Combined effect of physical properties and convective heat transfer coefficient of nanofluids on their cooling efficiency

Research output: Contribution to journalArticlepeer-review

Authors

  • Ehsan B. Haghighi
  • Adi T. Utomo
  • Morteza Ghanbarpour
  • Ashkan I T Zavareh
  • Rahmatollah Khodabandeh
  • Björn Palm

Colleges, School and Institutes

External organisations

  • Department of Energy Technology, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden
  • Dantherm Cooling AB
  • BHR Virtual PiE
  • The Fluid Engineering Centre
  • University of Birmingham

Abstract

The advantages of using Al<inf>2</inf>O<inf>3</inf>, TiO<inf>2</inf>, SiO<inf>2</inf> and CeO<inf>2</inf> nanofluids as coolants have been investigated by analysing the combined effect of nanoparticles on thermophysical properties and heat transfer coefficient. The thermal conductivity and viscosity of these nanofluids were measured at two leading European universities to ensure the accuracy of the results. The relative thermal conductivity of nanofluids agreed with the prediction of the Maxwell model within +/-10% even at elevated temperature of 50°C indicating that the Brownian motion of nanoparticles does not affect thermal conductivity of nanofluids. The viscosity of nanofluids is well correlated by the modified Krieger-Dougherty model providing that the effect of nanoparticle aggregation is taken into account. It was found that at the same Reynolds number the advantage of using a nanofluid increases with increasing nanofluid viscosity which is counterintuitive. At the same pumping power nanofluids do not offer any advantage in terms of cooling efficiency over base fluids since the increase in viscosity outweighs the enhancement of thermal conductivity.

Details

Original languageEnglish
Article number3245
Pages (from-to)32-42
Number of pages11
JournalInternational Communications in Heat and Mass Transfer
Volume68
Publication statusPublished - 1 Nov 2015

Keywords

  • Cooling efficiency, Heat transfer coefficient, Nanofluid, Thermal conductivity, Viscosity