بررسي تجربي خواص رئولوژي نانوسيال حاوي دو نانوذره به صورت همزمان در مخلوط آب و اتيلن گليكول

چكيده انگليسي :

83Experimental Investigation of Rheological Behavior of Nanofluid Containing Binary Nanoparticles in a Mixture of Water and Ethylene Glycol Shayan Chabok s chabok@me iut ac ir August 19 2015 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor A A Alemrajabi Assoc Prof rajabi@cc iut ac ir Abstract Nanofluids have attracted considerable attentions over the last two decades due to their special characteristics invarious fields including heat and mass transfer energy mechanical and biomedical applications Nanofluid is a fluidin which nanometer sized particles were dispersed Since the nanofluids benefit from the high heat transfercoefficient therefore one of the most important areas of their application is in the field of heat transfer As it isevident one of the important variables in heat transfer is viscosity Viscosity determines not only the heat transfercharacteristics but also the fluid flow characteristics in ducts as well as pumping power Viscosity of a nanofluid isaffected by a variety of factors In this project the effects of the major factors such as ultrasonication duration nanoparticle concentration shear rate temperature and base fluid on the viscosity and rheological properties of thenanofluid were experimentally investigated The nanofluids studied in the present res earch comprise two types ofnanofluids routine nanofluids nanofluids containing only one type of nanoparticles and hybrid nanofluids nanofluids containing two or more different types of nanoparticles The idea of using hybrid nanofluid in fact is toachieve a trade off between the desired properties of the constituent nanoparticles Due to their various advantagesand disadvantages alumina and copper oxide nanoparticles have been used in this project Among the advantages ofalumina good stability chemical inertness dispersibility in most fluids ease of access cost effectiveness and thebenefits of copper oxide relatively high thermal conductivity and anti wear characteristics could be mentioned Among the drawbacks of alumina higher nanofluid viscosity increase and lower thermal conductivity compared withthose of copper oxide nanofluids and disadvantages of copper oxide less stability of copper oxide nanofluids couldbe mentioned The base fluid used in the present research is the mixture of water and ethylene glycol Thenanoparticles were dispersed in the base fluid by ultrasonication technique By using uv visible spectrophotometry itwas found out that by increasing ultrasonication duratio n dispersibility of nanoparticle in the base fluid enhanced butalso viscosity of the nanofluid increased By increasing the nanoparticle concentration it was observed that theviscosity of nanofluid went up Among those tested the alumina nanofluid showed the highest enhancement ofviscosity and the copper oxide nanofluid showed the least and the hybrid nanofluids depending on the ratio of thecomposition of the nanoparticles took the intermediate values so that the nanofluids containing more aluminadisplayed more increase in viscosity Alumina nanofluid with weight concentration of 1 showed up to 53 increasein viscosity relative to that of the base fluid It was also shown the underestimation of the Einstein s and Batchelor stheoretical equations By investigation of the effect of the shear rate it was found out that all the nanofluids tested had non Newtonian and shear thinning behavior It was also observed that the nanofluids containing more aluminahad the greater degree of shear thinning Another issue that was made clear was that the degree of non Newtonianbehavior increases with the nanoparticle concentration so that for instance in a low concentration the copper oxidenanofluid showed a near Newtonian behavior The flow curve and the rheological behavior of the nanofluids werewell described by the Cross s Bingham s and Herschel Bulkley s empirical equations In the case of the effect of thebase fluid it w

چابك، شايان

بررسي تجربي خواص رئولوژي نانوسيال حاوي دو نانوذره به صورت همزمان در مخلوط آب و اتيلن گليكول

نانو سيال مركب , ويسكوزيته , آلومينا , اكسيد مس