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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
Fri Dec 25 2015
Journal Name
Iraqi Dental Journal
Comparison of Some Mechanical Properties of Silanated SiO2 and Polyester Fiber Composite Incorporation into Heat Cured Acrylic Resin.
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Publication Date
Mon Sep 10 2018
Journal Name
Iraqi Journal Of Physics
Thermal conductivity and diffusion coefficient of polymer blend 80%EP/20%UPE reinforced with sand particles
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New polymer blend with enhanced properties was prepared from (80 %) epoxy resin (Ep), (20%) unsaturated polyester resin (UPE) as a matrix material. The as-obtained polymer blend was further reinforced by adding Sand particles of particle size (53 μm) with various weight fraction (5, 10, 15, 20 %). Thermal conductivity and sorption measurements are performed in order to determine diffusion coefficient in different chemical solutions (NaOH, HCl) with concentration (0.3N) after immersion for specific period of time (30 days). The obtained results demonstrate that the addition of sand powder to (80%EP/20%UPE) blend leads to an increase of thermal conductivity, with an optimum/minimum diffusion coefficient in (HCl)/(NaOH), respectively.

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Publication Date
Wed Mar 30 2022
Journal Name
Journal Of Educational And Psychological Researches
Associations Between Phonological Processing and Working Memory in Students with and without Reading disabilities in Basic Education Cycle One Schools in Muscat
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The study aimed to examine the phonological processing profile for students with and without reading disabilities in cycle 1 schools of basic education in the Governorate of Muscat, Sultanate of Oman. The study participants included 306 students, 165 students with reading disabilities and 141 students without reading disabilities. The Comprehensive Test of Phonological Processing (CTOPP) and Working Memory Test (WMT) were administered to the participants. The results of the study showed that the mean score of students without reading disabilities was higher than that of students of reading disabilities in all measures of phonological processing, and that there are statistically significant differences on the  case of students in all

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Publication Date
Mon May 18 2026
Journal Name
Journal Of Baghdad College Of Dentistry
The effect of plasma treatment on shear bond strength of soft denture liner with two different types of denture base material (heat cure and light cure)
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Background: In this study we evaluate the effect of plasma treatment (oxygen and argon) gas in two different exposure times on the surface of heat cure and light cure acrylic resin. Materials and method: 100 specimens of heat cure and light cure acrylic resin were fabricated. The measurements of the samples were (75mm, 25mm and 4.5mm) length, width and depth respectively with stopper of 3mm depth. Two types of gas used oxygen and argon in (5,10) min by using (DC-glow discharge plasma device) then we apply cold cure soft lining material, with the help of Instron machine we test the shear stress value. Results: A highly significant effect after argon and oxygen gases treatment in both 5 and 10 min exposure times on shear bond strength to soft

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Publication Date
Fri Nov 26 2021
Journal Name
Nanomaterials
Solidification Enhancement in a Multi-Tube Latent Heat Storage System for Efficient and Economical Production: Effect of Number, Position and Temperature of the Tubes
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Thermal energy storage is an important component in energy units to decrease the gap between energy supply and demand. Free convection and the locations of the tubes carrying the heat-transfer fluid (HTF) have a significant influence on both the energy discharging potential and the buoyancy effect during the solidification mode. In the present study, the impact of the tube position was examined during the discharging process. Liquid-fraction evolution and energy removal rate with thermo-fluid contour profiles were used to examine the performance of the unit. Heat exchanger tubes are proposed with different numbers and positions in the unit for various cases including uniform and non-uniform tubes distribution. The results show that

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Publication Date
Sun Mar 01 2026
Journal Name
International Communications In Heat And Mass Transfer
Structural fin configurations for enhanced thermal performance of latent heat storage in building heating applications
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Publication Date
Fri Sep 02 2022
Journal Name
Frontiers In Built Environment
Thermal analysis of horizontal earth-air heat exchangers in a subtropical climate: An experimental study
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The earth-air heat exchanger (EHX) has a promising potential to passively save the energy consumption of traditional air conditioning systems while maintaining a high degree of indoor comfort. The use of EHX systems for air conditioning in commercial and industrial settings offers several environmental benefits and is capable of operating in both standalone and hybrid modes. This study tests the performance and effectiveness of an EHX design in a sandy soil area in Baghdad, Iraq. The area has a climate of the subtropical semi-humid type. Ambient air temperatures and soil temperatures were recorded throughout the months of 2021. During the months of January and June, the temperatures of the inlet and outflow air at varying air veloci

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Publication Date
Sat Oct 31 2020
Journal Name
Eastern-european Journal Of Enterprise Technologies
Design and development of high-accuracy machine for wire bending
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Publication Date
Thu Feb 01 2018
Journal Name
Applied Mathematical Modelling
Identification of a multi-dimensional space-dependent heat source from boundary data
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Publication Date
Wed Jan 01 2020
Journal Name
International Journal Of Mathematical Modelling And Numerical Optimisation
Reconstruction of an orthotropic thermal conductivity from non-local heat flux measurements
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