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Exergy Analysis of a Domestic Refrigerator
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An energy and exergy thermodynamic analysis using EES program was done for a domestic refrigerator working with R-134a using vapor compression refrigeration cycle. The analysis deals with the system component, i.e. compressor, condenser, evaporator and the expansion device. The analysis depends on the entropy generation minimization approach to improve the refrigerator performance by exploring the optimum design points. These design points were derived from three different theories governing the entropy generation minimization using exergy analyzing method. These theories were first applied to find the optimum balance between the hot inner condenser area and the cold inner evaporator area of the refrigerator and between its hot and cold thermal conductances. Nine types of condensers were used according to its internal surface area and thermal conductance, in order to reach the minimum entropy generation in the refrigerator. The results showed that the compressor has the lowest exergy efficiency of 25%. The expansion device was the second component after the compressor with exergy efficiency of 92%, followed by the condenser with an efficiency of 93%. The evaporator was found to have an exergy efficiency of 98 %. The experimental tests were repeated for the nine condensers sizes with three different ambient temperatures 25℃, 30℃ and 35℃.  The exergy analysis showed that the design of the refrigerator mainly depends on thermal conductance calculations rather than the surface inner area estimation.

 

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Publication Date
Sun Mar 01 2009
Journal Name
Diyala Journal Of Human Research
Stability of the Finite Difference Methods of Fractional Partial Differential Equations Using Fourier Series Approach
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The fractional order partial differential equations (FPDEs) are generalizations of classical partial differential equations (PDEs). In this paper we examine the stability of the explicit and implicit finite difference methods to solve the initial-boundary value problem of the hyperbolic for one-sided and two sided fractional order partial differential equations (FPDEs). The stability (and convergence) result of this problem is discussed by using the Fourier series method (Von Neumanns Method).

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Publication Date
Sat Jan 01 2011
Journal Name
Iraqi Journal Of Physics
Study of annealing effect on some Optical Properties of CuIn(SexTe1-x)2 Thin Films
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The optical properties for the components CuIn(SexTe1-x)2 thin films with both values of selenium content (x) [0.4 and 0.6] are studied. The films have been prepared by the vacuum thermal evaporation method with thickness of (250±5nm) on glass substrates. From the transmittance and absorbance spectra within the range of wavelength (400-900)nm, we determined the forbidden optical energy gap (Egopt) and the constant (B). From the studyingthe relation between absorption coefficient (α) photon energy, we determined the tails width inside the energy gap.
The results showed that the optical transition is direct; we also found that the optical energy gap increases with annealing temperature and selenium content (x). However, the width of l

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Publication Date
Sat Apr 01 2023
Journal Name
Journal Of Engineering
Influence of Design Efficiency of Water Supply Network Inside Building on its Optimum Usage: Review
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The water supply network inside the building is of high importance due to direct contact with the user that must be optimally designed to meet the water needs of users.  This work aims to review previous research and scientific theories that deal with the design of water networks inside buildings, from calculating the amount of consumption and the optimal distribution of the network, as well as ways to rationalize the use of water by the consumer.  The process of pumping domestic water starts from water treatment plants to be fed to the public distribution networks, then reaching a distribution network inside the building till it is  provided to the user.  The design of the water supply network inside the building is

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Publication Date
Fri Oct 30 2020
Journal Name
Journal Of Economics And Administrative Sciences
Environmental pollution of solid waste and methods of managing it Study in Ramadi Municipality Case
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The current research aims at finding out how to properly and correctly manage waste and solid waste and reduce the difficulties faced by all countries. However, it is becoming increasingly acute in developed cities because their economies are growing rapidly. It is necessary to identify the modern methods used in developed countries in managing wastes. The use of modern waste management techniques is a coordinated effort by international agencies within the borders responsible for them. The problem of the study can be identified in the lack of clarity of environmental management procedures in place. The importance of the research contributes to providing greater capacity to the administrative and technical leadership in the municipality

