High-Speed, Vacuum-Outlet GC Using Atmospheric-Pressure Air as Carrier Gas

An “explosive extratropical cyclone” is an atmospheric phenomenon that occurs when there is a very rapid drop in central atmospheric pressure. This phenomenon, with its characteristic of rapidly lowering the pressure in its interior, generates very intense winds and for this reason it is called explosive cyclone, bomb cyclone. With gusts recorded of 116 km/h, atmospheric phenomenon – “cyclone bomb” (CB) hit southern Brazil on June 30, the beginning of winter 2020, causing destruction in its influence over. One of the cities most affected was Chapecó, west of the state of Santa Catarina. The satellite images show that the CB generated a low pressure (976 mbar) inside it, generating two atmospheric currents that moved at high speed. In a northwest-southeast direction, Bolivia and Paraguay, crossing the states of Parana and Santa Catarina, and this draft that hit the south of Brazil, which caused the destruction of the affected states. Another moving to Argentina, southwest-northeast direction, due to high area of high pressure (1022 mbar). Both enhanced the phenomenon.

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Interactive Effects in Two-Droplets Combustion of RP-3 Kerosene under Sub-Atmospheric Pressure

Processes ◽

10.3390/pr9071229 ◽

2021 ◽

Vol 9 (7) ◽

pp. 1229

Author(s):

Hongtao Zhang ◽

Zhihua Wang ◽

Yong He ◽

Jie Huang ◽

Kefa Cen

Keyword(s):

Burning Rate ◽

Atmospheric Pressure ◽

High Speed ◽

Ambient Pressure ◽

Interactive Effects ◽

Propagation Time ◽

High Speed Camera ◽

Single Droplet ◽

Fuel Droplets ◽

Spacing Distance

To improve our understanding of the interactive effects in combustion of binary multicomponent fuel droplets at sub-atmospheric pressure, combustion experiments were conducted on two fibre-supported RP-3 kerosene droplets at pressures from 0.2 to 1.0 bar. The burning life of the interactive droplets was recorded by a high-speed camera and a mirrorless camera. The results showed that the flame propagation time from burning droplet to unburned droplet was proportional to the normalised spacing distance between droplets and the ambient pressure. Meanwhile, the maximum normalised spacing distance from which the left droplet can be ignited has been investigated under different ambient pressure. The burning rate was evaluated and found to have the same trend as the single droplet combustion, which decreased with the reduction in the pressure. For every experiment, the interactive coefficient was less than one owing to the oxygen competition, except for the experiment at L/D0 = 2.5 and P = 1.0 bar. During the interactive combustion, puffing and microexplosion were found to have a significant impact on secondary atomization, ignition and extinction.

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Investigation of Fuel and Load Flexibility in a SGT-600/700/800 Burner Under Atmospheric Pressure Conditions Using High-Speed OH-PLIF and OH Chemiluminescence Imaging

10.1115/1.0002804v ◽

2021 ◽

Author(s):

Arman Subash ◽

Haisol Kim ◽

Sven-Inge M\xf6ller ◽

Mattias Richter ◽

Christian Brackmann ◽

...

Keyword(s):

Atmospheric Pressure ◽

High Speed

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Cyclone rotational drying of lignite based on particle high-speed self-rotation: Lower carrier gas temperature and shorter residence time

Energy ◽

10.1016/j.energy.2021.123005 ◽

2021 ◽

pp. 123005

Author(s):

Pengbo Fu ◽

Hao Yu ◽

Qiqi Li ◽

Tingting Cheng ◽

Fangzheng Zhang ◽

...

Keyword(s):

Residence Time ◽

High Speed ◽

Gas Temperature ◽

Carrier Gas

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Performance Testing on Transonic Rotors

Mechanical Engineering ◽

10.1115/1.2010-aug-8 ◽

2010 ◽

Vol 132 (08) ◽

pp. 52-53

Author(s):

Anthony J. Gannon ◽

Garth V. Hobson

Keyword(s):

Mach Number ◽

Power Consumption ◽

Flow Rate ◽

Atmospheric Pressure ◽

High Speed ◽

Performance Testing ◽

Test Machine ◽

Naval Postgraduate School ◽

Scale Down ◽

Limit Power

This article discusses the performance testing of transonic rotors at the Turbopropulsion Laboratory at the Naval Postgraduate School. The Mach number is one of the most important parameters in the case of high-speed compressors. In order to limit power consumption in a test machine, the simplest change is to scale down the machine. A second concept to reduce the power consumption of the machine once it has been scaled down is to throttle the flow before the rotor rather than after it. As a high-speed rotor compresses the incoming air by around 1.4–1.6 times, the air leaving it is appreciably denser than that coming in. If one throttles upstream of the rotor, the exhaust air leaves the machine at atmospheric pressure, which means that the incoming air is below atmospheric pressure. With upstream throttling, care has to be taken to provide long enough ducting ahead of the test compressor to present as uniform as possible flow after the flow rate measuring nozzle.

