Engineering and Technology Journal

This paper presents the simulation results of the thermal behavior for an
externally cooled asynchronous electric motor in both steady and transient states
cases. For this purpose, a mathematical model based on the heat equation is first
developed to determine internal thermal sources such as copper, mechanical, and
iron losses. Then, a computer program is developed to numerically simulate the
proposed mathematical model. This program determines the radial distribution of
steady and transient states temperatures and predicts the effect of the ambient
temperature on the transient and permanent temperature distributions. This
makes it possible to calculate the specific speed of the motor as a function of its
rotation speed, the airflow rate, and the pressure dropping at the fan level. The
obtained results show that the engine heating is mainly due to the elements that
show thermal losses by the Joule effect. Moreover, the mitigation of these losses
is strictly related to the specific speed, making it possible to select the right
choice for the engine cooling system.

Window solar air collector is an imperative instrument for heating residential
buildings in cold regions. This paper presents a numerical investigation of the
thermal performance of a window solar air collector with seven moveable absorber
plates. With glass on the front and back sides of the collector. By the use of
FORTRAN 90; The three-dimensional steady-state turbulent forced convection
method was used to solve the Navier-Stokes equations. The seven plates opened
and closed at different angles in unison manually by a specific mechanical
mechanism. The effect of changing the plate angles has been tested, alongside the
effect of airflow rates and the intensity of solar radiation. Numerical results
illustrate that air temperature difference is higher at vertical plates position (angle
0°) compared to that at angle 90. In contrast, flexibility between sunlight
penetrating the room and hot air from the collector will be gained when the plates
are set on angle 90. Results indicate that the thermal performance was improved
by 67% when the plates were set at angle 0. Maximum thermal efficiency for angle
0 was 72% at a mass flow rate of 0.0298 kg/s. However, maximum thermal
efficiency was 51% at mass flow rate 0.0298 for angle 90°.

This paper develops a unit commitment multi-period energy management system
to minimize a low voltage microgrid's total operation and emission cost. The
optimization problem is formulated in the mixed-integer quadratic program. The
environment cost and battery degradation cost are taken into consideration in the
proposed optimization approach. The unit commitment strategy is employed to
minimize the total cost. A set of constraints are considered in the proposed
optimization approach. The proposed energy management system is applied to the
low voltage distribution grid, including different distributed generators, such as
diesel engines, fuel cells, and microturbines. The microgrid also contains storage
batteries, renewable energy resources, wind turbines, and photovoltaic panels. The
results reveal that the storage battery charging and discharging operations are
controlled to reduce the operation and emission cost even considering the battery
degradation cost.

The present work aims to study the effects of working fluids on the thermal
performance of the heat pipe with a wick and in a horizontal position. The
experiments were conducted using a copper heat pipe with a 20.8 mm inner
diameter, and the length of the evaporator, condenser, and the adiabatic regions
were 300 mm, 350 mm, and 300 mm, respectively. The working fluids selected
were water, Methanol, ethanol, and different binary mixtures (50: 50) %, (30: 70)
%, (70: 30) % mixing ratios. The filling ratio was 50% of the evaporator volume
for all working fluids, and the heat input values were 20, 30, 40, and 50 W. The
results show that the heat pipe charged with Methanol has a thermal resistance of
(0.85166oC/W), the lowest thermal resistance value. The lowest thermal resistance
of using mixtures is (0.785 oC/W) for (50 % methanol: 50% ethanol). Both are
achieved at 50 W heat input. Also, at 50 W heat input, the highest value of heat
transfer coefficient when using water as a working fluid is (510.386 W/m2. oC),
and for using a mixture (70 % water: 30% methanol) A R T I C L E I N F O is (556.78 W/m2. oC).

This study investigated the effect of exhaust gas re-circulation (EGR) on
performance and exhaust emissions in a single-cylinder, air-cooled, and directinjection
diesel engine. The Iraqi diesel fuel (D100) and European diesel fuel
(ED100) were utilized at different speeds from (2100 to 3300 in intervals of 300)
using the recycling of exhaust gas by a ratio (0%, 5%, 10%, 15%, and 20%. The
study showed that European diesel fuel positively impacts engine performance and
emissions. Compared to Iraqi diesel fuel, European decreased diesel fuel the
brake-specific fuel consumption by (10.96%), increased brake thermal efficiency
by (8.67%), decreased exhaust gas temperature by (9.99%), and (NOX, UHC, and
decreased (CO) emissions by (7.94%, 10.07%, and 36.98%) respectively. When
using the EGR ratio, the highest percentage that can be used is (20%). If this
percentage exceeds this, it will cause a flame loss because the recycled gases are
inert. Furthermore, the results indicate that brake-specific fuel consumption
increases by (15.395%) and brake thermal efficiency decreases by (13.44%) with
increased EGR ratio. In contrast, exhausting gas temperature and NOX emissions
decreases by (4.01% and 14.57%) respectively. Finaly, the UHC and CO
emissions increased with the increase of EGR ratio.

