Flame Spread Along PE-Insulated Wire in Sub-Atmospheric Pressure Enclosure

2007 ◽  
Author(s):  
Yuji Nakamura ◽  
Nobuko Yoshimura ◽  
Tomohiro Matsumura ◽  
Hiroyuki Ito ◽  
Osamu Fujita
Keyword(s):  
Flame Spread ◽  
Atmospheric Pressure ◽  
Total Pressure ◽  
Electric Circuit ◽  
Video Camera ◽  
Extinction Condition ◽  
Measured Temperature ◽  
Reduced Pressure ◽  
Flame Shape ◽  
The Wire

Flame spread over polymer-insulated wire in reduced (sub-atmospheric) pressure has been studied experimentally in order to evaluate the fire safety of electric circuit in the aircraft as well as the space habitats. Polyethylene (PE) insulated NiCr wire is used as the burning sample. Ambient gas is the mixture of nitrogen and oxygen, and the composition is fixed as air (79 vol.% of N2 and 21 vol.% of O2) throughout the study. Total pressure is reduced from atmospheric (101 kPa) to sub-atmospheric (20 kPa) in order to investigate the role of the reduced pressure on the flame spread along the wire. Spread event followed by the forced ignition is recorded by digital video camera to obtain any time-dependent flame behavior. Experimental results show that the flame shape is changed from typical “teardrop” to “round” (and even oval) with the decrease in total pressure. Flame spread rate increases in the reduced pressure although the partial pressure of oxygen is “reduced” with the total pressure. Such “pronounced” spread behavior is continuously observed until just before the extinction condition (∼25 kPa in the present study). The change in flame shape could enhance thermal input to the unburned PE through gas-phase conduction as well as conduction along the wire, and these should be responsible for the faster flame spread in sub-atmospheric pressure. Heat balance is roughly estimated with measured temperature and relative contribution of above two thermal input pathways is understood almost comparable. Importance of the presence of conductive material, such as metal wire, on flame spread is addressed in the current spread behavior.

scholarly journals Experimental study on flame propagation over overload-wire under varying inclination Angle

2021 ◽  
Vol 233 ◽  
pp. 01012
Author(s):  
Hu Wen ◽  
Xiangtao Zhao ◽  
Qing Tian ◽  
Weifeng Wang ◽  
He Jian
Keyword(s):  
Flame Propagation ◽  
Inclination Angle ◽  
Flame Spread ◽  
Low Voltage ◽  
Flame Height ◽  
Spread Rate ◽  
Flame Spread Rate ◽  
Conducting Wire ◽  
Flame Shape ◽  
The Wire

To better understand the process of fire caused by conducting wire, based on the study of overload of the low-voltage wire, the theoretical analysis of flame spread mechanism of overload-wire was proposed, and the functional relationship between flame shape characteristics and flame spread speed, current, and inclination angle was studied. The results show that: (1) the theoretical model of flame propagation can well reflect the changes of thermodynamic parameters in the process of flame propagation, and it is in better agreement with the experimental results. (2) When the current value is constant, with the increase of the inclination angle of the wire (0°-90°), the flame is elongated along the wire direction, the width of the flame base increases, and the angle between the flame front and the wire decreases. When the inclination angle is fixed, with the increase of the inclination angle of the conductor, the flame shape becomes more "high and wide" and the flame height increases at the same time. (3) When the current is constant, the flame spread rate increases with the increase of wire inclination angle; when the inclination angle is constant, the flame spread rate decreases sharply with the increase of current.

Epitaxial Silicon Layers Made by Reduced Pressure/Temperature CVD

1988 ◽  
Vol 129 ◽  
Author(s):  
J.L. Regolini ◽  
D. Bensahel ◽  
J. Mercier ◽  
C. D'Anterroches ◽  
A. Perio
Keyword(s):  
Thermal Processing ◽  
Atmospheric Pressure ◽  
Rapid Thermal Processing ◽  
Processing System ◽  
Epitaxial Silicon ◽  
Reduced Pressure ◽  
Selective Epitaxial Growth ◽  
Main Decomposition ◽  
Rate Limiting ◽  
Reactive Gas

