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.
lar water heating systems with heat pipes of three diameter groups of 16, 22 and 28.5 mm. The first and third groups had evaporator lengths of 1150, 1300 and 1550 mm. The second group had an additional length of 1800 mm. all heat pipes were of fixed condenser length of 200 mm. Ethanol at 50% fill charge ratio of the evaporator volume was used as the heat pipes working fluid. Each heat pipe condenser section was inserted in a storage tank and the evaporator section inserted into an evacuated glass tube of the Owens- Illinois type. The combined heat pipe and evacuated glass tube form an active solar collector of a unique design.
The resulting ten solar water heating systems were tested outdoors under the meteorological conditions of Bag
The problem of research was to identify after the use of cost technology based on specifications in the validity of determining and measuring the costs of the implementation of contracting, by applying to al-Mansour General Construction Contracting Company as an appropriate alternative to the traditional costing system currently adopted, which is characterized by many shortcomings and weaknesses Which has been reflected in the validity and integrity of the calculations. To solve this problem, the research was based on the premise that: (The application of cost technology based on specifications will result in calculating the cost of the product according to the specification required by the customer, to meet his wishes properly and witho
... Show MoreThree hundred Iraqi people participated in demographic and attitudes study about red and white meat consumption. The mean age of the participants was 50 SD ± 11 years (mean 30-72); 51% were females and 49% males, mostly in forties who lived ≥ 5 years in Baghdad. The results showed that 80% of individuals prefer red meat. A 90% of people prefer fresh meat compared to frozen and processed meat. A 60% of people buy meat from popular markets. Nearly 87% of respondents believe the improving of livestock sector is essential and 80% of people confirmed there are obstacles to development this sector. An 80% of participates thought the reasons of the high prices of local fresh meat is the lack of plann
... Show MoreInsurance actions has become a task of the vital foundations on which the international economy depends, where its presence helped in the development of economic resources in which human resource is considered the most important of these resources. Insurance companies play the biggest role in protecting this resource and minimizing the impact of the dangers that verify this condition.Human has worked hard to get rid of the dangers and its harm, and to devise many ways to prevent them. A risk management is considered within human’s creations in order to create a society with fewer negative risks impacts.
On this basis, th
... Show MoreTransparency considered being one of the modern administrational terms which started to be largely used in the last period, because of its political, economical, social and cultural dimensions. As well as, its administrational dimension that helps to create a work environment marked by order and flawless from wrong practices and Transparency provides credibility to the sides that pursue it in their practices, till it became a mean of distinction. The choice of the subject of the research ((Transparency and its effect on Level of Job satisfactions of Workers in General Insurance company)), which aims to measure the effect of Transparency in Level of Job satisfactions of Workers in Insurance company. Came in the time when many countries te
... Show MoreThe present study was performed to spotlight the potential role of soil bacteria in the Al-Rumaila oil field as a bioindicator of heavy metals pollution. For this purpose, nine soil samples were collected from different sites, with 20cm depth, to assess the pollution status depending on the total and available concentrations of heavy metals. The result indicates pollution of the studied soils with the following metals: Cd, Cu, Fe, Zn, and Pb. The mean of total concentration for all studied metals was higher than the allowed maximum limit based on the international limit:(3.394, 3.994, 39.993, 8844.979,150.372, and 103.347 µg/g), respectively. While measuring the total Metal concentration is important in determining the de
... Show MoreThe tax revenues achieved through projects of transition to private sector are regarded as an important source for using in achieving political, economic and social objectives. Since Iraq is heading towards free market economy, new strategies should be adopted to reform the taxation system from by a qualified taxation management office and to activate the taxation policy and to reconsider legislation in relation to the aware of the legible to the importance of disclosure of their taxable real income in order to arrive at contribution of privatization in the taxation revenues for the important role effect on economic activities. In the light of the above, the research is based upon a hypothesis which stipulates that privatization contribu
... Show MoreThe Islamic Banks including the Iraqi ones are often resorted to support their governance frameworks in order to improve its competitiveness in their communities. Where, those banks are looking for activities that enhance their governance; one of these activities is Shariah Audit that provided the auditing capabilities to face of developmental challenges and increase competitiveness. Therefore, the content of this paper, discusses know-how to use the Shariah Audit and its references in support of the Shariah Governance in the Iraqi Isla
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