Unsteady Three-Dimensional Natural Convection of Water Cooled Inside a Cubic Enclosure

Moraga, Nelson O.; Vega, Sylvana A.

doi:10.1080/10407780390244425

Cited by 22 publications

(4 citation statements)

References 14 publications

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“…The equations of conservation of mass, lineal momentum and discrete energy equations were discretized by using linear interpolation functions for the diffusion terms, while the convective terms were calculated by the fifth power law (Patankar 1980) . The SIMPLE algorithm was used to simultaneously solve the linear equations system using the line‐by‐line method (Moraga and Vega 2004). The tridiagonal matrix algorithm was used along with the Gauss–Seidel with successive under‐relaxation methods.…”

Section: Physical Situation and Mathematical Modelmentioning

confidence: 99%

Non‐newtonian Canned Liquid Food, Unsteady Fluid Mechanics and Heat Transfer Prediction for Pasteurization and Sterilization

Moraga

Torres

Guarda

et al. 2010

J Food Process Engineering

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Unsteady fluid mechanics and natural convective heat transfer during pasteurization and sterilization for aqueous (CMC solution) and fatty (soybean oil) liquid foods were numerically predicted by means of noncommercial computational program developed in this work. This software is based on the finite volume method and the food simulants are assumed to be non‐Newtonian fluids with a temperature‐dependent power‐law viscosity model. Different cylindrical container materials were analyzed (LDPE, PA, PP, galvanized steel), with h/d equal to 0.53, 1.56 and 3.12. Results obtained show that the time required for sterilization is strongly dependent on the liquid food rheological behavior. A recirculating flow pattern was found inside the cylindrical container for the aqueous food stimulant. The Tshz variation with the dimensionless time was faster heating when the h/d decreases. The fastest heating pasteurization and sterilization processes were obtained for CMC solutions inside cylindrical packages with a pseudoplastic behavior. PRACTICAL APPLICATIONS There is a vast body of literature about transport phenomena of thermal treatment of packaged food. However, this literature is restricted when the analyzed foods show a non‐Newtonian behavior. The methodology described in this paper aims to contribute to the understanding of pasteurization and sterilization of packaged non‐Newtonian liquid foods through the implementation of a fast and accurate tool for the optimization of the operational parameters in these treatments, as well as in the design of packaging materials. Commercially available computational fluid dynamics is a powerful tool for the analysis of transient heat transfer packages that allow it to simulate almost any geometry or even import it as Computer Aided Design (CFX, FLUENT and others). Also, rheological properties can be introduced by applying user‐defined functions. The noncommercial computational program developed in this work allows modifying operation, rheological and design parameters without restrictions. The versatility of these tools can complement experimental studies decreasing the time required to the design of the package and its associated costs. On the other hand, an accurate prediction of the unsteady fluid mechanics and natural convective heat transfer during thermal treatments allows estimating the adequate conditions to preserve the quality of packaged foods, along with reduction in energy consumption, resulting in low contamination.

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Section: Physical Situation and Mathematical Modelmentioning

confidence: 99%

Non‐newtonian Canned Liquid Food, Unsteady Fluid Mechanics and Heat Transfer Prediction for Pasteurization and Sterilization

Moraga

Torres

Guarda

et al. 2010

J Food Process Engineering

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“…A survey of the literature shows that correlations for natural convection from vertical and horizontal plates, vertical and horizontal cylinders, spheres, vertical channels, and elliptic cylinders have been reported for different thermal boundary conditions. Furthermore, numerical studies on heat transfer inside horizontal ducts, cavities, and enclosures have been reported by many authors for various boundary conditions [1][2][3][4][5][6][7][8][9][10][11], and natural convection in inclined rectangular enclosures have been studied by Rahman and Sharif [12] and by Sharif and Liu [13] for different aspect ratios and angles of inclination, respectively. However, limited numbers of analytical and numerical studies have been concerned with heat transfer from the external surface of rectangular ducts, which motivated the current study.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Natural Convection Around Isothermal Horizontal Rectangular Ducts

Zeitoun

Ali

2006

Numerical Heat Transfer, Part A: Applications

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Two-dimensional laminar natural-convection heat transfer in air around horizontal ducts with rectangular and square cross sections is studied numerically. Different aspect ratios are used for wide ranges of Rayleigh numbers. Results are presented in the form of streamlines and isothermal plots around the circumference of the ducts. The computational procedure is based on the finite-element technique. Temperature and velocity profiles are obtained near each surface of the ducts. Reverse flow and circulations are observed at high aspect ratios. Heat transfer data are generated and presented in terms of Nusselt number versus Rayleigh number for different aspect ratios. Correlation covering the aspect ratios used is obtained in dimensionless form of Nusselt number, Rayleigh number, and aspect ratio.

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“…The representative works on steady-state [1][2][3][4][5][6][7][8][9][10] and transient [11][12][13][14][15][16][17][18][19][20] natural convection have all revealed that the density inversion phenomenon had great effect on the flow pattern, temperature field and heat transfer characteristic. Meanwhile, influences of internal heat generation [21] and magnetic field [22] on natural convection of water near its density maximum in a rectangular cavity were also investigated.…”

Section: Introductionmentioning

confidence: 99%

Natural convection of water near its density maximum between horizontal cylinders

Yuan

et al. 2011

International Journal of Heat and Mass Transfer

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Unsteady Three-Dimensional Natural Convection of Water Cooled Inside a Cubic Enclosure

Cited by 22 publications

References 14 publications

Non‐newtonian Canned Liquid Food, Unsteady Fluid Mechanics and Heat Transfer Prediction for Pasteurization and Sterilization

Non‐newtonian Canned Liquid Food, Unsteady Fluid Mechanics and Heat Transfer Prediction for Pasteurization and Sterilization

Numerical Investigation of Natural Convection Around Isothermal Horizontal Rectangular Ducts

Natural convection of water near its density maximum between horizontal cylinders

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