E ff ect of Ultrasonication Duration on Colloidal Structure and Viscosity of Alumina − Water Nano fl uid

: Nano fl uids are promising fl uids for heat-transfer applications. Low stability and high viscosity are two important drawbacks for practical applications of nano fl uids. The aggregation and sedimentation of nanoparticles are related to the colloidal structure of nano fl uids, which directly a ff ects the stability and viscosity. An ultrasonic homogenizer can break the aggregation of particles. The aim of this work was to study the e ff ect of the duration of ultrasonic treatment on colloidal structure, including the stability and temperature-dependent viscosity of a nano fl uid. Speci fi cally, a 0.5 vol % Al 2 O 3 − water nano fl uid was prepared using an ultrasonic homogenizer for various durations from 0 to 180 min. The microstructure, colloid and particle sizes, precipitation, and zeta ( ζ ) potential were analyzed to investigate the aggregation and sedimentation of the nano fl uid. The viscosities of nano fl uids subjected to ultrasonic treatment for di ff erent durations were also measured at di ff erent temperatures from 15 to 45 ° C. Better particle dispersion, lower particle sizes, smaller colloid sizes, less precipitation, and higher ζ potentials were observed with increasing sonication time. The viscosity of Al 2 O 3 − water nano fl uid was found to increase with the sonication time up to 60 min and then subsequently decreased. In addition, the viscosity decreased with increasing temperature. The research concluded that more stabler and lower-viscosity nano fl uids can be obtained by applying ultrasonic treatment for durations of 90 min or longer.

[1]  M. A. Amalina,et al.  Migration properties of TiO2 nanoparticles during the pool boiling of nanorefrigerants , 2013 .

[2]  M. A. Amalina,et al.  Influence of particle concentration and temperature on thermal conductivity and viscosity of Al2O3/R141b nanorefrigerant , 2013 .

[3]  J. Philip,et al.  Probing of field-induced structures and tunable rheological properties of surfactant capped magnetically polarizable nanofluids. , 2013, Langmuir : the ACS journal of surfaces and colloids.

[4]  N. Rahim,et al.  Laminar Mixed Convection in Inclined Triangular Enclosures Filled with Water Based Cu Nanofluid , 2012 .

[5]  A. Jacobi,et al.  Ultrasonication effects on thermal and rheological properties of carbon nanotube suspensions , 2012, Nanoscale Research Letters.

[6]  H. Metselaar,et al.  A review of nanofluid stability properties and characterization in stationary conditions , 2011 .

[7]  A. F. Ismail,et al.  Stability and thermal conductivity enhancement of carbon nanotube nanofluid using gum arabic , 2011 .

[8]  Simon Tung,et al.  A review on development of nanofluid preparation and characterization , 2009 .

[9]  D. Kessler,et al.  An experimental study on the effect of ultrasonication on viscosity and heat transfer performance of multi-wall carbon nanotube-based aqueous nanofluids , 2009 .

[10]  Jung‐Kun Lee,et al.  Characterization of ZnO nanoparticle suspension in water: Effectiveness of ultrasonic dispersion , 2009 .

[11]  Yulong Ding,et al.  Ultrasound-assisted green synthesis of nanocrystalline ZnO in the ionic liquid [hmim][NTf2]. , 2009, Ultrasonics sonochemistry.

[12]  A. Hamidi,et al.  The effects of temperature, volume fraction and vibration time on the thermo-physical properties of a carbon nanotube suspension (carbon nanofluid) , 2008, Nanotechnology.

[13]  Seok Pil Jang,et al.  Effective viscosities and thermal conductivities of aqueous nanofluids containing low volume concentrations of Al2O3 nanoparticles , 2008 .

[14]  S. M. Sohel Murshed,et al.  Temperature dependence of interfacial properties and viscosity of nanofluids for droplet-based microfluidics , 2008 .

[15]  Nadia Grossiord,et al.  Controlling the dispersion of multi-wall carbon nanotubes in aqueous surfactant solution , 2007 .

[16]  E. Grulke,et al.  Thermal and rheological properties of carbon nanotube-in-oil dispersions , 2006 .

[17]  Chongyoup Kim,et al.  VISCOSITY AND THERMAL CONDUCTIVITY OF COPPER OXIDE NANOFLUID DISPERSED IN ETHYLENE GLYCOL , 2005 .

[18]  Sharon C. Glotzer,et al.  Origin of Particle Clustering in a Simulated Polymer Nanocomposite and its Impact on Rheology , 2003 .

[19]  Stephen U. S. Choi.  Enhancing thermal conductivity of fluids with nano-particles , 1995 .