|
Home>Products>Journal
and Reviews>I.RE.M.E.>Latest
issue
International Review of
Mechanical Engineering - Papers
Finite Element Method Analyses of Fracture Toughness of API X70 Pipeline Steels
by D. Zelmati, A. Amirat
Abstract
- One of the main properties of great interest in material design is its fracture toughness KIC that is used to assess crack growth phenomena. For instance pipelines made of high strength steel are structures which commonly present corrosion pits in service, that can propagate and cause failure. The determination of KIC values are usually achieved through exhaustive, costly and time consuming tests using Charpy specimens which are prepared from longitudinal and transversal direction of the parent tube. Therefore research of new method for KIC estimates as to reduce the production cost is strongly required. To come up to this requirement finite element method can bring accurate and rapid solution. The main aim of this work is to analysis the fracture toughness of API X70 pipeline steels using FEM under Castem 2005 code. The results, compared to experimental data, show good agreements.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Fracture toughness, pipe, X70, FEM, simulation.
Fretting Wear Performance of Multilayered PVD TiAlZrN/TiAlN/TiAl on AISI 4140 Steel
by B. Tlili, M. Nasri, F. Ayari, C. Nouveau
Abstract
- This Nowadays, most surface
treatments are realized through vapor deposition techniques as thin hard
coatings to guarantee; high surface hardness, low friction coefficient and
improve wear resistance. Several experimental investigations have let to the
development of a (TiAlCN/TiAlN/TiAl) and (TiAlZrN/TiAlN/TiAl) coatings in
preference to the traditional TiN coating. In the current paper research
conducted on fretting wear of a (TiAlCN/TiAlN/TiAl) and a (TiAlZrN/TiAlN/TiAl)
multilayer coatings deposited by reactive DC (magnetron sputtering) of Ti-Al and
Ti-Al-Zr alloys on AISI4140 steel. Fretting wear tests (20.000 cycles at 5 Hz)
were conducted in ambient conditions, where the interaction between normal load
and displacement amplitude determines the fretting regime. The influence of the
normal load and displacement amplitude on the coefficients of instantaneous
coefficient of friction and stabilized coefficient of friction is different from
the two multilayer coated steels. The PVD coating (TiAlZrN/TiAlN/TiAl) reduces
the friction. The worn volume of coated AISI4140 steel is sensitive to normal
load and displacement amplitude. The relation between worn volume and cumulative
dissipated energy was established for the two coated steels. The energetic
fretting wear coefficients were also determined. A multilayer (TiAlZrN/TiAlN/TiAl)
coating has a low energetic wear coefficient
.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Fretting wear, PVD, TiAlZrN, TiAlCN, friction coefficient, cracking, dissipated
energy.
by M. Iordache, N. Bourgeois, L. P. Moreira, M. Martiny, G. Ferron
Abstract
-
The strain-hardening behavior and
plastic anisotropy of a steel sheet of deep drawing quality has been
characterized in uniaxial tension tests, and several forming tests have been
performed to determine the Forming Limit Curve, the Limiting Dome Height in the
hemispherical punch test and the height of ears in the cup drawing test. The
experiments are compared with finite element predictions obtained with a
flexible model for orthotropic plasticity, which allows us to discuss the
importance of material parameters for obtaining reliable predictions by means of
the numerical simulation.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Sheet-metal forming, plastic anisotropy, forming limits, finite element modeling.
