Numerical Study of Entropy Generation in a Flowing Nanofluid Used in Micro- and Minichannels

Abstract

This article mainly concerns theoretical research on entropy generation influences due to heat transfer and flow in nanofluid suspensions. A conventional nanofluid of alumina-water (Al 2 O 3-H 2 O) was considered as the fluid model. Due to the sensitivity of entropy to duct diameter, mini-and microchannels with diameters of 3 mm and 0.05 mm were considered, and a laminar flow regime was assumed. The conductivity and viscosity of two different nanofluid models were examined with the help of theoretical and experimentally determined parameter values. It was shown that order of the magnitude analysis can be used for estimating entropy generation characteristics of nanofluids in mini-and microchannels. It was found that using highly viscous alumina-water nanofluid under laminar flow regime in microchannels was not desirable. Thus, there is a need for the development of low viscosity alumina-water (Al 2 O 3-H 2 O) nanofluids for use in microchannels under laminar flow condition. On the other hand, Al 2 O 3-H 2 O nanofluid was a superior coolant under laminar flow regime in minichannels. The presented results also indicate that flow friction and thermal irreversibility are, respectively, more significant at lower and higher tube diameters. Nomenclature Ф volume fraction C Specific heat J/KG. k ƒ friction factor K thermal conductivity D diameter of tube, m N shape constant Nu Nusselt Number Ρ density Reynolds Number ṁ mass flow rate Be Bejan Number µ Viscosity Ṡ entropy generation per unit length, W/m.k Subscript " heat flux per unit length, W/m BF base fluid C µ viscosity coefficient NF nanofluid C k thermal conductivity coefficient P nanoparticles

DOI: 10.3390/e15010144

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Showing 1-10 of 30 references

Two-phase study of fluid flow and heat transfer in gas-solid flows (nanofluids)

  • H Afshar, M Shams, S M M Nainian, G Ahmadi
  • 2012

Computer simulations of natural convection of single phase nanofluids in simple enclosures: A critical review

  • O Abouali, G Ahmadi
  • 2011

Numerical investigation of effective parameters in convective heat transfer of nanofluids flowing under a laminar flow regime

  • E Ebrahimnia-Bajestan, H Niazmand, W Duangthongsuk, S Wongwises
  • 2011

Entropy generation due to flow and heat transfer in nanofluids

  • P K Singh, K Anoop, T Sundararajan, S K Das
  • 2010

A benchmark study on the thermal conductivity of nanofluids

  • J Buongiorno, D C Venerus, +7 authors J L Alvarado
  • 2009

Effect of particle size on the convective heat transfer in nanofluid in the developing region

  • K Anoop, T Sundararajan, S K Das
  • 2009

Effect of reduced specific heats of nanofluids on single phase, laminar internal forced convection

  • T Bergman
  • 2009

Thermophysical and electrokinetic properties of nanofluids—A critical review

  • S Murshed, K Leong, C Yang
  • 2008
Showing 1-9 of 9 extracted citations