Effect of CuO Nanoparticle Concentration on R134a/Lubricant Pool Boiling Heat Transfer.
Effect of CuO Nanoparticle Concentration on
R134a/Lubricant Pool Boiling Heat Transfer.
Kedzierski, M. A.
Micro/Nanoscale Heat Transfer International Conference.
Proceedings. MNHT2008. January 6-9, 2008, Tainan,
Taiwan, ASME, New York, NY, 1-8 pp, 2008.
heat transfer; lubricants; copper oxide; nanoparticles;
tests; heat flux; uncertainity; experiments; volume
This paper quantifies the influence of CuO nanoparticle
concentration on the boiling performance of
R134a/polyolester 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
ester and 30 nm diameter CuO particles stably suspended
in the two mixtures 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
R134a/polyolester (99.5/0.5) of between 50% and 275%.
The same previous study had shown that increasing the
mass fraction of the 4% volume fraction nanolubricant
resulted in the 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
nanoparticles. Consequently, significant
refrigerant/lubricant boiling heat transfer enhancements
are possible with nanoparticles; however, the
nanoparticle concentration is an important determining
factor. Further research with nanolubricants and
refrigerants are required to establish a fundamental
understanding of the mechanisms that control nanofluid