Begell House
Journal of Porous Media
Journal of Porous Media
1091-028X
17
12
2014
A COMPREHENSIVE ANALYSIS OF THE SEEPAGE CHARACTERS OF NON-NEWTONIAN FLUIDS IN FRACTAL POROUS MEDIA
Study of non-Newtonian fluid flow characteristics in porous media has been one of the focuses in the field of transport in porous media. In this paper, a comprehensive study of nonlinear seepage in fractal porous media is performed, and the analytical expressions for the starting pressure gradient of Bingham fluids and power-law fluids as well as the relative permeability of power-law fluids in porous media, are obtained with the effect of capillary pressure included. Each parameter in the proposed models has clear physical meaning. The relationships among the starting pressure gradient, permeability, and relative permeability versus porosity, particle diameters, and wetting phase saturation are obtained, and good agreement between the model predictions and the available experimental data is obtained; the validity ofthe proposed models is thus verified.
Shiming
Zhang
School of Petroleum Engineering, China University of Petroleum, Beijing, China Geology Science Research Institute, Shengli Oil Field Lt. Com., Sinopec, China
Yeheng
Sun
School of Petroleum Engineering, China University of Petroleum, Beijing, China Geology Science Research Institute, Shengli Oil Field Lt. Com., Sinopec, China
Xiaodong
Wu
School of Petroleum Engineering, China University of Petroleum, Beijing, China
Tongjun
Miao
School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
Hongjing
Gao
School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
Fuquan
Song
School of Petroleum and Chemical Engineering, Zhejiang Ocean University, Zhoushan, Zhejiang, China
Boming
Yu
Huazhong University of Sci. & Tech.
1031-1044
EXISTENCE OF A CHARACTERISTIC TEMPERATURE IN THE CASE OF ADSORPTION ON ACTIVATED CARBON
We have studied adsorption on AC35 activated carbon for two adsorbates, methanol and acetone. For each one, we have carried out an investigation using two different approaches: (1) study of equilibrium isotherms, quantity of matter adsorbed in function of the pressure, the values read at equilibrium; (2) the kinetic isotherms, the quantity of matter adsorbed in function of the time. The two approaches confirm the existence of a characteristic temperature. The change ofthe geometric forms ofthe equilibrium isotherms for a certain value oftemperature clearly reveals the behavior of the adsorbent with regard to the adsorbate. This approach does not allow us to state with certitude the cause of this change of behavior. The utilized kinetic model lets appear the characteristic time of the matter adsorption (l/ω2). For each couple, the study of this characteristic time variation in the function of the temperature confirms the characteristic temperature and allows us to calculate its value. The thermal balance reveals that the adsorption speed is proportional to the thermal conductance and is seen as the duality between the thermal resistance and the characteristic adsorption time. The nonlinearity of the ω2 variation in the function of the temperature implies that the variation of the average thermal resistance in the function ofthe temperature is not linear.
Mhiri
Foued
Institut Preparatoire aux Etudes d'Ingenieurs de Monastir (University of Monastir), Rue Inb El Jazzar, 5019 Monastir, Tunisie
Abdelmajid
Jemni
Laboratoire d'Etudes des Systèmes Thermiques et Energétiques, Ecole Nationale d'Ingénieurs de Monastir, University of Monastir, Avenue Ibn El Jazzar, 5019, Monastir, Tunisie
1045-1052
SLIP VELOCITY EFFECTS ON CONVECTION FROM A VERTICAL SURFACE EMBEDDED IN A POROUS MEDIUM
In this work slip velocity effects on convection from a vertical plate embedded in saturated porous medium using the Darcy model are investigated numerically. The governing equations − continuity, Darcy law, and energy − are transformed into dimensionless form using a suitable set of dimensionless variables. The equations are solved numerically using a finite-difference method. Results obtained are shown graphically interdicted to illustrate the effects of slip velocity on the near-plate fluid velocity, temperature, shear stress, and Nusselt number. It was found that the increasing of slip velocity decreases velocity and increases heat transfer rates near the surface.
Hamzeh M.
Duwairi
Mechanical Engineering Department, Faculty of Engineering and Technology, The University of Jordan, 11942, Amman, Jordan
V. M.
Al-Khliefat
Jordanian Military Forces
1053-1059
THEORETICAL AND NUMERICAL ANALYSES ON THE ONSET AND GROWTH OF CONVECTIVE INSTABILITIES IN A HORIZONTAL ANISOTROPIC POROUS MEDIUM
A theoretical analysis of buoyancy-driven instability under transient basic fields is conducted in an initially quiescent, brine-saturated, horizontal, anisotropic porous layer. Through the upper boundary of the layer, CO2 dissolution is dissolved into the brine and the CO2-saturated brine induces the buoyancy-driven motion. Darcy's law is used to describe this motion, and linear stability theory is employed. The onset ofconvection is analyzed by employing the exact eigenanalysis, the quasi-steady-state approximation (QSSA), and the initial value problem approach (IVPA). The condition of the onset of buoyancy-driven instability is obtained as a function of the Darcy-Rayleigh number and the anisotropy ratio of permeability which is independent of the solution methods. To find out the anisotropy effect on the motion after the onset ofconvection, nonlinear numerical simulations also are conducted using the result ofthe linear analysis as a starting point. Nonlinear numerical simulations show that the fingerlike instability motion is not readily observable at τc and it becomes visible around τmin. Here τc is the critical time of the onset of convection and τmin is the time after the onset of convection at which the total flux reaches the first local minimum.
