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Experimental investigation of transient critical heat flux of water-based zinc–oxide nanofluids

Year: 2013

Journal: International Journal of Heat and Mass Transfer, 2013, 61, pp 425-431, 20130926

Authors: Vivek I. Sharma, Jacopo Buongiorno, Thomas J. McKrell, Lin W. Hu

Organizations: Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Room 24–206, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA; Nuclear Reactor Laboratory, 138 Albany Street, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Pool boiling experiments were conducted for sandblasted stainless steel (grade 316) plate heaters submerged in deionized (DI) water and water-based zinc–oxide nanofluid, for transient heat flux conditions with power through the heaters increasing quadratically with time. Heat flux in the experiments was increased from zero to CHF in short time frames of 1, 10 and 100 s. Consistent with previous studies, transient CHF for DI water was higher than steady state CHF, and CHF increased with decreasing duration of the transient. Additionally, it was observed that for nanofluid tests, a porous and hydrophilic nanoparticle layer started to deposit on the heater surface in short time frames of 10 and 100 s, and this layer was responsible for the enhanced CHF compared to DI water. However, for the 1 s tests, nanoparticle deposition did not occur and consequently the CHF was not enhanced. Finally, experiments with heaters pre-coated with nanoparticles were performed and it was found that CHF was enhanced for all transient durations down to 1 s, establishing firmly that the CHF enhancement occurs due to surface modifications by the deposited nanoparticles, and not by nanoparticles suspended in solution.