Enhanced Pool Boiling Heat Transfer by Nanofluids
Date Issued
2008
Date
2008
Author(s)
Wang, Chung-Kai
Abstract
Nanofluid is expected to be one of the most potential techniques for heat transfer enhancement. Hence, recently studies have been carried out on the heat transfer behavior of nanofluids in two-phase heat transfer regimes such as pool boiling. However, the amount and performance of proposed works are scant and insignificant. Therefore, the aim of this article attempts to explore whether a further enhancement could be achieved by altering the nanoparticle/base-fluid combination used in previous studies. This research, a two-step procedure was used to disperse titania (TiO2) nanoparticles into 1,1,1,2-tetrafluoroethane (R-134a) to prepare nanofluid. The preliminary qualitative analysis of the pool boiling heat transfer enhancement of nanofluid was conducted through nanofluid and pool boiling correlations in order to indicate the relationship between thermal conductivity and boiling heat transfer coefficient. Results of this study showed the boiling heat transfer coefficient of R-134a was shown to be increased by up to 150 % for nanofluid consisting of R-134a containing approximately 0.005 %vol. TiO2 nanoparticles of mean diameter 20 ~ 25 nm. On the other hand, the critical heat flux maintained the same by little deposition of nanoparticles. The short-range re-dispersibility and repeatability of data were found to be acceptable. To conclude, the R134a-based nanofluids may be better than water-based in pool boiling heat transfer enhancement application. Further, our modified empirical correlations need to be proved by detail experiments and theories precisely.
Subjects
Heat transfer enhancement
Pool boiling
Nanofluid
Titania
R-134a
Type
thesis
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