Corrosion Rate Measurement by Hydrogen Effusion In Dynamic Aqueous Systems At Elevated Temperature and Pressure

CORROSION ◽  
1959 ◽  
Vol 15 (4) ◽  
pp. 29-32
Author(s):  
M. KRULFELD ◽  
M. C. BLOOM ◽  
R. E. SEEBOLD
Keyword(s):  
Elevated Temperature ◽  
Corrosion Rate ◽  
Flow Velocity ◽  
High Flow ◽  
Low Flow ◽  
Aqueous Systems ◽  
Effusion Rates ◽  
Temperature And Pressure ◽  
Effusion Method ◽  
Hydrogen Effusion

Abstract A method of applying the hydrogen effusion method to the measurement of corrosion rates in dynamic aqueous systems at elevated temperature and pressure is described. Data obtained in low carbon steel systems are presented, including (1) reproducibility obtained in measured hydrogen effusion rates at a flow velocity of 1 foot per second at a temperature of 600 F and 2000 psi, and (2) a quantitative comparison between the hydrogen effusion rates in static and in low flow velocity dynamic systems at this temperature and pressure. Some observations are included on corrosion rate measurements in a high flow velocity (30 feet per second) loop by the hydrogen effusion method. Implications of these measurements with regard to the comparison between high flow velocity corrosion and low flow velocity corrosion are mentioned and some data indicating high local sensitivity of the hydrogen effusion method are noted. Some possible difficulties involved in the method are pointed out. 2.3.4

scholarly journals Simulation and analysis of flow patterns around the scleractinian coral Madracis mirabilis (Duchassaing and Michelotti)

2003 ◽  
Vol 358 (1437) ◽  
pp. 1551-1557 ◽  
Author(s):  
Jaap A. Kaandorp ◽  
Evert A. Koopman ◽  
Peter M. A. Sloot ◽  
Rolf P. M. Bak ◽  
Mark J. A. Vermeij ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Flow Patterns ◽  
External Flow ◽  
High Flow ◽  
Low Flow ◽  
Stagnant Region ◽  
Computed Tomography Scanning ◽  
X Ray Computed

Three–dimensional morphologies of Madracis mirabilis were obtained using X–ray computed tomography scanning techniques. The morphologies were used to simulate the flow patterns around the colony. In the simulations, the thin–branching low–flow morph with a relatively larger branch–spacing was compared with the more compact high–flow morph of M. mirabilis . For both morphologies, the inside–colony flow velocities were computed for Reynolds numbers ranging from 154 to 3840. In the high–flow morph, it was found that in the range of investigated Reynolds numbers a stagnant region develops within the colony, whereas in the low–flow morph the stagnant region disappeared. Experiments done under natural conditions suggest that a morph is adapted to a certain external flow velocity and develops a stagnant region below a particular threshold for the external flow velocity. When the external flow velocity exceeds a certain threshold, which is characteristic for the growth form, the core velocity becomes equal to the external velocity. A potential application of a profile of core velocities for a range of Reynolds numbers for a certain morph is the prediction of the optimal external flow velocity for a certain morph, and this can be used to assess the state of the physical (palaeo–) environment.

scholarly journals Experimental Study on Hydroelectric Energy Harvester Based on a Hybrid Qiqi and Turbine Structure

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7601
Author(s):  
Bin Bao ◽  
Quan Wang ◽  
Yufei Wu ◽  
Pengda Li
Keyword(s):  
Energy Harvesting ◽  
Flow Velocity ◽  
Water Flow ◽  
Energy Harvester ◽  
Hybrid Structure ◽  
High Flow ◽  
Low Flow ◽  
Flow Rates ◽  
Hydroelectric Energy ◽  
Wide Range

The Qiqi structure design can automatically upset and spill its content once it arrives at limit capacity under vertical water flow excitation. Considering this function, the Qiqi structure has been utilized for small hydroelectric energy harvesting lately. To investigate the tradeoff between the Qiqi structure and the turbine structure for small hydroelectric energy harvesting, an energy harvester based on a hybrid Qiqi and turbine structure is proposed for vertical water flow hydroelectric applications. The hybrid structure is composed of a rectangular Qiqi structure, with two blades inserted on both sides. Self-tipping function of the hybrid Qiqi structure and working principle of the structure is investigated in detail. The proposed structure has both the advantages of low flow velocity energy harvesting of the Qiqi structure and high flow velocity energy harvesting of the turbine structure. A hydroelectric energy harvesting application using the hybrid structure is given to demonstrate that the hybrid structure had a higher rotational speed than the Qiqi structure under vertical low water flow excitation and was able to work at relatively high flow rates. Thus, the investigated hybrid structure can help small rotational hydropower achieve better energy harvesting performance and work at wide-range flow rates under vertical ultra-low water flow applications. At 600 mL/min, 902 μJ of electrical energy was charged by the investigated structure, which is six times higher than that using the Qiqi structure alone.

