Experimental and numerical investigations on nanofluids flows at different geometrical configurations and different thermo-fluid conditions show a significant enhancement on the convective heat transfer while the pumping power cost remains reasonable. However, many problems such as sedimentation and agglomeration of nanoparticles in nanofluids and their dispersion stability have not been well addressed in order to be widely used in different industrial installation. Nanofluid stability is affected by many factors such as Brownian motion, thermophoresis, drag force and DLVO (Derjaguin, Landau, Verwey and Overbeek) surface forces. This paper intends to theoretically study the dispersion stability of nanofluids considering these effects. The kinetic energy of particles is resulted from the balance of the Brownian force, thermophoretic force and drag force while the potential energy between the nanoparticles is determined using DLVO theory. It is considered the particles agglomerate if the particle kinetic energy could overcome the DLVO barrier potential energy exists around the target particle. The values of these forces depend on different parameters such as fluid temperature, temperature gradient, nanoparticle diameter and base fluid and particles physical properties. Therefore, the effects of these parameters including temperature of nanofluid, thermal gradient and nanoparticles mean diameter on the stability of different nanofluids have been studied.
Journal: TechConnect Briefs
Volume: 2, Nanotechnology 2011: Electronics, Devices, Fabrication, MEMS, Fluidics and Computational
Published: June 13, 2011
Pages: 539 - 542
Industry sectors: Advanced Materials & Manufacturing | Sensors, MEMS, Electronics
Topic: Micro & Bio Fluidics, Lab-on-Chip