University of Thi-Qar Journal for Engineering Sciences

Laminar counter and parallel flows in a double pipe heat exchanger is studied experimentally using two types of nanofluids as a cooling medium. The nanofluids consist of Al2O3 and TiO2 nanoparticles, which were added to the base fluid (deionized water). The average diameter of nanoparticles is approximately 20 nm for both Al2O3 and TiO2 nanoparticles. The volume concentrations of nanofluid was varied with a range of (0.05-0.3) percentage and the flow rates of the base and nanofluids were varied with a range of (0.5-2) L/min. Hot fluid (water) is flowing in the inner tube of heat exchanger with constant inlet temperature and the cold fluid (nanofluid) is introduced in the outer tube with constant inlet temperature.Compared to the base fluid, the results showed that the nanofluid containing Al2O3 and TiO2 nanoparticle exhibits enhanced heat transfer, and this enhancing is clearly reflected by the increase in the inside and outside heat transfer coefficients, thus the overall heat transfer coefficient, where the percentage enhancement in heat transfer coefficient of nanofluid per base fluid is (18.25 and 15.5) % for Al2O3-water and TiO2-water nanofluid respectively. The enhanced performance of heat exchanger is due to high value of thermo physical properties of fluid when dispersing nanoparticles in the base fluid.

In this research, a study of strengths for PA (Nylon 6,6) sheets welded by FSW process is analyzed by Minitab-16 program. For this purpose a commercial PA sheets provided with dimension of 250× 150× 8 mm were used. An especial tool was designed with 16 mm diameter for the shoulder, while pin length and diameter were 7.8 and 4 mm respectively. The rotation speeds used were (2000, 1570, 1255, 994, and 780) rpm, and traverse speeds were (27, 42, and 62) mm/min.tensile and impact tests were done in order to evaluate mechanical behavior of material. For analysis the effect of the variables on strength of the joint, software program (Minitab 16) used to design plan for joint and show the effects of the variables by analysis them. It was found that welding strength increases with increasing rotational speed and decreases with traverse speed increase and the optimum properties were obtained when these speeds were 1570 rpm and 42 mm/min respectively.

An approximated mathematical model for uniform internal pressure is studied, theoretically based on an ideal elastoplastic deformation theory and based on an equal divided thin walled circular shell,which numerically solved and used the results for testing experimentally and simulate by NX 8 Siemens finite element software under the resulted stress constrain criteria in yield stress and more 5% of it, with a limit of plastic deformation appearance in the model selected for two different material Steel 1006 and Aluminum 6053, which were under An investigation of bending test ,for estimations the resulted displacements values during elastoplasticde formation. The using of getting model given an error percentage compared with the basic theoretical mathematical equation of internal uniform pressure, which given 1.5-2%for Steel 1006 and 0.1-0.19% for Aluminum 6053, which is supported the correctness and the acceptance of using the suggested getting approximated mathematical model in this study.

This paper investigates the modeling of the Reactive Powder Concrete (RPC) beams reinforced with the different types of the reinforcement (steel and Sand-coated CFRP). The ANSYS 11 program was used. The experimental works included casting of eight RPC concrete beams. Four of them reinforced with steel bars, while the others were casted using sand-coated CFRP bars. The mechanical properties of the RPC were experimentally obtained. The manufacturing data were used for CFRP bars. The RPC was modeled by Solid 65 element. The steel plate for loading and support was modeled by. The steel and CFRP Bars were modeled by discrete bar element. The study includes the effect of the distribution of the steel fibers on the flexural behavior in term of load-deflection relation. The uniformly distributed of the steel fiber longitudinally and vertically gave the best behavior than the corresponding experimental results for both types of reinforcements.

The first part of the present research is to estimating the relationship between the overall friction power and rotating speed of a 4-stroke single cylinder diesel engine practically by using an electrical motor which was directly connected to the engine with a suitable coupling, and the input power was controlled by using an inverter,(current and volts) were measured by using a digital clamp-meter for different rotating speeds of (600,1200,1800, 2400, 3000 and 3600) rpm. From the data achieved an equation (polynomial third order) was estimated which represents the friction losses as a function of engine speed. The estimated equation is used in simulation program (QBASIC ), for predicting the effects of friction on some parameters (power ,efficiency and fuel consumption ) .The second goal is to developing the estimated equation and using it many cylinders and many displacement volume diesel engines by multiplying it by displacement ratio and number of cylinders.Finally the results showed good agreement.

