Experimental investigation of convective heat transfer growth on ZnO@TiO2/DW binary composites/hybrid nanofluids in a circular heat exchanger

Waqar Ahmed, S. N. Kazi, Z. Z. Chowdhury, M. R.B. Johan, Naveed Akram, M. A. Mujtaba, M. Gul, C. S. Oon

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Abstract: The thermophysical properties of freely suspended ZnO and TiO2 nanoparticles in a base fluid (DW) with different mass% concentrations of ZnO@TiO2/DW binary composite nanofluids (0.1, 0.075, 0.05 and 0.025 mass%) are deliberated. ZnO have been synthesized by using a facile single-pot sonochemical method and mixed with TiO2 under high probe sonication to prepare binary composite nanofluid. The experiment of effective thermal conductivity was executed in the temperature range of 20–45 °C. The positive improvement in thermal conductivity value for ZnO@TiO2/DW binary composite nanofluids was recorded for 0.1 mass%, and the highest improvement was measured up to 36%, greater than the base fluids (DW). The convective heat transfer properties of the ZnO@TiO2/DW binary composite nanofluids with different concentrations and base fluid (DW) were also examined by using complete experimental test rig with a circular heat exchanger based on a constant heat flux boundary conditions. All the concentrations were examined to check the local and average improvement in heat transfer with Reynolds range from 5849 to 24,544. The increase in nanoparticles mass% in base fluid causes to raise the heat transfer coefficient (h) which is due to the composite nanoparticles. Finally, the maximum 600–1950 W m−2 K−1 enhancement was found in convective heat transfer with an increase in 0.1 mass% of composite nanoparticles, which is 69% greater than base fluid, while all other concentrations also shows positive enhancement as compared to base fluid (600–1870, 600–1700 and 600–1500) W m−2 K−1 correspondingly. Graphic abstract: [Figure not available: see fulltext.].

Original languageEnglish
Pages (from-to)879-898
Number of pages20
JournalJournal of Thermal Analysis and Calorimetry
Issue number2
Publication statusPublished - Jan 2021
Externally publishedYes


  • Heat transfer
  • Nanofluids
  • Nanoparticles
  • Thermal conductivity
  • ZnO@TiO/DW binary composites

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