Biomedical Engineering Reference
In-Depth Information
10.1 Comparison of thermal conductivity of common liquids and
solids.
.
clogging of microchannels
.
erosion of pipelines
.
increase in pressure drop.
These problems substantially limited the application of milli- or micrometer
sized dispersed particles. Thus, the success of enhancing the thermal
conductivity of a fluid by dispersing solid particles seems to crucially depend
on the ability to develop a stable suspension without the danger of
sedimentation, clogging or erosion.
10.2 The development of nanofluids
Recent advances in materials technology have made it possible to produce
nanometer-sized particles that can overcome the above stated problems to a
large extent. More than a decade ago, it was demonstrated that fluids with
suspended nanoparticles, forming a stable colloid and maintaining a quasi-
single-phase state (called nanofluids), can offer an extraordinary level of
heat transport property for a very small amount of dispersion (
1 vol%).
The term nanofluid was coined by Choi (1995) of Argonne National
Laboratory, USA, in 1995. Earlier studies of tailored nanofluids showed
that there is about 40% enhancement in thermal conductivity with 0.3 vol%
of copper nanoparticles of about 10 nm size (Eastman et al., 2001).
Nanofluids have now emerged as a promising field in the nanotechnology
domain and represent the meeting point of nanoscience, nanotechnology,
and thermal engineering.
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