HEAT TRANSPORT PERFORMANCE OF NANOPARTICLES IN GASES: CASE STUDY OF Al2O3 NANOAEROSOL

The concept of nanofluids has already shown that the heat transfer potential of traditional working fluids could be improved by dispersing various nanosized particles in them. Up to now, liquids are used as the base materials and dispersed nanoparticles are solid. In the present paper, we study solid nanoparticles dispersed in a gaseous medium (nanoaerosol), and the behavior of heat transfer of nanoparticles mixed with a gas fl ow is analyzed. Nanoparticles of Al₂O₃ mixed with an air stream are considered inside a tube subjected to a constant heat flux of 696.534 kW/m² . The timescale analysis of heat transfer in a nanoparticle–gas mixture is carried out. The effect of the particle volume fraction and the Reynolds number Re on the convective aerosol heat transfer coeffi cient and the Nusselt number is analyzed. The timescale study shows that conduction is dominant in a nanoaerosol. The maximum 59% and 55.27% enhancements in the convective aerosol heat transfer coefficient and the Nusselt number, respectively, are obtained with increasing the particle volume fraction in the range 0.002–0.01 and Re in the range 8000–20,000. These characteristics are compared with the values based on different correlations, and the results are shown to fall in the acceptable region. Moreover, particle inclusion and the rise in Re yield the maximum enhancement in the flow exit temperature equal to 1.72%. Finally, nanoaerosol-based coolants are recommended as the future of gas-based cooling systems.
   
Author:  V. Khadanga, S. Mukherjee, P. C. Mishra, S. Chakrabarty
Keywords:  nanoaerosol, nanoparticles, heat transfer, convective aerosol heat transfer coeffi cient, heat transfer performance
Page:  1214