/water hybrid nanofluid with 0.10 vol% volume concentration was discovered to have the maximum value for h(av),Q(av), and Nu(av). However, it was also observed that a further increase in the hybrid nanoparticles' volume concentration led to their deterioration at various temperature gradients. The maximum enhancements of 44%, 49%, and 42% were noted for h(av),Q(av), and Nu(av), respectively, at increment T = 50 degrees C, in comparison with the base fluid. Al2O3-MWCNT/water hybrid nanofluids application in a square cavity demonstrated enhanced natural convection. This present study concluded that hybrid nanofluids as heat transfer fluid significantly improved heat transfer performance compared to the base fluid.

Automated summary

The use of hybrid nanofluids for convectional heat transfer has shown great potential in improving heat transfer efficiency. This study experimentally investigated the natural convection heat transfer performance of alumina-multiwalled carbon nanotube/water hybrid nanofluids in a square cavity and found that the hybrid nanofluid with a volume concentration of 0.10 vol% exhibited the best heat transfer performance.