Tikrit Journal of Engineering Sciences

In this paper a numerical study of velocity and temperature distribution in air conditioned space have been made. The computational model consists of the non-isothermal 3-D turbulent with (k-ε) model. The numerical study is made to conduct air distribution in a room air-conditioned space with real interior dimensions (6×4×3)m and to analyze the effect of changing angle of grille vanes on the flow pattern, velocity, and temperature distribution in the room under a set of different condition, and under a supply air temperature of 16˚C to examine the final result on air distribution performance index (ADPI). The results show a significant effect within the change of supply air angle, the maximum air distribution performance index (ADPI) is 52% when air change per hour (ACH) is equal to 10 at 16˚C inlet temperature with angle (15˚ down), and the minimum value of (ADPI) is 20% when ACH is equal to 15 at 16˚C inlet temperature and angle (degree).

Liquid-phase axial dispersion coefficients have been measured for air-water system in bubble columns of 10, 15 and 30 cm diameter. The experiments are carried out using a transient method (the tracer response method). Dispersion coefficient is obtained by adjusting the experimental profiles of tracer concentration with the predictions of the model. The experimental results show that one-dimensional axial dispersion coefficient, Dax,L, reveal strong scale dependence. Backmixing of liquid phase increases with the increase of reactor diameter and superficial gas velocity. Axial dispersion coefficient for large column reactors can be easily predicted from the developed relation . Comparison of calculated with the experimental data and with the published data of other authors shows good agreement which ensure the reliability and confusability of the adopted correlations to be used in further design and scale-up purposes.

This study was devoted to limit the stability conditions of the wastewater treatment unit. LABVIEW was a powerful and versatile graphical programming language in automation control and date acquisition of the system. The on-line show that accurate and stable control responses were obtained in the present work. The actual phase plane proved to a better technique to limit the regions of the non-linear system stability compared to other theoretical techniques. Limit cycle did not appear in the present system.

Great benefits can be achieved by using wireless remote control in electrical wiring systems of buildings. Probably the main advantage of this application is the drastic saving in wiring installations, which in turn will give higher reliability, safety and economy. The idea of this application can be summarized in the following explanation. ” Instead off connecting each point of electrical system to individual switch by wires, a remote receiver can be situated in a place near to the point. The transmitter is used to operate the point remotely. The mains are connected to the receiver which will connect or disconnect the load as required. Many points can be connected to one receiver and can be operated by one or more transmitter.

In this research, two models are developed to simulate the steady state fixed bed reactor used for styrene production by ethylbenzene dehydrogenation. The first is one-dimensional model, considered axial gradient only while the second is two-dimensional model considered axial and radial gradients for same variables. The developed mathematical models consisted of nonlinear simultaneous equations in multiple dependent variables. A complete description of the reactor bed involves partial, ordinary differential and algebraic equations (PDEs, ODEs and AEs) describing the temperatures, concentrations and pressure drop across the reactor was given. The model equations are solved by finite differences method. The reactor models were coded with Mat lab 6.5 program and various numerical techniques were used to obtain the desired solution. The simulation data for both models were validated with industrial reactor results with a very good concordance.

Forming limit stress diagram represent the maximum acceptable limits of principal stresses in sheet metal forming. This diagram show the limits of major and minor true stresses for different strain paths (uniaxial tension, plane strain and equibiaxial stretching path) in sheet metal forming. It is confirmed that the Forming limit stress diagram and the Forming Limit Strain Diagram are two mathematically equivalent representations of forming limits in stress space and strain space respectively. The Forming limit stress diagram of the sheet metal is gained by the transformation relations between the strain state and stress state in deformation of sheet metal. In this paper, the Forming limit stress diagram is theoretically determined using Marciniak-Kuczynski analysis and Hosford yield criterion for steel 1021 sheet ,and compared with the experimental Forming limit stress diagram based on the experimental Forming limit strain diagram of steel 1021 sheet & theory of plasticity. The influence of normal anisotropic ratio, index of yield criterion, inhomogeneous factor and strength coefficient on the theoretical FLSD is also presented. It is shown that the limit stresses in theoretical Forming limit stress diagram is raised by increased values of the normal anisotropic ratio, the inhomogeneous factor and the strength coefficient. The limit stresses are lowered when the index of Hosford yield criterion increased.

Groundwater quality is considered as an important subject. Studies about groundwater are increased due to the increase of water demand. This study Focus on Samarra region. Chemical characteristics of ground water is determined for 21 wells for the period November 2007 till april 2008.covering 400 km2 on both banks of Tigris river. The results indicated that the quality of ground water in the studied region is incompetence for various uses according to Iraqi standards No. 417 at 2007.