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Publication Date
Sat Dec 28 2019
Journal Name
Journal Of Mechanics Of Continua And Mathematical Sciences
NEW ROBUST ESTIMATOR OF CHANGE POINT IN SEGMENTED REGRESSION MODEL FOR BED-LOAD OF RIVERS
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Publication Date
Wed Dec 31 2014
Journal Name
Al-khwarizmi Engineering Journal
Catalytic Cracking of Iraqi Vacuum Gasoil Using Large and Medium Pore Size of Zeolite Catalysts
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Abstract 

The catalytic cracking conversion of Iraqi vacuum gas oil was studied on large and medium pore size (HY, HX, ZSM-22 and ZSM-11) of zeolite catalysts. These catalysts were prepared locally and used in the present work. The catalytic conversion performed on a continuous fixed-bed laboratory reaction unit. Experiments were performed in the temperature range of 673 to 823K, pressure range of 3 to 15bar, and LHSV range of 0.5-3h-1. The results show that the catalytic conversion of vacuum gas oil increases with increase in reaction temperature and decreases with increase in LHSV. The catalytic activity for the proposed catalysts arranged in the following order:

HY>H

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Publication Date
Sun Jun 01 2014
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
The Role of Audit Committees on Corporate Governance Effectiveness of Iraqi Special Banks (Filed Study)
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Consistent with developments emerging environmental and canaccept by Iraq of the opportunities and challenges ahead in many fields,including economic areas, it requires the face of those developments andadaptation by adopting a lot of related concepts, including the concept ofcorporate governance and commitment to its principles, standards andmechanisms, especially those related to the formation of audit committeesand identify the tasks and duties entrusted to its members and terms oftheir independence as well as the rehabilitation of both scientific andpractical manner that is consistent with the interests of shareholders andother stakeholders in the companies, including banks, research sample, theresearch aims to shed light on the conc

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Publication Date
Wed May 10 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Gross and Histological Structure of the Caudal Fin of Adult Mosquitofish , Gambusia Affinis , (Baird & Girard)
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The  present  study  showed  that  the  caudal  fin  of  adult mosquitofish  (Gambusia  affinis)  is  homocercal  and  rounded . It  consists  of  22-24 fin rays (Lepidotrichia) . Each fin ray  consists  of  many  segments . Some of these rays are short and  unbranched  whereas  others long and branched dichotomously. Pigment cells are shown to be dispersed on the fin and they are condensened at the edges of the fin rays and at the regions of their dichotomy .        Histologically the transverse section of the fin is surrounded by a fin membrane (composed of epidermis and dermis)

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Publication Date
Fri Mar 31 2017
Journal Name
Journal Of Engineering
Experimental Measurements of Viscosity and Thermal Conductivity of Single Layer Graphene Based DI-water Nanofluid
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Experimental measurements of viscosity and thermal conductivity of single layer of graphene . based DI-water nanofluid are performed as a function of  concentrations (0.1-1wt%) and temperatures between (5 to 35ºC). The result reveals that the thermal conductivity of GNPs nanofluids was increased with increasing the nanoparticle weight fraction concentration and temperature, while the maximum enhancement was about 22% for concentration of 1 wt.% at
35ºC. These experimental results were compared with some theoretical models and a good agreement between Nan’s model and the experimental results was observed. The viscosity of the graphene nanofluid displays Newtonian and Non-Newtonian behaviors with respect to nanoparticles concen

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Publication Date
Wed Apr 01 2015
Journal Name
Journal Of Educational And Psychological Researches
The Reasons of the Student of Secondary School Abstention From Participation in The Theatrical Activity
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The present study aims at knowing the reasons of the student of secondary school abstention from participation in the theatrical activity, and to know the reasons that resulted in this abstention. In addition to that, the study aims at knowing the differences according to variables (gender, scholastic stage, and major of study). The sample of the study was chosen from the secondary schools in Baghdad in the random manner from Al-Karakh and Al-Rusafa districts of (147) students. The questionnaire was used to collected data.

          The result showed that all the items are intense, the item of (Students do not know how to use their leisure time) obtained the hi

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