Effect of Acoustic Excitation on R134a/Al2O3 Nanolubricant Mixture Boiling on a Reentrant Cavity Surface

Published

November 1, 2014

Author(s)

Mark A. Kedzierski, Steven E. Fick

Abstract

This paper quantifies the influence of acoustic excitation of Al2O3 nanoparticles on the pool boiling performance of R134a/polyolester mixtures on a commercial (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 and a heat flux of approximately 6.9 kW/m2. 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 enhancement averaged over the tested heat flux range was approximately 12 % and 2 % for applied power levels 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 at all applied power levels. The average agreement between measurements and predictions was approximately 1 % for all power levels.

Citation

Journal of Heat Transfer

Pub Type

Journals

Keywords

acoustics, additives, aluminum oxide, boiling, enhanced heat transfer, nanolubricant, nanotechnology, refrigerants, refrigerant/lubricant mixtures, structured surface, ultrasound

Citation

Kedzierski, M. and Fick, S. (2014), Effect of Acoustic Excitation on R134a/Al2O3 Nanolubricant Mixture Boiling on a Reentrant Cavity Surface, Journal of Heat Transfer (Accessed October 9, 2024)