Water vapor interference in the measurement of ozone in ambient air by ultraviolet absorption

1991 ◽  
Vol 62 (1) ◽  
pp. 223-228 ◽  
Author(s):  
C. P. Meyer ◽  
C. M. Elsworth ◽  
I. E. Galbally
Keyword(s):  
Water Vapor ◽  
Ambient Air ◽  
Ultraviolet Absorption

Effect of Water Vapor and SOx in Air on the Cathodes of Solid Oxide Fuel Cells

2007 ◽  
Vol 1041 ◽  
Author(s):  
Seon Hye Kim ◽  
Toshihiro Ohshima ◽  
Yusuke Shiratori ◽  
Kohei Itoh ◽  
Kazunari Sasaki
Keyword(s):  
Water Vapor ◽  
Solid Oxide Fuel Cells ◽  
Degradation Mechanism ◽  
Chemical Species ◽  
Cell Voltage ◽  
Ambient Air ◽  
Open Circuit ◽  
Constant Current ◽  
Constant Current Density

AbstractAmbient air is used as an oxygen source in SOFCs to be commercialized. Various chemical species which can lead to poisoning of SOFC cathodes are included as minor constitutions in air, such as water vapor, SOx, NOx and NaCl etc. However, their effects on the cathode performance have not yet well known, even though they are expected to cause a degradation of the electrode performance and to reduce the long-term durability of SOFCs. Therefore, in this study, we focused on the poisoning caused by water vapor and SOx in the oxygen source to clarify their effects on SOFCs performances and to reveal the degradation mechanism of cathodes. SOFCs with typical electrolyte-supported structure were used in this work, which were composed with ScSZ (10 mol% Sc2O3, 1mol% CeO2, 89 mol% ZrO2) plate with the thickness of 200 µm as electrolyte, NiO-ScSZ (mixture of 56 wt% NiO and 44 wt% ScSZ) porous layer as anode, and two cathode layers of LSM ((La0.8Sr0.2)0.98MnO3) and LSM-ScSZ (mixture of 50 wt% LSM and 50 wt% ScSZ). Power generation characteristics of the cells had been analyzed by measuring cell voltage at a constant current density (200 mA/cm2) and by comparing changes in cell impedance, upon supplying the artificially-contaminated air with water vapor or SOx, to the SOFC cathodes at various operational temperatures. High-resolution FESEM (S-5200, Hitachi) was used to analyze microstructural changes caused by the impurities. Mg Kα radiation from a monochromatized X-ray source was used for XPS measurements (ESCA-3400, KRATOS). AC impedance was measured at various temperatures under the open circuit voltage condition by an impedance analyzer (Solatron 1255B/SI 1287, Solatron), in a frequency range from 0.1 to 105 Hz with an amplitude of 10 mV.

Humidity-Dependent Cold Cells on the Antenna of the Stick Insect

2007 ◽  
Vol 97 (6) ◽  
pp. 3851-3858 ◽  
Author(s):  
Harald Tichy
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Partial Pressure ◽  
Systematic Study ◽  
Water Vapor Pressure ◽  
Ambient Air ◽  
Stick Insect ◽  
Proper Choice ◽  
Impulse Frequency ◽  
Order Of Magnitude

We present the first systematic study of the response of insect “cold cells” to a variation in the partial pressure of water vapor in ambient air. The cold cells on the antenna of the stick insect respond with an increase in activity when either the temperature or the partial pressure of water vapor is suddenly reduced. This double dependency does not in itself constitute bimodality because it could disappear with the proper choice of parameters involving temperature and humidity. In this study, we demonstrate that the evaporation of a small amount of water from the sensillum surface resulting from a drop in the water vapor pressure—leading to a transient drop in temperature and thus to a brief rise in impulse frequency—is the most plausible explanation for this bimodal response. We also show with an order-of-magnitude calculation that this mechanism is plausible and consistent with the amounts of water vapor potentially present on the sensillum. We hypothesize that a film of moisture collects on the hygroscopic sensillum surface at higher humidity and then tends to evaporate when humidity is lowered. The water might even be bound loosely within the cuticular wall, a situation conceivable in a sensillum that contains two hygroreceptive cells in addition to the cold cell.

