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ARPN Journal of Engineering and Applied
Sciences
May 2013 | Vol. 8 No. 5 |
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Title: |
Numerical
simulation of nozzle flow with chemical equilibrium |
Author (s): |
Mohamed A. Al
Kady and Farouk M. Owis |
Abstract: |
The compressible two-dimensional planar and
axisymmetric Navier-Stokes equations are solved in generalized
curvilinear coordinates to simulate non-reacting and chemical
equilibrium nozzle flows. A zonal turbulence model of
is used in the simulations to compute the
eddy viscosity. A numerical method is developed to discretize
the governing equations using the finite difference technique.
The convective terms in the governing equations are solved
numerically using a second order flux difference splitting
method of Roe while a second order central difference is used
for the viscous terms. The discretized equations are
integrated implicitly in time to increase the stability of the
numerical scheme. The flow solver is coupled with a chemical
equilibrium module to compute the composition of gas mixture
of known enthalpy and pressure. Few test cases are performed
to illustrate the capabilities of the flow solver to predict
nozzle flow with and without chemical equilibrium. The results
are compared with the published data and the results are in
good agreement with those published simulations of the same
test cases. |
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Title: |
Effect of
green inhibitor on the corrosion behaviour of reinforced carbon
steel in concrete |
Author (s): |
Eyu D.G,
Chukwuekezie C, Esah H, Idris J. and Mohammad I. |
Abstract: |
The effect of inhibitors on the corrosion
behaviour of carbon steel reinforced in concrete exposed to
3.5% NaCl solution has been studied by electrochemical and
weight loss tests. The corrosion potential and concrete
resistivity were determined during the immersion time of the
concrete specimens. The results show that calcium nitrite and
vernonia amygdalina extract reduced corrosion rate compared to
sodium nitrite. However, vernonia amygdalina inhibition was
more effective in the immersed concrete in simulated seawater.
The weight loss results demonstrated that 2% sodium nitrite
was more effective with efficiency of 96% in comparison with
2% calcium nitrite and 6% vernonia amygdalina with efficiency
of 92% and 75% respectively. From the results, it is evident
that the extract from vernonia amygdalina (bitter leaf) acts
as an excellent corrosion inhibitor for rebar steel,
efficiency increases with increase in dosage, and the
inhibition mechanism was by physical adsorption which is
responsible for shielding the specimen from corrosive
environment. |
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Title: |
Optimization
of water distribution networks path |
Author (s): |
Ioan Sarbu
and Emilian Stefan Valea |
Abstract: |
The determination of pipe
network optimal path is important for an effective modeling
and optimization of water-distribution systems. A principal
application of the branched network optimal path is to
evaluate the hydraulic performance of the distribution system
based on selected schemes for many types of network analysis
(e.g., design, operation, calibration).
Already
known algorithms
for solving this
problem
usually determine a
sole
solution
which in some
cases
proves to be
suboptimal.
This paper
is a mathematical approach of the branched pipe network path
optimization for water distribution. It is developed an
algorithm based on graph-theory which
generates
all
minimal
trees
of
the graph
comprising
nodes
where
consumers are
placed and links
(pipes)
between them
and is implemented in a computer program for PC microsystems.
Thus, can be determined all optimal solutions, for a given
criterion. The optimization model is applicable to design of
the distribution networks for hydro-urban and
hydro-amelioration systems. Numerical example will be
presented to demonstrate the accuracy and
efficiency of the
proposed optimization model.