Numerical Analysis of Ammonia Absorption in a Falling Film
by H. Dardour, S. Mazouz, P. Cézac, J. M. Reneaume, A. Bellagi
Abstract
- A numerical analysis of a counter
current ammonia-water falling film absorption process in a vertical plate
absorber is performed. Simultaneous steady state heat and mass transfer
processes occurring during the absorption process are considered. In order to
withdraw the heat released near the liquid-vapour interface during the
absorption process and thus control the absorption temperature, the plates are
supposed to be water cooled. A mathematical model of the process has been built
up on the basis of mass and energy balances and heat and mass transfer rate
equations. Empirical correlations in combination with the Chilton-Colburn
analogy are used to predict the heat and mass transfer coefficients near the
liquid-vapour interface. The mathematical model results in a system of
differential equations, the numerical integration of which is performed after
spatial discretization. The algebraic non linear equations system thus obtained
is solved using a Newton-Raphson FORTRAN coded method in combination with an
optimization procedure. For a given geometry and operating conditions the model
predicts the behaviour of the absorber. Evolution along the absorber length of
several parameters is computed such as: temperature and concentration of the
vapour and liquid phases, temperature and liquid and vapour compositions at the
interface, coolant temperature as well as the ammonia and water molar fluxes
through the liquid-vapour interface. It was found that the liquid side mass
transfer resistance controls the overall absorption process. The resistance in
the vapour phase is negligible. On the other hand, heat transfer resistance is
dominant in the vapour phase. The simulation reveals the existence of water
desorption phenomenon occurring near the bottom of the absorber: While ammonia
vapour is absorbed into the liquid, liquid water evaporated first into the
vapour flow.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Absorption, combined heat and mass transfer, plate absorber,
falling film.
Statistical Analysis of Temperature Effect on Fatigue Lifetime of Thin Welded Stainless Steel Sheets
by A. Merabtine, K. Chaoui, Z. Azari
Abstract
- Martensitic stainless steel sheets
with 12% Cr are used as protective envelopes for hot and vibrating structures
such as aircraft engines and gas turbines. Since the envelope shape may be
complex, butt welding is chosen to assemble the parts which can undergo fatigue
failure especially in the heat-affected zone (HAZ). The aim of this study is to
present experimental fatigue life results showing the effect of temperature and
to present a reliable statistical approach in order to correctly describe a
given loading level, in relation to its fatigue life, which has not yet been
tested using the only available experimental data. This situation is dictated by
optimizing the costly and lengthy fatigue experiments for modeling. Normal and
Weibull statistical models are used to predict fatigue lifetime based on S-N
curves in welded and seamless plates. Both models provide comparable results
with experimental data at 293 K and 690 K for failure probability limits of 5%
and 95%. Based on Weibull model, untested levels are assessed using a cumulative
fatigue life function. Two new dimensionless parameters (X: square stress ratio
and H: thermal life ratio) are used to calculate, for a given stress level, the
corresponding fatigue life in accordance to the sought lower and upper
confidence limits. The proposed modified Weibull approach delivers results
within less than 5% error.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
AISI 410 Steel, Welding, Fatigue, Temperature Effect, Statistical Analysis.
Prediction and Measurement of the Damping Properties of Carbon-Fibre Reinforced Plastics Rectangular Plates
by L. Kherredine, A. Amirat, N. Zeghib
Abstract
-
The main objective of the present investigation was to examine how the damping
properties of laminated composite plates vary with changes in the plate
dimensions. Also, it was very important for plates with different
ply-orientations to see how the dynamic characteristics vary from one plate to
another or when the fibre-orientation was changed. The theoretical prediction of
the natural frequency, mode shape and specific damping capacity for each mode
obtained using the finite element method was to be compared with experimental
results.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
F.E.method, laminated composite, frequency, damping, ply-orientation.
Homogenous Numerical Models For Porous Hyperelastic Materials
by J. Mars, F. Dammak, A. Dhieb
Abstract
- In this work, a general
micromechanics framework for the development of constitutive models of the
large-strain deformation of porous elastomeric materials is developped. The
framework is applicable to any type of isotropic hyperelastic matrix material
which obeys pointwise incompressibility: such as the Neo–Hookean, Mooney–Rivlin
and Ogden model. The strain energy density function depends on the properties of
the incompressible hyperelastic matrix material, the initial level of porosity,
and the macroscopic deformation. The constitutive model is used to predict the
stress–strain behavior of the pore-containing matrix as a function of initial
porosity and macroscopic loading conditions. As an example, a constitutive model
is analytically developed for a porous Neo–Hookean material. The stress is
observed to depend on the material properties of the elastomers matrix, the
initial void volume fraction (porosity) and the applied state of strain.
Constitutive model predictions compared well with those obtained from a
numerical three-dimensional micromechanical cell model for a range of initial
void volume fractions and tensile load cases. The applicability of the model to
compressive loading situations is discussed, such as uniaxial compression.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Cavitation, behavior, rubber, elastomers, damage process,
fracture.
