The second law of thermodynamic analysis for longitudinal strip inserted nanodiamond-Fe3O4/water hybrid nanofluids

Abstract

Experiments to estimate the Nusselt number, friction factor, exergy efficiency, and thermal entropy generation of longitudinal strip inserted water diluted nanodiamond-Fe3O4 hybrid nanofluids circulate in a conduit have been carried out. The studies were carried out using Reynolds numbers ranging from 2000 to 22000, particle volume concentrations ranging from 0% to 0.2%, and longitudinal strip insert aspect ratios ranging from 0 to 4, respectively. In contrast to water data, the Nusselt number of 0.2% vol. hybrid nanofluid is raised by 29.55% at a Reynolds number of 18572. Similarly, when 0.2% vol. hybrid nanofluid with a longitudinal strip inserts aspect ratio of 1, the Nusselt number is 87.21% higher than water in a plain tube. In comparison to water, the friction factor penalty is 11.36% at 0.2% vol. of hybrid nanofluid and 46.33% at 0.2% vol. of nanofluid and with longitudinal strip insert aspect ratio of 1. Increased particle concentrations reduce the thermal entropy generation, which is further reduced by using a longitudinal strip insert with an aspect ratio of 1. Furthermore, the formation of frictional entropy is increased as particle concentrations and inserts. The exergy efficiencies for water and 0.2% vol. of hybrid nanofluid are 18.95% and 25.55%, respectively, but at 0.2% vol. of hybrid nanofluid and with longitudinal strip insert of aspect ratio 1 and at a Reynolds number of 18521, it is raised by 64.85%. The calculated thermal performance factor for all of the test situations is more than 1, indicating that hybrid nanofluids and inserts are effective at enhancing heat transfer. Nusselt number and friction factor generalized correlations were developed.