Wind energy has a potency of playing a vital role in the future of energy demand providing and environment freshening in many areas of the world. Utilizing wind turbine systems has become a competitive recourse among other renewable energy sources in terms of cost-effectiveness and the transition toward renewable energy usage. Researchers and developers are constantly dedicated to innovating to improve the technology of designing wind turbine systems. Wind energy depends mainly on the wind velocity and the area that swept them, increasing the wetted area. This is done by either upscaling the area of the wind rotor or constructing multi-wind turbines according to the type of designs that fit modern innovative systems. Though large wind turbine units do not fit with all sites, especially in cities, these turbines may be installed offshore and onshore. This paper aims to explore the relevant works technologies related to the wind energy potential, developments, design improvements, and multi-rotor horizontal axis wind turbine systems (HAWTs). This was achieved based on favorable characteristics such as economic viability and clean energy resources. Hence, these aspects reduce the environmental impacts and improve technological advantages and profitability. The results of this paper provide a recognizable system's facts and platforms that can be easily utilized. Wind Energy has the potency of hybridization with other renewable energy resources, which play an important role in urban planning, smart cities, and Buildings integration.

Sandwich composites are one such kind of light-weight composites developed for
structural and vehicle body buildings etc. Due to their remarkable features such as
high specific strength, high toughness and resistance to inter laminar shear
strength. In this study, commercially available aluminium sandwich composite
(ASC) laminate was considered for investigating its flexural behavior and buckling
behavior as it was mostly used for various structural applications. Flexural analysis
was done for different aspect ratios in order to analyze the influence of cross
section of the specimen and support span on the flexural capability of the sandwich
beam. The composite specimens prepared for flexural test consist of length 150
mm and widths 15, 12 and 10 mm. The flexural test was done for support span of
90, 110 and 130 mm respectively. The performance measures of flexural test are
maximum bending load, deflection, flexural stiffness and inter-laminar shear
stress. The flexural analysis revealed the fact that the aspect ratio appreciably
affected the flexural capacity of the sandwich composite laminates. Maximum
flexural capacity with bending load around 3.5 to 4 kN and flexural stiffness
around 2.5 to 4.7 kN/mm respectively was observed for the sandwich specuimen
for the aspect ratios L/t = 30 and b/t = 5. Being a anisotropic structure, the flexural
behavior of this sandwich composite exposed as a combination of bending and
shear failure. The soft core material and ductile skin face sheets resulted in a
combined failure against flexural load in static condition.

A spur gear is one of the most common forms of precision cylindrical gear. In the
industry, reducing the weight of gears while keeping their useful properties has
become an even more pressing challenge. As a result, the investigators have made
many attempts to reduce the weight of the gears. Despite these efforts, the problem
still requires more research. This study presented a spur gear's modeling and finite
element analysis using different materials. A three-dimensional spur gear was
designed, modeled, and simulated using ANSYS software. Five different
materials, including two conventional materials (stainless steel and copper alloy)
and three different composite materials, including 50% carbon fibers reinforced in
epoxy resin, 1.5% filler containing acetal, i.e., Graphene Reinforced Acetal, and
glass-filled polyamide. Composites were fabricated by varying the graphene
quantity in Acetal nanocomposites. The spur gear stress was calculated
theoretically using the Hertzian equation, and FEM was analyzed using ANSYS
14.0 under limited loading conditions and rotational speed. Although the obtained
results showed that both methods were comparable, there was a significant
difference between the two methods when 50% carbon fibers reinforced in epoxy
resin matrix were used, which is Hertzian analysis was 250.13 MPa. In contrast,
this result was reduced up to 152.13 MPa in FEM. The study concluded that among
the different presented materials, 50% carbon fibers reinforced in epoxy resin
matrix were the optimal material for spur gear fabrication due to their high strength
and low density. Hence, the spur gear material can be replaced by 50% carbon
fibers reinforced in the epoxy resin matrix.