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Investigation of R134a Flow Boiling Heat Transfer and Pressure Drop in the Evaporator Test Section of Refrigeration System
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This paper presents an experimental and theoretical analysis to investigate the two-phase flow boiling heat transfer coefficient and pressure drop of the refrigerant R-134a in the evaporator test section of the refrigeration system under different operating conditions. The test conditions considered are, for heat flux (13.7-36.6) kW/m2, mass flux (52-105) kg/m2.s, vapor quality (0.2-1) and saturation temperature (-15 to -3.7) ˚C. Experiments were carried out using a test rig for a 310W capacity refrigeration system, which is designed and constructed in the current work. Investigating of the experimental results has revealed that, the enhancement in local heat transfer coefficient for relatively higher heat flux 36.6 kW/m2 was about 38% compared to 13.7 kW/m2 at constant operating conditions. The enhancement in heat transfer coefficient was about 57% when the mass flux increased from 52 kg/m2.s to 105 kg/m2.s at constant test conditions. The enhancement in the heat transfer coefficient was about 64% when the saturation temperature increased from -8 to -3.7 at fixed refrigerant mass velocity and heat flux. The effect of mass velocity on pressure drop was relatively higher by about 27% than that for heat flux at specified test conditions. The comparison between the experimental and theoretical results has shown an acceptable agreement with an average deviation of 21%.

 

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Publication Date
Mon Jun 01 2020
Journal Name
Journal Of Engineering
Thermal Modeling of Solar Still Coupled with Heat Pipes and Experimental Validation
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Water is the basis of the existence of all kinds of life, so obtaining it with good quality represents a challenge to human existence and development especially in the desert and remote cities because these areas contain small populations and water purification requires great materials and huge amounts of fossil fuels resulting pollution of the environment. Cheap and environmentally friendly desalination methods have been done by using solar distillations. Passive solar stills have low yields, so in this research, the problem is overcome by connecting four heat pipes which are installed on the parabolic concentrator reflector with passive solar still to increase the temperature of hot water to more than 90°C, as a resul

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Publication Date
Tue Jan 01 2019
Journal Name
Iraqi Journal Of Agricultural Sciences
Role of calcium-regulating hormones, adipocytokines and renal function test in the progress of type 2 diabetes mellitus in a sample of Iraqi patients
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A cross-sectional study was conducted on 80 type 2 diabetic patients aged 20-60 years in Baghdad and 20 non diabetic persons as controls. Laboratory assessment of glucose related parameters; Fasting blood sugar (FBS), Glycated hemoglobin (HbA1c), Insulin and Insulin resistance (IR), renal function test; Blood urea, serum creatinine, Calcium (Ca) and Phosphorus (P), Calcium regulating hormones; Parathyroid hormone (PTH), calcitonin and vitamin D, cytokines, Adiponectin and Tumor necrosis factor (TNF-α) and comparison these parameters between patients and controls. The results: a high significant (p˂0.01) increase in FBG level in the patients (211.34 ± 11.20 mg/dl) as compared with control (85.89 ± 3.07 mg/dl). A high significant (p˂0.01

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Publication Date
Thu May 18 2023
Journal Name
Journal Of Engineering
Theoritical and Experimental Investigation of the Dynamical Behaviour of Complex Configuration Rotors
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The present work considers an alternative solution for a complex configuration of rotor discs by applying Galerkin Method. The theoretical model consists of elastic shaft carrying number of discs and supported on number of journal bearings. The equation of motion was discretized to finite degree of freedom in terms of the system generalized coordinates. The various effects of the dynamical forces and moments arising from the bearing, discs and shaft were included. Rayleigh beam model is used for analyzing the shaft while the discs are considered rigid . The validity and convergence of the present analysis was carefully checked by comparing with the Finite Element solution. An example of rotor consists of three different size discs and su

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Publication Date
Mon Jan 01 2018
Journal Name
Ibn Al-haitham Journal For Pure And Applied Science
Investigation of the Structural, Optical and Electrical Properties of AgInSe2 Thin Films
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Publication Date
Sun Apr 02 2017
Journal Name
Journal Of Educational And Psychological Researches
IQ TEST STANDARDIZATION OF MARTEN LOTHER JOHAN WITH CHILDREEN OF THE SEVEN YEAR
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This study aimed to IQ test standardization of Marten Lother Johan which used with childreen of the tow  stage at primary schools who aged (7) years old in Baghdad (Resafaa and Kharh).