Electrokinetic micropumps received extra attention due to its applications in pumping of biological and chemical fluids, such as blood, DNA, and saline PBSs. In this paper the electroosmotic flow in microchannel has been numerically investigated by developing a model from the basic governing equations (continuity, momentum, energy, and Laplace and Poison-Boltzmann equations) through a square channel with contraction of different geometries. Utilizing the numerical analysis, a mathematical model has been built in order to study the electroosmosis-based microflow of the negatively charged messenger proteins to the negatively charged nucleus to shed more light on the electroosmotic flow behavior through microchannels with contraction. The results obtained show a considerable effect of the zeta potential on the velocity and many parameters studied such as shapes, depth and number of contractions and channel wall material. Adding materials with different thermal conductivity to channel wall,affect the heat distribution throughout channel length. In particular, five wall materials typically used in Microelectromechanical systems (MEMS). It shows that a material with low thermal conductivity works as isolation against dissipating the heat generated from Joule heating effect.

The refrigerant R134a widely used in refrigerating and air conditioning units.It has zero ozone depilation potential factor (ODP) but have 1300 global warming potential (GWP) and their interaction with heat radiation. It is necessary to minimize the global warming, by changing R134a with the ones that are not depleting the ozone layer and very little in Global Warming Potential (GWP). In this paper, a new azeotropic refrigerant mixture of three refrigerants named R134a, R290 and R600a with four different .mixing ratio of mass are used as an alternatives refrigerant to.R134a..The theoretical model show that, all new refrigerant mixtures give higher refrigerating effect than that of R134a. Meanwhile experimental results revealed that the obtained COP by the new mixtures is less than that of R134a, and the most suitable refrigerant that can be used instead of R134a was Mix2.The COP of Mix2 is 8 % less than that of R134a at 24 °C room temperature

Laminar mixed convective flow in a ventilated square cavity with baffle has been studied numerically using finite element method with software package (FlexPDE). The bottom wall is heated with a constant heat flux and the other walls are adiabatic. The flow is assumed to be two-dimensional. The air enters the cavity through an opening at the bottom of the left wall and exits from another opening at the top of the right wall. Laminar regime is considered under steady state condition. In addition, the two horizontal guide baffle, first baffle was attached from the left vertical wall and the other baffle was attached from the right vertical wall with a constant height Hb1= 0.5L and length Lb= 0.25L and the third baffle was put in the center with different height Hb2= 0.25L, 0.5L and 0.75L and Lb1= 0.4L. A parametric study was performed presenting the influence of; Reynolds' number (50 ≤ Re ≤ 200), Richardson number (0.1≤ Ri≤ 10) and Prandtl number (Pr= 0.71).Results were presented with streamlines, isotherms, Nusselt numbers and average non-dimensional temperature. And the result show the increasing of Nu with increasing Re, Ri and with decreasing the location of the baffle from the bottom wall. A comparison was made between the present work and that obtained by [1]which it reveals good agreement

Geographic Information Systems (GIS) have contributed in the optimal planning of cities in general, and evaluate the distribution of services locations within cities, including the civil defense service in particular. The city of Nasiriyah was chosen to study the different geographic data collection belonging to the reality of the civil defense service offered, in addition to the collection of more than 600 fire accident have been processed for 2015, and using ArcGIS program has been the introduction and management of different data and evaluated statistically, and it turned out that the ratio the largest of fire accidents had occurred within the civil defense center Numan service scope and earned the Al-Sharquia district (south east of the city), the largest number of them. The main conclusions of this study is that 63% of fires in open areas were causes messes the kids, either the main recommendations of the study can be summarized the need to increase the number of detachments of civil defense during the summer, especially the need to use the Global Positioning System GPS to ensure the precise location of the incident and therefore increased processing speed.