Experimental Research on Pressure Drop to Optimize Twisted Strips with Holes in Tubes of Condensers

2011 ◽  
Vol 347-353 ◽  
pp. 448-452
Author(s):  
De Qi Peng ◽  
Ya Jie Zhou ◽  
Wei Qiang Wang ◽  
Tian Lan Yu ◽  
Huan Yu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Power Plant ◽  
Pressure Drop ◽  
Flow Velocity ◽  
Experimental Research ◽  
Thermal Power Plant ◽  
Thermal Power ◽  
High Flow ◽  
Low Flow ◽  
High Flow Velocity

In order to reduce the pressure drop increase caused by self-rotating plastic twisted-strips in heat transfer tubes of vacuum condensers in thermal power plant, the twisted strips structure is optimized. There are holes distributed in twisted strip uniformly. The holes diameter and interval are optimized through experimental research. The results show that when holes diameter is less than 6mm, holes can reduce the pressure drop increase at low flow velocity while the pressure drop with holes is greater than that without holes at high flow velocity. The holes diameter is 4~5mm when the pressure drop is the lowest. The pressure drop with holes is always larger than that without holes when holes diameter is more than 6mm. The pressure drop will increase as holes interval decreases at high flow velocity, while it will reduce at low flow velocity.

scholarly journals Near-occlusion is difficult to diagnose with common carotid ultrasound methods

2021 ◽  
Vol 63 (5) ◽  
pp. 721-730
Author(s):  
Elias Johansson ◽  
Davide Vanoli ◽  
Isa Bråten-Johansson ◽  
Lucy Law ◽  
Richard I Aviv ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Sensitivity And Specificity ◽  
Low Flow ◽  
Reference Standard ◽  
Carotid Ultrasound ◽  
Ultrasound Method ◽  
Velocity Parameter ◽  
Near Occlusion

Abstract Purpose To assess the sensitivity and specificity of common carotid ultrasound method for carotid near-occlusion diagnosis. Methods Five hundred forty-eight patients examined with both ultrasound and CTA within 30 days of each other were analyzed. CTA graded by near-occlusion experts was used as reference standard. Low flow velocity, unusual findings, and commonly used flow velocity parameters were analyzed. Results One hundred three near-occlusions, 272 conventional ≥50% stenosis, 162 <50% stenosis, and 11 occlusions were included. Carotid ultrasound was 22% (95%CI 14–30%; 23/103) sensitive and 99% (95%CI 99–100%; 442/445) specific for near-occlusion diagnosis. Near-occlusions overlooked on ultrasound were found misdiagnosed as occlusions (n = 13, 13%), conventional ≥50% stenosis (n = 65, 63%) and < 50% stenosis (n = 2, 2%). No velocity parameter or combination of parameters could identify the 65 near-occlusions mistaken for conventional ≥50% stenoses with >75% sensitivity and specificity. Conclusion Near-occlusion is difficult to diagnose with commonly used carotid ultrasound methods. Improved carotid ultrasound methods are needed if ultrasound is to retain its position as sole preoperative modality.

scholarly journals A large fixed bed reactor for MRI operando experiments at elevated temperature and pressure

2021 ◽  
Vol 92 (4) ◽  
pp. 043711
Author(s):  
Harm Ridder ◽  
Christoph Sinn ◽  
Georg R. Pesch ◽  
Jan Ilsemann ◽  
Wolfgang Dreher ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Temperature And Pressure

scholarly journals Soil microbial inoculation during flood events shapes headwater stream microbial communities and diversity

2021 ◽  
Author(s):  
Florian Caillon ◽  
Katharina Besemer ◽  
Peter Peduzzi ◽  
Jakob Schelker
Keyword(s):  
Microbial Diversity ◽  
Bacterial Diversity ◽  
Soil Water ◽  
Headwater Streams ◽  
High Flow ◽  
Low Flow ◽  
Flood Events ◽  
Flow Conditions ◽  
Soil Microbial ◽  
Microbial Inoculation

AbstractFlood events are now recognized as potentially important occasions for the transfer of soil microbes to stream ecosystems. Yet, little is known about these “dynamic pulses of microbial life” for stream bacterial community composition (BCC) and diversity. In this study, we explored the potential alteration of stream BCC by soil inoculation during high flow events in six pre-alpine first order streams and the larger Oberer Seebach. During 1 year, we compared variations of BCC in soil water, stream water and in benthic biofilms at different flow conditions (low to intermediate flows versus high flow). Bacterial diversity was lowest in biofilms, followed by soils and highest in headwater streams and the Oberer Seebach. In headwater streams, bacterial diversity was significantly higher during high flow, as compared to low flow (Shannon diversity: 7.6 versus 7.9 at low versus high flow, respectively, p < 0.001). Approximately 70% of the bacterial operational taxonomic units (OTUs) from streams and stream biofilms were the same as in soil water, while in the latter one third of the OTUs were specific to high flow conditions. These soil high-flow OTUs were also found in streams and biofilms at other times of the year. These results demonstrate the relevance of floods in generating short and reoccurring inoculation events for flowing waters. Moreover, they show that soil microbial inoculation during high flow enhances microbial diversity and shapes fluvial BCC even during low flow. Hence, soil microbial inoculation during floods could act as a previously overlooked driver of microbial diversity in headwater streams.

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