scholarly journals Effects of Water Vapor Partial Pressure on Microstructure Evolution in YBa2Cu3O7-y Films Deposited by Advanced TFA-MOD Method

2004 ◽  
Vol 39 (11) ◽  
pp. 578-584 ◽  
Author(s):  
Junko S. MATSUDA ◽  
Yoshitaka TOKUNAGA ◽  
Ryo TERANISHI ◽  
Koichi NAKAOKA ◽  
Hiroshi FUJI ◽  
...  
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Microstructure Evolution ◽  
Vapor Partial Pressure ◽  
Water Vapor Partial Pressure

Exposure Test Results of Lu2Si2O7 in Combustion Gas Flow at High Temperature and High Speed

2004 ◽  
Author(s):  
Isao Yuri ◽  
Tohru Hisamatsu ◽  
Shunkichi Ueno ◽  
Tatsuki Ohji
Keyword(s):  
Weight Loss ◽  
Water Vapor ◽  
Partial Pressure ◽  
Gas Flow ◽  
Loss Rate ◽  
Gas Temperature ◽  
Weight Loss Rate ◽  
Combustion Gas ◽  
Vapor Partial Pressure ◽  
Water Vapor Partial Pressure

In order to understand recession behavior and the amount of recession of Lu2Si2O7 in the combustion gas flow, sintered Lu2Si2O7 specimens were manufactured by hot pressing and exposed under various combustion gas flow conditions (T = 1300–1500 °C, P = 0.3 MPa, V = 150 m/s, PH2O = 27–69 kPa, t = 10h). After the exposure tests, etch pits, which are assumed to form due to volatilization of SiO2 in the grain boundary phase, were observed at the surface of specimen. The amount of Lu2SiO5 phase at the surface of specimen increased with the increase of gas temperature or water vapor partial pressure. A corresponding decrease in the amount of Lu2Si2O7 phase was observed. Furthermore, by using the average weight loss rate for exposure times of ten hours, the influence of gas temperature and water vapor partial pressure on weight loss rate was examined, and the amount of recession under gas turbine conditions was calculated.

Degradation of Silicon Carbide in Combustion Gas Flow at High-Temperature and Speed

2000 ◽  
Author(s):  
I. Yuri ◽  
T. Hisamatsu ◽  
Y. Etori ◽  
T. Yamamoto
Keyword(s):  
Silicon Carbide ◽  
Weight Loss ◽  
Water Vapor ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Flow Rate ◽  
Gas Flow ◽  
Gas Flow Rate ◽  
Vapor Partial Pressure ◽  
Water Vapor Partial Pressure

Effects of various basic factors of combustion gas flow conditions on degradation behaviors of silicon carbide have been experimentally determined. The exposure tests were performed for widely varied experimental parameters of the gas temperatures (T = 900–1500°C), pressure (P = 0.3–0.8MPa), gas flow rate (V = 50–250m/s), water vapor partial pressure (PH2O = 32–82kPa) and oxygen partial pressure (PO2 = 24–44kPa). Degradation behaviors of silicon carbide were expressed as the weight loss of the substrate. The weight loss rate depends on the water vapor partial pressure remarkably. The effect of the oxygen partial pressure on the weight loss was smaller than that of the water vapor partial pressure, and the weight loss decreased with the increase of the oxygen partial pressure. Considering the effects of partial pressures of oxygen and water vapor, the gas temperature and the pressure didn’t have much effect on the weight loss. The weight loss depends on the gas flow rate, the increase rate of the weight loss for the gas flow rate becomes small with the gas flow rate. Consequently, the water vapor partial pressure, the oxygen partial pressure, the gas temperature, the pressure and the gas flow rate dependence of the weight loss rate is expressed as PH2O1.9 V0.6 P0.3 / PO20.6.

In Situ Optical Diagnostics for Measurements of Water Vapor Partial Pressure in a PEM Fuel Cell

2005 ◽  
Vol 3 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Saptarshi Basu ◽  
Hang Xu ◽  
Michael W. Renfro ◽  
Baki M. Cetegen
Keyword(s):  
Water Vapor ◽  
Fuel Cell ◽  
Partial Pressure ◽  
Pem Fuel Cell ◽  
Membrane Electrode ◽  
Flow Channels ◽  
Vapor Partial Pressure ◽  
Temperature And Humidity ◽  
Water Vapor Partial Pressure

A fiber optic coupled diode laser sensor has been constructed for in situ measurements of water vapor partial pressure in active proton-exchange membrane (PEM) fuel cell systems. The bipolar plate of a prototypical PEM fuel cell was modified to allow for transmission of a near infrared laser beam through the flow channels on either the fuel or oxidizer side of its membrane-electrode assembly. The laser wavelength was scanned over several water rotational and vibrational transitions and the light absorption was detected by measuring the transmitted laser power through the device. The intensity and line shape of the measured transition was used to extract path-averaged values for the water vapor partial pressure. Measurements were initially taken in a non-operating cell with known temperature and humidity input gas streams to calibrate and test the optical device. A technique for rapid determination of the water partial pressure was developed. The optical technique is applicable over a significant temperature and humidity operating range of a PEM fuel cell. The measurement technique was applied to an operating PEM fuel cell system to examine the effects of incoming gas humidity and load on the water vapor partial pressure variation in one of the flow channels.