Electrothermal Properties of Porous Ceramic Fiber Media Containing Carbon Materials

2007 ◽  
Vol 7 (11) ◽  
pp. 3776-3779
Author(s):  
Sung Park ◽  
Young Pil Kwon ◽  
Hyuck Chon Kwon ◽  
Ju-Hyeon Lee ◽  
Hae-Weon Lee ◽  
...  
Keyword(s):  
Water Vapor ◽  
Carbon Materials ◽  
Porous Ceramic ◽  
Ambient Air ◽  
Ceramic Fiber ◽  
Regeneration System ◽  
Sample Weight ◽  
Experimental Apparatus ◽  
Electrothermal Desorption

Electrically regenerable porous ceramic fiber media containing nanoporous carbon from 2.5% to 19.2% have been prepared for adsorption/regeneration system. An experimental apparatus was built for in situ measurement of the sample weight during adsorption and electrothermal desorption of gaseous adsorbates. Adsorption and electrothermal desorption behavior of gaseous adsorbates on carbon contained porous ceramic fiber media was explained by physical and electrothermal properties of these materials measured in this work. In situ thermal desorption and adsorption experiments showthat a considerable amount of water vapor is adsorbed on the carbon contained media exposed to ambient air.

scholarly journals In situ measurements of water vapor, heat, and CO2 fluxes within a prescribed grass fire

2006 ◽  
Vol 15 (3) ◽  
pp. 299 ◽  
Author(s):  
Craig B. Clements ◽  
Brian E. Potter ◽  
Shiyuan Zhong
Keyword(s):  
Water Vapor ◽  
Dynamic Environment ◽  
Ambient Air ◽  
Lower Atmosphere ◽  
Fuel Load ◽  
Fire Plumes ◽  
Smoke Plumes ◽  
Water Vapor Mixing Ratio ◽  
Good Agreement

Fluxes of water vapor, heat, and carbon dioxide associated with a prescribed grass fire were documented quantitatively using a 43-m instrumented flux tower within the burn perimeter and a tethered balloon sounding system immediately downwind of the fire. The measurements revealed significant increases of temperature (up to 20°C), heat flux (greater than 1000 W m–2), and CO2 (larger than 2000 parts per million by volume) within the smoke plumes, as well as an intensification of turbulent mixing. Furthermore, the observations revealed an increase in water vapor mixing ratio of more than 2 g kg–1, or nearly 30% over the ambient air, which is in good agreement with theoretical estimates of the amount of water vapor release expected as a combustion by-product from a grass fire. These observations provide direct evidence that natural fuel-load grass-fire plumes may modify the dynamic environment of the lower atmosphere through not only heat release and intense mixing, but also large addition of water vapor.

scholarly journals Aktifasi Campuran Zeolit Alam Dan Flyash Batubara Menggunakan Microwave Sebagai Filter Udara Untuk Meningkatkan Akselerasi Mesin Sepeda Motor Bensin 4-Langkah

2020 ◽  
Vol 8 (2) ◽  
pp. 25-28
Author(s):  
Bintoro Niko Renardy ◽  
Herry Wardono ◽  
M Dyan Susila ES
Keyword(s):  
Water Vapor ◽  
Coal Combustion ◽  
Chemical Process ◽  
Engine Performance ◽  
Ambient Air ◽  
Density Variation ◽  
Petrol Engine ◽  
Activation Time ◽  
Air Filters

Combustion is a chemical process between fuel and oxygen utilizing heat. Ambient air contains avariety of gases such as nitrogen, oxygen, and other gases, causing incomplete combustion in thecombustion chamber of a 4-stroke petrol engine. The use of artificial air filters with zeolite-flyashcomposition activated by microwave can adsorb the air that enters the combustion chamber. So thatit can improve the quality of combustion. Zeolite is a mineral that is found in limestone mountainousareas, while coal flyash is material from coal combustion at PLTU. Both of these materials have theability to adsorb molecular sized particles such as nitrogen, CO and water vapor in the air, so theuse of both materials is able to produce air with rich oxygen. The performance of the 4-stroke petrolengine is influenced by a decrease in fuel consumption, able to increase acceleration, and reduceexhaust emissions containing CO and HC. To find out the effect of the use of activated zeolite-flyashfilters on engine performance, an acceleration test of 0-60 kph was performed. Filter beingactivated by Microwave with 80% power, 6 minutes activation time, and density (variation in thenumber of pellets in the filter) 50%, 75%, 100%, and use the Z0: F100, Z25: F75, Z50: F50, Z75:F25, Z100: F0. The best filter is the composition of Z100:F0 with a compactness of 50% able toincrease acceleration by 7.17%, followed by filter with composition of Z25:F75 with a compactnessof 50% able to increase acceleration by 4,04%.Keywords : Zeolites, Coal Flyash, Petrol Engine, Air Filters