In this study, The Discrete Differential Dynamic Programming (DDDP) has been applied to the operation of Mosul dam reservoir on Tigris river, North of Iraq. The simulation technique (SM) has been used to evaluate the results obtained from the (DDDP) model. The aim of this study is to obtain the present and future optimal monthly reservoir operation policies for the years (2007, 2017, and 2027) through fulfilling the irrigation requirements of Jazira Irrigation Project and water supply requirements according to different operation states. The states included the operation of Northern only, Northern and Eastern; and the Northern, Eastern and Southern Jazira Irrigation Projects for minimum annual inflow in all states. The results indicated water deficit occurrence with the second and third states. For optimization model, the water deficits were distributed over long periods which helped to minimize the penalty, and the reservoir storages were within the upper and lower operating storage limits. Whereas for simulation model the water deficits were concentrated within short periods and the reservoir storages declined below the lower operating storage limit.

Eichhornia crassipes is a tropical aquatic plant of American origin that grows on the surface of fresh water. Eichhornia at recent time is used to treat domestic and industrial wastewater. In this research, Eichhornia is used to decrease the concentrations of lead and cadmium in water media. The current changes over the plants endurance for different concentrations by continuing the morphological changes, which have appeared during the experiment, has been studied. The heavy metals concentrations of the media are measured during two days. At the end of the experiment, analysis for metals are also carried out on the plant samples to determine the effect of different media on metal accumulation by roots and aerial parts of the plants. The results showed that the plant is able to absorb the lead and accumulate it in its rooted part more than aerial part along with the preservation of its growth and shape at the concentration up to 100ppm. However, it cannot survive in a good way in the water media which contain cadmium of concentrations (3.07-61.93ppm).

Baiji thermal station supplied by heavy fuel HFO from Baiji refinery, while the gas station is operated by heavy fuel HFO and light fuel LFO, the first unit operates using LFO, the third unit operates using HFO. The results showed that the specific fuel consumption is reduced by rising the load, when the load is reduced to 20Mw s.f.c almost 0.765m3/Mw.hr this rate start to fall to become 0.35m3/Mw.hr when the unit operate near its maximum capacity for LFO, while the heavy fuel increases by 15% for the same number above. It’s correct that LFO is good but it is expensive which costs 1000$ per imported ton , in order to cover the load of 8000Mw for one year itcosts 1.92E+10$ for imported LFO ,9.6E+10$ for the local LFO, and 2.8E+9$ for HFO, the difference is obvious which is ten times the total cost. Also the studied performance of the gas units showed that the net is experience from a downturn of frequency along 24hr except in the let hours at night, while the allowed frequency is 50HZ±1.5, and the true efficiency of the units is a function of the load which stabilized at 29%±0.2 for the first unit and 25% for the third unit, while the thermal efficiency is stabilized at48% for the first unit and 51% for the third, therefore the unit efficiency is improved by 4% when we use LFO. When in take in to account the pollution, the heavy fuel HFO contains 4.5% sulpher which releases sulpheric acid and 1% vanadium treated by adding inhibitor about 1.5L/Mw.hr, these ratio are not considered for LFO with respect to HFO.

The objective of this research is to study the effect of the resin type and fibers in composite material on fatigue behavior by using two types of fibers and resin. The resin types are epoxy and polyester type and the fiber types are uniform carbon fiber (90-0) and particle carbon fiber type . Where The specimen are made for four slates from these materials ,in 30% volume fraction for the uniform carbon fiber (90-0), and 5% for particle carbon fiber. These specimen are cut in proper dimension according to the properties of fatigue testing device. At least These specimens are tested in order to know the effect of matrix and fiber type on the fatigue performance in a composite material.

This research is devoted to study the wear resistance, coefficient of friction and contact temperature of free cutting brass under dry sliding wear conditions over steel counterface disc using pin-on-disc technique. Five load values 3.5, 7, 11, 15 and 20 N were used at constant sliding speed 10.4458 m.s-1 and time 30 min. An increase in wear rate and surface damage of brass specimens was observed by increasing the applied load and a transition from mild to severe wear was occurred at 11 N. A plastic deformation phenomena at macroscopical scale when applying 20 N was detected at the contact surfaces of the brass specimens. The average of the measured contact temperatures of brass was increased from 94 to 268 oC by increasing the applied load from 3.5 to 20 N, while the smallest and greatest calculated kinetic friction coefficient for the sliding pair( free cutting brass / steel) was 0.49 and 0.67 at applied loads 7 and 20 N respectively. Furthermore, an important observations were revealed which includes oxidation and dezincification of the wear rate and contact temperature measuring specimens respectively at their external surface contacting the iron housing far from their contact surfaces with steel disc at 20 N applied load.