scholarly journals High-temperature volcanic gas flow from the summit lava dome of Tarumai Volcano, Hokkaido, Japan

2013 ◽  
Vol 119 (7) ◽  
pp. V-VI
Author(s):  
Takeshi Hasegawa ◽  
Jun'ichi Miyamura ◽  
Yuji Fushiya ◽  
Yuji Takahashi
Keyword(s):  
High Temperature ◽  
Gas Flow ◽  
Lava Dome ◽  
Volcanic Gas

DISPERSED PHASE VELOCITY IN A HIGH-TEMPERATURE GAS FLOW

2019 ◽  
Vol 23 (4) ◽  
pp. 319-328
Author(s):  
Dmitry V. Nesterovich ◽  
Oleg G. Penyazkov ◽  
Yu. A. Stankevich ◽  
M. S. Tretyak ◽  
Vladimir V. Chuprasov ◽  
...  
Keyword(s):  
High Temperature ◽  
Phase Velocity ◽  
Gas Flow ◽  
Dispersed Phase ◽  
High Temperature Gas

Passive Auto-Focus Algorithm for Correcting Image Distortions Caused by Gas Flow in High-Temperature Measurements of Surface Phenomena

2012 ◽  
Vol 17 (4) ◽  
pp. 379-384 ◽  
Author(s):  
Krzysztof Strzecha ◽  
Tomasz Koszmider ◽  
Damian Zarębski ◽  
Wojciech Łobodziński
Keyword(s):  
High Temperature ◽  
Gas Flow ◽  
Temperature Measurements ◽  
Surface Phenomena ◽  
Auto Focus ◽  
High Temperature Measurements

Abstract In this paper, a case-study of the auto-focus algorithm for correcting image distortions caused by gas flow in high-temperature measurements of surface phenomena is presented. This article shows results of proposed algorithm and methods for increasing its accuracy.

Comparative Study of GaN Growth Process by MOVPE

1999 ◽  
Vol 572 ◽  
Author(s):  
Jingxi Sun ◽  
J. M. Redwing ◽  
T. F. Kuech
Keyword(s):  
High Temperature ◽  
Comparative Study ◽  
Gas Phase ◽  
Residence Time ◽  
Gas Flow ◽  
Flow Sheet ◽  
Flow Zone ◽  
High Quality ◽  
Phase Temperature ◽  
High Temperature Gas

ABSTRACTA comparative study of two different MOVPE reactors used for GaN growth is presented. Computational fluid dynamics (CFD) was used to determine common gas phase and fluid flow behaviors within these reactors. This paper focuses on the common thermal fluid features of these two MOVPE reactors with different geometries and operating pressures that can grow device-quality GaN-based materials. Our study clearly shows that several growth conditions must be achieved in order to grow high quality GaN materials. The high-temperature gas flow zone must be limited to a very thin flow sheet above the susceptor, while the bulk gas phase temperature must be very low to prevent extensive pre-deposition reactions. These conditions lead to higher growth rates and improved material quality. A certain range of gas flow velocity inside the high-temperature gas flow zone is also required in order to minimize the residence time and improve the growth uniformity. These conditions can be achieved by the use of either a novel reactor structure such as a two-flow approach or by specific flow conditions. The quantitative ranges of flow velocities, gas phase temperature, and residence time required in these reactors to achieve high quality material and uniform growth are given.

High Temperature Stability of MGCs Gas Turbine Components in Air and Combustion Gas Flow Environments

2004 ◽  
Author(s):  
Narihito Nakagawa ◽  
Hideki Ohtsubo ◽  
Kohji Shibata ◽  
Atsuyuki Mitani ◽  
Kazutoshi Shimizu ◽  
...  
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Flow ◽  
Temperature Stability ◽  
High Temperature Strength ◽  
High Temperature Stability ◽  
Combustion Gas ◽  
Air Atmosphere ◽  
Low Nox Emission ◽  
Very High

Melt growth composites (MGCs) have a unique microstructure, in which continuous networks of single-crystal phases interpenetrate without grain boundaries. Therefore, the MGCs have excellent high-temperature strength characteristics, creep resistance, oxidation resistance and thermal stability in an air atmosphere at very high temperature. To achieve ultra-high thermal efficiency and low NOx emission for gas turbine systems, non-cooled turbine nozzle vanes and heat shield panels of combustor liners has been fabricated on an experimental basis. These components are thermally stable after heat treatment at 1700°C for 1000 hours in an air atmosphere. In addition, we have just started the exposure tests to evaluate the influence of combustion gas flow environment on MGCs.

scholarly journals First In-Situ Measurements of Plume Chemistry at Mount Garet Volcano, Island of Gaua (Vanuatu)

