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Theoretical and experimental investigation of a heat pipe heat exchanger for energy recovery of exhaust air
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Heat pipes and two‐phase thermosyphon systems are passive heat transfer systems that employ a two‐phase cycle of a working fluid within a completely sealed system. Consequently, heat exchangers based on heat pipes have low thermal resistance and high effective thermal conductivity, which can reach up to the order of (105 W/(m K)). In energy recovery systems where the two streams should be unmixed, such as airconditioning systems of biological laboratories and operating rooms in hospitals, heat pipe heat exchangers (HPHEs) are recommended. In this study, an experimental and theoretical study was carried out on the thermal performance of an air‐to‐air HPHE filled with two refrigerants as working fluids, R22 and R407c. The heat pipe heat exchanger used was composed of two rows of copper heat pipes in a staggered manner, with 11 pipes per row. Tests were conducted at different airflow rates of 0.14, 0.18, and 0.22m3/h, evaporator inlet‐air temperatures of 40, 44, and 50°C, filling ratios of 45%, 70%, and 100%, and ratios of heat capacity rate of the evaporator to condenser sections (Ce/Cc) of 1 and 1.5. For HPHE's steady‐state operation, a mathematical model for heat‐transfer performance was set and solved using MATLAB. Results illustrated that the heat transfer rate was in direct proportion with the evaporator inlet‐air temperature and flow rate. The highest HPHE's effectiveness was obtained at a 100% filling ratio and (Ce/Cc) of 1.5. The predicted and experimental values of condenser outletair temperature were in good agreement, with a maximum difference of 3%. HPHE's effectiveness was found to increase with the increase in evaporator inletair temperature and number of transfer units (NTU) and with the decrease in airflow rate, up to 33% and 20% for refrigerants R22 and R407c, respectively. Refrigerant R22 was the superior of the two refrigerants investigated.

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Publication Date
Sun Apr 16 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Theoretical Design of Electrostatic Lens Accelerating and Decelerating Operated Under Different Magnification Conditions
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  In this paper,  design computationl investigation in the field of charged-particle optics with the aid of numerical analysis methods  under the absence of space charge effects. The work has been concentrated on the design of three-electrode  einzel electrostatic  lens accelerating and decelerating operated under different magnification conditions.     The potential field distribution of  lens has been represented by exponential function.  The paraxial-ray equation has been solved for the proposed field to determine the trajectory of charged-particles traversing in the lens.  From The axial  potential distribution and its first and second derivatives, the optical propertie

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Publication Date
Mon Jan 31 2022
Journal Name
Iraqi Journal Of Science
Qualitative and Quantitative Investigation of Iraqi Grapefruit ( Citrus padisi) Flavonoids From Peel and Seeds and Comparing Their Aqueous Extracts for Antimicrobial Activity
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Iraqi grapefruit ( Citrus paradisi, family Rutaceae) flavonoids were investigated qualitatively and quantitatively. The total isolated flavonoids from seeds and peel were 3.6 mg and 12.53 mg respectively in each gram of powder. The antimicrobial activity of aqueous extracts and total isolated flavonoids from seeds and peel were assessed against strains of Gram positive bacteria( Staphylococcus aureus, Staphylococcus epidermidis), Gram negative bacteria( Escherichia coli, Pseudomonas aeruginosa) and yeast( Candida albicans). The aqueous extracts lacked antimicrobial activity against all bacteria and yeast, while the total flavonoids showed a moderate inhibitory effect against test bacteria and yeast. This difference in inhibitory activity

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Publication Date
Thu Apr 28 2022
Journal Name
Iraqi Journal Of Science
Effect of Excitation Energy and Mass number on Most probable exciton number
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Exciton model describes the excitation of particles in pre-equilibrium region of nuclear reaction by exciton. In pre-equilibrium region there is a small probability for occurring emission and the number of excitons be the probability of the emission of it possible more is called most probable exciton number MPEN. In this paper the MPEN formula was derived for protons and neutrons separately and so MPEN formula derived with taking into account the non equidistant spacing between the energy states. The MPEN was studied with the mass number where it is noticed the MPEN increases with increasing the mass number. Also, MPEN studied for different isotopes of Al, the MPEN increases with increasing mass number of isotopes. MPEN for neutron is co

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Publication Date
Thu Jun 30 2016
Journal Name
Al-kindy College Medical Journal
Prevalence Of Energy Drinks Consumption Among Students Of Alkindy Medical College
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Background: Energy drinks are non alcoholic beverages which contain stimulant drugs chiefly caffeine and marketed as mental and physical stimulators. Consumption of energy drinks is popular practice among college students as they are exposed to academic stress. Caffeine which is the main constituent of energy drinks could become an addictive substance or cause intoxication. Objectives: This study aims to assess the prevalence of energy drinks consumption among medical students of alkindy college of Medicine.Type of the study: A cross sectional study.Methods: It was performed at alkindy medical college on March 2016. A total number of 600 students were contacted to participate in this study. A self administered questionnaire was used to c

