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.
Abstract
Purpose: The research attempts to Stand on the reality of the effective application of of strategic information systems in telecommunications companies in the Kurdistan Region, and what is the amount of the impact of such systems on promoting of Strategic Intelligence.
Design/Methodology/Approach: The Applied method has been used, In order to achieve the objectives of the research has been the development of a questionnaire prepared for this purpose and then distributed to (11) Company of Iraqi communications operating in Kurdistan Region companies, it has been used questionnaire to collect data in order to develop
... Show MoreThis research examines the impact of cornering on the aerodynamic forces and stability of a Nissan Versa (Almera) passenger sedan car by introducing novel modifications. These modifications included single inverted wings with end plates as a front spoiler, double‐element inverted wings with end plates as a rear spoiler, and incorporating the ground as a diffuser under the car trunk. The goal is to enhance the performance and stability of conventional passenger cars. To ensure the accuracy of the numerical data, the study utilized multiple methodologies to model the turbulence model, ultimately selecting the most suitable option. This involved comparing numerical data with wind tunnel experimental d
This research aims to introduce the general tax on sales in gordan and the most important concepts related to this type of taxes and identify the most on characteristics and stand on its role in supplying the general budget of the necessary fundig to cover the over head of the state and the factorsinfluencing it and whether such a tax has been able to chieve the desired goals.including in contribute to an important and growing role in puplic revenues or not to be able to achieve these goals through the use of descriptive and analytical technique based on the data and information relevant.wasreached some conclusion and recommendations was most important is that the general sales tax comes in
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The aim of the current study lies in showing and demonstrating the effect of the independent variable of organizational integrity with its dimensions represented by (organizational optimism, organizational trust, organizational integrity, organizational sympathy) on the dependent variable of strategic drifts through its dimensions represented by (organizational culture, leadership, innovation, strategic planning) .The analytical descriptive approach has been adopted and the questionnaire has been used as a tool to obtain data and information from the sample of (57) people who are at the administrative levels (seni
... Show MoreInvestment in high education is considered to be most important factors of production which the return an individual and social than economic returns found by searching the growing problem of unemployment, especially among youth graduates, where the unemployment rate in 2010 (50%) of these high rates have led to increased migration of scientific minds graduate recently, "to search for job opportunities outside Iraq for not hiring functions and this is in vain" clear "in the human and financial resources lead to structural imbalances in the Iraqi economy. When calculating the correlation coefficient between the graduates and the unemployment rate where it reached (0.21) emerged from the results of
... Show MoreMonitoring water quality in hemodialysis systems is extremely important to maintain adequate quality services for patients suffering from kidney failure. This work aims to examine and evaluate bacteriological characteristics and endotoxin contamination levels in hemodialysis water produced in dialysis centers. Forty‐eight water samples were collected and analyzed from four major hospitals in Baghdad for one year to evaluate seasonal effects. The analysis included the determination of total heterotrophic bacteria using the pour plate method, identification of bacterial isolate using the Vitek2 compact instrument, and the determination of endotoxins levels using Limulus ameboc
Soil is a crucial component of environment. Total soil analysis may give information about possible enrichment of the soil with heavy metals. Heavy metals, potentially contaminate soils, may have been dumped on the ground. chromium, nickel and cadmium,
The objective of this study is to attempt to provide a quantitative analysis to the causes of unemployment in Iraq and its mechanisms of generation, as well as a review of the most important types of both visible and invisible unemployment, and an attempt to measure the disguised unemployment and analyze the causes. The problem of the research lies in the fact that the Iraqi Economy has been suffered for a long time although its characterized by abundant physical and natural resources, from the existence of the phenomenon of unemployment in the previous two types. Causing a lot of economic problems, represented by the great waste of resources and
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This research aims to determine the role of the quality of higher education in achieving organizational excellence at the universities of Baghdad and Al-Nahren, was based on research on the main hypothesis is:First:- There is correlation and between the quality of higher education dimensions (continuous improvement, measurement and analysis, the culture of the organization, optimal use of resources , customer satisfaction) and organizational excellence dimensions (strategic planning, focusing on the market and the customer, information and analysis, the effectiveness of operations, processes and resources), Second:- Second, there is the impact of relationship sig
... Show MoreBusiness Ethics play a major role in explaining the behavior of those interested in the management of tourism enterprises in the field of management gains, which sometimes turn to manipulation in the specification of the service of tourism and influence in the technical characteristics at the expense of the brand and market share, as well as misleading beneficiaries about the fact that the performance of the service of tourism, may depend activities tourist dramatically when submitting and sharing various services on the types of mutual relations the framework for moral distinct, in interaction or direct contact between producers of tourism services and tourists or their beneficiaries, in order to provide comfort and recreation a
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