ABSTRACTIn a rapid thermal processing system working at a total pressure of a few Torr, we have obtained selective epitaxial growth of silicon at temperatures as low as 650°C. When using SiH2Cl2 (DCS) as the reactive gas, no addition of HCl is needed. Nevertheless, using SiH4 below 950°C a small amount of HCl should be added.Some kinetic aspects of the two systems, DCS/HCI/H2 and SiH4/HCl/H2, are presented and discussed. For the DCS system, we show that the rate-limiting reactions are slightly different from those commonly accepted in the literature, where the results are from systems working at atmospheric pressure or in the 20-100 Torr range.Our model is based on the main decomposition of DCS, SiH2Cl→SiHCl + HCl, instead of the widely accepted reaction SiH2Cl2→SiCl2 + H2. This is the main reason why no extra HCl is required in the DCS/H2 system to obtain full selectivity from above 1000°C down to 650°C.

scholarly journals Static and Motional Feedthrough Capacitance of Flexural Microresonator

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
Wen-Teng Chang
Keyword(s):  
Silicon Carbide ◽  
Atmospheric Pressure ◽  
Network Analyzer ◽  
Reduced Pressure ◽  
Flexural Mode ◽  
Microelectromechanical System ◽  
Order Of Magnitude ◽  
Bode Plots

The present paper evaluates the static and motional feedthrough capacitance of a silicon carbide-based flexural-mode microelectromechanical system resonator. The static feedthrough capacitance was measured by a network analyzer under atmospheric pressure. The motional feedthrough was obtained by introducing various values into the modeling circuit in order to fit the Bode plots measured under reduced pressure. The static feedthrough capacitance was 0.02 pF, whereas the motional feedthrough capacitance of an identical device was about 0.2 pF, which is one order of magnitude larger than the static feedthrough capacitance.

scholarly journals The influence of pressure on the boiling points of metals

1910 ◽  
Vol 83 (565) ◽  
pp. 483-491 ◽  
Keyword(s):  
Atmospheric Pressure ◽  
Boiling Point ◽  
High Vacuum ◽  
Similar Type ◽  
Exact Relation ◽  
Reduced Pressure ◽  
Boiling Points ◽  
Experimental Values ◽  
Low Pressures ◽  
Very High

Part I. — Pressures below 760 mm . In a previous communication (‘Proc.’, A, vol. 82, 1909, p. 396) the approximate boiling points of a number of metals were determined at atmospheric pressure. Apart from the question of finding the exact relation between the boiling point and pressure, it is an important criterion of any method for fixing the temperatures of ebullition to demonstrate that the experimental values obtained are dependent on the pressure. It is specially desirable when dealing with substances boiling at temperatures above 2000° to have some evidence that the points indicated are true boiling points. Previous work on the vaporisation of metals at different pressures has been confined to experiments in a very high vacuum except for metals like bismuth, cadmium, and zinc, which boil at relatively low temperatures under atmospheric pressure. The observations were limited to very low pressures on account of the difficulty of obtaining any material capable of withstanding a vacuum at temperatures over 1400° and the consequent necessity for keeping the boiling point below this limit by using very low pressures. Moreover in the case of the majority of the metals, e. g. , copper, tin, ebullition under reduced pressure has never been observed. The difficulties indicated above were avoided by using a similar type of apparatus to that previously described, and arranging the whole furnace inside a vacuum enclosure, thus permitting of the use of graphite crucibles to contain the metal.

scholarly journals Comments on nitrogen excretion from the diver’s organism during the reduced pressure at the final decompression station (< 1 ata)

2016 ◽  
Vol 54 (1) ◽  
pp. 31-36
Author(s):  
Tadeusz Doboszyński ◽  
Bogdan Łokucijewski
Keyword(s):  
Sea Level ◽  
Atmospheric Pressure ◽  
Mountain Lakes ◽  
Air Transport ◽  
Nitrogen Excretion ◽  
Reduced Pressure ◽  
Proper Consideration

Abstract The authors discuss the effect of reduced pressure at the final decompression station on nitrogen excretion from the organism of a diver. The assumed basis for the said considerations was the course of decompression during dives performed in lakes located at a significant altitude above sea level and diver transportation by plane following dive completion. Based on the presented calculations the authors conclude that air transport can take place only upon the lapse of time calculated with regard to the diving conditions and the expected altitude of the flight. Diving in mountain lakes requires proper consideration of the effects of the decreased atmospheric pressure.

