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Article
Study the Effect of the Flow on the Performance of a shell and Tube Type Heat Exchanger Using Experimental Design Technique

Authors: Zuher Hassan Abdullah --- Saad Sami Farhan --- Thamer K. Salem
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 2 Pages: 38-45
Publisher: Tikrit University جامعة تكريت

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Abstract

In the current research an experimental study was done to show the effect of pulse flow on the effectiveness of shell and tube type heat exchanger. the study was in the case of steady and pulse flows with a changing mass flow rate of hot water flowing inside the pipes of the heat exchanger for the range between (0.0273-0.0819 kg / s) at fix mass flow rate of cold water that flows through the shell and on the outer surface of the pipes when (0.0416 kg / s), to obtain pulsing a used was solenoid valve. The research aims to measure the percentage effect of independent factors which were presenting the mass flow rate of hot water, flow type and the surrounding environment conditions of the experimental side upon shell and tube type heat exchanger performance using experimental design technique at the significant level (0.05).The results derived from the experimental tests showed that pulse flow leads to increase internal heat transfer coefficient (hi) comparing with its value in the steady flow and the highest increase was by (9.75%) at a mass flow rate of hot water (0.0416 kg / s) and increases the overall heat transfer coefficient (U), where the highest percentage was by )4.68%) at a mass flow rate of hot water (0.0416kg/s). The results also showed increasing both the number of transmitted units (NTU) and the effectiveness of the shell and tube type heat exchanger ( ) in the case of pulse flow of its value in the steady flow and the highest percentage of increase occurring was (4.75%) and (1.85%), respectively, and at the mass flow rate of hot water (0.0416 kg / s). Percentage effect of mass flow rate of hot water was (97%, 97.42%, 95.5%, 99.48%) and the percentage effect of each flow type and the errors were (2.8%, 2.25%, 2.44%, 0.4%) and (0. 2, 0.33%, 2.06%, 0.12) respectively.


Article
The Effects of Lime Addition and Fineness of Grinded Clinker on Properties of Portland Cement

Authors: Nadia S. Ismael --- Mostafa N. Ghanim
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 2 Pages: 86-95
Publisher: Tikrit University جامعة تكريت

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Abstract

Two types of Portland Cement Clinker "PCC" were used in this study: high fineness grinded and low fineness grinded , and after grinding of PCC, hydrated lime was used in 5%,10% and 15%; by weight, as a replacement of the blend cement with a constant 3% addition of gypsum by the blend weight. The importance of this study is to show the influences of different fineness on the physical properties of the blended cement, and to find the probability of using hydrated lime (that could be a by-product) in cement and declare its effects on the blend, so the solid waste "lime" and air pollutant of cement factories will reduce. In this research, the low fineness blend exhibited about 87% from compressive strength of high fineness blend at 28 days age. The results show that the using of hydrated lime up to 10%; by weight, as a replacement of cement will give good compressive strength and workability, and will reduce moderately the setting time, but the use of hydrated lime by more than 10% will reduce the compressive strength and increase the unsoundness of the blend (from 3mm expansion at 10% hydrated lime to 29mm expansion at 15% hydrated lime).


Article
Settlement and Collapse of Gypseous Soils

Authors: Ahmed A. H. Al-Obaidi --- Ibtihal H. S. Al-Mafragei
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 1 Pages: 20-31
Publisher: Tikrit University جامعة تكريت

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Abstract

The work in this research presents an experimental, theoretical and field study in order to investigate the settlement of Gypseous soils and the effect of water percolation on collapsibility of this soil. In this research, more than five sites where chosen to extract the gypseous soil samples with different gypsum content; the sites located in different regions in Salah Aldeen Governorate. In order to estimate the settlement and collapse of gypseous soils, field tests consist of standard penetration test for depths (1m to 5m) for each site and plate load test were conducted in dry and soaked cases.The results show that the settlement of gypseous soils in dry condition is less than the same soils that have low values of gypsum in its formation, the settlement value of lightly gypseous soils can be evaluated from the basic equations depending on data of SPT.In soaking case with short term flooding, gypseous soils shows compressible and they are sufficiently reliable soil base, while in the case of long term flooding settlement develops due to dissolution of salts and gypsum. The magnitude and the rate of the settlement depend on initial gypsum content, relative amount of leached salts, the mineralogy and type of soil and soil properties and acting load. The standard penetration test does not use in calculating the settlement for the soils that have gypsum in its formation in soaking condition.

