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Natural Convection Effect on Solidification Enhancement in a Multi-Tube Latent Heat Storage System: Effect of Tubes’ Arrangement
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The solidification process in a multi-tube latent heat energy system is affected by the natural convection and the arrangement of heat exchanger tubes, which changes the buoyancy effect as well. In the current work, the effect of the arrangement of the tubes in a multi-tube heat exchanger was examined during the solidification process with the focus on the natural convection effects inside the phase change material (PCM). The behavior of the system was numerically analyzed using liquid fraction and energy released, as well as temperature, velocity and streamline profiles for different studied cases. The arrangement of the tubes, considering seven pipes in the symmetrical condition, are assumed at different positions in the system, including uniform distribution of the tubes as well as non-uniform distribution, i.e., tubes concentrated at the bottom, middle and the top of the PCM shell. The model was first validated compared with previous experimental work from the literature. The results show that the heat rate removal from the PCM after 16 h was 52.89 W (max) and 14.85 W (min) for the cases of uniform tube distribution and tubes concentrated at the bottom, respectively, for the proposed dimensions of the heat exchanger. The heat rate removal of the system with uniform tube distribution increases when the distance between the tubes and top of the shell reduces, and increased equal to 68.75 W due to natural convection effect. The heat release rate also reduces by increasing the temperature the tubes. The heat removal rate increases by 7.5%, and 23.7% when the temperature increases from 10 °C to 15 °C and 20 °C, respectively. This paper reveals that specific consideration to the arrangement of the tubes should be made to enhance the heat recovery process attending natural convection effects in phase change heat storage systems.

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Publication Date
Sat May 01 2021
Journal Name
Journal Of Physics: Conference Series
The influence of temperature and size on the absorption coefficient of CdSe quantum dots
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Abstract<p>Because of Cadmium selenide quantum dots (CdSe quantum dots) has a tuning energy gap in the visible light range, therefore; it is provided a simple theoretical model for the absorption coefficient of CdSe quantum dots, where the absorption coefficient determines the extent to which the light of a material can penetrate a specific wavelength before it is absorbed. CdSe quantum dots have an energy gap can be controlled through two effects: the temperature and the dot size of them. It is found that; there is an absorption threshold for each directed wavelength, where CdSe quantum dots begin to absorb the visible spectrum at a size of 1.4 nm at room temperature for a directed wavelength 3</p> ... Show More
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Publication Date
Tue Jun 01 2021
Journal Name
Ibn Al-haitham International Conference For Pure And Applied Sciences (ihicps)
Influence of ultrasonic pre-treatment on Pyrolysis and Combustion of Sewage Sludge by TG
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The combustion and pyrolysis processes of sewage sludge were studied in the current report. Two kinds of sewage sludge(SS) were used, SS the sewage sludge was not treated, while SS-U90KHz the ultrasonic bath pre-treated sewage sludge with a frequency of 90KHz was not treated. Wastewater treatment plants are the origins of waste sludge. Analyses were performed roughly and finally. Thermogravimetric research analyzed the thermal behaviour of the analysed sewage bucket (TGA). The samples were heated at a constant rate of 25 to 800 Celsius by air (combustion) and nitrogen flow (pyrolysis). For sludges which have been investigated. In the TG/DTG curves, comparable thermal profiles were available. All of the TG/curves DTG’s were divided into th

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Publication Date
Sun Jan 01 2023
Journal Name
Iraqi Journal Of Applied Physics
Effects of Magnetic Field on Growth and Electrical Characteristics of Tornado Gliding Arc Discharge
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This study investigates the characterization and growth dynamics of a Magnetically Stabilized Gliding Arc Discharge (MSGAD) system, generating non-thermal plasma with argon gas under atmospheric pressure and flow rates of 1-5 L/min. The electrical properties and growth patterns concerning gas flow rates and applied voltages were examined utilizing a magnetic field for stability. Using a digital oscilloscope, a correlation between voltage reduction and increased current was uncovered. An algorithm analyzes digital images to compute arc length, area, and volume. Results reveal how gas flow rate and applied voltage directly impact arc growth. Furthermore, the magnetic field's role in guiding and stabilizing the plasma discharge was explored. T

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Publication Date
Tue May 01 2018
Journal Name
Journal Of Physics: Conference Series
Cytotoxic effects of new synthesis heterocyclic derivatives of Amoxicillin on some cancer cell lines
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A new Schiff base [I] was prepared by refluxing Amoxicillin trihydrate and 4-Hydroxy- 3,5-dimethoxybenzaldehyde in aqueous methanol solution using glacial acetic acid as a catalyst. The new 1,3-oxazepine derivative [II] was obtained by Diels- Alder reaction of Schiff base [I] with phthalic anhydride in dry benzene. The reaction of Schiff base [I] with thioglycolic acid in dry benzene led to the formation of thiazolidin-4-one derivative [III]. While the imidazolidin-4-one [IV] derivative was produced by reacting the mentioned Schiff base [I] with glycine and triethylamine in ethanol for 9 hrs. Tetrazole derivative [V] was synthesized by refluxing Schiff base [I] with sodium azide in dimethylformamid DMF. The structure of synthesized compound

