Effect of CuO Nanolubricant on R134a Pool Boiling Heat Transfer With Extensive Measurement and Analysis Details.
Effect of CuO Nanolubricant on R134a Pool Boiling Heat
Transfer With Extensive Measurement and Analysis
Details.
(436 K)
Kedzierski, M. A.; Gong, M.
NISTIR 7454; 45 p. September 2007.
Keywords:
heat transfer; boiling point; additives; copper;
nanotechnology; refrigerants; lubricants; mixtures
Abstract:
This paper quantifies the influence of CuO nanoparticles
on the boiling perfonnance of
R134a/polyolester mixtures on a roughened, horizontal,
flat surface. Nanofluids are liquids
that contain dispersed nano-size particles. A lubricant
based nanofluid (nanolubricant) was
made with a synthetic ester and 30 run diameter CuO
particles stably suspended in the
mixture to a 4% volume fraction. For the 0.5%
nanolubricant mass fraction, the
nanoparticles caused a heat transfer enhancement
relative to the heat transfer of pure
R134a/polyolester (99.5/0.5) of between 50% and 275%. A
smaller enhancement was
observed for the R134a/nanolubricant (99/1) mixture,
which had a heat flux that was on
average 19% larger than that of the R134a/polyolester
(99/1) mixture. Further increase in
the nanolubricant mass fraction to 2% resulted in a
still smaller boiling heat transfer
improvement of approximately 12% on average.
Consequently, significant
refrigerant/lubricant boiling heat transfer enhancements
are possible with nanoparticles.
Thermal conductivity measurements and a
refrigerant\lubricant mixture pool-boiling model
were used to suggest that increased thennal conductivity
is responsible for only a small
portion of the heat transfer enhancement due to
nanoparticles. Further research with
nanolubricants and refrigerants are required to
establish a fundamental understanding of the
mechanisms that control nanofluid heat transfer.
