Begell House Inc.
Heat Transfer Research
HTR
1064-2285
37
7
2006
Control of Free Convection Passage Across Square Cavities with Heated/Cooled Vertical Sidewalls by Manipulating "On" and "Off" Deflectors
571-591
Antonio
Campo
Department of Mechanical Engineering, The University of Vermont, Burlington, VT 05405, USA
Ignacio J. Benitez
Sanchez
Departamento de Ingenieria de Sistemas y Automática, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain
El Hassan
Ridouane
Department of Mechanical Engineering, The University of Vermont, 33 Colchester Ave., 201 Votey Bldg., Burlington, VT 05405
The physical system consists of a square cavity filled with a mass of compressible air bounded by two vertical walls differentially heated and two horizontal walls insulated from the surroundings. The variable of interest is the amount of heat transferred across the cavity. To exert proper control on the amount of heat, an arrangement made with insulated deflectors in contact with the hot wall was implemented. In the two situations, an automatic controller handles three possible orientations of the deflectors. The automatic controller imparts rotation to the deflectors that gyrate around an axle that passes through their mid-point. The three possible orientations are: (1) an "on" horizontal position placed at 0°, (2) an "off" vertical position at 90° and (3) an intermediate "off" inclined position at 45°. The integration of the conservation equations was carried out with the finite volume technique. Based on numerical/experimental guidelines available for the avoidance of oscillatory regimes, the numerical calculations were limited to Rayleigh numbers ≤ 106 . A simple, reliable positioning control for the two sets of deflectors regulates the heat flow in the cooled vertical wall, keeping it below a certain value or threshold. The desired position or angle can be entered through a user interface, being transformed in a series of digital pulses by an indexer. For the case of one large deflector, the maximum heat transfer suppression is obtained at RaH = 104 , when the deflector is placed in a position of 0°. The minimal heat transfer suppression occurs at RaH = 106 when the deflector is placed at a position of 45°. For the case of two small deflectors, the maximum heat transfer suppression takes place in the RaH sub-interval 10 < RaH ≤ 106. The minimal heat transfer suppression occurs at RaH = 106. In both cases, the deflector is placed at a position of 45°.
Numerical Simulation of Vortical Heat Transfer in Tube Banks
593-605
P. A.
Baranov
Saint-Petersburg State University of Civil Aviation, Saint-Petersburg, 196210, Russia
T. A.
Baranova
A. V. Luikov Heat and Mass Transfer Institute, National Academy of Sciences of Belarus, Minsk, Belarus
N. A.
Kudryavtsev
Academy of Civil Aviation, St. Petersburg, Russia
Based on the use of multiblock computational technologies, a numerical investigation of convective heat transfer in ordered in-line tube banks is carried out. An analysis of the effect of viscosity on the vortical structure and heat transfer from a far-off cylinder inside the bank is given. An approach to simulation of vortical heat transfer within the framework of the concept is justified with the use of periodic boundary conditions, and the limits of its applicability are determined.
Numerical Computation of the Temperature Evolution in the Human Eye
607-617
El Hassan
Ridouane
Department of Mechanical Engineering, The University of Vermont, 33 Colchester Ave., 201 Votey Bldg., Burlington, VT 05405
Antonio
Campo
Department of Mechanical Engineering, The University of Vermont, Burlington, VT 05405, USA
Currently, most refractive surgery on the cornea is done by minimally invasive laser methods. Developing or improving new methods in laser medicine often is accompanied by theoretical modeling of the heat transmission in the human eye. The purpose of this study is to develop a mathematical model of the human eye based on the heat transfer equation. The intraocular temperature distribution is calculated using the finite volume method. The development of an accurate model of the human eye is difficult due to the lack of reliable biological data available on the constants and parameters that are used in the model. The different values for the parameters reported in the literature are employed in the model. The sensitivity of the temperature distribution to uncertainties in the parameters is investigated. The ambient temperature and blood flow rate lead to significant changes in the temperature in the anterior regions. In addition, remarkable effect is observed from the variation of the thermal conductivity of lens and blood temperature.
Predictive Control Based on the Third-Order Laguerre-Volterra Model: Application to Regulate a Humidifying Process
619-649
A.
Mbarek
Unité de Recherche ATSI, Ecole Nationale d'Ingénieurs de Monastir, Rue Ibn EL Jazzar 5019 Monastir, Tunisia
Hassani
Messaoud
Research Unit ATSI, National School of Engineers of Monastir, University of Monastir, Rue Ibn El Jazzar, 5019 Monastir, Tunisia
T.
Garna
Unité de Recherche ATSI, Ecole Nationale d'Ingénieurs de Monastir, Rue Ibn EL Jazzar 5019 Monastir, Tunisia
This paper proposes a new predictive control algorithm developed on the third-order nonlinear Laguerre−Volterra model which results from the expansion of discrete Volterra kernels on an independent Laguerre basis. The coefficients of such model are obtained by exploiting a new estimation technique of Support Vector Machines (SVM) based on the Statistical Learning Theory (SLT) that yields a unique and optimal solution. The new proposed predictive control algorithm is applied for the regulation of the humidity inside a drying blower.