Eventos Anais de eventos
ENCIT 2018
Brazilian Congress of Thermal Sciences and Engineering
BOILING HEAT TRANSFER BEHAVIOR FOR NANOCOATED SURFACES UNDER CONFINED CONDITIONS
Submission Author:
Jessica Martha Nunes , SP
Co-Authors:
Jessica Martha Nunes, Reinaldo Rodrigues de Souza, Elaine Maria Cardoso
Presenter: Jessica Martha Nunes
doi://10.26678/ABCM.ENCIT2018.CIT18-0497
Abstract
Nanocoating techniques have been used to increase the heat transfer coefficient by changing the surface morphology, which could potentially increase the heat transfer in case of pool boiling systems. The present work aims to study the effect of nanocoated surfaces and the gap size during the pool boiling of deionized water, at atmospheric pressure and saturation temperature. The tests were performed on copper heating surfaces with two different roughness values, corresponding to smooth and rough surfaces. The nanocoated surfaces were produced by alumina (Al2O3) nanoparticle deposition with 0.3 g/l volumetric concentration, via nanofluid boiling process. A gap size of 1.0 mm, corresponding to Bond number equal to 0.4, was analyzed in this study. Concerning to the heat transfer coefficient, the coated surfaces showed deteriorations in the HTC as compared with the uncoated ones mainly due to the fouling resistance formed on the heating surface, confirmed by the surface characterization (SEM images). The coating process significantly increases the surface wettability, which in turn, increases the re-wetting capacity during the confined boiling process. It was observed an enhancement of 83% in the dryout heat flux, for smooth surfaces with coating layer.
Keywords
Boiling Heat Transfer, Nanocoated surfaces, Confined nucleate boiling
