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The Experimental Assessment of R134a and Its Lower GWP Alternative R1234yf in an Automobile Air Conditioning System

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
Sat Jan 01 2022
Journal Name
Materials Today: Proceedings
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Publication Date
Thu Nov 30 2023
Journal Name
Iraqi Journal Of Science
Novel Definitions of α-Fractional Integral and Derivative of the Functions

     An α-fractional integral and derivative of real function have been introduced in new definitions and then, they compared with the existing definitions. According to the properties of these definitions, the formulas demonstrate that they are most significant and suitable in fractional integrals and derivatives. The definitions of α-fractional derivative and integral coincide with the existing definitions for the polynomials for 0 ≤ α < 1. Furthermore, if α = 1, the proposed definitions and the usual definition of integer derivative and integral are identical. Some of the properties of the new definitions are discussed and proved, as well, we have introduced some applications in the α- fractional derivatives and integral

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Publication Date
Fri Jan 26 2024
Journal Name
Iraqi Journal Of Science
Vascularization of Leaves and Stem of the Species Galium Aparine L.

The research is an anatomical study for the stem and leaves of Galium aparine
L.The nodal anatomy was carefully investigated ,by the cross sections at the node
provide that what was called "cyclic arrangement" of leaves is in fact includes just
two opposite leaves which take their vascularization from the stele by two leaf
traces.The rest four leaf- like appendages on the node are stipules ,and take their
vascularization from the vascular ring which bond the two opposite leaves,and
refered for some morphological and anatomical characters of the plant species in this
work.

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Publication Date
Mon Mar 08 2021
Journal Name
Baghdad Science Journal
Some properties of the Osvillatory and nonoscillatory solutions of second order

in this paper sufficient conditions of oscillation of all of nonlinear second order neutral differential eqiation and sifficient conditions for nonoscillatory soloitions to onverage to zero are obtained

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Publication Date
Sun Mar 06 2011
Journal Name
Baghdad Science Journal
Isochronal Studies of the Structural and Electrical Properties of CdTe Films

The paper reports the influence of annealing temperature under vacuum for one hour on the some structural and electrical properties of p-type CdTe thin films were grown at room temperature under high vacuum by using thermal evaporation technique with a mean thickness about 600nm. X-ray diffraction analysis confirms the formation of CdTe cubic phase at all annealing temperature. From investigated the electrical properties of CdTe thin films, the electrical conductivity, the majority carrier concentration, and the Hall mobility were found increase with increasing annealing temperatures.

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Publication Date
Sun Feb 03 2019
Journal Name
Journal Of The College Of Education For Women
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Publication Date
Sat Oct 01 2022
Journal Name
Al–bahith Al–a'alami
Trends of journalists and consumers about the phenomenon of food fraud

Food comes after air and water in terms of importance in the survival of human beings, In addition, it is the support and strength of health and support, if lost or destroyed man would die or get sick and become a heavy burden on himself and his society. Food, like other sources of life, is subject to various risks and corruption comes from countless sources. Among these dangers is the result of spontaneousness, lack of knowledge or compulsion due to the interaction of variables beyond the will of the producer and the consumer, such as pollution of water, air and environment and their reflection on food consumed by people. However, we can’t deny that some reasons of corruption are intentional and resulting from a planning in advance in

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Publication Date
Thu Mar 01 2012
Journal Name
Journal Of Economics And Administrative Sciences
Practices of managers and their impact on the contributions of personnel

This research was based on two pillars. The first is a comparison between of research done and the result of a particular  variable of research  indebendently in the united state, and second, knowledge and determine the effect of managers  practices on the contributions of personnel. The manager and staff are considered to be the most important elements in the organization and all of them  have a duty towards the others which governed by the relationship rules of procedure of the ministry researched, on the one  hand  and the interests of the organization and hence employees , whether executives  or employees within management formations that the availability of an acceptable level of good pract

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Publication Date
Wed Jun 27 2018
Journal Name
Journal Of The College Of Education For Women
Kinds of unknowns and government linkages -empirical study of the application

It is no secret that the prophets speech is of great importance, as the second source of Islamic legislation after the Holy Quran, and as such we must reserve and verify the authenticity of the novel and the narrators seizure, and all the conditions laid down by the scholars.

The subject of our research here concerns part of this verification, which is the unknown, the subject of the unknown hadith is considered a matter of great interest by the modernists because it relates to the validity of the novel and the narrators, and the methods of the modernists varied in terms of the reasons for this weakness, the fool never entertained them by the reckless narrative.

I chose the subject of my research the types of Mahjail and

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Publication Date
Wed Jan 10 2024
Journal Name
The American Journal Of Interdisciplinary Innovation And