Dependence of the Electrochemical Performance of Ni/YSZ Anode on Water Vapor Partial Pressure

2019 ◽  
Vol 91 (1) ◽  
pp. 1973-1978
Author(s):  
Riyan Achmad Budiman ◽  
Tomohiro Ishiyama ◽  
Shu-Sheng Liu ◽  
Katherine Develos- Bagarinao ◽  
Haruo Kishimoto ◽  
...  
Keyword(s):  
Water Vapor ◽  
Electrochemical Performance ◽  
Partial Pressure ◽  
Vapor Partial Pressure ◽  
Water Vapor Partial Pressure

Air Dehumidification with the Porous Hydrophobic Wall in Underground Tunnel

2012 ◽  
Vol 518-523 ◽  
pp. 4409-4412
Author(s):  
Zhong Qing Cheng ◽  
Hai Bo Jiang ◽  
Yan Ru Li
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Mass Transfer Rate ◽  
Subsurface Temperature ◽  
Air Velocity ◽  
Tunnel Wall ◽  
Concentration Difference ◽  
Underground Tunnel ◽  
Vapor Partial Pressure ◽  
Humidity Range

Air can be dehumidified with the porous hydrophobic wall in mostly underground tunnel in constant zone of subsurface temperature. For water vapor through the wall, it must produce a concentration difference between both sides of the wall. According to this principle, a test is done combined with repair works on an underground tunnel. The hydrophobic porous mortar is scraped on geotextile, which is pasted on the painted original tunnel wall as hydraulic conductivity layer where vapor condense and water flow away. It is recognized that temperature and mass transfer rate is relative to tunnel air velocity, air temperature and partial pressure of water vapor, the temperature in constant zone of subsurface temperature and the saturated water vapor partial pressure. Comparative test results show that the condensation dew on the wall is disappeared completely, the wall dehumidifies air effectively, and saving dehumidifier power is more than 50% in normal humidity range.

Interaction of H2O, O2 and H2 with Proton Conducting Oxides Based on Lanthanum Scandates

2019 ◽  
pp. 88-100
Author(s):  
A. S. Farlenkov ◽  
N. A. Zhuravlev ◽  
Т. A. Denisova ◽  
М. V. Ananyev
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Gas Phase ◽  
Molecular Hydrogen ◽  
Proton Magnetic Resonance ◽  
Partial Pressure Of Oxygen ◽  
Proton Conducting ◽  
Conducting Oxides ◽  
Temperature Range ◽  
Apparent Level

The research uses the method of high-temperature thermogravimetric analysis to study the processes of interaction of the gas phase in the temperature range 300–950 °C in the partial pressure ranges of oxygen 8.1–50.7 kPa, water 6.1–24.3 kPa and hydrogen 4.1 kPa with La1–xSrxScO3–α oxides (x = 0; 0.04; 0.09). In the case of an increase in the partial pressure of water vapor at a constant partial pressure of oxygen (or hydrogen) in the gas phase, the apparent level of saturation of protons is shown to increase. An increase in the apparent level of saturation of protons of the sample also occurs with an increase in the partial pressure of oxygen at a constant partial pressure of water vapor in the gas phase. The paper discusses the causes of the observed processes. The research uses the hydrogen isotope exchange method with the equilibration of the isotope composition of the gas phase to study the incorporation of hydrogen into the structure of proton-conducting oxides based on strontium-doped lanthanum scandates. The concentrations of protons and deuterons were determined in the temperature range of 300–800 °C and a hydrogen pressure of 0.2 kPa for La0.91Sr0.09ScO3–α oxide. The paper discusses the role of oxygen vacancies in the process of incorporation of protons and deuterons from the atmosphere of molecular hydrogen into the structure of the proton conducting oxides La1–xSrxScO3–α (x = 0; 0.04; 0.09). The proton magnetic resonance method was used to study the local structure in the temperature range 23–110 °C at a rotation speed of 10 kHz (MAS) for La0.96Sr0.04ScO3–α oxide after thermogravimetric measurements in an atmosphere containing water vapor, and after exposures in molecular hydrogen atmosphere. The existence of proton defects incorporated into the volume of the investigated proton oxide from both the atmosphere containing water and the atmosphere containing molecular hydrogen is unambiguously shown. The paper considers the effect of the contributions of the volume and surface of La0.96Sr0.04ScO3–α oxide on the shape of the proton magnetic resonance spectra.

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