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Investigation of the effects of adding nanoparticle to a fluid on the mechanims of critical heat flux during convectve boiling and surface reweting under film boiling conditions

Grant number: 11/13119-0
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): June 01, 2012
Effective date (End): June 30, 2016
Field of knowledge:Engineering - Mechanical Engineering - Thermal Engineering
Principal researcher:Gherhardt Ribatski
Grantee:Francisco Júlio Do Nascimento
Home Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil


The present proposal concerns a doctoral research dealing with an experimental investigation on the effects of adding nanoparticles to a fluid on the critical heat flux during convective boiling in micro-scale channels and surface rewetting under film boiling conditions. In the proposed study, boiling curves will be obtained for convective boiling of nanofluids inside micro-scale channels for different experimental conditions including different nanoparticle material and size and covering a broad range of mass velocities, heated lengths, heat fluxes and degrees of subcooling at the test section inlet. The CHF experiments will be run by increasing progressively the heat flux up to its critical value. For each heat flux step, it will be determined the flow pattern, the pressure drop and the heat transfer coefficient. To evaluate the effects on the surface rewetting promoted by nanofluids, a stainless steel cylinder having a diameter of 10 mm and a length of 30 mm at a temperature of 800°C will be submerged in a nanofluid pool. The internal temperature of the cylinder will be monitored by thermocouples placed in its interior and the mean heat transfer coefficient on its external surface estimated through inverse methods with the heat flux based on the cooling cylinder cooling rate, using a code already developed. From these results, boiling curves based on the instantaneous decreasing heat flux will be built and hydrodynamic of the convective cooling process of the cylinder registered by a high speed camera (100.000 frames/s). For this purpose, illumination techniques will be developed. The nanofluid will be prepared from deionized water and nanoparticles, by ultrasonication without adding any stabilizing products. Experiments will be performed for the following nanoparticles: (i) gama alumina, mean diameters of 25 nm and 60 nm; (ii) silicon oxide, mean diameters of 15 nm and 80 nm and (iii) carbon nanotubes, characteristic dimension of 15 nm. The deposition of nanoparticles will be analyzed by electronic microscopy examining the test sections before and after the experiments. Based on these results, the critical heat flux and surface rewetting mechanisms for nanofluids will be analyzed and correlations to predict these parameters will be developed.

Scientific publications (4)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
DO NASCIMENTO, FRANCISCO JULIO; MOREIRA, TIAGO AUGUSTO; RIBATSKI, GHERHARDT. Flow boiling critical heat flux of DI-water and nanofluids inside smooth and nanoporous round microchannels. INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, v. 139, p. 240-253, AUG 2019. Web of Science Citations: 0.
DOS SANTOS FILHO, E.; DO NASCIMENTO, F. J.; MOREIRA, D. C.; RIBATSKI, G. Dynamic wettability evaluation of nanoparticles-coated surfaces. EXPERIMENTAL THERMAL AND FLUID SCIENCE, v. 92, p. 231-242, APR 2018. Web of Science Citations: 3.
MOREIRA, TIAGO AUGUSTO; DO NASCIMENTO, FRANCISCO JUILO; RIBATSKI, GHERHARDT; GRP, HEAT TRANSFER RES. An investigation of the effect of nanoparticle composition and dimension on the heat transfer coefficient during flow boiling of aqueous nanofluids in small diameter channels (1.1 mm). EXPERIMENTAL THERMAL AND FLUID SCIENCE, v. 89, p. 72-89, DEC 2017. Web of Science Citations: 10.
SOUZA LARA LEAO, HUGO LEONARDO; DO NASCIMENTO, FRANCISCO JULIO; RIBATSKI, GHERHARDT. Flow boiling heat transfer of R407C in a microchannels based heat spreader. EXPERIMENTAL THERMAL AND FLUID SCIENCE, v. 59, p. 140-151, NOV 2014. Web of Science Citations: 9.

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