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The Experimental Assessment of R134a and Its Lower GWP Alternative R1234yf in an Automobile Air Conditioning System
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Reducing global warming potential (GWP) of refrigerants is needed to the decrease of ozone-depleting of refrigeration systems leakages. Refrigerant R1234yf is now used to substitute R134a inside mobile air conditioning systems. Thermodynamic properties of R1234yf are similar to R134a. Also, it has a very low GWP of 4, compared to 1430 for R134a, making it a proper choice for future automobile refrigerants. The purpose of this research is to represent the main operating and performance differences between R1234yf and R134a. Experimental analysis was carried out on the automotive air conditioning system (AACS) with 3 kW nominal capacity, to test and compare the performance of R134a with R1234yf. Experiments were accomplished for both refrigerants in almost the same working conditions and procedure with a range of ambient temperature varied from 26oC to 50oC. Parameters studied were ambient temperature, type of refrigerant in the system at compressor speed 1450 rpm, and internal thermal loads of passenger room. The performance characteristics of the system, including COP and cooling capacity, were studied by changing different parameters. The results show that COP of R134a is higher than R1234yf by 12.6%, while the refrigeration effect of R134a is higher than R1234yf by 25%. This shows that R1234yf is a suitable and good candidate for drop-in replacement of R134a in AACS.

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Publication Date
Thu Apr 01 2021
Journal Name
Journal Of Bridge Engineering
Experimental Investigation of Curved-Soffit RC Bridge Girders Strengthened in Flexure Using CFRP Composites
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Publication Date
Fri Jul 21 2023
Journal Name
Journal Of Engineering
Experimental Study of Natural Convection Heat Transfer in Confined Porous Media Heated From Side
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Transient three-dimensional natural convection heat transfer due to the influences of heating from one side of an enclosure filled with a saturated porous media, whereas the opposite side is maintained at a constant cold temperature, and the other four sides are adiabatic, were investigated in the present work experimentally. Silica sand was used as a porous media saturated with distilled water filled in a cubic enclosure heated from the side,using six electrical controlled heaters, at constant temperatures of (60, 70, 80, 90, and 100oC). The inverse side cooled at a constant temperature of (24oC) using an aluminum heat exchanger, consisted of 15 channels feeded with constant temperature water. Eighty thermocouples were used to control t

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Publication Date
Mon Dec 01 2025
Journal Name
Results In Engineering
Experimental investigation of a solar HDH desalination unit with Pottery tubes in babylon province
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The Humidification-Dehumidification (HDH) desalination technique offers a viable solution for providing freshwater to populations in water-scarce, remote areas. This study experimentally investigates a novel humidifying method by cross airflow over water-wetted pottery tubes, which function as a humidifier, incorporating a thermoelectric cooler to condense water vapor for freshwater production. To optimize freshwater production and thermal efficiency, meticulous design of these components and appropriate operational parameters are selected. Experiments were performed in three environments with differing temperatures and relative humidity levels, while air velocity varied from 1.02 to 1.89 m/s, and thermoelectric cooler voltage ranged from 6

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Publication Date
Thu Jun 01 2017
Journal Name
Journal Of Economics And Administrative Sciences
Efficiency of public investment spending and its impact on economic growth in Iraq For the period 2003- 2013
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Occupy public investment spending, a great deal of attention since the thirties of the last century, to play important role in economic and social development process and therefore most of the countries are trying different degree of economic development to the completion of the largest amount of public investment, especially in infrastructure, which is one of the pillars essential to economic development, and in order to maximize utilization of the completion of public investment should focus on achieving efficiency in completion.
    The current reality of public projects in Iraq, indicating the absence of several key characteristics that must be provided if these proje

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Publication Date
Mon Apr 01 2019
Journal Name
Journal Of Educational And Psychological Researches
Violence Efficacy of Parents in Consolidating the Positive Values and Its Relation with Socialization among Intermediated School Students
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The research aims to identify the effectiveness of violence by parents in the consolidation of positive values among students. Additionally, the research aims to identify the differences in violence levels among students regarding their gender (males & females). The study was limited to the intermediate school students in Baghdad city / Karkh2 for the academic year 2017-2018. The results showed that males are more violent than females do and that discrimination led to experience violence more than other methods. The researcher recommends the need to create a positive atmosphere within the school context. For future studies, the researcher suggests conducting a study to identify the violence and its relation to some personal character

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Publication Date
Sun Dec 01 2019
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
Adoption of ISSAI 5600 (Peer Review) by SAIs and its Impact on its Performance
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    تعد مراجعة النظير واحدة من الأســاليب الحديثة فــي مجال الرقابة والتدقيق ونشــأة كأداة لقياس مــدى فاعليــة الرقابــة علــى الجــودة هو لبنة أساسية في إدارة الجودة الشاملة ووسيلة لتحســين أدوات الرقابــة المعمول بها، وللتحقق من مدى الانسجام بين المعايير الدولية للأجهزة العليا للرقابة المالية والمحاسبة والاجراءات المعمول بها من قبل الاجهزة العليا للرقابة وعليه فأن مراجعة النظير أداة تستخدم ف

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Publication Date
Sat Sep 30 2023
Journal Name
Iraqi Geological Journal
Radiological Effects Assessment in East Baghdad Oil Field, Southern Area
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Radiological assessment for the East Baghdad oilfield-southern part was conducted in the current study. 10 samples (scale, soil, sludge, water, and oil) from the different stages of oil production were collected. 232Th, 226Ra, and 40K in the samples were analyzed with 40% efficiency for Gamma spectrometry. system based on HPGe. The findings indicated that the examined sites exhibit comparatively lower levels of NORM contamination, in contrast to other global oilfields. Nevertheless, certain areas, particularly those within separation stages, demonstrate relatively elevated NORM concentrations exceeding the global average in soil and sludge. The maximum value of 226Ra, 232Th, was found in sludge sample the findings indicated that ove

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Publication Date
Wed Jan 01 2025
Journal Name
Modern Sport
Vertical Resistance and Its Relationship with Speed-Strength and Biomechanical Variables During the Takeoff Phase and the Performance of Selected Activities in Individual and Team Sports
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Jumping ability is a fundamental variable in many sports, as its execution requires an integration of muscular strength Q1 and certain biomechanical variables. This is particularly evident in gymnastics jumping events and jump shots in ball games, both of which rely on a high level of vertical resistance. Vertical resistance serves as an indicator of an athlete’s ability to overcome their body weight while counteracting gravitational force to achieve optimal performance. As such, it is considered one of the key factors in movements that demand explosive power and speed. The researchers believe that despite the significant relationship between vertical resistance, speed-strength of the arms and legs, and certain biomechanical varia

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Publication Date
Mon Aug 21 2023
Journal Name
Communications In Mathematical Biology And Neuroscience
New techniques to estimate the solution of autonomous system
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This research aims to solve the nonlinear model formulated in a system of differential equations with an initial value problem (IVP) represented in COVID-19 mathematical epidemiology model as an application using new approach: Approximate Shrunken are proposed to solve such model under investigation, which combines classic numerical method and numerical simulation techniques in an effective statistical form which is shrunken estimation formula. Two numerical simulation methods are used firstly to solve this model: Mean Monte Carlo Runge-Kutta and Mean Latin Hypercube Runge-Kutta Methods. Then two approximate simulation methods are proposed to solve the current study. The results of the proposed approximate shrunken methods and the numerical

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Publication Date
Sun Dec 01 2013
Journal Name
Political Sciences Journal
Yemeni political system: a study of the internal variables
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النظام السياسي اليمني : دراسة في المتغيرات الداخلية

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