scholarly journals High-accuracy continuous airborne measurements of greenhouse gases (CO<sub>2</sub> and CH<sub>4</sub>) using the cavity ring-down spectroscopy (CRDS) technique

2010 ◽  
Vol 3 (2) ◽  
pp. 375-386 ◽  
Author(s):  
H. Chen ◽  
J. Winderlich ◽  
C. Gerbig ◽  
A. Hoefer ◽  
C. W. Rella ◽  
...  
Keyword(s):  
Water Vapor ◽  
Greenhouse Gases ◽  
Ambient Air ◽  
High Accuracy ◽  
Mean Difference ◽  
Pressure Broadening ◽  
Cavity Ring Down Spectroscopy ◽  
Airborne Measurements ◽  
The Mean ◽  
Cavity Ring Down

Abstract. High-accuracy continuous measurements of greenhouse gases (CO2 and CH4) during the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia) phase B campaign in Brazil in May 2009 were accomplished using a newly available analyzer based on the cavity ring-down spectroscopy (CRDS) technique. This analyzer was flown without a drying system or any in-flight calibration gases. Water vapor corrections associated with dilution and pressure-broadening effects for CO2 and CH4 were derived from laboratory experiments employing measurements of water vapor by the CRDS analyzer. Before the campaign, the stability of the analyzer was assessed by laboratory tests under simulated flight conditions. During the campaign, a comparison of CO2 measurements between the CRDS analyzer and a nondispersive infrared (NDIR) analyzer on board the same aircraft showed a mean difference of 0.22±0.09 ppm for all flights over the Amazon rain forest. At the end of the campaign, CO2 concentrations of the synthetic calibration gases used by the NDIR analyzer were determined by the CRDS analyzer. After correcting for the isotope and the pressure-broadening effects that resulted from changes of the composition of synthetic vs. ambient air, and applying those concentrations as calibrated values of the calibration gases to reprocess the CO2 measurements made by the NDIR, the mean difference between the CRDS and the NDIR during BARCA was reduced to 0.05±0.09 ppm, with the mean standard deviation of 0.23±0.05 ppm. The results clearly show that the CRDS is sufficiently stable to be used in flight without drying the air or calibrating in flight and the water corrections are fully adequate for high-accuracy continuous airborne measurements of CO2 and CH4.

The Thermodynamics of Air-Water Vapor Mixtures

2000 ◽  
Author(s):  
George A. Adebiyi
Keyword(s):  
Water Vapor ◽  
Thermodynamic Analysis ◽  
Ambient Air ◽  
Moist Air ◽  
Humidity Ratio ◽  
Atmospheric Air ◽  
Analysis And Evaluation ◽  
Vapor Mixtures ◽  
Reference Environment ◽  
Traditional Approaches

Abstract Traditional approaches to the thermodynamic analysis of processes involving air-water vapor mixtures are often limited to a psychrometric analysis and a first-law analysis. The substances involved are moist air (a mixture of dry air and moisture), and water (either as vapor, or as a liquid). A complete thermodynamic analysis must, however, include a second-law analysis. This article presents a complete outline for the thermodynamic analysis and evaluation of processes involving air-water vapor mixtures. With regards to exergy analysis, in particular, it is noted that the published and widely accepted equation for the exergy of moist air is indeterminate when the humidity ratio of the ambient air is zero. This raises questions about the appropriate reference environment for water or water vapor when the atmospheric air does not contain moisture. The alternative of an expanded reference environment, which includes a large pool of water co-existing with ambient air is proposed in this article. The resulting equations for the exergy of moist air are determinate regardless of the humidity ratio of the atmospheric air in the reference environment.