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Publication Date
Tue Dec 01 2020
Journal Name
Journal Of Engineering Science And Technology
THE INFLUENCE OF CHEMICAL COMPOSITION OF ASPHALT CEMENT ON THE PHYSICAL AND RHEOLOGICAL PROPERTIES
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Failure in asphalt mixture and distress in pavement are major issues to roads infrastructure. Selecting an appropriate chemical composition of asphalt cement is a key component in avoiding these issues. This work aimed to investigate the effect of the chemical composition of different polar fractions on the rheological and physical properties of asphalt cement. Four types of asphalt cement with penetration grades of 20/30, 40/50, 60/70 and 85/100 were divided into four fractions. Complex shear modules, rutting resistance and rotational viscosity of the asphalt cement were determined by using a Dynamic Shear Rheometer and a Rotation Viscometer, respectively. The results show that an increase in the asphaltene content and Gastel index resulte

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Publication Date
Thu Jan 01 2015
Journal Name
Iraqi Postgraduate Medical Journal
Effects of Coriandrum Sativum on the Spermatogenesis of Rat Testis: Histological and Morphometrical Studies
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ABSTRACT: BACKGROUND: Coriandrum Sativum is a native of Mediterranean region and is grown in North Africa, central Europe, and Asia as culinary herb and medicament. In addition to the other health-supporting reputation, coriander has hypoglycemic, hypolipidemic, and aphrodisiac effects. OBJECTIVE: To study the effect of Coriandrum Sativum on process of spermatogenesis. MATERIALS AND METHODS: Coriandrum sativum was given daily to mature male rats in a dose of 50mg/ 100g body weight for 14 days. 10% formalin fixed paraffin-embedded tissue sections were performed for histological and morphometrical studies. RESULTS: Histological study showed wider seminiferous tubules & increased spermatocytes population with an increased sperm density

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Publication Date
Mon Jan 01 2024
Journal Name
Sustainable Construction Materials And Technologies (scmt)
TRIAXIAL TEST OF HYDRATED LIME ON THE MECHANICAL PROPERTIES OF HOT MIX ASPHALT CONCRETE
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This paper reports on the experimental study, which conducted a series of triaxial tests for the asphalt concrete using hydrated lime as a mineral additive. Three HMA mixes, prepared by the specification for wearing, levelling and base layers, were studied under three different temperatures. The test results have demonstrated that, compared with the control mixes excluding HL, the permanent deformation resistance of the HL modified mixes has significant improvement. The deformation has been reduced at the same load repetition number, meanwhile the flow number has been considerably increased. The degree of improvement in permanent deformation resistance using HL is more pronounced at high stress deviation states and high temperature.

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Publication Date
Sun Jun 05 2016
Journal Name
Baghdad Science Journal
Asemi-Empirical Study of the Adsorption of Some Organic Pollutants on Modified Iraqi Clays
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In this work semi–empirical method (PM3) calculations are carried out by (MOPAC) computational packages have been employed to calculate the molecular orbital's energies for some organic pollutants. The long– chain quaternary ammonium cations called Iraqi Clays (Bentonite – modified) are used to remove these organic pollutants from water, by adding a small cationic surfactant so as to result in floes which are agglomerates of organobentonite to remove organic pollutants. This calculation which suggests the best surface active material, can be used to modify the adsorption efficiency of aniline , phenol, phenol deriviatives, Tri methyl glycine, ester and pecticides , on Iraqi Clay (bentonite) by comparing the theoretical results w

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Publication Date
Mon Dec 03 2018
Journal Name
Journal Of Engineering
The Influence of Clay Bricks Dust Incorporation on the Self-Curing of Cement Mortar
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Self- curing is the potential of lightweight aggregate to absorption great amount of water thru mixing which prominently can moves to the paste during hydration process. Self- curing empowers a water to be distributes more evenly act out the cross section. Whereas, the external curing water is only able to penetrate several millimetres into concrete with low water cement ratio. Brick dust accumulates in the demolish site creates serious environmental contamination. This study investigates the effect of brick dust recovered from construction site on the Properties of mortar cured in three curing conditions. Mortar in this study produced using BD as cement additive with (2, 4, 6, and 8) % by weight of cement. BD was used a

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Publication Date
Tue Sep 19 2017
Journal Name
Al-academy
Peer Education Strategy and its Impact on the Development of Skill of Perspective Drawing
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       After the twenty – first century become  necessary for us motorcade era in educational a chevements by searching  for the best  strategies and teaching methods and  techniques  artotalbagesh  resorting to the strategy

Did not use in use in the teaching of the foreseeable  material  general by voice and teaching  perspective  for the student of the class fourth science

In particular ,so the researcher asking the question follows:

Can the peer education strategy to have an impact in perspective drawing skill development ?

   From here it demonstrated the importance of current research know the impact of  p

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