Universal Model for Superconductor-Magnet Forces in the Static Limit
by J. L. Perez-Diaz, J. C. Garcia-Prada, J. A. Diaz-Garcia
Abstract
-
London and Maxwell equations are used in order to derive an exact and universal
expression for the force and torque between a magnetic field (eventually a
magnet) and a superconductor. This expression is useful for any shape and size
of both magnet and superconductor and is suitable for finite elements
calculations in the static limit. Furthermore, the equivalence of our general
purpose expression with the well-known method of images is demonstrated for the
case of a semi-infinite plane superconductor.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Meissner effect, method of images, magnetic levitation,
superconductor levitation.
Reducing the Short-Term Aging of Asphalt with Hydrated Lime
by B. Ali, F. H. Chehade, M. Sadek
Abstract
- The environment which the pavement
must serve is in continuous change which induces a significant impact on
pavement performance. Consequently, highway engineers are constantly looking for
new materials and methods to optimize rheological properties of asphalt. Recent
researches have shown multiple advantages of the use of hydrated lime as
modifier that could enhance performance of asphalt concrete. In the present
survey and in recognition of the importance of the binder, the hydrated lime is
directly added to the asphalt binder unlike most of earlier researches where the
hydrated lime was added to the aggregates. The paper is composed of three parts:
the first part includes a literature review on asphalt aging and the beneficial
effect of lime addition to HMA mixtures. The second part describes rheological
properties of two types of asphalt used in this study and analyzes the influence
of short-term aging on each type of asphalt. The last part presents a comparison
of properties obtained for both cases of non-modified asphalt and lime-modified
asphalt both subjected to short-term aging. Results show a significant
improvement of the resistance to short-term aging and better adhesion properties
of the lime-modified asphal.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Asphalt, asphalt concrete, hydrated lime, short-term aging,
adhesion.
The Kinematic Elution of 99mtc Radio Labelled Red Blood Cells in a Channel of Gravitational Field Flow Fractionation (Grfff)
by A. Saad, A. Echchelh, F. Lahlou, K. Gueraoui, P.Cardot
Abstract
- Field flow fractionation (FFF) is a
chromatographic like methods suitable for the purification and characterisation
of macromolecules, colloids and particulate species. Natural sciences are a wide
application and development domain, cells separation according to difference in
their biophysical characteristics is therefore possible using the FFF principle.The
position of the cell population in the channel is not located before and none is
known about the kinetic and the kinematic motion of the sample during elution
inside the channel. For this reason we are interested in this work in the
dispersion of red blood cells introduced into a system of gravitational field
flow fractionation GrFFF, by means of a kinematic study of the transport of
these particles inside the channel. This original of study was made possible
using a 99mTc radio labelled red blood cells, and a specific experimental set up
witch performed by means of a scintigraphic camera placed on the great surface
of the channel with a series of virtual detectors device positioned in different
channel length. Thus it becomes possible to define position, velocity and
acceleration along and across the channel, and consequently to deduce an
experimental model of the hydrodynamic lift force, its intensity and direction
variation. We could also show the steric hyperlayer mode of red blood cells
elution and the influence of the injection mode of the sample (flow injection
(FI) or stop flow injection) on particles behaviour.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Dispersion, red blood cells (RBC), gravitational field flow fractionation
(GrFFF), hydrodynamic force, steric_hyperlayer, flow injection (FI), stop flow
injection (SFI), Kinematic.
Object-Oriented Intelligent Database System for Composite Materials Selection
by M. Ayman Al-Ahmar
Abstract
- The continuing growth of composite materials industry has produced an increasing need for more computerization in this field. The object-oriented model, applied to an intelligent database system, seems to be the most suitable and promising modeling method for computerization of data and knowledge related to selection of composite materials. In this study, an object-oriented intelligent database system for composite materials selection is developed. The system combines the database and expert systems technologies to provide a decision support tool that aids design engineers in selecting the proper composite material. Interactions with the system are supported through a friendly graphical user interface. The modeling developed provided a considerably flexible and extendable system.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Composite Material, Intelligent Database System, Object-oriented Model.
