Abstract:
One of the most restricting factors in the performance of
industrial heat transfer processes is the low thermal conductivity
of the thermal fluids commonly used. Hence, dispersions of
nanoparticles with high thermal conductivity in conventional
fluids, nanofluids, have received increasingly interest over last
decades in order to obtain improvements in heat transfer
processes. The thermophysical properties are necessary to their
flow behaviour characterization and they are not commonly
available in the literature. Therefore, laboratories with wide
experience in thermophysical characterization should call
attention to this issue.
This study aims to determine those properties with a
noticeable influence on the heat transfer capability for
dispersions of functionalized graphene nanoplatelets in a
propylene glycol:water mixture at (30:70) % mass ratio, usually
employed in thermal facilities. Initially, nanofluid stabilities
were investigated analyzing zeta potential measurements,
optimizing the pH value. Tests for obtaining densities, heat
capacities, thermal conductivities and dynamic viscosities were
developed for different nanoadditive mass concentrations (0.25,
0.50, 0.75 and 1.0) wt.% over throughout the temperature range
from (293.15 to 323.15) K. Thus, density values were obtained
by using a pycnometric technique, a differential scanning
calorimeter was utilized to measure heat capacities, thermal
conductivities were determined with a transient hot wire
technique while rheological tests were carried out by means of a
rotational rheometer with cone-plate geometry. Secondly,
thermal conductivity focused our attention due to its important
role in the heat transfer process. Remarkable increases, up to 16
%, were found in this property.
Description:
Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .
