Numerical analysis of nanofluid thermal performance using a nozzle-type mixer and computation fluid-dynamics

Abstract

Abstract This study numerically investigates the thermal performance of a Therminol VP-1-based nanofluid using computational fluid dynamics. The research focuses on analyzing the localand global effects of nanoparticle dispersion on temperature distribution and heat transfer efficiency within a symmetric channel under forced convection, uniform heat flux, and defined inlet velocities; traditional thermal fluids are limited by low thermal conductivity, which motivates the use of nanofluids-suspensions of metallic or metallic oxide nanoparticles-known for significantly improving thermal conductivity and heat transfer properties. A single-phase computational fluid dynamics model was employed, treating the nanofluid as a homogeneous medium with temperature-dependent thermophysical properties, assuming a constant silver nanoparticle volumetric fraction of 1%. Effective nanofluid properties were calculated using classical correlations that combine the properties of the base fluid (Therminol VP-1) and silver nanoparticles, defined as a function of temperature within a range of 303.15 K to 498.15 K; boundary conditions included a uniform inlet velocity of 10 m/s and a temperature of 300 K, a zero relative pressure outlet, a constant upper wall temperature of 423 K (heat source), and adiabatic conditions for the remaining walls. A mesh independence study was conducted to ensure numerical convergence, with variations in the Nusselt number below 1% for element sizes smaller than 5.0×10 −5 m, confirming the reliability of the obtained data; the maximum Nusselt number values approached 16 at a heat load of 12400 W·m −2 , particularly in configurations with larger nozzle diameters, representing over a 700% increase compared to lower heat loads. This highlights a substantial improvement in convective efficiency due to thermal expansion and fluid mixing in less restrictive areas. The temperature contours visually validated the mixing effect of the nozzle, showing a more homogeneous thermal distribution towards the channel axis in high heat flux conditions. The study concludes that the nozzle geometry’s effectiveness as a thermal mixer is highly dependent on the applied thermal load, demonstrating significant improvements only under high energy thermal regimes.