Deformation of a Two-Dimensional, Shear Deformable Cantilever Beam Using Gradient Elasticity and Finite Differences
by L. T. Tenek, E. C. Aifantis
Abstract
- In the paper it has been studied
the deformation of a cantilever beam using gradient elasticity and the finite
difference method. The basic equilibrium equations are derived for an
infinitesimal area for linear and gradient elasticity. Higher order expressions
for the strain are considered, and from the differential equilibrium equation
for gradient elasticity separate differential equations for the displacements,
in terms of the linear solution, were formulated. Subsequently, recursive
formulas are derived by replacing the derivatives with difference expressions
over points. Computer implementation is performed and the deformation of a
cantilever beam (tension, bending, through-the-thickness) is studied with the
finite difference method. Solutions of exponential and periodic type are
obtained.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Cantilever beam, linear elasticity, gradient elasticity, finite difference
method, beam deformation, recursive formulas, predictor/corrector method.
Experimental Study of the Behaviour of Welded Connections Under Cyclic Loading
by B. Nasser, M. Bensafi, A. Mahmoudi, R. Soltani, A. Boutaleb, S. Boudraa
Abstract
-
Modern codes give the design rules of welded plate-beams connections based on
static loads. The aim of this paper is to study the effect of cyclic loading on
the behaviour of the welded plate-beam connection. In order to achieve this
goal, a program of five tests was carried out. The parameters which were
analysed were the web slenderness, the yield stress, the ration (beff/b)
and the quality of the welds.
The analysis of the experimental results makes it possible to highlight the
validity of certain lawful regulations; in particular those relating to the
local resistance of the web in compression. The quality of welding used also
proves to be a major factor in resistance during traction.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Connections, welds, cyclic, collapse, strength.
Numerical Finite Element Analysis of the Behavior of Structure Near to Deep Excavations in Urban Area
by F. H. Chehade, W. Chehade, H. Mroueh, I. Shahrour
Abstract
- The aim of this paper is to study
the effect of deep excavations on the structure behavior on the soil surface. To
better explain the interaction between the main elements (excavation, soil,
retaining wall and structure), a numerical approach based on the finite element
method is used. This allows taking into account the excavation stages, the
structure and its foundations. An elastic-plastic constitutive law based on the
Mohr-Coulomb criteria is used to describe the soil behavior, and contact
soil-retaining wall is modeled by interface elements. Parametric studies
according to the influence of the position of the structure according to the
deep excavation and its flexibility are performed. A comparison with classical
approaches which decouple the problem of interaction soil-excavation-structure
is also proposed.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Deep excavations, elastic-plastic, flexibility, interaction, structure.
Influence of Heat Treatments on the Impact Strength for Welded Constructions
by M. Zaoui, A. Bouchoucha
Abstract
- The
welded joints are the seat of high residual stresses, localized in the vicinity
of the cracks of the weld cord. Their presence has a major part with respect to
certain damaging modes such as stress corrosion, tiredness, the brutal rupture
and the increase in the temperature of ductile-brittle transition. The welding
operation can be comparable, from the point of view of the heating effect, with
a process of nonuniform heating. Where cooling, at room temperature, the welding
cord and the close zones towards the base metal are partially obstructed by the
little overheated zone during welding. Tensile residual stresses will then occur
in the cord and in adjacent zones. These stresses which are balanced by
residual stresses of compression will be developped in the zones further away
from the cord. Welding is generally followed by a heat treatment after in order
to reduct the residual stresses and secondly to obtain the desired nuance of the
molten zone and the thermically affected zone.
The discussion is based on observations and analyzes of the phenomenon resulting
from the various tests carried out under various conditions by using recent
techniques.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Welding, Heat treatments, Residual stresses,
Brittle
fracture,
Impact strength.
