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Experimental Study on Double-Pass Solar Air Heater with and without using Phase Change Material
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In this paper, an experimental study was conducted to enhance the thermal performance of a double-pass solar air heater (SAH) using phase change material (PCM) for thermal storage at climatic conditions of Baghdad city - Iraq. The double-pass solar air heater integrated with thermal storage system was manufactured and tested to ensure that the air heating reserved after the absence of the sun. The rectangular cavity filled with paraffin wax was used as a latent heat storage and incorporated into the lower channel of solar air heater. Experiments were carried out to evaluate the charging and discharging characteristics of two similar designed solar air collectors with and without using phase change material at a constant air mass flow rate of (0.0375 kg/sec). The parameters that affect the thermal performance of the SAH with and without the PCMs presented by solar radiation, the difference in air temperature, outlet air temperature, instantaneous thermal efficiency, and daily efficiency are evaluated. The experimental results show that when using the PCM, the temperature of the outlet air was enhanced and increased over the ambient temperature by (1.5 - 6.5 C) after sunset for 5 hours period. It was found that the instantaneous thermal efficiency of the heater using thermal storage exceeds 100% after sunset, this is due to a large amount of heat stored in the paraffin wax that has been released during the discharge process. Also, it was found that the daily efficiency of the double pass SAH integrated with and without thermal energy storage unit was (56, 47%) respectively.

 

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Publication Date
Sun Mar 02 2008
Journal Name
Baghdad Science Journal
Developing production techniques of copper powder less than 125 micron without grinding
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Publication Date
Wed Dec 30 2020
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
Experimental Investigation of Pomegranate Peel and Grape Seed Powder Additives on the Rheological and Filtration Properties of Un-Weighted WBM
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   The chemical additives used to enhance the properties of drilling mud cause damage to humans and the environment. Therefore, it is necessary to search for alternative additives to add them to the drilling mud. Thus, this study investigates the effects of pomegranate peel and grape seed powders as natural waste when added to un-weighted water-based mud. The test includes measurements of the rheological properties and filtration, as well as the alkanity and density of the drilling mud. The results showed a decrease in PH values ​​with an increase in the concentrations of pomegranate peel or grapeseed, and a decrease in mud density with an increase in powders of pomegranate peel and grape seed concentrations that resulted f

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Publication Date
Thu Mar 01 2012
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
Predicting changes on budget expenditures using Markov chains with practical application
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The researchers have a special interest in studying  Markov  chains as one of the probability samples which has many applications in different fields. This study comes to deal with the changes issue that happen on budget expenditures by using statistical methods, and Markov chains is the best expression about that as they are regarded reliable  samples in the prediction process. A transitional matrix is built for three expenditure cases (increase ,decrease ,stability) for one of budget expenditure items (base salary) for three directorates (Baghdad ,Nineveh , Diyala) of one  of the ministries. Results are analyzed by applying  Maximum likelihood estimation  and Ordinary least squares  methods resulting

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Publication Date
Mon Feb 07 2022
Journal Name
مجلة الدراسات الاقتصادية والادارية
Measuring readiness to accomplish organizational change through personal characteristics: Crisis management approach: An exploratory study of the opinions of a sample of managers at Central Technical
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The self-evident truth existing in today's business environment is the continuity of change and its continuity and turmoil, also its increase over time as it is more abundant, abundant, wide and complex than ever before, and it is the dominant feature in the business environment, as different organizations and operating units can find themselves shifting from the top to the bottom. And then it requires its departments to strive to adapt to these rapid and turbulent shifts and changes by bringing about a series of organizational and adaptive changes that are not limited to one organizational aspect only but rather include all organizational components. Accordingly, this research came to determine the readiness of public organizations to chan

