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.
Oilwell cementing operations are crucial for drilling and completion, preserving the well's productive life. However, weak and permeable formations pose a high risk of cement slurry loss, leading to failure. Lightweight cement, like foamed cement, is used to avoid these difficulties. This study is focused on creating a range of foamed slurry densities and examining the effect of gas concentration on their rheological properties. The foaming agent and foam stabilizer are tested, and the optimal concentration is determined to be 2% and 0.12%, respectively, by the weight of the cement.
Furthermore, the construction of samples of foam cement with different densities (0.8, 1.0, 1.2, 1.4, and 1.6) g/cc is performed to f
... Show MoreThe research aims to how to deal with certain situation to ensure the continuous competitive excellence of business market under the situation of covid-19, especially how to deal with major challenges, identifying the capabilities of tourism industry, investigating the ability of tourism agencies to resist the dynamic change of both internal as well as external environment to ensure their sustainability.
The important here as the paper notice, is how to be efficient and trying to find solutions in order to grow and survive through choosing certain strategies that aligned the critical issues.
Thus to achieve this level, many scenarios planed that could adopt in case of such pande
... Show MoreCutaneous leishmaniasis (CL) is a widespread, yet often overlooked, parasitic disease caused by the Leishmania protozoan, which is prevalent in numerous countries, including Iraq. This condition is marked by the appearance of skin lesions on various exposed areas of the body. In most old-world regions, sodium stibogluconate (SSG) is the classical widely used drug to treat CL. The progression of skin ulceration is controlled by different inflammatory modulators including cytokines and enzymes. In this study, the possible role of the enzyme Matrix metalloproteinase9 (MMP-9) and its inhibitor Metallopeptidase inhibitor-1 (TIMP-1) as immunological markers was evaluated in CL patients suffering from cutaneous leishmaniasis before and aft
... Show MoreA novel analytical method is developed for the determination of azithromycin. The method utilizes continuous flow injection analysis to enhance the chemiluminescence system of luminol, H2O2, and Cr(III). The method demonstrated a linear dynamic range of 0.001–100 mmol L-1 with a high correlation coefficient (r) of 0.9978, and 0.001–150 mmol L-1 with a correlation coefficient (r) of 0.9769 for the chemiluminescence emission versus azithromycin concentration. The limit of detection (L.O.D.) of the method was found to be 18.725 ng.50 µL−1 based on the stepwise dilution method for the lowest concentration within the linear dynamic range of the calibration graph. The relative standard deviation (R.S.D. %) for n = 6 was less than 1.2%
... Show MoreDeconstructionism opened the door wide to multiple readings and restore the reader his authority that he lost in the modernism, thus became more able to decipher the plastic discourse through reconstruction according to what he wants or what the plastic discourse gives him of possibilities beyond consumerism and thus the author has been canceled. The problem of the current research is limited to the following question: does deconstructionism in postmodern arts have a role in teaching the artistic tasting for the learner? The aim of the current research is to reveal the deconstruction work mechanisms in postmodern arts and their role in teaching the artistic tasting for the learner. As for the theoretical framework, the first section focu
... Show MoreThe main purpose of the research is to demonstrate the importance of the insurance sector in the economy through its role in providing security for all economic sectors and thus stimulating the gross domestic product and reducing dependence on the output of the oil sector, which may expose the Iraqi economy to several problems and imbalances, I have found that there is a great weakness in the role of the insurance sector in Iraq at the level of government, companies and individuals, and the reason for this is the lack of policies supporting the insurance sector and the lack of work in the strategy of economic diversity and the decrease of security awareness by individuals so became Developing the sector to ensure the urgent need
... Show MoreThe auditor has a role in allocating joint costs in the gas industry, and the auditor's procedures are considered as systematic critical examination, analysis and evaluation of everything related to costs in general and joint costs in the gas industry in particular, with the aim of controlling the joint costs of gas industry products, and knowing the share of the cost of each product from the total industry costs Gas products reflect the reality of the company's performance by discovering weaknesses, defects and any errors, to ensure increased effectiveness and efficiency of the parties concerned with auditing them and imposing control and control over the company's resources, as well as
... Show MoreAbstract : This research is a field study of international cities that hosted various events of which (Sports, Exhibitions, Scientific, Cultural) and other events, these positive impacts on the city driven by such hosts were identified. The research goal was to support hosting events to improve the hostess city and to draw future plans for further developments and to invest event’s hosting to strengthen the city’s value according to a strategic vision that looks for the future the most important conclusions are Entering events hosting is a part of urban development strategies and The most important recommendations are coordination between hosting event activities and its facilities with the infrastructure structure of the host city, its
... Show MoreThe current study investigates the impact of virtual reality technology on industrial product design. The focus of this study is on the development of industrial products that utilize virtual reality technology, specifically examining the effects of this technology on the visual and design aspects of these products. The aim is to continuously improve the functionality of industrial products and enhance the user experience through virtual reality integration.
The first chapter of the study addresses the research problem, which centers around exploring the technological influence of virtual reality used in industrial products and understanding the functionalities it brings to the design process. Virtual reality technology facilitates th