Abstract
Second law efficiency (exergy) was studied experimentally for transition flow in a tube of 40:60% (weight) p4ropylene glycol and water mixture based nanodiamond nanofluid. Prior to prepare the stable nano-diamond (ND) nanofluid, its soot was rinsed by strong chemicals. The experiments were carried out for several values of particle loading (0.2% to 1.0%) and of Reynolds number (2000 to 8000). The experimental analysis was also conducted for the heat transfer, friction factor and pumping power characteristics of the ND nanofluid. By increasing the values of particle concentration and Reynolds number, the results indicate an increase of heat transfer, Nusselt number, friction factor, pumping power and thermal performance factor, and a decrease of the thermal entropy generation. In comparison with the base fluid data, the heat transfer coefficient, Nusselt number, pressure drop, pumping power, friction factor and the thermal performance factor of the ND nanofluid augment by 36.83%, 24.16%, 15.38%, 13.18%, 19.9%, and 16.94%, respectively, and the thermal entropy generation decreases by 26.92% for 1.0 vol% and Reynolds number of 5321.16.
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•The heat transfer coefficient is raised by 36.83% at Re = 5321.16 and at ϕ = 1.0%.•The Nusselt number is increased by 24.16% at Re = 5321.16 and at ϕ = 1.0%.•Thermal performance factor is increased to 16.94% at Re = 5321.16 and at ϕ = 1.0%.•Thermal entropy generation of 1.0 vol% of nanofluid is decreased to 26.92%.