Author
Karimzadehkhouei, M., Sezen, M., Şendur, K., Mengüç, Mustafa Pınar, Koşar, A.
Publication Date
2017
Publication Place
-
Elsevier
Subject
Subcooled flow boiling, Heat transfer coefficient, Al2O3 nanoparticle/water nanofluid, Nanoparticle deposition, Nanoparticle agglomeration
Type
Periodical
Language
English
Digital
Yes
Manuscript
No
Library
Özyeğin University
Library Asset ID
1359-4311
Record ID
3e70e4d4-e909-4fbd-b5e6-bf74ab9f42bf
Library Location
Mechanical Engineering
Date
2017
Notes
SUNUM; FENS
Sample Text
In this study, subcooled flow boiling heat transfer characteristics of nanofluids were investigated at micro scale. For this purpose, the effect of γ-Al2O3 (gamma-alumina) nanoparticles with an average solid diameter of 20 nm was considered. In the experiments, various mass fractions were considered in horizontal smooth stainless steel microtubes with inner and outer diameters of ∼502 µm and ∼717 µm, respectively, at mass fluxes of 1200 and 3400 kg m−2 s−1. Nanoparticles were added to distilled water (base fluid) at five mass fractions (low mass fractions 0.05 wt% and 0.2 wt%; high mass fractions 0.5 wt%, 1 wt% and 1.5 wt%). According to our results, subcooled flow boiling heat transfer coefficients for nanofluids with low mass fractions were nearly the same as those of the pure water. However, heat transfer deteriorated for nanofluids with high mass fractions. Observations of dynamic light scattering measurements for low and high mass fractions before and after the experiments revealed that agglomeration of nanoparticles is an important parameter in deterioration of heat transfer at higher concentrations. Besides, Scanning Electron Microscopy images of microtube inner surfaces showed that deposition of nanoparticles and agglomerated nanoparticles on the inner surface of the microtubes also contributed to the heat transfer deterioration at high mass fractions. Generally, the deterioration in heat transfer beyond a specific mass fraction value was linked to the disturbance in the stability of suspended nanoparticles and deposition of nanoparticles upon boiling.
DOI
10.1016/j.applthermaleng.2017.08.041
Cilt
127
