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The Effect of Sonication Time on Alumina Nanofluids with Paradoxical Behavior 

 

Jawaz Pasha1, Ramis M.K.1*,Yashawantha K.M.2
1P.A. College of Engineering, Mangalore, India
2Srinivas Institute of Technology, Mangalore, India
 

Abstract

Nanofluids can be considered to be the next-generation heat transfer fluids as they offer exciting new possibilities to enhance heat transfer performance compared to pure liquids. Heat transfer enhancement using Nanofluids have been reported in literature pertinent to thermal conductivity under the static conditions, convective heat transfer and phase change heat transfer. Except for the studies from the first category where the Nanofluids exhibited much higher thermal conductivities than those of base liquids, the investigations on Nanofluids behaviour under convective heat transfer studies and phase change heat transfer studies have reported conflicting results. The present study aims at a critical analysis of this apparently paradoxical behaviour of heat transfer with a special focus on the effect of sonication time on the heat transfer behaviour of Nanofluids. To this end Alumina Nanofluids of different concentrations (0.05%, 0.1%, 0.15%, 0.2%) are prepared at various sonication times (2, 3 and 4 hours) and their effects on the heat transfer characteristics are investigated. Subsequently an unsteady state heat transfer analysis of a heated vertical cylinder cooled in the foresaid alumina Nanofluids is carried out. It can be concluded from these investigations that the sonication time greatly influences the heat transfer performance of the Nanofluids and this influence is affected by the nanoparticles concentration. However a solid conclusive remark as an increasing or decreasing trend could not be observed during these studies. A comparative study of the heat transfer coefficient of different concentration Nanofluids at various sonication time indicates that the best performance characteristics is spreading over the spectrum of the nanofluids of all mass concentration under consideration. Thus it can be concluded that the sonication time determines the role of particle-fluid slip and sedimentation which seems to be important in the heat transfer process and requires to be investigated more closely in the future. 

 

Keywords:

domperidon qtc

domperidon yan etkileri domperidon beipackzettel domperidon en parkinson
Alumina, heat transfer co efficient, nanofluids, sonication time. 

Received:                   Published Date:

02 Aug 2014             05 Jan 2015


     
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  Keywords
Alumina
heat transfer co efficient
nanofluids 
sonication time.
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