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Publication Date
Fri Dec 23 2022
Journal Name
Innovative Infrastructure Solutions
Experimental modeling of a single pile in liquefiable soil under the effect of coupled static-dynamic loads
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In this work, a single pile is physically modeled and embedded in an upper liquefiable loose sand layer overlying a non-liquefiable dense layer. A laminar soil container is adopted to simulate the coupled static-dynamic loading pile response during earthquake motions: Ali Algharbi, Halabjah, El-Centro, and Kobe earthquakes. During seismic events with combined loading, the rotation along the pile, the lateral and vertical displacements at the pile head as well as the pore pressure ratio in loose sandy soil were assessed. According to the experimental findings, combined loading that ranged from 50 to 100% of axial load would alter the pile reaction by reducing the pile head peak ground acceleration, rotation of the pile, and lateral displacem

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Publication Date
Fri Jun 30 2023
Journal Name
Iraqi Journal Of Science
Technical and Economic Evaluation of Electricity Generation and Storage Using Renewable Energy Sources on Socotra Island, Yemen
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     Renewable energy sources are a promising hope for avoiding many environmental and economic problems such as the problems of climate change and environmental pollution resulting from fossil fuels combustion, in addition to the problems of oil derivatives high prices and their absence in many countries, which in turn affected the rise in electricity prices. Yemen is considered one of the countries most affected by electricity prices rise due to lack of oil derivatives as a result of the ongoing wars in Yemen. This paper presents a technical and economic study of renewable energy sources for producing and storing electricity. It gives a clear scientific and economic vision for implementation of these projects in one of the Yemeni i

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Publication Date
Thu Feb 27 2020
Journal Name
Iraqi Journal Of Science
Studying the Effect of Laser Pump Pulse Energy and Delay Time on Conversion Efficiency of KTP
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     In this study, the effect of increasing pump pulse energy and delay time on the energy conversion efficiency of the Potassium Titanyl Phosphate (KTP) crystal at room temperature was investigated. It was found that the higher the pump pulse the greater the efficiency at a certain value of the delay time. Moreover, at the delay time 3.524ns, we found that the efficiency of the conversion of energy increases from 0.0112 to 0.0159. We  also observed that the lower delay time between the pump and the probe pulses leads to increase the rate of energy conversion efficiency of the KTP crystal, where the reaches up to 3, which is higher than the value recorded in the absence of a pump pulse. The highest value of the

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Publication Date
Wed Aug 28 2019
Journal Name
Journal Of Engineering
Treatment of Simulated Carwash Wastewater by Electrocoagulation with Sonic Energy
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Oily carwash wastewater is a high organic and chemical wastewater. This paper targeted to investigate a treatment to decrease the water consumption and contaminants in car-washing stations. Electrocoagulation combined with ultrasonic energy (Sono-Electrocoagulation) was suggested so that the carwash wastewater is treated to be reused. The effect of both the voltage and time of treatment on the removal of COD, turbidity, conductivity, and total dissolved solids (TDS) were studied at constant initial pH 7 and electrode distance 2 cm. The results showed the best results of removal COD, turbidity, TDS, and reduce electrical conductivity is when the voltage was 30 V and a treatment time of 90 minutes.

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Publication Date
Fri Mar 11 2016
Journal Name
International Journal Of Applied Linguistics And English Literature
The Illusion of Untranslatability: A Theoretical Perspective with Reference to the Translation of Culture-Bound Euphemistic Expressions in the Qur'an
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The present study investigates the notion of untranslatability where the concept of equivalence is reconsidered since the misconceptions, related to the said concept, inevitably lead to the emergence of untranslatability. Identifying equivalence as relative, approximate and necessary identity makes the notion of untranslatability a mere theorization. The objectives of the present study are (1) to investigate the notion of untranslatability in terms of the misconceptions associated with the concept of equivalence (2) to examine the possibility of translatability from Arabic into English focusing on culture-bound euphemistic expressions in the Quran as an area of challenge in translation. Data on the translation of culture-bound euphemistic e

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Publication Date
Tue Jun 14 2005
Journal Name
Iraqi Journal Of Laser
Design and Operation of Mini-TEA CO2 Laser and Investigation of Preionization Effect
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A Mini-TEA CO2 laser system was designed and operated to obtain a pulse at 10.6 μm. Output energy of 30 mJ, with preionization pins, and pulse duration of 100ns were obtained. While an output energy of 6mJ and pulse duration of 100 ns in absence of pre-ionization were obtained. The system was operated with Ernest profile main-discharge electrodes. Dependencies of supply voltage and output laser energy on the pressure inside laser cavity were investigated as well as dependencies of supply voltage and output energy on the main capacitor(8CO2 : 8N2 : 82He :2CO). Efficiency of was calculated to be 4.4%.

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