Keywords

Gypseous soils --- Settlement --- Collapsibility --- SPT --- PLT


Article
Proportioning of Lightweight Concrete by the Inclusions of Expanded Polystyrene Beads (EPS) and Foam Agent

Authors: Eethar Thanon Dawood --- Ali Jihad Hamad
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 2 Pages: 65-73
Publisher: Tikrit University جامعة تكريت

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Abstract

This paper illustrates the performance of lightweight concrete using various amounts of expanded polystyrene beads (EPS) and different amounts of foam agent to produce lightweight concrete. The objective of this paper is to produce lightweight concrete with good workability and strength, by different mix proportion of foam agent (0.4, 0.6, 0.8, 1, 1.2 kg/m3) and varying water cement ratio (w/c) depending on the flow. Besides, various proportions using different percentages of EPS in order of volume fractions are used. The flow range used in the study is 110-130%. Each mix proportion is tested for compressive strength, modulus of rupture, density and voids ratio. The results gives acceptable ranges of strength for lightweight concrete produced by the inclusions of EPS beads and foam concrete. Therefore, the lightweight concrete produced in this work can be used for structural applications like multistory building frames, floors, bridges and prestressed or precast elements.


Article
Properties of Keene's Cement-Quick Set Locally Product

Authors: Nadia S. Esmael --- Muhanned S. Gereed
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 1 Pages: 53-60
Publisher: Tikrit University جامعة تكريت

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Abstract

Gypsum has been used as building material over a very long period of time. The production of gypsum plaster in Iraq confined on three types; plaster of Paris, ordinary gypsum and mechanical gypsum. The purpose of this study is to present a proposal to produce another type of gypsum plaster called Keene's cement, it has improvement characterizes than the other types of gypsum. In this study different percentage of alum solution has been used to soaked in gypsum lumps and different recalcinating temperatures also have been used. The results show that 12% of alum and 250 C° recalcinating temperature gave the highest result of compressive strength of Keene's cement product.

Keywords

Gypsum --- Keene's cement --- Alum


Article
Mechanical Properties of Self-Compacted Concrete

Authors: Ammar SaleemKhazaal --- Alyaa Abbas Ali --- Assim Mohammed Lateef
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 1 Pages: 40-52
Publisher: Tikrit University جامعة تكريت

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Abstract

In this research, trial mixes were conducted according to Self-Compacted Concrete (SCC) specifications, a mix that gave a higher compressive strength to the age of seven days has been selected. Then after selecting the appropriate mix, concrete samples had poured and were distributed into five groups; each group consists of six cubes, six cylinders, and six prisms. The samples of each group are testing for compressive, tensile splitting, and flexure strengths respectively for the ages of 7, 14, 28, 60, and 90 days respectively. Before of conduction of destructive tests, the samples were tested using ultrasonic waves to determine the relationship between the concrete strength and pulse velocity and in the same way for all ages in above. Experimental results showed that, all concrete mechanical properties have improved, and the maximum improve was in flexural strength followed by compressive strength and tensile splitting strength. The cube compressive strength increased according to (G1 at 7 days curing) from 34.3% to 71.8%, the percentage of increase of tensile strength according to (G1 at 7 days curing) from 16.8% to 64.3% , modulus of rupture increased according to (G1 at 7 days curing) from 34.6% to 98.7% for ages (14, 28, 60, 90 days) respectively. Pulls velocity increased according to (G1 at 7 days curing): For cube from 5.1% to 23.9%, for cylinder from 21.4% to 40.3%, for prisms from 7.1% to 29.2%.