Physiological responses of a rodent to heliox reveal constancy of evaporative water loss under perturbing environmental conditions

2014 ◽  
Vol 307 (8) ◽  
pp. R1042-R1048 ◽  
Author(s):  
Christine Elizabeth Cooper ◽  
Philip Carew Withers
Keyword(s):  
Water Vapor ◽  
Metabolic Rate ◽  
Environmental Conditions ◽  
Water Loss ◽  
Physiological Responses ◽  
Ambient Air ◽  
Minute Volume ◽  
Evaporative Water Loss ◽  
Evidence Based ◽  
Evaporative Water

Total evaporative water loss of endotherms is assumed to be determined essentially by biophysics, at least at temperatures below thermoneutrality, with evaporative water loss determined by the water vapor deficit between the animal and the ambient air. We present here evidence, based on the first measurements of evaporative water loss for a small mammal in heliox, that mammals may have a previously unappreciated ability to maintain acute constancy of total evaporative water loss under perturbing environmental conditions. Thermoregulatory responses of ash-grey mice ( Pseudomys albocinereus) to heliox were as expected, with changes in metabolic rate, conductance, and respiratory ventilation consistent with maintaining constancy of body temperature under conditions of enhanced heat loss. However, evaporative water loss did not increase in heliox. This is despite our confirmation of the physical effect that heliox augments evaporation from nonliving surfaces, which should increase cutaneous water loss, and increases minute volume of live ash-grey mice in heliox to accommodate their elevated metabolic rate, which should increase respiratory water loss. Therefore, mice had not only a thermoregulatory but also a hygroregulatory response to heliox. We interpret these results as evidence that ash-grey mice can acutely control their evaporative water loss under perturbing environmental conditions and suggest that hygroregulation at and below thermoneutrality is an important aspect of the physiology of at least some small mammals.

scholarly journals Comparison of nitrous oxide (N<sub>2</sub>O) analyzers for high-precision measurements of atmospheric mole fractions

2016 ◽  
Vol 9 (3) ◽  
pp. 1221-1238 ◽  
Author(s):  
Benjamin Lebegue ◽  
Martina Schmidt ◽  
Michel Ramonet ◽  
Benoit Wastine ◽  
Camille Yver Kwok ◽  
...  
Keyword(s):  
Water Vapor ◽  
High Precision ◽  
Temperature Stability ◽  
Ambient Air ◽  
Observation System ◽  
Monitoring Networks ◽  
Atmospheric Measurements ◽  
Short Term ◽  
Highly Nonlinear

Abstract. Over the last few decades, in situ measurements of atmospheric N2O mole fractions have been performed using gas chromatographs (GCs) equipped with electron capture detectors. This technique, however, becomes very challenging when trying to detect the small variations of N2O as the detectors are highly nonlinear and the GCs at remote stations require a considerable amount of maintenance by qualified technicians to maintain good short-term and long-term repeatability. With new robust optical spectrometers now available for N2O measurements, we aim to identify a robust and stable analyzer that can be integrated into atmospheric monitoring networks, such as the Integrated Carbon Observation System (ICOS). In this study, we present the most complete comparison of N2O analyzers, with seven analyzers that were developed and commercialized by five different companies. Each instrument was characterized during a time period of approximately 8 weeks. The test protocols included the characterization of the short-term and long-term repeatability, drift, temperature dependence, linearity and sensitivity to water vapor. During the test period, ambient air measurements were compared under field conditions at the Gif-sur-Yvette station. All of the analyzers showed a standard deviation better than 0.1 ppb for the 10 min averages. Some analyzers would benefit from improvements in temperature stability to reduce the instrument drift, which could then help in reducing the frequency of calibrations. For most instruments, the water vapor correction algorithms applied by companies are not sufficient for high-precision atmospheric measurements, which results in the need to dry the ambient air prior to analysis.

Preparation of microporous carbon foams for adsorption/desorption of water vapor in ambient air

2008 ◽  
Vol 23 (3) ◽  
pp. 216-220 ◽  
Author(s):  
Naoto Ohta ◽  
Yoko Nishi ◽  
Takahiro Morishita ◽  
Yumiko Ieko ◽  
Akifumi Ito ◽  
...  
Keyword(s):  
Water Vapor ◽  
Ambient Air ◽  
Microporous Carbon ◽  
Carbon Foams ◽  
Adsorption Desorption
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