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Effect of Different Compressor Speeds on the Energy and Exergy of an Automobile Air-Conditioner Using R134a in the Absence and Presence of a Liquid-Suction Heat Exchanger
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Refrigerant R134a has been widely utilized in automotive air conditioning systems (AACSs); R134a has a high global warming potential (GWP) of 1430 despite having zero ozone depletion potential (ODP). Coming refrigeration systems must include refrigerants with low GWP and zero ODP. The aim of this experimental study is to evaluate the thermal performance of an (AAC) with different values of compressor speeds, i.e., (1000, 1700, and 2400 rpm) and two thermal loads, i.e., (500 and 1000 Watt) with the absence and presence of liquid suction heat exchanger (LSHX) using R134a. The results showed that adding LSHX enhanced the COP cycle by 7.18%, 10.7%, and 3.09% for the first, second, and third speed, respectively, at 500 Watt, while the enhancements were 10.27 %, 23.3 %, and 11.5 % for the first, second, and third speed, respectively, at 1000 Watt. Increasing the compressor speed decreased COP due to a reduction in RE and increased the compression effect, increasing the work done by the motor on the compressor that caused a reduction in COP. The compressor exergy destruction (X des. Comp.) decreased when LSHX was added by 6.13%, 2.22%, and 18.8% for the first, second, and third speed, respectively. However, X des. comp. increased with compressor speed due to the system’s pressure difference rise because of decreasing evaporation and increasing condensation pressures. As a result, the entropy generation increased. The increase in discharge temperature and pressure of the compressor led to a high friction force between the moving part of the compressor and the refrigerant, so the energy losses increased. Increasing the compressor speed decreased the total exergy performance of the cycle by 5.8 %, 7.5 %, and 16.7 % for the first, second, and third speed, respectively, due to increasing the compressor discharge temperature, increasing the X des. comp. and thermostatic expansion device and decreasing condenser and evaporator. Increasing X des. comp was higher than the destruction in the condenser and evaporator, which canceled the effect of others, so the total exergy performance of the cycle decreased.

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Publication Date
Tue Sep 17 2024
Journal Name
Evolutionary Studies In Imaginative Culture
The Effect of the Siberian Air Altitude on the Characteristics of the Climate of the Northern Arabian Peninsula
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The field of climatic geography focuses on the study of the Earth's surrounding atmosphere, particularly the lower (surface) part close to the Earth's surface. This field examines the interactions within the atmosphere resulting from the solar radiation that reaches the Earth and the subsequent distribution of atmospheric pressure. Consequently, certain surface pressure systems, both high and low, emerge and vary in their temporal and spatial impacts on the climate of the Arabian Peninsula. Therefore, it is essential to conduct a comprehensive and detailed study to understand the causes, development, movement, geographical distribution, and monthly and seasonal recurrence of these pressure systems. For this purpose, a minor climatic

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Publication Date
Sat Jan 01 2022
Journal Name
International Journal Of Clinical Dentistry
THE EFFECT OF A PROTECTIVE BARRIER ON THE SHEAR BOND STRENGTH OF DIFFERENT ORTHODONTIC BRACKETS
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Background and objectives: This study aimed at testing the effect of plastic sleeve or barrier, used to cover the guide of the light cure unit to prevent cross-infection, on the shear bond strength and site of bond failure of stainless steel and ceramic orthodontic brackets. Materials and methods: Forty orthodontic brackets; twenty stainless steel and twenty ceramic brackets bonded to forty extracted human maxillary first premolars using light cure adhesive cured with and without the use of a protective plastic barrier on the guide. Comparing the effect of this barrier on the shear bond strength and adhesive remnant index was performed using an independent t-test and Chi-square test. Results: The protective barrier had decreased the shear b

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Publication Date
Thu Jan 06 2022
Journal Name
Chemical Papers
A solvent collection technique using dispersive liquid–liquid microextraction coupled with spectrophotometry for the trace determination of folic acid in pure, dosage forms and flaxseed
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A simple, rapid and environmentally friendly dispersive liquid–liquid microextraction method-based spectrophotometric method for the trace determination of folic acid has been developed. The proposed method is based on the formation of a deep yellow product via reaction of folic acid and 1,2-naphthoquine-4-sulfonate at pH = 9. The formed complex was extracted using a mixture of chloroform and ethanol. Then, the tiny organic droplets were measured at λ = 520 nm. At the optimum conditions, linearity was ranged from 0.05 to 1.5 μg/mL for the standard and samples, with a linear correlation coefficient of 0.9996. The detection limits were 0.02, 0.027, 0.03, 0.02 and 0.04 μg/mL for standard, tablet (5 mg), tablet (1 mg), syrup and fl

