Journal of Thermal Analysis and Calorimetry

, Volume 139, Issue 2, pp 1565–1574 | Cite as

Experimental investigation of natural convection heat transfer of SiO2/water nanofluid inside inclined enclosure

  • Maryam Torki
  • Nasrin EtesamiEmail author


Natural convection heat transfer of SiO2/water nanofluids in a rectangular enclosure was investigated at different concentrations and inclination angles, experimentally. Results indicated that heat transfer has not significantly changed for low concentrations of nanofluids. However, at volume fraction of nanoparticles greater than 0.005, heat transfer coefficient decreased with concentration of nanofluid. The effect of tilt angle on heat transfer was also examined. It was found that at low concentrations of nanofluid, the effect of tilt angle on Nusselt number is more pronounced. Influence of concentration of nanofluid on Nusselt number decreases with increasing inclination angle of the cavity or approaching the heated wall to vertical state. The highest values of Nusselt number were obtained for tilt angles of 0° or horizontal state, and heat transfer rate was decreased with inclination angle.


Natural convection heat transfer Nanofluids Enclosed cavity Inclination angle 

List of symbols


Heat transfer area, m2


Specific heat, J kg−1 K−1


Acceleration of gravity, m s−2


Average heat transfer coefficient, W m−2 K−1


Applied current to the heater, A


Thermal conductivity, W m−1 K−1


Distance between hot and cold plates, m


Average Nusselt number


Heat flux, W m−2




Rayleigh number


Temperature, K




Applied voltage to the heater, V


Experimental measured variable

Greek symbols


Thermal expansion coefficient, K−1


The ratio of the nanolayer thickness to the original particle radius


Dynamic viscosity, N s m−2


Density, kg m−3


Volume fraction of nanoparticles


Inclination angle, °



Base fluid


Cold wall


Hot wall







Partial financial support of Isfahan University of Technology is appreciated.


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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2019

Authors and Affiliations

  1. 1.Department of Chemical EngineeringIsfahan University of TechnologyIsfahanIran

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