- Author
-
Kedzierski, M. A.
|
Gong, M.
- Title
- Effect of CuO Nanolubricant on R134a Pool Boiling Heat Transfer With Extensive Measurement and Analysis Details.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
Chinese Academy of Sciences, Beijin, China
- Report
-
NISTIR 7454
September 2007
45 p.
- Keywords
-
heat transfer
|
boiling point
|
additives
|
copper
|
nanotechnology
|
refrigerants
|
lubricants
|
mixtures
- Identifiers
- copper (II) oxide; refrigerant/lubricant mixtures; test surface; measurements and uncertainties; experimental results
- 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.