Abstract
This paper presents the results of bio-based functionalized nanofluids on heat transfer and pressure drop investigation in square and circular tube heat exchangers to obtain enhanced heat dissipation. Graphene nanoplatelet (GNP) was covalently functionalized with the clove bud extractions. At different concentrations of graphene in nanofluid, the results showed higher thermal conductivity with the rising of the suspension concentrations. The nanofluid was compared with the traditional working fluid (water), and the result showed higher thermal conductivity and improved heat transfer coefficient. The present experimental investigation focused on the performance of heat transfer, thermophysical properties and pressure drop of GNP-based water nanofluid in different configurations of heat exchanger tubes. Substantial improvement in the rate of heat transfer with the loading of well-dispersed GNPs in the base fluid was observed. The nanofluid enhances the heat transfer coefficient irrespective of the circular or square flow passage configurations. Furthermore, the heat transfer coefficient enhanced with the increase in concentrations of the nanoparticles in the fluid and the pressure loss increment was much less relative to the gain in heat transfer. The Nusselt number in the circular test section was higher than that in the square test section. Thus, the GNP water-based nanofluids emerged as a potential high-performance heat exchanging liquid utilizing circular flow passage.