Papers by Keyword: Inert Gas

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Authors: Nanik Indayaningsih, Dedi Priadi, Anne Zulfia Syahrial, Suprapedi
Abstract: The main compound of natural fibers is a hydrocarbon. The heating of hydrocarbon in inert gas produces charcoal or carbon. Carbon materials are widely used for several purposes depending on the physical and electric properties, for example for hydrogen storage, conductive or reinforced plastics, catalyst supports, batteries and fuel cells. The main raw material of Gas diffusion Layer (GDL) of the Proton Exchange Membrane Fuel Cell (PEMFC) is a carbon. The properties of GDL are porous and electron-conductive material, because of the function of GDL is to distribute the gas as fuel and electricity conductors. This study aims to analyze the carbon fibers made from coconut fibers for the application of GDL materials. The carbon fiber was made using pyrolysis process in the inert gas (nitrogen) at a certain temperature according to the analysis of Differential Thermal Analysis (DTA) 3000C, 4000C, 5000C, 6000C, and 9000C. The crystalstructure, carbon content, powder density and morphology of carbon fibers were observed using X-Ray Diffraction (XRD), fixed carbon according to ASTM D 1762-64, Archimedes method (BS 19202 Part 1A), and Scanning Electron Microscope (SEM), respectively. The results showed that the structure of carbon was amorphous, and content of 51% ̶ 71%, powder density of 0.42g/cm3 ̶ 0.71g/cm3. The morphology having many parallel hollows like a tube that are close to each other with diameters of 2m ̶ 10m, and in the wall of tube there are some porous with sizes around 1m. According to this analysis, the coconut carbon fiber enables to be applied as candidate for a basic material of GDL.
Authors: Hyun Chul Park, Ju Haeng Lee, Il Ho Kim, Muhammad Sajjad, Kwang Ho Ahn, Kwang Soo Kim
Abstract: The purpose of this study was to investigate the sound proof properties of the double layer acryl plates with various packing materials inside. The acryl plates were filled with vacuum pressure ranged from-20 to-80 kPa, fumed silica as nanoporous materials, and HCFC (hydrochloro-fluorocarbon) as inert gas. The sound pressure level passed though panels was measured to compare soundproof performance. All other panel showed better performance from 500-1000 Hz than air layer panel. For the vacuum layer panel, panel with-80 kPa showed the best performance among other vacuum layer panel throughout all range of frequency. It is found that the more nanomaterial filled in panel, the lower sound proof performance. When it comes to panel filled with inert gas, the sound proof performance improved when it has greater pressure of gas.
Authors: Nurkholis Hamidi, Nasrul Ilminnafik
Abstract: In this study, the inert effects of CO2 on the flammability limit and flame propagation of LPG has been investigated experimentally. The observation was done using cubic combustion bomb with the dimension of 500 mm x 200 mm x 10 mm. The results showed that the lower flammability limit (LFL) of LPG-Air mixtures is found to be 2.7% (by volume) and upper flammability limit (UFL) is 8.6% (by volume) with upward propagation of flame. The CO2 dilution effects on the flammability limits have been explored, the limits of flammability was narrowed by adding CO2 and propagation flame was reduced accordingly. The results indicated that to formulate an inflammable refrigerant mixture, using CO2, with substantial hydrocarbon content is not possible.
Authors: Maryam Yarveicy, Ali Mohammad Hadian
Abstract: Al-Cu joints have been widely used in electronic and heat exchanger industries due to their excellent electrical and thermal conductivity. Meanwhile, the use of Al in the Al-Cu joints can result in lower weight and cost of the final structure. The purpose of the current study is to join Al to Cu by furnace brazing using ultrafine Al-Si powder. To study the microstructure of the join area, the brazing tests were conducted in the range of 590 to 610°C for 5 to 15 minutes under inert atmosphere. The microstructure of Al/Cu joints was studied by scanning electron microscopy (SEM). The elemental analysis was conducted using an energy dispersive spectrometry (EDS) system. Experimental results show that two kinds of intermetallic compounds (IMCs) mainly Cu3Al2 and CuAl2 phases are formed near the interface of copper and in the braze layer region. The bulky prismatic structure which is formed on the side of Al substrate was found to be α-Al+CuAl2 eutectic.
Authors: Zai Liang Chen, Tian Qi Huang
Abstract: In this paper, a mathematical model of the process of bubble dissolution is built .In this model , the DeWitt constitutive equation reflect is used, it can reflect the performance of non-Newtonian fluid and calculation is relatively simple. The model was solved by finite difference method, and the results show that the initial bubble radius and the outside pressure is the main factor affecting the bubble dissolution.
Authors: Jia Guo, Yu Shu Xie, Jun Fang, Chen Zheng, Li Feng Xie
Abstract: In this paper, dynamic responses on radiation energy intensity of inert gas are simulated in use of software ANSYS / LS-DYNA when inert gas is stimulated by explosion of solid propellants to emit visible light. The effects for the visible light energy intensity emitted by inert gas are analyzed on different initial pressures in the inert gas container and with different igniting methods by propellants. Simulation results show that, the bigger initial pressure in the container is, the higher the peak value of visible light energy density intensity is and the better the effect of the visible light emitted by inert gas is. There are fewer effects on the peak value of visible light energy intensity emitted by inert gas with different igniting methods. However, it has an impact on the stability when inert gas emitting visible light. The stability is the best when central point of the propellant column is ignited.
Authors: Erika Ardelean, Marius Ardelean, Teodor Hepuț, Florin Drăgoi
Abstract: The existence of gases in the solid metals (hydrogen and nitrogen) assumes the presence of these gases in metals even before solidification, respectively in the elaboration, secondary treatment and casting phases. Usually, great amounts of gases dissolved in steels can be detected, between 3.5-8ppm for hydrogen and 0.02-0.03% for nitrogen, respectively. There are also cases when the purpose is to alloy with nitrogen, this being the case of austenitic stainless steels where the nitrogen content can reach 0.5% using ferrochromium or ferromanganese alloyed with nitrogen in 3-5.5 %. The main method of removing these gases is bubbling with inert gases and /or treating the steel in a vacuum facility. The paper presents a study regarding increasing the removal efficiency of nitrogen from the liquid steel by changing the bubbling parameters (flow, pressure, duration) but also the basicity of the refining slag. The equations of the regression surface and the identified fields are of a real help for the technologists, allowing quick decisions but they are also important for the quality of the metallic products [.
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