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Prediction of Heat Transfer Coefficient and Pressure Drop in Wire Heat Exchanger Working with R-134a and R-600a
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An experimental and theoretical works were carried out to model the wire condenser in the domestic refrigerator by calculating the heat transfer coefficient and pressure drop and finding the optimum performance. The two methods were used for calculation, zone method, and an integral method. The work was conducted by using two wire condensers with equal length but different in tube diameters, two refrigerants, R-134a and R-600a, and two different compressors matching the refrigerant type. In the experimental work, the optimum charge was found for the refrigerator according to ASHRAE recommendation. Then, the tests were done at 32˚C ambient temperature in a closed room with dimension (2m*2m*3m). The results showed that the average heat transfer coefficient for the R-600a was higher than the R-134a, so the length of the wire tube was longer with R-134a than R-600a. The pressure drop for the smaller tube diameter was higher than the other tube. The second law thermodynamic efficiency was higher for R-600a, which reached 41%.  The entropy generation minimization analysis showed that the R-600a refrigerant type and smaller tube diameter are approached the optimum point.

 

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Publication Date
Tue Jan 29 2019
Journal Name
Journal Of The College Of Education For Women
The Separation Worry and its Correlation with Working Memory of the Primary School Pupils
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The concept of the separation worry is considered one of the common disorders in children. The causes and effects of this worry influence the child mental and cognitive ability and the child ability to communicate with others, has friendship and the ability of adaptive with the environment, peers and teachers and it also influences the child's academic and social performance.
The importance of this study is represented in handling the working memory, one of important subject in cognitive psychology. Many universal studies show that the working memory is very important in several daily functions such as continuous attention, followinstructions, implement instructions of many steps, the moment of information remembering and keep focusin

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Publication Date
Mon Jan 01 2024
Journal Name
Dental Hypotheses
Effect of Surface Treatments with Plasma and Chemical Bond on Shear Bond Strength of Acrylic Denture Teeth to Flexible and Heat-Cured Denture Base Material: An In Vitro Study
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Introduction: We aimed to evaluate the shear bond strength of acrylic denture teeth to flexible and heat-cured denture base material after surface treatments with argon plasma, chemical bonding agent (PALFIQUE universal), and combination. Methods: A total of 80 incisor acrylic denture teeth were treated with a argonplasma, chemical bond (PALFIQUE universal bond), and a combination with 10 samples for each group. The neck (gingival portion) of teeth was cut at a 45° angle, and the teeth were attached to heat-cured acrylic resin and flexible denture base material. All the specimens were stored in artificial saliva for 7 days in an incubator (37 °C). A shear

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Publication Date
Mon Sep 20 2021
Journal Name
Key Engineering Materials
Heat Treatment at Different Temperatures and its Effect on the Optical Properties of Pure PMMA and PMMA-Coumarin
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The effect of thermal treatment on optical constants of pure PMMA and with addition (15 and 35) ml of coumarin at different temperatures (100, 110 and 120) C0 for 1 hour were investigated. Cast method used to prepares films of pure PMMA and PMMA with (15 and 35) of coumarin. UV/VIS spectrometer technique used to measure the absorption spectra for these films. The optical constant (absorption spectra and absorption coefficient) don’t changes after applied temperatures in pure PMMA film but the optical constant (absorption spectra and absorption coefficient) in PMMA with (15 and 35) ml of coumarin increased with applied temperatures. The optical energy gap of pure PMMA and PMMA with (15 and 35) ml of coumarin sl

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Publication Date
Sun Dec 09 2018
Journal Name
Baghdad Science Journal
Enhancement of the Tensile and the Compression Properties for Heat- Cured Acrylic Resin Denture Base Materials
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This work aims to investigate the tensile and compression strengths of heat- cured acrylic resin denture base material by adding styrene-butadiene (S- B) to polymethyl methacrylate (PMMA). The most well- known issue in prosthodontic practice is fracture of a denture base. All samples were a blend of (90%, 80%) PMMA and (10%, 20%) S- B powder melted in Oxolane (Tetra hydro furan). These samples were chopped down into specimens of dimensions 100x10x2.5mm to carry out the requirements of tensile tests. The compression strength test specimens were shaped into a cylinder with dimensions of 12.7mm in diameter and 20mm in length. The experimental results show a significant increase in both tensile and compression strengths when compared to cont