Dhananjay
Yadav
School of Mechanical Engineering, Yonsei University Seoul, South Korea
MinChan
Kim
jeju national university
1061-1074
NUMERICAL SOLUTION OF FLUID FLOW AND CONJUGATE HEAT TRANSFER IN A CHANNEL FILLED WITH FIBROUS POROUS MEDIA-A LATTICE BOLTZMANN METHOD APPROACH
In this paper, numerical simulation of fluid flow and heat transfer in a 2D planar channel with straight walls, which is occupied partially and fully with fibrous porous media, is performed by the lattice Boltzmann method. A set of fibrous arrays with square cross section, representing a porous medium, is placed at specific location of this channel perpendicular to the flow direction. A discrete pore-scale level model with standard bounce-back boundary condition on solid fibers has been used due to direct modeling of ordered fibrous medium. Considering the local thermal nonequilibrium led to define another distribution function for the solid phase of porous media. The criterion for enhancement in heat transfer due to the presence of fibrous porous structures is local and average walls Nusselt numbers. The obtained results indicate that porosity, aspect ratio, and relative location of the fibrous are the main parameters that lead to variation of the local and average Nusselt number in the characteristics length of the channel, which is filled by fibrous structures symmetrically and asymmetrically with respect to the centerline ofthe channel. Comparison between fully and partially filled channels shows that in the case of asymmetric arrangement, especially at high porosity, the increase in pressure drop and average Nusselt number on the upper wall are lower and higher than symmetric ones, respectively.
Alireza
Salehi
Mechanical Engineering Department, Amirkabir University of Technology, Hafez Ave., Tehran, Iran; Isfahan University of Technology, Mechanical Engineering Department, Isfahan, Iran
Abbas
Abbassi
Mechanical Engineering Department, Amirkabir University of Technology 424 Hafez Avenue, P.O. Box 15875-4413, Tehran, Iran
Mohsen
Nazari
Shahrood University of Technology; Department of Mechanical Engineering, University of Tehran, Iran
1075-1091
A NEW MATHEMATICAL MODEL FOR THE SOLVENT CHAMBER EVOLUTION IN THE VAPOR EXTRACTION PROCESS
Extensive physical modeling of vapor extraction (VAPEX) has been studied in the past two decades, yet the theoretical modeling of VAPEX has not gained much progress. The major VAPEX mechanisms, i.e., oil viscosity reduction through solvent dissolution and gravity drainage, occur mainly in a thin solvent − heavy oil transition zone. Therefore, modeling ofthe transition zone is the key to model the VAPEX process. Current analytical models are based on some potentially unreliable assumptions for the transition zone, such as steady-state mass transfer and constant boundary moving velocity. Numerical models cannot fully capture the physical features because the gridblock is usually much larger than the transition-zone thickness. This paper develops a new mathematical model for the VAPEX transition zone that is simplified as a piecewise linear profile and updated step by step. In each step, first, a solvent concentration distribution is calculated by using Fick's second law. Then the oil drainage velocity is computed by using Darcy's law. Finally, the momentary boundary moving velocity is estimated by using a mass balance equation. The VAPEX model is not only able to describe the evolution ofthe solvent chamber, but also characterize the dynamic oil properties across the transition zone. Compared with numerical simulation, this new model shows more sensitivity to the diffusion coefficient.
Xinfeng
Jia
Faculty of Engineering and Applied Science, University of Regina, Regina, SK, S4S 0A2, Canada
Fanhua
Zeng
University of Regina
Yongan
Gu
Petroleum Technology Research Center, University of Regina, Regina, Saskatchewan, S4S 0A2
1093-1108
CONJUGATE HEAT TRANSFER IN POROUS ANNULUS
The effect of conductivity ratio on temperature at a solid-porous interface is one of the most important aspects in conjugate heat transfer. The present work is undertaken to investigate heat transfer behavior in a porous annular vertical cylinder having a solid wall at the inner surface The main objective ofthe present study is to evaluate the effect of solid wall thickness and conductivity ratio on heat transfer characteristics ofthe porous medium. The inner and outer surfaces of the annulus are maintained isothermally at Th and T∞ respectively, such that Th > T∞. The increase in conductivity ratio leads to an increase in temperature at the solid-porous interface. It is noticed that the temperature variation along the porous region is almost linear for higher values ofconductivity ratio and wall thickness ratio. It is found that the fluid velocity decreases with increase in wall thickness. It is observed that the Nusselt number decreases with increase in solid wall thickness. The effect ofthe aspect ratio is found to be negligible when porous conductivity is much higher than that of the solid wall conductivity. The attainment of the maximum Nusselt number at Ar ~1 in a porous annulus does not hold good for the conjugate heat transfer problem. The variation in Nusselt number is sensitive for higher wall thickness ratio and lower conductivity ratio.
Ahmed N. J.
Salman
Faculty of Engineering & Technology, Multimedia University, 75450 Bukit Beruang, Malacca, Malaysia
Sarfaraz
Kamangar
Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
Irfan Anjum
Badruddin
Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
Abdullah A. A. A.
Al-Rashed
Public Authority for Applied Education and Training, Industrial Training Institute, 13092, Kuwait
G. A.
Quadir
School of Mechatronic Engineering, University Malaysia Perlis (UniMAP), Pauh Putra, 02600, Arau, Perlis, Malaysia
H. M. T.
Khaleed
Department of Mechanical Engineering, Faculty of Engineering, Islamic University, Madinah Munawwarra, Kingdom of Saudi Arabia
T. M. Yunus
Khan
Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
1109-1119
CONTENTS
1120-1129