Modeling Nanoparticle Electrification in the Radiative Boundary Layer Flow of Nanofluid with Internal Heat Generation

Abstract

Nanofluids are colloidal suspensions of nanosized solid particles in a liquid. newlineRecently conducted experiments have indicated that nanofluids tend to have newlinesubstantially higher thermal conductivity than base fluids. Among the many newlineadvantages of nanofluids over conventional solid liquid suspensions, the following newlineare worth mentioning higher specific surface area, higher stability of the colloidal newlinesuspension, lower pumping power required to achieve the equivalent heat transfer, newlinereduced particle clogging compared to conventional colloids, and a higher level of newlinecontrol of the thermodynamics and transport properties by varying the particle newlinematerial, concentration, size, and shape. newlineHeat transfer enhancement or augmentation or intensification refers to the newlineimprovement of thermal performance of any heat transport process, heat newlineexchanging medium, component, device, or equipment. It could mean that the heat newlinetransfer rate of a given surface is increased; the peak temperature of a chip hot spot newlineis reduced; the critical heat flux for pool boiling heat transfer is soared; the thermal newlineconductivity, specific heat capacity, or latent heat of an energy storage medium is newlineraised; etc. A variety of techniques or methodologies can be applied to such effects. newlineThe methodologies for augmenting convective heat transfer were generally newlineclassified into three categories: passive techniques, active techniques, and newlinecompound techniques. The passive ones do not require external power through newlinetechniques such as extended surfaces (fins), rough surfaces, treated surfaces, newlinedimples and protrusions, inserts, coiled tubes, swirl-flow devices, displaced newlineenhancement devices, or fluid or particle additives; whereas, the active techniques newlinerequire external power to bring about the effect, including mechanical aids, surface newlinevibration, fluid vibration, electric or magnetic field, injection, suction, jet newlineimpingement, etc. Compound enhancement combines two or more of the above newlinetechniques to produce an effect that is larger than any of the enhancement newlinetechniques op