Effect Of Water Vapor Research Articles

How Does a Pinatubo‐Size Volcanic Cloud Reach the Middle Stratosphere?

AbstractVolcanic explosions are the most critical replenishing mechanism of the stratospheric aerosol Junge layer. A fresh volcanic cloud comprises mostly sulfur‐bearing gases, volcanic ash, and water vapor. It is commonly assumed that only sulfate aerosols remain in an aged volcanic cloud. Accurate simulation of the initial evolution of multicomponent fresh volcanic clouds is largely missing due to insufficient spatial resolution and a lack of relevant physics in global climate models. However, this initial stage is essential, as the vertical structure, composition, and altitude of a freshly developed volcanic cloud affect its long‐term evolution. To fill this gap, we modified a regional WRF‐Chem model to study the dispersion of a Pinatubo‐size volcanic cloud in the equatorial belt with a 25 km grid spacing explicitly accounting for the SO2, ash, sulfate, water vapor, and hydrometeors radiative effects. The model best reproduces the observed evolution of the Pinatubo optical depth when eruptive products are injected above the cold tropical tropopause at 17 km. During the first week, the volcanic cloud in our simulations rises 1 km/day. Ash is primarily responsible for the heating and lofting of the volcanic products. Radiative heating of SO2 is weaker than that of ash and sulfate but is sufficient to position the core of the SO2 layer 1–2 km above the sulfate layer. Utilizing a more realistic description of the volcanic cloud's initial stage potentially improves overall volcanic cloud predictability. It might also be essential to designing geoengineering technologies based on the injection of aerosol precursors in the lower stratosphere.

Effects of water vapour on 2-mercaptobenzothiazole corrosion inhibitor films deposited on copper

The effects of water on 2-mercaptobenzothiazole (2-MBT) film pre-formed on copper at low pressure and room temperature was investigated in situ by X-ray photoelectron spectroscopy. Upon exposure to water vapour at 5 × 10−6 mbar, the 2-MBT molecules not directly bonded to copper desorb, until only one monolayer remains adsorbed. Further exposure leads to cleavage of the bond between exocyclic sulphur and copper, whereas nitrogen remains bonded to copper. Dissociative adsorption of water is observed, without copper oxidation for exposure up to 3 × 106 L. This work brings new molecular scale insight into corrosion inhibition mechanisms in water-containing environments.

Structure-controllable synthesis of ZnO nanowires using water vapor in an atmospheric-pressure microwave plasma system

Although the use of atmospheric-pressure microwave plasma to synthesize ZnO nanowires addresses various issues associated with conventional synthesis methods, it is difficult to obtain nanowires with controlled diameters and lengths. Herein, we investigated the effects of microwave input power and water vapor on the structure of ZnO nanowires grown using an atmospheric-pressure microwave plasma system. It was found that the aspect ratio of ZnO nanowires could be controlled by adjusting the plasma temperature and the amount of OH radicals. This method successfully produced ZnO nanowires in a structure-controllable manner with a wide range of aspect ratios from 10 to 340. Interestingly, we found that the sensitivity of the ZnO nanowires to UV irradiation was closely related to the morphology. In particular, the ZnO nanowires with high aspect ratios and densities showed excellent sensing characteristics.

Simplification of the CCVD method used in the growth of carbon nanotube forests on titanium substrate

The carbon nanotubes (CNTs) play an important role in nanotechnology research today as they have the potential to be used in several areas. Environmental protection is highly discussed nowadays, which is why it is necessary to be able to produce CNT forests with less energy investment and simply, for these reasons we used the dip-coating layer construction method, which is a simple process. We also would like to simplify the production of CNT forests by changing several parameters used in the syntheses (concentration of ink, catalyst ratios, temperature, the effect of heat-treatment, hydrogen, and water vapor, reaction time, carbon source). For these reasons, this research uses a dip-coating method to form a catalyst layer on the surface of the substrate, as well as to investigate various parameters to produce CNT forests directly on the titanium substrate, as it is important today to use a conductive substrate.

Chemical kinetic analysis of in-cylinder ion current generation under direct water injection within internal combustion Rankine cycle engine

Direct water injection provides feasible solution for combustion optimization and efficiency enhancement within internal combustion Rankine cycle engine, while the feedback signal of close-loop direct water injection control is still absent. Ion current detection monitors in-cylinder electron variation which shows potential in revealing direct water injection process. For better understanding of unprecedented augment of ion current signal under direct water injection within internal combustion Rankine cycle engine, a chemical kinetic model is established to calculate the effect of intake oxygen fraction, fuel quantity, initial temperature, and residual water vapor on in-cylinder electron formation based on GRI Mech 3.0 and ion current skeleton mechanism. The simulation results indicate direct water injection process show significant impact on in-cylinder electron formation through chemical interactions between H2O and other intermediate species including HO2, O2, CH3, and H, these reactions provides additional OH radical for propane oxidation facilitation, which result in large portion of CH radical formation and therefore, lead to higher in-cylinder electron generation. The initial temperature plays a vital role in determining whether residual water vapor show positive or negative effect by in-cylinder temperature co-ordination of direct water injection. Results of this work can be used to explain phenomenon related to direct water injection and ion current signal variation under both internal combustion Rankine cycle or traditional petrol engine.