scholarly journals Measurements of Water Pressure in Moulins as Part of a Movement Study of the White Glacier, Axel Heiberg Island, Northwest Territories, Canada

1972 ◽  
Vol 11 (61) ◽  
pp. 53-58 ◽  
Author(s):  
Almut Iken
Keyword(s):  
Northwest Territories ◽  
Atmospheric Pressure ◽  
Total Pressure ◽  
Water Pressure ◽  
Surface Velocity ◽  
Pressure Data ◽  
Measuring Range ◽  
Surface Measurements ◽  
Movement Study ◽  
Different Depths

AbstractIn 1970 water pressure was measured in several moulins on the White Glacier. Pressure variations in some moulin channels extended over the full measuring range of the instruments (0–1 and 0–2 bar above atmospheric pressure), even at depths of less than 50 m below the surface. Measurements at different depths showed that total pressure variations were sometimes greater than this. The pressure data are compared with variations in the surface velocity of the glacier.

Influence of high atmospheric pressure on flame spread over electric wire at different inclinations

2020 ◽  
Vol 136 ◽  
pp. 66-75 ◽  
Author(s):  
Yanli Zhao ◽  
Jian Chen ◽  
Xiao Chen ◽  
Youjie Sheng ◽  
Shouxiang Lu ◽  
...  
Keyword(s):  
Flame Spread ◽  
Atmospheric Pressure ◽  
High Atmospheric Pressure

Ein neues Verfahren zur Präparation von Tantal/Silber und Niob/Silber Tunnel- kontakten / A New Method for the Preparation of Tantalum/Silver and Niobium/Silver Tunneling Contacts

1976 ◽  
Vol 31 (7) ◽  
pp. 858-860
Author(s):  
Klaus Gärtner
Keyword(s):  
Transition Metal ◽  
Thermal Oxidation ◽  
Ultrahigh Vacuum ◽  
Electron Gun ◽  
New Method ◽  
Tunneling Barrier ◽  
Reduced Pressure ◽  
The Wire ◽  
Smooth Sphere

Abstract The preparation starts from material in wire-form. One end of the wire is degassed under ultrahigh-vacuum conditions by a very simple electron-gun and finally melted to form a small smooth sphere. The tunneling barrier is formed by thermal oxidation of the investigated superconductor with oxygen under reduced pressure. The handling of the whole sample (masking and contacting procedures included) is very simple and allows to use this method for systematic tunneling-studies of the transition metal superconductors.

scholarly journals Vertical Field Emission Air-Channel Diodes and Transistors

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 858 ◽  
Author(s):  
Wen-Teng Chang ◽  
Hsu-Jung Hsu ◽  
Po-Heng Pao
Keyword(s):  
Metal Oxide ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Ambient Pressure ◽  
Electron Flow ◽  
Mean Free Path ◽  
Oxide Semiconductor ◽  
Radiation Environment ◽  
Reduced Pressure ◽  
Transport Distance

Vacuum channel transistors are potential candidates for low-loss and high-speed electronic devices beyond complementary metal-oxide-semiconductors (CMOS). When the nanoscale transport distance is smaller than the mean free path (MFP) in atmospheric pressure, a transistor can work in air owing to the immunity of carrier collision. The nature of a vacuum channel allows devices to function in a high-temperature radiation environment. This research intended to investigate gate location in a vertical vacuum channel transistor. The influence of scattering under different ambient pressure levels was evaluated using a transport distance of about 60 nm, around the range of MFP in air. The finite element model suggests that gate electrodes should be near emitters in vertical vacuum channel transistors because the electrodes exhibit high-drive currents and low-subthreshold swings. The particle trajectory model indicates that collected electron flow (electric current) performs like a typical metal oxide semiconductor field effect-transistor (MOSFET), and that gate voltage plays a role in enhancing emission electrons. The results of the measurement on vertical diodes show that current and voltage under reduced pressure and filled with CO2 are different from those under atmospheric pressure. This result implies that this design can be used for gas and pressure sensing.

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