Friction losses of Newtonian and non-Newtonian fluids flowing in laminar regime in a helical coil

• Tipo: Artigo em Revista Científica Internacional
• Data: 2012

Autores

T. A. Pimenta (Autor) Outra; J. B. L. M. Campos (Autor) FEUP

Revista

Título: Experimental Thermal and Fluid Science

Vol. 36

Páginas: 194-204

ISSN: 0894-1777

Editora: Elsevier

Indexação

ISI Web of Knowledge - 34 Citações

ISI Web of Science

Scopus - 40 Citações

COMPENDEX

Classificação Científica

FOS: Ciências da engenharia e tecnologias > Engenharia mecânica

CORDIS: Ciências Tecnológicas > Engenharia > Engenharia química

Outras Informações

ID Authenticus: P-002-HGA

DOI: 10.1016/j.expthermflusci.2011.09.013

Abstract (EN): This study aimed to carry out experimental work to determine, for Newtonian and non-Newtonian fluids, the friction factor (f(c)) with simultaneous heat transfer, at constant wall temperature as boundary condition, in fully developed laminar flow inside a vertical helical coil. The Newtonian fluids studied were aqueous solutions of glycerol, 25%, 36%, 43%, 59% and 78% (w/w). The non-Newtonian fluids were aqueous solutions of carboxymethylcellulose (CMC), a polymer, with concentrations of 0.2%, 0.3%, 0.4% and 0.6% (w/w) and aqueous solutions of xanthan gum (XG), another polymer, with concentrations of 0.1% and 0.2% (w/w). According to the rheological study done, the polymer solutions had shear-thinning behavior and different values of viscoelasticity. The helical coil used has an internal diameter, curvature ratio, length and pitch, respectively: 0.00483 m, 0.0263, 5.0 m and 11.34 mm. It was concluded that the friction factors, with simultaneous heat transfer, for Newtonian fluids can be calculated using expressions from literature for isothermal flows. The friction factors for CMC and XG solutions are similar to those for Newtonian fluids when the Dean number, based in a generalized Reynolds number, is less than 80. For Dean numbers higher than 80, the friction factors of the CMC solutions are lower those of the XG solutions and of the Newtonian fluids. In this range the friction factors decrease with the increase of the viscometric component of the solution and increase for increasing elastic component. The change of behavior at Dean number 80, for Newtonian and non-Newtonian fluids, is in accordance with the study of Ali [4]. There is a change of behavior at Dean number 80, for Newtonian and non-Newtonian fluids, which is in according to previous studies. The data also showed that the use of the bulk temperature or of the film temperature to calculate the physical properties of the fluid has a residual effect in the friction factor values.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 11