These show a good performance of the new
model. |
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Title: |
Investigating
the effects of some parameters on hydrogen sulphide stripping
column using aspen hysys |
Author (s): |
Saidat
Olanipekun Giwa, Abdulwahab Giwa and Hale Hapoglu |
Abstract: |
This work has been carried out to investigate
the effects of fresh water volumetric flow rate, column tray
number, wastewater feed tray number and boilup ratio on the
stripping column used for the purification of wastewater
containing hydrogen sulphide as the main impurity. The
stripping column was modelled with the aid of Aspen HYSYS
using Electrolyte NRTL as the Fluid Package. The wastewater
feed and the stripping liquid (fresh water) feed were passed
into the stripping column at a temperature of 25 oC
and a pressure of 1 atm. From the results obtained from the
investigations carried out, it was revealed that pure water
was obtained as the bottom product of the stripping column
used for the purification of the wastewater but the mass
fractions of the hydrogen sulphide and the purified water in
the top product was found to vary with the changes in the
parameters considered. So, it is recommended that the values
of the parameters should be chosen for the treatment of the
wastewater containing hydrogen sulphide based on whether
hydrogen sulphide is expected to be in low or high
concentration in the top product of the column. |
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Title: |
A
comprehensive survey on multi-port bidirectional dc-dc
converters for renewable energy systems |
Author (s): |
Venmathi. M
and Ramaprabha. R |
Abstract: |
Renewable energy sources such as fuel cells,
photovoltaic (PV) arrays are increasingly being used in
automobiles, residential and commercial buildings. For
stand-alone systems energy storage devices are required for
backup power and fast dynamic response. A power electronic
converter interfaces the sources with the load along with
energy storage. Existing converters for such applications use
a common dc link. High frequency ac-link based systems have
recently been explored due to its advantages of reduced part
count, reduced size and centralized control. Such a high
frequency ac link based converter is termed as a multi-port
converter in which ports are connected with the energy
sources, energy storage devices and the load. It is desirable
to have bi-directional, isolated power flow between energy
storage devices and the sources. This paper deals about the
multi-port bidirectional converters with different topologies
either with voltage fed or current fed structure.
Bidirectional power flow between the load port and the energy
storage devices are achieved in order to maintain the power
balance in the system. The power flow between ports can be
controlled by suitable control strategy and phase-shifting the
square wave outputs of the bridges in combination with pulse
width modulation (PWM) control scheme. Moreover the converter
also has high efficiency due to soft-switching operation in
all the ports. This paper deals about an elaborate review on
bidirectional multi-port dc-dc converters for interfacing the
renewable sources. |
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Title: |
Magnetic
susceptibility, remanent magnetization and coercivity variations
along soil profile |
Author (s): |
N. D.
Nurgalieva and P.G. Yassonov |
Abstract: |
The determination of magnetic susceptibility
χ, remanent magnetization Jr
and coercivity Bcr
variations along Glifada automorphic soil
profile has been carried out using
χ
- meter
MS2-B and
unique lab
coercivity spectrometer permitting to
distinguish paramagnetic magnetization and saturation remanent
magnetization and to determine Jr
and coercivity
Bcr. These parameters
give the consideration of soils components in
terms of
paramagnetic, ferromagnetic, ferrimagnetic, or
antiferromagnetic states. The results have revealed that
investigated soil profile was recorded in magnetic parameters
variations and controlled by environmental factors. |
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Title: |
Assessment of
carbon emissions under the uncertainty of the energy using for
the production of pig meat |
Author (s): |
Prayong
Keeratiurai |
Abstract: |
Carbon is an
important element for humans because it is the primary element
of both plants and animals and it cycles through living and
non-living components. Pigs are energy using animals that are
raised for their meat, and produce emissions of CO2. The
carbon footprint is also the alternative for consumers to
choose products with the least release of greenhouse gases
into the environment. Therefore it is important to study and
understand the relationship between the carbon emissions and
carbon transfer to pig’ energy use to develop carbon
footprints for meat production. The focus of this study was to
develop carbon footprints for pig meat production. To
accomplish this we studied the rate of the carbon emissions
from electricity, petroleum, LPG used during meat production.
The results shown that the carbon emission were 0.21±0.05,
1.22±0.13 and 0.24±0.05 kg.C/head/day from the using of
electricity energy, transportation energy, and LPG,
respectively. The carbon emission from the using of
transportation energy was quite high in terms of energy using
but low in the using of electricity and LPG activities. The
results also shown that the carbon emission of the energy
using from farms and slaughterhouses were 1.98±0.17 and
1.11±0.04 kg.C/head/day, respectively. The carbon footprint
from energy using were 26.33±0.33 kg.CO2.eq./1 kg.meat.
Therefore, farmers should reduce emissions from energy
consumption such as reduce electricity utilization in farms,
slaughterhouses and reduce distance for animal feed
transportation to farms, animals to farms and slaughterhouses.
