Effect of CuO Nanoparticle Concentration on R134a/Lubricant Pool Boiling Heat Transfer With Extensive Analysis.
Effect of CuO Nanoparticle Concentration on
R134a/Lubricant Pool Boiling Heat Transfer With
Kedzierski, M. A.
NISTIR 7450; 33 p. September 2007.
heat transfer; lubricants; boiling point; additives;
copper; nanotechnology; tests; refrigerants; mixtures;
This paper quantifies the influence of copper (II) oxide
(CuO) nanoparticle concentration on
the boiling perfonnance of R134a1polyolester mixtures on
a roughened, horizontal flat
surface. Nanofluids are liquids that contain dispersed
nano-size particles. Two lubricant
based nanofluids (nanolubricants) were made with a
synthetic polyolester and 30 nm
diameter CuO particles to a 4 % and a 2 % volume
fraction, respectively. As reported in a
previous study for the 4 % volume fraction
nanolubricant, a 0.5 % nanolubricant mass
fraction with R134a resulted in a heat transfer
enhancement relative to the heat transfer of
pure R134a1polyolester (99.5/0.5) of between 50 % and
275 %. The same study had shown
that increasing the mass fraction of the 4 % volume
fraction nanolubricant resulted in
smaller, but significant, boiling heat transfer
enhancements. The present study shows that
use of a nanolubricant with half the concentration of
CuO nanoparticles (2 % by volume)
resulted in either no improvement or boiling heat
transfer degradations with respect to the
R134a/polyolester mixtures without nanopartic1es.
refrigerant/lubricant boiling heat transfer enhancements
are possible with nanopartic1es;
however, the nanopartic1e concentration is an important
detennining factor. Further research
with nanolubricants and refrigerants are required to
establish a fundamental understanding of
the mechanisms that control nanofluid heat transfer.