Heat transfer coefficients from Newtonian and non-Newtonian fluids flowing in laminar regime in a helical coil

• Tipo: Artigo em Revista Científica Internacional
• Data: 2013

Autores

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

Revista

Título: International Journal of Heat and Mass Transfer

Vol. 58 Nº 1-2

Páginas: 676-690

ISSN: 0017-9310

Editora: Elsevier

Indexação

ISI Web of Knowledge - 38 Citações

Scopus - 46 Citações

INSPEC

Classificação Científica

FOS: Ciências da engenharia e tecnologias > Engenharia mecânica

Outras Informações

ID Authenticus: P-002-07K

DOI: 10.1016/j.ijheatmasstransfer.2012.10.078

Abstract (EN): This study aimed to carry out experimental work to obtain, for Newtonian and non-Newtonian fluids, heat transfer coefficients, at constant wall temperature as boundary condition, in fully developed laminar flow inside a helical coil. The Newtonian fluids studied were aqueous solutions of glycerol, 25%, 36%, 43%, 59% and 78% (w/w) and the non-Newtonian fluids aqueous solutions of carboxymethylcellulose (CMC), a polymer, with concentrations 0.1%, 0.2%, 0.3%, 0.4% and 0.6% (w/w) and aqueous solutions of xanthan gum (XG), another polymer, with concentrations 0.1% and 0.2% (w/w). According to the rheological study performed, the polymer solutions had shear thinning behavior and different values of elasticity. The helical coil used has internal diameter, curvature ratio, length and pitch, respectively: 0.004575 m, 0.0263, 5.0 m and 11.34 mm. The Nusselt numbers for the CMC solutions are, on average, slightly higher than those for Newtonian fluids, for identical Prandtl and generalized Dean numbers. As outcome, the viscous component of the shear thinning polymer tends to potentiate the mixing effect of the Dean cells. The Nusselt numbers of the XG solutions are significant lower than those of the Newtonian solutions, for identical Prandtl and generalized Dean numbers. Therefore, the elastic component of the polymer tends to diminish the mixing effect of the Dean cells. A global correlation, for Nusselt number as a function of Peclet, generalized Dean and Weissenberg numbers for all Newtonian and non-Newtonian solutions studied, is presented.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 15