Kedzierski, M.
and Fick, S.
(2014),
Effect of Acoustic Excitation on R134a/Al2O3 Nanolubricant Mixture Boiling on a Reentrant Cavity Surface with Extensive Measurement and Analysis Details, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.TN.1836
(Accessed November 23, 2024)
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Effect of Acoustic Excitation on R134a/Al2O3 Nanolubricant Mixture Boiling on a Reentrant Cavity Surface with Extensive Measurement and Analysis Details
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Author(s)
,
Abstract
This paper quantifies the influence of acoustic excitation of Al2O3 nanoparticles on the pool boiling performance of R134a/polyolester mixtures on a Turbo-BII-HP boiling surface. A nanolubricant with 10 nm diameter Al2O3 nanoparticles at a 5.1 % volume fraction in the base polyolester lubricant was mixed with R134a at a 1 % mass fraction. The study showed that high frequency ultrasound at 1 MHz can improve R134a/nanolubricant boiling on a reentrant cavity surface by as much as 44 %. This maximum enhancement occurred for an applied power level to the fluid of approximately 6 W (39 kW m-2). Applied power levels larger and smaller than 6 W resulted in smaller boiling heat transfer enhancements. In total, five different applied power levels were studied: 0 W, 4 W, 6 W, 8 W, and 12 W. The largest and smallest average enhancement was approximately 15 % and 2.5 % for an applied power level of 6 W and 4 W, respectively. In-situ insonation at 1 MHz resulted in an improved dispersion of the nanolubricant on the test surface. An existing pool boiling model for refrigerant/nanolubricant mixtures was modified to include the effect of acoustic excitation. For heat fluxes greater than 25 kWm-2, the model was within 4.5 % of the measured heat flux ratios for mixtures for all applied power levels. The average agreement between measurements and predictions was approximately 1 % for all power levels.Citation
Technical Note (NIST TN) - 1836
Report Number
1836
NIST Pub Series
Pub Type
NIST Pubs
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Keywords
acoustics, additives, aluminum oxide, boiling, enhanced heat transfer, nanolubricant, nanotechnology, refrigerants, refrigerant/lubricant mixtures, structured surface, ultrasound
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Created August 6, 2014, Updated November 10, 2018