It is suggested that the use of fuel for transportation should
be reduced because it creates the highest carbon emission. |
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Title: |
Coordination
of PSS and facts devices for power system stability enhancement:
a review of the state-of-the-art |
Author (s): |
J. Usman, M.W.
Mustafa and G. Aliyu |
Abstract: |
Power systems stability has been a concern and
it will continue to be the major concern in power system
operations due to power system oscillations caused by complex
interconnections. Efforts have been attracted towards damping
the power system oscillations for enhancing stability in power
systems. The instability that has been affected by the complex
interconnections is the small signal stability. Power system
stabilizers (PSS) are promising in damping small signal
stability. Although, PSS are
confronted with some drawbacks of serious variation in the
voltage profiles and it may also results in leading power
factor operations which may cause reduction of system
stability under heavy disturbances. In large
multimachine power systems, the application of only
conventional PSS may cease to provide adequate damping for
inter-area oscillations and effect of variation in voltage
profile. However, power electronic device known as Flexible
Alternating Current Transmission System (FACTS) devices are
effective in damping the inter-area oscillations and capable
of handling the variations in voltage profile. Therefore this
paper presents a comprehensive review and evaluation of PSS
and FACTS power oscillation damping (POD) controllers in
mitigating low frequency oscillations based on computational
intelligence methods. Technical paper publications on design,
optimal location and optimal parameter tuning associated with
PSS and FACTS based controllers are highlighted. Finally the
potential future research directions for novel PSS and FACTS
devices is proposed as a reference for interested researchers. |
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Title: |
Effects of
chemical reaction and radiation absorption on the unsteady MHD
free convective flow past an infinite vertical moving plate
with constant heat source |
Author (s): |
A.G. Vijaya
Kumar, K. Raveendra Babu, B. Reddappa and S.V.K. Varma |
Abstract: |
An analysis has been
carried out to investigate the effects of the heat source,
chemical reaction and radiation absorption on unsteady MHD
flow with heat and mass transfer of an incompressible,
viscous, electrically conducting fluid past an infinite
vertical moving plate with constant temperature in the
presence of transverse applied magnetic field. An exact
solution for the flow problem has been obtained by solving the
governing equations using Laplace-transform technique. At time
ť > 0, the plate is given an impulsive motion with a constant
velocity µ0.
At the same time, the plate temperature and concentration
levels near the plate are raised to T́
ww and C´w, respectively. The
velocity, temperature, concentration and the rate of mass
transfer are discussed through graphs while the numerical
values of Nusselt number are presented in a table. |
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Title: |
Methyl
acetate reactive distillation process modeling, simulation and
optimization using aspen plus |
Author (s): |
Abdulwahab
GIWA |
Abstract: |
The modeling, simulation, and
optimization of the reactive distillation esterification
process used for the production of methyl acetate have been
carried out in this work with the aid of Aspen PLUS. The Aspen
PLUS reactive distillation process model was developed and
simulated using Rad Frac packed column, the rectification and
the stripping sections of which was filled with Raschig Type
packing of dimension 25 mm and the reaction section of which
was filled with Sigma Type packing material of 10 mm
dimension. In addition, Non-Random Two-Liquid property method,
volumetric feed rates of both acetic acid and methanol of 0.03
L/min, feed temperature and pressure of 25 oC and 1
atm respectively were used. The optimization of the process
was accomplished using the Optimization Section of Model
Analysis Tools of Aspen PLUS. The good convergence obtained
from the simulation of the developed Aspen PLUS model of the
reactive distillation process has shown the versatility of
Aspen PLUS in successfully representing the behavior of the
complex reactive distillation process used for methyl acetate
production. Furthermore, the achievement of the value of the
objective function given by the optimization of the process
when the estimated optimum values of reflux ratio and reboiler
duty were used to run the developed model revealed that the
optimum values obtained from Aspen PLUS were valid ones. |
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Title: |
Effects of
slip condition and multiple constrictions on couple stress fluid
flow through a channel of non uniform cross section |
Author (s): |
Gurju Awgichew
and G. Radhakrishnamacharya |
Abstract: |
Steady incompressible couple stress fluid flow
through a non-uniform channel with two stenoses is
investigated. Assuming the stenoses to be mild and using the
slip boundary condition, the equations governing the flow of
the proposed model are solved and closed form expressions for
the flow characteristics (resistance to flow and wall shear
stress) are derived. Both the resistance to flow and the wall
shear stress increase with the heights of the stenoses and
slip parameter but decrease with Darcy number. The effects of
wall exponent parameter on the flow characteristics also have
been studied. |
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