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Total pressure

About: Total pressure is a research topic. Over the lifetime, 5199 publications have been published within this topic receiving 66658 citations.


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TL;DR: In this paper, optical emission spectroscopy (OES) and double Langmuir probe measurements were used to investigate the dissociation degree of N2 in a hollow cathode RF discharge system.
Abstract: N2?x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5?33?Pa), and different fractions of argon (7 ? x ? 80), at a constant applied RF power of 300?W. N2 dissociation degree has been investigated qualitatively by both the actinometry method and the ratio of the atomic nitrogen line emission intensity at 672.3?nm to the vibrational band (0?0) of the N2 second positive system at 337.1?nm. Both methods showed that the increase in argon fraction enhances the dissociation of N2, with a maximum at x = 50 for the pressure of 5?Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12?300?K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57?1.75?eV, the density varies between 5 ? 109 and 1.4 ? 1010?cm?3 and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma?polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3?nm) intensity is obtained, atomic carbon line (833.52?nm) and the band emission (0?0) from the CN (B?2?+?X?2?+) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased.

39 citations

Journal ArticleDOI
TL;DR: In this article, the effect of catalyst shape on performance of a terrace wall reactor has been studied, and it has been shown that a multichannel cylinder is a good choice among different alternative catalyst pellet shapes.
Abstract: High catalyst activity plays an important role in the safe and efficient operation of methane-steam reforming reactors. Since transport resistance limits the effectiveness factor in the reactor to values much less than unity, increasing the catalyst surface area increases its activity. Using a mathematical model of a terrace wall reactor, the effect of catalyst shape on performance of the reactor has been studied. Considering different parameters of catalyst effectiveness factor, reaction gas temperature, reactor pressure drop and mechanical strength, it has been shown that a multichannel cylinder is a good choice among different alternative catalyst pellet shapes. Compared to a standard spherical shape, a multichannel cylinder gives 10% less total pressure drop and its effectiveness factor is almost three times higher.

39 citations

Journal ArticleDOI
01 Oct 1989
TL;DR: In this paper, an ion-drag pump in a vertical, axisymmetric configuration was built, where the ions were injected into the fluid where the viscous shear stresses were the highest.
Abstract: An ion-drag pump in a vertical, axisymmetric configuration was built. Two pumping sections with 1 and 10 electrode pairs were constructed. The total length of the pumping loop with one electrode pair was 133.0 cm; with 10 electrode pairs it was 186.0 cm. The electrodes were designed from the fluid mechanics standpoint. The ions were injected into the fluid where the viscous shear stresses were the highest. The fluid used was dodecylbenzine, and all the experiments were conducted at 25 degrees C. Pumping velocities as high as 33.4 cm/s (corresponding mass flow rate of 1.1 kg/s and total pressure generation of 111.9 Pa) at 25 kV have been achieved. The highest pump power efficiency obtained was 6.0%. The effect of the electrical conductivity level of dodecylbenzine on the pump performance was also studied. Increasing the conductivity level reduced the pumping velocity. >

38 citations

Journal ArticleDOI
TL;DR: In this paper, the depletion of antioxidants was effectively monitored using the high pressure oxidative induction (HP-OIT) test, whereas the oxidation of the polymer was evaluated using tensile and melt index tests.

38 citations

Journal ArticleDOI
TL;DR: In this article, the effect of acetic acid on the corrosion behavior of X 65 and C 1018 carbon steel in two-phase stratified flow was studied in a low pressure-high temperature multiphase flow horizontal loop using electrochemical and mass loss techniques.
Abstract: The effect of acetic acid on the corrosion behavior of X 65 and C 1018 carbon steel in vapor-water two-phase stratified flow (Vsg: 2 m/s; Vsl: 0.1 m/s) at 2 bars total pressure, 1.54 bars CO2 partial pressure, pH 5.5, and 80°C was studied in a low pressure-high temperature multiphase flow horizontal loop using electrochemical and mass loss techniques. The liquid phase is composed of 1% NaCl aqueous solution containing different concentrations of acetic acid (500 to 5000 ppm total acetic acid), and the gas phase is composed of CO2-acetic acid-water vapor mixture. The corrosion rates, on both the top and bottom of the line, increase with increase in acetic acid concentration, which was attributed to the contribution of hydrogen ions by the free acetic acid to the cathodic reaction. Partial coverage of the metal surface by FeCO3 on both the top and bottom of the line is reported to be responsible for the observed localized corrosion. Surface analysis investigated with SEM and XRD is reported. A vapor-liquid ...

38 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202316
202225
2021127
2020147
2019153
2018128