A Nonlinear Model of Floating Caliper Disk Brake with Respect to Squeal
by T. Jearsiripongkul, P. Hagedorn
Abstract
-
Considerable effort is spent in the design and testing of disk brakes in modern
passenger cars. This effort can be reduced if refined mathematical-mechanical
models are used to study the dynamics of these disk brakes before prototypes are
available. Disk brake squeal is a self-excited vibration and dynamic instability
arising from the friction force is agreed to be the reason behind. Intensive
researches on low frequency squeal (noise between 1-5 kHz) have been carried out
by the authors and the present paper is devoted to the modeling of the floating
caliper disk brake and the stability analysis. The model includes the brake
disk, housing, pistons, and brake pads. The floating nature of the caliper has
also been taken into account. The equations of motion are discretized using the
Rayleigh-Ritz method. The onset of squeal due to the instability of the trivial
solution is shown by linearizing the equations of motion for constant braking
force and solving the associate eigenvalue problem. The instability appears even
with a constant friction coefficient between the brake disk and pad. Limit
cycles are obtained in presence of nonlinearity of the brake lining stiffness.
The nonlinear model produces all the prominent features of squeal, e.g.
independence of the frequency on speed etc. and was also validated on a test
rig.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Disk brake, squeal, stability.
Improving Motorcycle Front Suspension Through a Gas Spring
by J. A. Calvo, M. J. López Boada, V. Díaz, E. Olmeda
Abstract
- This paper presents a practical application of a progressive suspension system which was developed for the front-end motorcycle suspension called HYBRID FORK SUSPENSION® (HFS®). The theory exposed was practically tested and applied on a wide range of commercial motorcycles, which showed improvement in its front suspension performance. A simulation-based study is conducted with two different configurations of the front suspension, an originally designed coil spring and equipped with the (HFS®) system, while driving on two kinds of road roughness. Simulation results show that the HFS® system improves the vertical behavior of the motorcycle suspension system. The (HFS®) front suspension is most progressive than the original one, it filters better the road’s irregularities and, as a consequence, improves the comfort level of the ride. HYBRID FORK SUSPENSION® has been international patented and HFS® is a registered trademark.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Motorcycle front suspension; Coil spring; Gas spring; Hybrid fork suspension.
Vibration Isolation of Hand-Held Tools to Prevent Human Hand-Arm Vibration
Syndrome
by A. M. Abu Hanieh
Abstract
- This paper discusses two main ideas for vibration isolation of hand-held tools
to avoid health syndrome of men working on these machines. The first technique
is based on using integral force feedback active control in parallel with
passive damping. Simulation results of this technique have shown high
performance for this technique on transmitted vibrations. The second technique
is based on frequency reduction for the purpose of vibration isolation using
proportional plus integral feedback active control technique. Simulation and
some experimental results on a similar system are shown at the end of the paper.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Hand-Arm Vibrations, Vibration isolation, Integral Force Feedback,
Proportional plus Integral Controller.
An Efficient Tolerances Optimization Algorithm Based in Taguchi Gradients Method
by I. Belaidi, K. Mohammedi, B. Brachemi
Abstract
- We present in this paper an optimization algorithm based in Taguchi gradient method for statistical synthesis of tolerances, adapted to be integrated in Computer Aided Tolerancing systems. Because the analysis and the synthesis of the dimensional and geometrical tolerances are two significant tools in the simulation of the product life cycle, the algorithm for optimisation of the tolerances and calculation of performances criteria such as loss of quality, costs total, function of acceptance, were developed and implemented under MatlabTM. The precision and the simplicity of this algorithm compared to others (finite differences, soft-computing) were highlighted using a comparative study on a published assembly case.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Computer Aided Tolerancing, CADCAM, Tolerances analysis, Tolerances Optimisation, statistical synthesis of Tolerances, Tagouchi method.
Experimental and Numerical Scalar Dissipation Rate Investigation in Variable Density Turbulent Axisymmetric Jets (Thermal Effects)
by M. E-A. Dris, A. Bounif, I. Gökalp
Abstract
- This paper considers an experimental and numerical investigation of variable density in axisymmetric turbulent free jets. Special attention is paid to the study of the scalar dissipation rate. In this case, dynamic field equations are coupled to scalar field equations by the density which can vary by the thermal effect (jet heating). The numerical investigation is based on the first and second order turbulence models. For the discretization of the equations system characterizing the flow, the finite volume method described by Patankar (1980) was used. The experimental study was conducted in order to evaluate dynamical characteristics of a heated axisymmetric air flow using the Laser Doppler Anemometer (LDA) which is a very accurate optical measurement method. Experimental and numerical results are compared and discussed. This comparison do not show large difference and the results obtained are in general satisfactory.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Scalar dissipation rate, Thermal effects, Turbulent axisymmetric jets, Second order modelling, Velocimetry laser Doppler.