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Shellside Vacuum Condensation With a Noncondensable Gas

Volume 8: Heat Transfer and Thermal Engineering ◽

10.1115/imece2016-67417 ◽

2016 ◽

Author(s):

Susan N. Ritchey

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Atmospheric Pressure ◽

High Speed ◽

Process Conditions ◽

Transfer Data ◽

Noncondensable Gas ◽

Overall Heat Transfer Coefficient ◽

Vacuum Condensation

Shell-and-tube vacuum condensers are present in many industrial applications such as chemical manufacturing, distillation, and power production [1–3]. They are often used because operating a condenser under vacuum pressures can increase the efficiency of energy conversion, which increases the overall plant efficiency and saves money. Typical operating pressures in the petrochemical industry span a wide range of values, from one atmosphere (101.3 kPa) down to a medium vacuum (1 kPa). The current shellside condensation methods used to predict heat transfer coefficients are based on data collected near or above atmospheric pressure, and the available literature on shellside vacuum condensation generally lacks experimental data. The accuracy of these methods in vacuum conditions well below atmospheric pressure has yet to be validated. Recently, HTRI designed and constructed the Low Pressure Condensation Unit (LPCU) with a rectangular shellside test condenser. To date, heat transfer data have been collected in the LPCU for shellside condensation of a pure hydrocarbon and of a hydrocarbon with noncondensable gas at vacuum pressures ranging from 2.8 to 45 kPa (21 to 338 Torr). Traditional condensation literature methods underpredict the overall heat transfer coefficient by 20.8% ± 20.4% for the pure condensing fluid; whereas they overpredict heat transfer by 36.8% ± 40.0% with the addition of the noncondensable gas. Over or under predicting the overall heat transfer coefficient in the presence of noncondensable gases leads to inefficient condenser designs and the inability to achieve desired process conditions. With the addition of the noncondensable gas, the measured heat exchanger duty was significantly reduced compared to the pure fluid, even at inlet mole fractions below 5%. In one case, a noncondensable inlet mole fraction of 0.63% was estimated to reduce the duty by approximately 10%. Analysis of the acquired high-speed videos shows that the film thickness changes significantly from the top row to the bottom. The videos also display condensate drainage patterns and droplet interactions. The ripples and splashing of the condensate observed in the videos indicates that the Nusselt idealized model is not appropriate for analysis of a real condenser. This article presents the collected heat transfer data and high-speed images of shellside vacuum condensation flow patterns.

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Vertical Field Emission Air-Channel Diodes and Transistors

Micromachines ◽

10.3390/mi10120858 ◽

2019 ◽

Vol 10 (12) ◽

pp. 858 ◽

Cited By ~ 3

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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Investigation into the Operating Characteristics of a “Microarc” Atmospheric-Pressure Glow Discharge

Applied Spectroscopy ◽

10.1366/0003702794925840 ◽

1979 ◽

Vol 33 (3) ◽

pp. 230-240 ◽

Cited By ~ 9

Author(s):

R. I. Bystroff ◽

L. R. Layman ◽

G. M. Hieftje

Keyword(s):

Glow Discharge ◽

Atmospheric Pressure ◽

Thermal Effects ◽

High Speed ◽

Atmospheric Pressure Glow Discharge ◽

Operating Characteristics ◽

Pressure Glow Discharge ◽

Current Voltage ◽

Improved Stability ◽

Oxygen Impurities

Details of the processes occurring during sample atomization from a “microarc” discharge have been studied photometrically, by use of high-speed color cinematography and through current-voltage waveforms. The microarc studied here is an atmospheric-pressure inert-gas glow discharge supported between 0.25 mm diameter tungsten wires; quiescent argon-1% H2 provides reactive-sputtering conditions and improved behavior in the presence of oxygen impurities. Excitation temperatures of ca. 5000°K are measured for the argon glow. Samples of Na, Al, and Sr illustrate the influence of volatile, refractory, insulating, and electron-emitting sample properties on the temporal-spatial-electrical behavior of the discharge. The step-by-step events occurring in the discharge are described qualitatively and a variety of processes are invoked to explain sample volatilization, including sputtering, chemical reactions, and purely thermal effects. In the first stages of the discharge, instabilities are related to the placement and insulating character of deposits. With heating, electron emission becomes important in directing the discharge to or away from the sample; abnormal glow wandering and glow-to-arc transitions can ensue. Improved stability is achieved by uniformly depositing multi-element samples along the electrode, which localizes the initial discharge and promotes ablative cooling of the sample and electrode.

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