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.
Autorías: Suhair Meteab Munaf, Ali Abdulateef Ali, Mohannad Salman Dawood. Localización: Revista iberoamericana de psicología del ejercicio y el deporte. Nº. 4, 2022. Artículo de Revista en Dialnet.
This research aims to apply the Performance Focused Activity Based Costing System in the offices of scientific and advisory services at the University of Technology for the purpose of measuring the cost of services provided by these offices in order to reduce costs. To test the hypothesis of the research, the research was applied in the consulting offices of the University of Technology through the financial statements for the year ending 12/31/2017 of the Scientific and Consulting Services Office of the University of Technology, because the data of these years were issued and audited by the Federal Office of Financial Supervision.
A number of
... Show MoreBackground: The microorganisms can impend the life of health care professional and particularly the dental practitioners. They can be transmitted by different ways like airborne and droplet transmission. The current study was carried out to identify whether the arch wires that received from the manufactures are free from microbial contamination and to determine the bacterial species attached to the arch wires. Materials and Methods: This study involved eighty samples, consisted of two types of arch wires (nitinol and stainless-steel) from four companies (3M, G&H, Jiscop, OrthoTechnology). These wires inserted in a plane tube that contains 10 -ml of (Tris [tris(hydroxymethyl)aminomethane] and EDTA (ethylenediaminetetraacetic acid) tri
... Show MoreAbstract A descriptive study to assess of factors that contributes of lung cancer. The study was carried out in Specialized Surgery teaching hospital, Ibin Al- Beetar hospital and Ibin Al- Nafees hospital for the period From January 2004 to October 2004 .The study aimed to assess the factors that contribute to lung cancer and to identify the relationship between the variables of the study with lung cancer. A purposive (non-probability) sample of (70) patients with lung cancer was selected for the study. An assessment form was employed for the purpose of the study. Test- retest reliability was employed through
The present study took up the different ways to cultivate the species Epipremnum aureum by two habitat water and soil and comber the anatomical features of the root, stem, and leaf. The results showed amazing significant anatomical features to the ecosystem. The root and stem anatomy showing decrease in all characters that studied but the leaf anatomy showing increase of palisade, spongy tissue thickness, midrib thickness, number of vessels in the xylem also the long and width of stomata of the soilless plants than soil ones. The upper epidermis empty from the stomata for the two treatment and the stoma diffuse in the lower epidermis, the type of it paracytic type. Also the total of flavonoids in the plant that were growth in soil reached 1
... Show MoreThe aim of the present study is to formulate floating effervescent microsponge tablet of the narrow absorption window drug, Baclofen (BFN) for controlling drug release and thereby decrease the side effect of the drug. The microsponges of BFN were prepared by non-aqueous emulsion solvent diffusion method (oil in oil emulsion method). The effects of drug: polymer ratio, stirring time and type of Eudragit polymer on the physical characteristics of microsponges were investigated and characterized for production yield, loading efficiency, particle size, surface morphology, and in vitro drug release from microsponges. The selected microsponge formula was incorporated into the floating effervescent gastro-retentive tablet. The prepared fl
... Show MoreNon-additive measures and corresponding integrals originally have been introduced by Choquet in 1953 (1) and independently defined by Sugeno in 1974 (2) in order to extend the classical measure by replacing the additivity property to non-additive property. An important feature of non –additive measures and fuzzy integrals is that they can represent the importance of individual information sources and interactions among them. There are many applications of non-additive measures and fuzzy integrals such as image processing, multi-criteria decision making, information fusion, classification, and pattern recognition. This paper presents a mathematical model for discussing an application of non-additive measures and corresp
... Show MoreInternal control is system,defined and implemented under its responsibility , which aims to ensure that; laws and regulations are complied with; the instructions and directional guidelines fixed by Executive Management or the Management Borad are applied; the company internal processes are functioning correctlly , particularly those implicating the security of its assets; Financial Information is reliable; and generally contributes to the control over its activities , to the efficiency of its operation and to the efficient utilisation of its Resources. By helping to anticipate and control the risks involved in not meeting the objectives the company has set for itself, the internal control system plays akey role in conducting & monito
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