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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
Mon Jan 30 2023
Journal Name
Iraqi Journal Of Science
Investigation of Aluminum Arsenide Honeycomb Monolayer via Density Functional Theory
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    First principle calculations are performed to theoretically predict the physical properties of hexagonal aluminium arsenide planar and buckled monolayers. The structural characteristics showed that the buckled parameter is about 0.32 A°. Cohesive energies have favourable values and it indicates the fabrication possibility. Phonon dispersion properties indicated that the planar aluminium arsenic monolayers are dynamically unstable, while the buckled is less dynamically unstable. The elastic constant parameters achieved the required characteristics of stable hexagonal monolayer structures. The study of electronic band structure prefers to indirect semiconductor band gaps, and the density of states showed strong orbital hybridizati

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Publication Date
Wed Jan 01 2020
Journal Name
Aip Conference Proceedings
Investigation hydraulic performance of splash fills packing in cooling tower
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Heat is one of the most energy forms emitted to atmosphere by industrial processes. Water is considered to be the best material to reduce heat energy since its available in nature in abundance and has the ability to absorb heat efficiently. Cooling towers are ideal alternatives to re-cool hot water instead of throwing it especially in places that lack natural water resources or when there are environmental precautions because water with high temperature would be harmful to the ecosystem when it recycled to natural resources such as rivers and lakes. Also, cooling towers considered economically feasible when using west water. This paper interests with hydraulic characteristics of a counter flow wet cooling tower which was investigated experi

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Publication Date
Tue Mar 28 2017
Journal Name
Iraqi Journal Of Pharmaceutical Sciences ( P-issn 1683 - 3597 E-issn 2521 - 3512)
Phytochemical Investigation of Alkaloids in the Iraqi Echinops heterophyllus (Compositae)
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Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms . They are a large family of compounds synthesized by plants in addition to the bacteria, fungi, and animals,  they often have pharmacological effects. The aim of this study is to isolate and identified alkaloids in a newly studied, wild Iraqi plant named

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Publication Date
Mon Dec 18 2017
Journal Name
Al-khwarizmi Engineering Journal
Using Smart Control System to Enhancement the Split Air Conditioning System Performance
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In IRAQ, the air conditioners are the principal cause of high electrical demand. In summer, the outer temperature sometimes exceeds 500C which significantly effects on the A/C system performance and power consumed. In the present work, the improvement in mechanical and electrical performance of split A/C system is investigated experimentally and analytically. In this paper, performance and energy saving enhancement of a split-A/C system was experimentally investigated to be efficiently compatible with elevated temperature weathers. This improvement is accomplished via Smart Control System integrate with Proportional-Integral- Differential PID algorithm. The PIC16F877A micro-controller has been programmed with the PID and PWM c

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Publication Date
Sat Dec 13 2014
Journal Name
Environmental Monitoring And Assessment
Estimating the health risks associated with air pollution in Baghdad City, Iraq
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Publication Date
Wed Feb 08 2023
Journal Name
Iraqi Journal Of Science
Theoretical Design of Anticancer Agents of Some Crown Substituent's Through complexation with Cellular Potassium Ion
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Theoretical study of ten crown ethers substituents were established to investigate some parameters that give clear view about their validity and applicability in the design of anticancer agents. Restricted hartree fock method (RHF/3-21G) were used to determine the energy difference between highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO-LUMO gap) , ionization energy, global hardness and total energy. Strong binding ability with potassium ion were obtained in some of these compounds depend on the type of substituents added to both nitrogen atoms out of the ring cavity. Such binding with potassium in abnormal and divided cancer cells result in inhibition of tumor cell growth by disrupting potassium ion home

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Publication Date
Wed Feb 20 2019
Journal Name
Political Sciences Journal
The concept of violence in political thought (Theoretical study, compared with the concept of terrorism)
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The researcher of human history finds that the first social relations on earth were represented by the violence of Adam, peace be upon him, Cain and Abel. Violence has been a phenomenon of life and society. The history of history is full of all forms of violence and its forms. It speaks of cruelty, oppression and states. History began, in some of its chapters, written with the blood of the victims. It is a testimony to the cruelty of human beings. His human nature and his sin have played a major role that can not be overlooked in the development of important and fundamental developments in some historical turning points where violence was a necessity for life, and its launching change, renewal and reform, and major revolutions in human h

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Publication Date
Sat Dec 11 2021
Journal Name
Engineering, Technology & Applied Science Research
Experimental and Numerical Analysis of the Punching Shear Resistance Strengthening of Concrete Flat Plates by Steel Collars
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In this study, six square reinforced concrete flat plates with dimensions of (1500×1500×100) mm were tested under a concentrated load applied on a column located at the center of the slabs. One of these slabs was the control specimen, whereas, in the others, steel angles (steel collars) were used, fixed at the connection region between the slab and the column to investigate the effect of the presence of these collars on punching shear strength. Five thicknesses were used (4, 5, 6, 8, 10mm) with constant legs of angles (75×75) mm of the steel collars to investigate the effects on the punching shear resistance with respect to the control slab. The results of the experimental study show that the punching shear resistance increased b

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Publication Date
Wed Jun 27 2018
Journal Name
Iraqi Journal Of Science
Proposed Method of Air Traffic Routing in Dynamic Environment Usiing Modifed rrt With Collision Avoid Nace
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     In the current Airlines Air Traffic Management (ATM), the Air Traffic Control Operators (ATCO), with the Air Traffic Control systems (ATC), operate air traffic paths with a small number of fixed routes. Problems of fixed routes appear such that even when they reduce the chance for conflict, they also produce flight paths plans that do not reduce flight time or fuel usage. In nowadays Airlines are heavily overloaded and anxious to minimize the aircrafts fuel usage costs, increase airplanes, and optimize the paths or the flight routes in order to find the most optimal suitable flight paths. This paper presents a new path planning method that deal with such problem effectively, the idea was to produce flights routes

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Publication Date
Mon Nov 01 2021
Journal Name
Energy Reports
Global solar radiation prediction over North Dakota using air temperature: Development of novel hybrid intelligence model
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