 The importance of this study are :

1-The  importance of childhood and its role to develop the personality.

2-The importance of this age as the child will exposure to different kind of official teaching .

3-The capability for early detection of special category for early intervention in order to provide the necessary care .

4-Using the current test could consider as a predictive tool to screen the intelligent children .

In order to achieve the study aim, the researcher had followed the

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Publication Date
Sun Oct 02 2016
Journal Name
Journal Of Educational And Psychological Researches
IQ TEST STANDARDIZATION OF MARTEN LOTHER JOHAN WITH CHILDREEN OF THE SIX YEAR
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This study aimed to IQ test standardization of Marten Lother Johan which used with childreen of the one stage at primary schools who aged (6) years old in Baghdad (Resafaa and Kharh).

 The importance of this study are :

1-The  importance of childhood and its role to develop the personality.

2-The importance of this age as the child will exposure to different kind of official teaching .

3-The capability for early detection of special category for early intervention in order to provide the necessary care .

4-Using the current test could consider as a predictive tool to screen the intelligent children .

In order to achieve the study aim, the researcher had followed the follow

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Publication Date
Wed Dec 01 2010
Journal Name
Iraqi Journal Of Physics
Effect of Furnace Vacuum Pressure on the Joining Strength of Alumina Bonded Kovar
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Ceramic to metal joining technique, which was used in this investigation includes the use of active filler alloy as a sandwich between the alumina and kovar alloy for brazing. High purity powdered metals of silver, copper, and additives of titanium were used to prepare the active filler alloy, through compacting the mixed powders and alloying in a furnace with argon atmosphere at the temperature of 800oC for 10 minutes. To use it as an active filler metal, it has been modified to a proper thickness. Two groups of alumina were prepared with different sintering temperatures (1450oC and 1650oC) and each group was tested under atmospheric pressure, vacuum furnace pressure of 2*10-4 torr and vacuum furnace pressure of 2*10-6 torr. All the pro

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Publication Date
Mon Dec 05 2022
Journal Name
Baghdad Science Journal
Investigation of the Electron Coefficients of (Ar, He, N2, O2) Gases in the Ionosphere
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In this study, the electron coefficients; Mean energy , Mobility and Drift velocity  of different gases  Ar, He, N2 and O2  in the  ionosphere have been calculated using BOLSIG+ program to check the solution results of Boltzmann equation results, and effect of reduced electric field (E/N) on electronic coefficients. The electric field has been specified in the limited range 1-100 Td. The gases were in the ionosphere layer at an altitude frame 50-2000 km. Furthermore, the mean energy and drift velocity steadily increased with increases in the electric field, while mobility was reduced. It turns out that there is a significant and obvious decrease in mobility as a result of inelastic collisions and in addition lit

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Publication Date
Tue Jul 20 2021
Journal Name
Materials Science Forum
Investigation into the Distribution of Erosion-Corrosion in the Furnace Tubes of Oil Refineries
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Crude oil is one of the most important sources of energy in the world. To extract its multiple components, we need oil refineries. Refineries consist of multiple parts, including heat exchangers, furnaces, and others. It is known that one of the initial operations in the refineries is the process of gradually raising the temperature of crude oil to 370 degrees centigrade or higher. Hence, in this investigation the focus is on the furnaces and the corrosion in their tubes. The investigation was accomplished by reading the thickness of the tubes for the period from 2008 to 2020 with a test in every two year, had passed from their introduction into the work. Where the thickness of more than one point was measured on each tube in the sa

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Publication Date
Fri Nov 01 2019
Journal Name
Journal Of Engineering
Analysis of Shell and Double Concentric Tube Heat Exchanger Using CFD Application
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This study focuses on CFD analysis in the field of the shell and double concentric tube heat exchanger. A commercial CFD package was used to resolve the flow and temperature fields inside the shell and tubes of the heat exchanger used. Simulations by CFD are performed for the single shell and double concentric tube.

This heat exchanger included 16 tubes and 20 baffles. The shell had a length of 1.18 m and its diameter was 220 mm. Solid Works 2014, ANSYS 15.0 software was used to analyze the fields of flow and temperature inside the shell and the tubes. The RNG k-ε model was used and it provided good results. Coarse and fine meshes were investigated, showing that aspect ratio has no significant effect. 14 million

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