2020 ◽  
Vol 10 (20) ◽  
pp. 7293
Author(s):  
Joao Lages ◽  
Yves Moussallam ◽  
Philipson Bani ◽  
Nial Peters ◽  
Alessandro Aiuppa ◽  
...  
Keyword(s):  
High Temperature ◽  
Emission Rates ◽  
Gas Composition ◽  
Gas Analyzer ◽  
Total Volatile ◽  
Volcanic Gas ◽  
So2 Flux ◽  
Gas Chemistry

Recent volcanic gas compilations have urged the need to expand in-situ plume measurements to poorly studied, remote volcanic regions. Despite being recognized as one of the main volcanic epicenters on the planet, the Vanuatu arc remains poorly characterized for its subaerial emissions and their chemical imprints. Here, we report on the first plume chemistry data for Mount Garet, on the island of Gaua, one of the few persistent volatile emitters along the Vanuatu arc. Data were collected with a multi-component gas analyzer system (multi-GAS) during a field campaign in December 2018. The average volcanic gas chemistry is characterized by mean molar CO2/SO2, H2O/SO2, H2S/SO2 and H2/SO2 ratios of 0.87, 47.2, 0.13 and 0.01, respectively. Molar proportions in the gas plume are estimated at 95.9 ± 11.6, 1.8 ± 0.5, 2.0 ± 0.01, 0.26 ± 0.02 and 0.06 ± 0.01, for H2O, CO2, SO2, H2S and H2. Using the satellite-based 10-year (2005–2015) averaged SO2 flux of ~434 t d−1 for Mt. Garet, we estimate a total volatile output of about 6482 t d−1 (CO2 ~259 t d−1; H2O ~5758 t d−1; H2S ~30 t d−1; H2 ~0.5 t d−1). This may be representative of a quiescent, yet persistent degassing period at Mt. Garet; whilst, as indicated by SO2 flux reports for the 2009–2010 unrest, emissions can be much higher during eruptive episodes. Our estimated emission rates and gas composition for Mount Garet provide insightful information on volcanic gas signatures in the northernmost part of the Vanuatu Arc Segment. The apparent CO2-poor signature of high-temperature plume degassing at Mount Garet raises questions on the nature of sediments being subducted in this region of the arc and the possible role of the slab as the source of subaerial CO2. In order to better address the dynamics of along-arc volatile recycling, more volcanic gas surveys are needed focusing on northern Vanuatu volcanoes.

Reduced-Polymer-Loading, High-Temperature Fracturing Fluids by Use of Nanocrosslinkers

SPE Journal ◽  
2016 ◽  
Vol 22 (02) ◽  
pp. 622-631 ◽  
Author(s):  
Feng Liang ◽  
Ghaithan Al-Muntasheri ◽  
Hooisweng Ow ◽  
Jason Cox
Keyword(s):  
High Temperature ◽  
Gas Flow ◽  
Laboratory Data ◽  
Gelling Agent ◽  
Formation Damage ◽  
Fluid System ◽  
Temperature Range ◽  
Enhanced Production ◽  
Fracturing Fluids ◽  
Polymer Loading

Summary In the quest to discover more natural-gas resources, considerable attention has been devoted to finding and extracting gas locked within tight formations with permeability in the nano- to microdarcy range. The main challenges associated with working in such formations are the intrinsically high-temperature and high-pressure bottom conditions. For formations with bottomhole temperatures at approximately 350–400°F, traditional hydraulic-fracturing fluids that use crosslinked polysaccharide gels, such as guar and its derivatives, are not suitable because of significant polymer breakdown in this temperature range. Fracturing fluids that can work at these temperatures require thermally stable synthetic polymers such as acrylamide-based polymers. However, such polymers have to be used at very-high concentrations to suspend proppants. The high-polymer concentrations make it very difficult to completely degrade at the end of a fracturing operation. As a consequence, formation damage by polymer residue can reduce formation conductivity to gas flow. This paper addresses the shortcomings of the current state-of-the-art high-temperature fracturing fluids and focuses on developing a less-damaging, high-temperature-stable fluid that can be used at temperatures up to 400°F. A laboratory study was conducted with this novel system, which comprises a synthetic acrylamide-based copolymer gelling agent and is capable of being crosslinked with an amine-containing polymer-coated nanosized particulate crosslinker (nanocrosslinker). The laboratory data have demonstrated that the temperature stability of the crosslinked fluid is much better than that of a similar fluid lacking the nanocrosslinker. The nanocrosslinker allows the novel fluid system to operate at significantly lower polymer concentrations (25–45 lbm/1,000 gal) compared with current commercial fluid systems (50–87 lbm/1,000 gal) designed for temperatures from 350 to 400°F. This paper presents results from rheological studies that demonstrate superior crosslinking performance and thermal stability in this temperature range. This fracturing-fluid system has sufficient proppant-carrying viscosity, and allows for efficient cleanup by use of an oxidizer-type breaker. Low polymer loading and little or no polymer residue are anticipated to facilitate efficient cleanup, reduced formation damage, better fluid conductivity, and enhanced production rates. Laboratory results from proppant-pack regained-conductivity tests are also presented.

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