Article
Effect of using Windows Waste Glass as Fine Aggregate on some Properties of Concrete

Authors: Abdelmaseeh Bakos Keryou --- Gailan Jibrael Ibrahim
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 3 Pages: 47-54
Publisher: Tikrit University جامعة تكريت

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Abstract

The main goal of this study is to investigate the effect of using waste glass (WG) on some mechanical properties of concrete at both fresh and hardened stages. In our study, we used local windows waste glass (WG) as partial replacement of fine aggregates with 0, 20, 25, and 30% percentages (by weight). The experimental results obtained from testing specimens prepared from concrete mixes with water/cement ratio equal to 0.5, showed that the optimum percentage of fine waste glass to be used within the concrete mix was 20%. At this percentage of replacement the compressive strength obtained at 28-days age was 39 MPa compared with 30.32 MPa for reference concrete mix.


Article
CFD Simulation of Air Cyclone Separator

Authors: Nuha wathq Nema --- Saad Nahi Saleh --- Fayadh Mohamed Abed
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 3 Pages: 25-36
Publisher: Tikrit University جامعة تكريت

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Abstract

A computational fluid dynamics model was developed for air cyclone separator in order to predict the flow pattern inside the cyclone using an Eulerian approach, three dimensions Reynolds Average Navier-Stokes equations, closed via the Reynolds Stress model as a turbulence model for air flow. The particles were modeled as a discrete phase model using the Lagrangian transport model with turbulent particle dispersion. Computational fluid dynamics modeling was employed to investigate fluid flow patterns and particle trajectories at steady state operating conditions of Stairmand cyclone. Analysis of a computational fluid dynamics simulation accurately revealed that the air flow behavior in cyclone separator consists of two vortexes : an outer vortex with a downwardly directed axial flow and an inner vortex with an upwardly directed flow, this f low profile known as Rankine vortex. A low-pressure zone appeared in the center line of the cyclone due to high swirling velocity. The results showed that the pressure drop increased with increasing the inlet air velocity. The results of the collection efficiency showed that the efficiency increased as the particles diameter increased. A good agreement achieved between the simulation results and published experimental results. The computational fluid dynamics code (ANSYS FLUENT 14.5) with the Reynolds Stress model as the turbulence model, predicted very well the flow field parameters of cyclones and can be used in cyclone design for any dimensions.


Article
Modeling and Simulation of Nonvolatile Memory Based on copper sulfide

Author: Khalid Khaleel Mohammad
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 2 Pages: 103-109
Publisher: Tikrit University جامعة تكريت

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Abstract

The memory cells has become one of the computer basics electronic components, especially nonvolatile ion-dependent growth of filament or so called Conductive Bridge Random Access Memory (CBRAM) type. The memory cells in this work is focused on using copper sulfide as ionic compound Cu2S, the model proposed to identify the behavior of the cell in terms of voltage and current. The model cell is then simulated in order to extract the variables that affect the behavior of the cell and the factors which can be identify the optimal dimensions and specifications in terms of their small size and minimum power dissipation as possible at the same time. The simulation results show that the best thickness of the cell is about 20 nm with a radius equal to 10 nm, These dimensions of the cell has a resistance ratio of high resistance state HRS to low resistance state LRS(Roff / Ron) which correspond to different logic is about 1014 .


Article
Acidic Attack Resistance of Cement Mortar Treated with Alkaline

Author: Nadia Nazhat Sabeeh
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 3 Pages: 96-104
Publisher: Tikrit University جامعة تكريت

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Abstract

The negative effect of acidic attack on the properties of concrete and cement mortar is a topic of increasing significance in the recent years. Many attempts has occurred to mitigate this negative impact by improving the properties of concrete and increase resistance to acids by using additives. The present study includes treatment of sand by alkaline material and examine the effect of treatment on cement mortar resistance towards hydrochloric and sulfuric acid. Results show that sand treatment by alkaline material significantly enhance mortar ability to resist acids. In terms of loss weight, the maximum weight rate gain was 25.54% for specimens immersed in Hydrochloric acid with water cement ratio 40%. For specimens immersed in HCl, the average gain in compressive strength is (20.15-19.433)% for w/c (40-45)% respectively. The average gain in modulus of rupture toward the influence of H2SO4 is (18.37–17.99)% for w/c (40-45)%, respectively.

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