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Publication Date
Wed Dec 31 2014
Journal Name
Al-khwarizmi Engineering Journal
Energy Saving of Heat Gain by Using Buried Pipe Inside a Roof
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Abstract

    This work deals with a numerical investigation to evaluate the utilization of a water pipe buried inside a roof to reduce the heat gain and minimize the transmission of heat energy inside the conditioning space in summer season.     The numerical results of this paper showed that the reduction in heat gain and energy saving could be occurred with specific values of parameters, like the number of pipes per square meter, the ratio of pipe diameter to the roof thickness, and the pipe inlet water temperature. Comparing with a normal roof (without pipes), the results indicated a significant reduction in energy heat gain which is about 37.8% when the number of pipes per m

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Publication Date
Mon Oct 17 2016
Journal Name
Proceedings Of The Institution Of Mechanical Engineers, Part B: Journal Of Engineering Manufacture
Development and control of shaped metal deposition process using tungsten inert gas arc heat source in additive layered manufacturing
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Tungsten inert gas arc welding–based shaped metal deposition is a novel additive manufacturing technology which can be used for fabricating solid dense parts by melting a cold wire on a substrate in a layer-by-layer manner via continuous DC arc heat. The shaped metal deposition method would be an alternative way to traditional manufacturing methods, especially for complex featured and large-scale solid parts manufacturing, and it is particularly used for aerospace structural components, manufacturing, and repairing of die/molds and middle-sized dense parts. This article presents the designing, constructing, and controlling of an additive manufacturing system using tungsten inert gas plus wire–based shaped metal deposition metho

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Publication Date
Sat Jan 01 2022
Journal Name
Journal Of International Society Of Preventive And Community Dentistry
Investigating tensile bonding and other properties of yttrium oxide nanoparticles impregnated heat-cured soft-denture lining composite in vitro
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Aims: This study was conducted to assess the effect of the addition of yttrium oxide (Y2O3) nanoparticles on the tensile bond strength, tear strength, shore A hardness, and surface roughness of soft-denture lining material. Materials and Methods: Y2O3 NPs with 1.5 and 2 wt.% were added into acrylic-based heat-cured soft-denture liner. A total of 120 specimens were prepared and divided into four groups according to the test to be performed (tensile bond strength, tear strength, surface hardness, and surface roughness). Results: There was a highly significant increase in tensile bond strength between the soft liner and the acrylic denture base, tear strength, and hardness at both concentrations as compared to the control group, whereas ther

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Publication Date
Wed Jun 28 2023
Journal Name
Engineering Applications Of Computational Fluid Mechanics
Comprehensive analysis of melting enhancement by circular Y-shaped fins in a vertical shell-and-tube heat storage system
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Publication Date
Sat Jan 01 2022
Journal Name
Journal Of Energy Storage
Intensifying the thermal response of PCM via fin-assisted foam strips in the shell-and-tube heat storage system
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Publication Date
Sun Jun 30 2013
Journal Name
College Of Islamic Sciences
 Quranic ills of the use of the heat (d. 637 AH)
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Praise be to the one who taught the pen. Without the pen, the knowledge of the first two would not have reached the others. Then, praise the one who taught man from the printing industry unless he knew, and prayers and peace be upon those who guide all nations to the invention and the follower in the matter of religion, and to his family and companions.
      The use of Qur’anic use is an integrated and important topic that examines the building and the meaning, which are two major titles in the study of Arabic, so the goal of scholars when going into these explanations was to find out the wonderful linguistic miracle of this great book.
     Scholars have worked hard to talk

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