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Publication Date
Thu Apr 01 2021
Journal Name
J Nanostruct
Effect of Sulfur and Nitrogen co-Doped Graphene Quantum Dots on Co3O4 Nanoparticles as Solar Induced Photocatalyst
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The photocatalyst process is considered the most promising method for the removal of water contamination. For excellent chemical and structural properties of Co3O4 nanoparticles, various Co3O4-based nanostructures can be applied as a photocatalyst. In this work, carbon quantum dots is prepared via an eco-friendly process and linked to Co3O4 effectively. X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible absorption spectroscopy and Fourier transform infrared spectroscopy (FT-IR). The photocatalyst process reveals that prepared nanocomposites can be degraded methylene blue under solar irradiation strongly. Results showed that methylene blue and methyl orange are degraded via

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Publication Date
Sun Jan 06 2019
Journal Name
Progress In Industrial Ecology – An International Journal,
Effect of V, In and Cu doping on properties of p-type ZnSe/Si heterojunction solar cell
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The enhancement of ZnSe/Si Heterojunction by adding some elements (V, In and Cu) as impurities is the main goal because they contribute to the manufacturing of renewable energy equipment, such as solar cells. This paper describes the preparation of thin films ZnSe with V, In and Cu doped using thermal evaporation method with a vacuum of 10–5 Torr. The thin film was obtained from this work could be applied in heterojunction solar cell because of several advantages including high absorption coefficient value and direct band gap. The samples prepared on a glass and n-type Si wafer substrate. These films have been annealed for 1 h in 450 K. X-ray diffraction XRD results indicated that ZnSe thin film possesses poly-crystalline structure after

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Publication Date
Tue Jan 01 2019
Journal Name
Progress In Industrial Ecology, An International Journal
Effect of V, In and Cu doping on properties of p-type ZnSe/Si heterojunction solar cell
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Publication Date
Fri Mar 01 2019
Journal Name
Al-khwarizmi Engineering Journal
Mass-Transfer Characteristics of Air- Suction Type Fermentors
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Liquid-side mass-transfer coefficients (KLa) were measured in air-suction type fermentors using physical absorption of oxygen.  A fermentor of 0. 5 m i.d. was used with a working capacity of 60 liters of liquid. Tap water was used as the liquid phase, and air was used as the gas phase. The bioreactor mixing system consists of shrouded-disk/curved-blade turbine with six evacuated bending blades. The effect of liquid submergence (S) was investigated. Further, the effects of the ratio of the impeller diameter (D) to the tank diameter (T), and the clearance of the impeller from the tank bottom(C) were also studied.  The agitation speed (N) was varied in the range of 50-800 rpm. It was found that the value of  K

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Publication Date
Tue Oct 01 2024
Journal Name
Dental Hypotheses
Evaluation of Impact, Tensile, and Flexural Strength of Natural Wool Fiber Reinforced Polymethyl Methacrylate Denture Base Material: An In Vitro Study
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Introduction: This study was carried out to assess the effect of natural wool fiber addition on the impact, tensile, and flexural strengths of the heat-cured acrylic denture base material. Methods: Short wool fibers with and without chemical surface treatment were added to polymethyl methacrylate (PMMA) at a percentage of 0.25% by weight. A total of 90 acrylic specimens were prepared and divided into three groups according to the tests performed. Impact strength, tensile strength, and flexural strength tests were evaluated. The statistical analysis of the results data was performed using the one-way analysis of variance (ANOVA) test and Tukey’s post hoc test

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Publication Date
Fri Feb 03 2023
Journal Name
Buildings
Flexural Performance of a Novel Steel Cold-Formed Beam–PSSDB Slab Composite System Filled with Concrete Material
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In this study, the flexural performance of a new composite beam–slab system filled with concrete material was investigated, where this system was mainly prepared from lightweight cold-formed steel sections of a beam and a deck slab for carrying heavy floor loads as another concept of a conventional composite system with a lower cost impact. For this purpose, seven samples of a profile steel sheet–dry board deck slab (PSSDB/PDS) carried by a steel cold-formed C-purlins beam (CB) were prepared and named “composite CBPDS specimen”, which were tested under a static bending load. Specifically, the effects of the profile steel sheet (PSS) direction (parallel or perpendicular to the span of the specimen) using different C-purlins c

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