Iraqi journal of mechanical and material engineering

In this investigation NiAl-based composites containing a dispersion of Al2O3 particles
are prepared by sintering technique at 1350°C for 90 min. in an argon atmosphere.
Intermetallic compound NiAl was prepared from a mixture of nickel and aluminum
powders by using reactive sintering technique at 600°C for 12 Hrs. in an argon
atmosphere. To improve the ductility of NiAl three weight percents of Cr (3.5, 4,
4.5 wt %) were added to the composite (NiAl-Al2O3). Series of experiments showed
that:
- adding of (Al2O3) to (NiAl) leads to increase its compressive strength and its
hardness but with a decrease in its ductility;
- adding Cr to the intrmetallic composite (NiAl-Al2O3) leads to increase its
compressive strength and its hardness with an ability to improve its ductility.
An addition of (4.5 wt% Cr) to the composite containing (10wt%Al2O3) led to
improve the compressive strength by (25%), hardness by (9%) and ductility by
(94%) in comparison with that containing no Cr.

Fuel and oxidant gas delivery plate, or fuel cell plate, is a key component of a Proton
Exchange Membrane (PEM) fuel cell. To develop low-cost and high performance fuel
cell plates, advanced computer modeling and finite element structure analysis are used
as useful tools for the optimization of the plates at the early design stage.In a fuel cell
application, these fuel cell plates are routinely heated up to 80oC with structure
pressure loads. The temperature induced thermal stresses is found to be much higher
that the structure loading stress. Thus, the thermal stresses plays a key role in the
structure design and optimization of the plates.To carry out the analysis, a model of
the serpentine plate is analyzed using finite element analysis model for both linear and
nonlinear elasticity analysis. Design optimization is applied to minimize the
maximum stress within the plate, subject to constraint with both geometry and
material parameters as design variables. The study reveals the characteristics of the
printed plates, and provides guidelines for the structure and material design of the fuel
cell plate.

This study included air drying of a single le kernel of fruits (apple, apricot or grape)
which is taken as a sphere. Convective heat and mass transfer takes place between the
sample surface and its drying environment; while, unsteady heat conduction and
moisture diffusion take place within the drying body without phase change for liquid
(evaporation occurs at the surface only). The mass, energy conservation equations
was solved by using the finite difference technique. A set of empirical correlations
have been employed to determine the product properties which assumed to be
changed during drying process like (thermal conductivity, specific heat and
coefficient of moisture diffusion) and other properties was assumed to be constant
through the process as (the coefficients of heat and mass transfer and the density). The
results showed that the product temperature is increased and its moisture content will
decrease during the drying process. The numerical results were compared with
experimental results and showed good agreement.

Studying of effect polymers addition on drag force for flowing crude oil are presented.
Two types of Iraqi crude oil have been studied namely, Karkok crude oil with
API=35.8 and Basrah crude oil with API=31.2 .
Three types of linear polymers (poly isobutylene PIB150K, PIB90K and poly
isoprene PIP) are used, the polymers are injected through pumping system at different
concentrations rounded between (10-50) ppm with temperatures range of 30o to 50oC.
Several experiments were carried out to determine the best concentration of polymer
which is satisfied lowest drag force on of crude oil flow rate .The results show that the
best execution are realization for PIB150K at 30 ppm and 45oC for two types of crude
oil.

It is well established that Aluminum and its alloys are widely used in aerospace
industries, for their good mechanical and physical properties. In addition, to reliable
toughness and low density which is the prime importance factor in selecting materials
for aerospace industries.
Duralumin (Al-4% Cu) is one of these important alloys and it is one of (2XXX) series
where Copper is the major alloying element. However, in spite of its high strength, it
has low thermal stability, which imposes limitations on Airplanes speeds, from which
Air frame is made. This work represents an attempt to improve thermal stability.
Several techniques were adopted to evaluate the role of thermo-mechanical treatments
and alloying elements. Results show an interesting behaviour and significant
improvement in properties.

Considering pollution problems today, investigations have been concentrated on
lowering the concentration of toxic components in combustion products. A gasoline
lead additive at a concentration of 0.6 g/l is used to provide a gasoline with an octane
number of 98. In many countries methyl tertiary butyl ether (MTBE) is used instead
of lead to produce gasoline with the same octane number. Presently, 15% by volume
of MTBE is added to unleaded gasoline to provide a gasoline with an octane number
of 98. However, the leaded gasoline is still used in many countries.
The purpose of this research is to experimentally study the possibility of using ethanol
as a lead / MTBE replacement for spark ignition engines fuels. The effect of ethanol
addition to unleaded gasoline on the research octane number, performance and
pollutant emission of the spark ignition engine is studied. A Ricardo E6/US engine is
used in this study. Results showed that the use of 15.% by volume of ethanol is a good
alternative for replacing lead or MTBE in gasoline fuel and the resulted blended fuel
satisfies the global specifications.
The results of the standard ASTM methods showed that with increasing the ethanol
content, the research octane number of the blended fuel increases, while the Reid
vapor pressure of the blended fuel initially increases to a maximum value at 10 % by
volume ethanol and then decreases. The results also showed that the addition of
ethanol, (from 0% to 30% by volume), increases the break power, break thermal
efficiency and break specific fuel consumption, and reduces NOx, CO, and HC
emissions. The higher useful compression ratio, which produced maximum break
power, is directly proportional to ethanol percentage in the blended fuel

An unsteady- state model of vapor compression refrigeration system is presented.
Thermal and flow processes occurring in a small-scale refrigeration system have been
discussed. A theoretical description of the processes in the system components has
been proposed in order to develop a theoretical model of the entire system.
Components model include the heat exchangers (condenser and evaporator),
expansion valve and compressor. For the condenser and evaporator mathematical
model, assume two approaches for homogenous refrigerant, the first approach is the
lumped model and the second is distributed model.
Experimental investigations are carried out on the laboratory scale system model
RCT/EV.
The results obtained from the two models prediction are in a good agreement with the
experimental results. The system approaches its final steady-state operating condition
in a few minutes.

Buckling, a distinguished word appears in the most failure case of the more sensitive
applications such as cylinder. Buckling analysis presents the most important once in
which huge helpful information (the failure modes, types of failure, and critical failure
load respectively) must be taken in the considerations in the design of any structure.
In this paper, buckling analysis was done on stiffened composite cylindrical shell to
obtain the critical load and modes of failure under different conditions. The
mathematical formulation of the problem was achieved by the ANSYS (Analysis
System) finite element program. Effects of some parameters (fiber orientation, skin
thickness, and elastic material properties) were studied. A numerical program includes
all above features written in APDL (Ansys Parametric Design Language) was
achieved.