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Publication Date
Sat Oct 08 2022
Journal Name
Journal Of Computational Design And Engineering
Twisted-fin parametric study to enhance the solidification performance of phase-change material in a shell-and-tube latent heat thermal energy storage system
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Abstract<p>Phase change material (PCM) is considered as one of the most effective thermal energy storage (TES) systems to balance energy supply and demand. A key challenge in designing efficient PCM-based TES systems lies in the enhancement of heat transmission during phase transition. This study numerically examines the privilege of employing twisted-fin arrays inside a shell-and-tube latent heat storage unit to improve the solidification performance. The presence of twisted fins contributes to the dominating role of heat conduction by their curved shapes, which restricts the role of natural convection but largely aids the overall heat-transfer process during solidification. The heat-discharge </p> ... Show More
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Publication Date
Sat Jul 05 2025
Journal Name
Journal Of Baghdad College Of Dentistry
The effect of adding single walled carbon nanotube with different concentrations on mechanical properties of heat cure acrylic denture base material
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Background: The most widely used material for fabrication of denture base is poly methyl methacrylate, despite its popularity, the main problems associated with it as a denture base material are poor strength particularly under fatigue failure inside the patient mouth, impact failure outside the patient mouth, which are the main causes for fracture of denture, several studies was done to increase mechanical properties of denture base. The present study was conducted to evaluate and compare the effect of addition single walled carbon nanotubes in different concentrations to polymethyl methacrylate on some mechanical properties (surface hardness, surface roughness, impact strength and transverse strength). Materials and methods: Forty eight

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Publication Date
Fri Sep 22 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Air Gap Effect on the Properties of Unsaturated Symmitrical Double Polepiece Lenses
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The  preferable  design  for  unsaturated  symmetrical  spherical

double-pole  piece electron  lens required good focal properties,  and in this  present  study  investigate  effect  of  air  gap  wide  (S)  on  the properties  of  the  projector  lens  specialized  the  minimum  projector

focal  length  1Fr) .     and  the  properties  of  the  axial  magnetic  field

\            lnlll

distribution:(the   maximum

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Publication Date
Sat Jan 01 2022
Journal Name
Indonesian Journal Of Electrical Engineering And Computer Science (ijeecs)
A new smart approach of an efficient energy consumption management by using a machine-learning technique
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Many consumers of electric power have excesses in their electric power consumptions that exceed the permissible limit by the electrical power distribution stations, and then we proposed a validation approach that works intelligently by applying machine learning (ML) technology to teach electrical consumers how to properly consume without wasting energy expended. The validation approach is one of a large combination of intelligent processes related to energy consumption which is called the efficient energy consumption management (EECM) approaches, and it connected with the internet of things (IoT) technology to be linked to Google Firebase Cloud where a utility center used to check whether the consumption of the efficient energy is s

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Publication Date
Sat Jul 05 2025
Journal Name
Journal Of Baghdad College Of Dentistry
An Evaluation of the Efficacy of Different Gingival Retraction Materials on the Gingival Tissue Displacement (A Comparative In Vivo Study)
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Background: An accurate adaptation of the crown to the finish line is essential to minimize cement dissolution and to preserve periodontium in fixed partial denture cases. An accurate adaptation of crown is possible only when preparation details are captured adequately in the impression and transferred to cast. For these reasons, gingival displacement is necessary to capture subgingival preparation details.The aim of the present study is to measure in vivo the horizontal displacement of the gingival sulcus obtained by using three new cordless retraction materials (Magic Foam Cord®, Racegel and Astringent Retraction Paste) in comparison to medicated retraction cord. Materials and method: Thirty-two patients requiring porcelain fused to me

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Publication Date
Tue Nov 01 2016
Journal Name
Materials Science Forum
Study the Effect of Liquid Layer Level on the Formation of Zinc Oxide Nanoparticles Synthesized by Liquid-Phase Pulsed Laser Ablation
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This work is focused on studying the effect of liquid layer level (height above a target material) on zinc oxide nanoparticles (ZnO and ZnO2) production using liquid-phase pulsed laser ablation (LP-PLA) technique. A plate of Zn metal inside different heights of an aqueous environment of cetyl trimethyl ammonium bromide (CTAB) with molarity (10-3 M) was irradiated with femtosecond pulses. The effect of liquid layer height on the optical properties and structure of ZnO was studied and characterized through UV-visible absorption test at three peaks at 213 nm, 216 nm and 218 nm for three liquid heights 4, 6 and 8 mm respectively. The obtained results of UV–visible spectra test show a blue shift accomp

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Publication Date
Wed May 29 2019
Journal Name
Indian Journal Of Physics
Effect of lasing energy on the structure and optical and gas sensing properties of chromium oxide thin films
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