A Study on Improving Convection Heat Transfer in a Medium Temperature Furnace
by A. A. A. Minea
Abstract
- This paper presents a theoretical study concerning air circulation in industrial medium temperature furnaces. Studies can reveal the influence of the heat chamber geometry on the air flow circulation. I am proposing a theoretical study for increasing heat transfer in medium temperature furnaces. I obtained theoretical equations that describe the heat transfer between heated walls, and are referring at temperature gradient between walls and air rate in heated chamber.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
heat transfer, radiant panels, furnace, temperature gradient, mathematical model.
Performance Analysis of Irreversible Combined Refrigeration Cycles Based on Finite Time Thermodynamic Theory
by S. Frikha, M. S. Abid
Abstract
- This paper provides a performance analysis of combined refrigeration cycles. A theoretical survey based on finite time thermodynamic (FTT) analysis was presented to evaluate the operating performance of two different combined irreversible vapour compression refrigeration cycles: the conventional cascade (CC) and the integrated cascade (IC). The purpose here is to appreciate a new FTT investigation by stage (FTTS) for complicated architecture systems like the IC system that can’t be divided into separate cycles. In this FTTS approach, the system will be divided into n stages where each stage is defined by two consecutive heat exchangers. We began by detailing finite time thermodynamic analyses by cycle (FTTC) and by stage (FTTS) for the CC system. Then FTTS analysis was applied for the IC systems to derive a simple expression for the coefficient of performances (COP). Numerical examples are given to evaluate effects of internal irreversibility and intermediate heat-exchanger temperatures on the coefficient of performance of the CC and IC systems. It was found that at fixed condensing and evaporating temperatures and for same intermediate heat-exchanger temperature ratio, the IC is more efficient than the CC system. The coefficient of performance of the IC system can be more enhanced under the condition of minimum intermediate heat exchanger irreversibilities (less glide between the two counter-flow intermediate heat exchanger).
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Conventional cascade, Integrated cascade, Finite time thermodynamics, Irreversible refrigeration cycle, Coefficient of performance.
Bubble Two-Phase Flow Simulation with Volume of Fluid Interface Tracking Method
by D. Merrouche, K. Mohammedi, I. Belaidi
Abstract
- Numerical methods developed in simulation of two phase flows, explicitly resolve and track the interface with special numerical techniques of either Lagrangian or Eulerian type. While Lagrangian techniques are suited for small deformations of the interfaces, Eulerian techniques are usually preferred for highly distorted complex interfaces. For the most of flow regimes, the shape and evolution of the interfaces are not easily implemented in calculation codes, and this explains the interest in the development of interface tracking methods. In this paper, we present some of the main techniques used in the modelling of two phase flows. We will focus on the application of the Volum Of Fluid method of SURFER code in the prediction of the flow around a spherical and Taylor bubbles rising in a quiescent liquid.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Multiphase Flow, Bubbles, Interface Tracking and Capturing, VOF Method.
System Modeling and Parameter Effects on Design and Performance of a New Refrigeration Machine
by S. Mazouz, H. Dardour, A. Bellagi
Abstract
- This paper presents a thermodynamic model of a recent patent of a diffusion refrigeration machine. The thermodynamic simulation of this cycle is based on both mass and energy balances applied to each component of the cycle. The equations written for each component are coupled and must be resolved simultaneously. A set of independent data and assumptions, are considered. The set of resulting equations are solved using the EES software. The developed model predicts most of the features of the machine especially the coefficient of performance COP which reaches 0,5. A parametric study is performed in order to investigate the effects of the bypass introduced by this patent as well as the pinches of temperature, and the rate of degassing on the COP.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Absorption, ammonia-water, modeling, refrigeration.
| 