Understanding the Effect of Water on CO2 Adsorption

Carbon capture from large sources and ambient air is one of the most promising strategies to curb the deleterious effect of greenhouse gases. Among different technologies, CO2 adsorption has drawn widespread attention mostly because of its low energy requirements. Considering that water vapor is a ubiquitous component in air and almost all CO2-rich industrial gas streams, understanding its impact on CO2 adsorption is of critical importance. Owing to the large diversity of adsorbents, water plays many different roles from a severe inhibitor of CO2 adsorption to an excellent promoter. Water may also increase the rate of CO2 capture or have the opposite effect. In the presence of amine-containing adsorbents, water is even necessary for their long-term stability. The current contribution is a comprehensive review of the effects of water whether in the gas feed or as adsorbent moisture on CO2 adsorption. For convenience, we discuss the effect of water vapor on CO2 adsorption over four broadly defined groups of materials separately, namely (i) physical adsorbents, including carbons, zeolites and MOFs, (ii) amine-functionalized adsorbents, and (iii) reactive adsorbents, including metal carbonates and oxides. For each category, the effects of humidity level on CO2 uptake, selectivity, and adsorption kinetics under different operational conditions are discussed. Whenever possible, findings from different sources are compared, paying particular attention to both similarities and inconsistencies. For completeness, the effect of water on membrane CO2 separation is also discussed, albeit briefly.

Monitoring precipitable water vapour in near real-time to correct near-infrared observations using satellite remote sensing

Context. In the search for small exoplanets orbiting cool stars whose spectral energy distributions peak in the near infrared, the strong absorption of radiation in this region due to water vapour in the atmosphere is a particularly adverse effect for ground-based observations of cool stars. Aims. To achieve the photometric precision required to detect exoplanets in the near infrared, it is necessary to mitigate the effect of variable precipitable water vapour (PWV) on radial-velocity and photometric measurements. The aim is to enable global PWV correction by monitoring the amount of precipitable water vapour at zenith and along the line of sight of any visible target. Methods. We developed an open-source Python package that uses imagery data obtained with the Geostationary Operational Environmental Satellites (GOES), which provide temperature and relative humidity at different pressure levels to compute the near real-time PWV above any ground-based observatory that is covered by GOES every 5 min or 10 min, depending on the location. Results. We computed PWV values on selected days above Cerro Paranal (Chile) and San Pedro Mártir (Mexico) to benchmark the procedure. We also simulated different pointing at test targets as observed from the sites to compute the PWV along the line of sight. To asses the accuracy of our method, we compared our results with the on-site radiometer measurements obtained from Cerro Paranal. Conclusions. Our results show that our publicly available code proves to be a good supporting tool for measuring the local PWV for any ground-based facility within the GOES coverage, which will help to reduce correlated noise contributions in near-infrared ground-based observations that do not benefit from on-site PWV measurements.

Effect of Water Vapor on Alumina Scale Growth Based on First-Principles Calculations

Despite much effort directed at elucidating the impact of water vapor on the high-temperature oxidation behavior of metallic materials, a complete understanding of its atomistic mechanisms remains ...

The effect of H2O on the sulfation of Havelock limestone under oxy-fuel conditions in a thermogravimetric analyser.

A gas mixture representing oxy-fuel combustion conditions was employed in a thermogravimetric analyser to determine the effect of water vapor and SO2 concentration on limestone sulfation kinetics over the temperature range of 800 to 920 °C. Here, experiments used small samples of particles (4 mg), with small particle sizes (dp < 38 µm) and large gas flow rates (120 mL/min@NTP) in order to minimize mass transfer interferences. The gas mixture contained 5000 ppmv SO2, 2% O2, and the H2O content was changed from 0% to 25% with the balance CO2. When water vapor was added to the gas mixture at lower temperatures (800–870 °C), the limestone SO2 capture efficiency increased. However, as the temperature became higher, the enhancement in total conversion values decreased. As expected, Havelock limestone at higher temperatures (890 °C, 920 °C, and 950 °C) experienced indirect sulfation and reacted at a faster rate than for lower temperatures (800–870 °C) for direct sulfation over the first five minutes of reaction time. However, the total conversion of Havelock limestone for direct sulfation was generally greater than for indirect sulfation.

Investigation on the effect of superheated water vapor on gas production from pyrolysis of long-flame coal

A self-developed superheated water vapor pyrolysis system was used to conduct superheated water vapor pyrolysis experiments on Tashan and Madaotou long-flame coals at 350–534 °C. The gas phase products were analyzed by gas chromatography. The yield and composition of gas phase pyrolysis products from two different long-flame coals were determined, and the role of superheated water vapor in the pyrolysis process was elucidated. The optimal temperature of the long-flame coal injection superheated water vapor mining technology was obtained through heat value analysis. The results showed that when the temperature of the superheated water vapor exceeded 400 °C, the yield and combustible components of the gas phase products rapidly increased. As such, the release rate reached 10–15 times that observed below 400 °C, and the components of the combustible gases, such as hydrocarbon gas and hydrogen, exceeded 80%. Superheated water vapor not only is an excellent heat and mass transfer medium, but also provides a reactant for the re-formation reaction of hydrocarbon gas. The pyrolysis of long-flame coal under superheated water vapor at 500 °C yielded the best economic benefits. The low calorific value of gas phase products produced via pyrolysis per ton of coal per unit time could reach 715 MJ/(t·h).

Corrosion behaviour of iron and nickel aluminide coatings under the synergistic effect of NaCl and water vapour

Fe-Al and Ni-Al coatings were prepared by aluminizing ferritic-martensitic steels without and with pre-electroplating a Ni film, respectively. The corrosion behaviour of two aluminide coatings in marine environment, where high temperature oxidation and corrosion occur under the synergistic effect of solid NaCl and water vapour, were investigated. The results indicated that Ni-Al coatings showed superior corrosion resistance to Fe-Al coatings, the improved performance is mainly due to the beneficial influence of the Ni-plating layer on inhibiting self-sustainable oxychlorination, tungsten outward diffusion and interdiffusion behaviour. The detrimental effects of Fe on breakaway oxidation of Fe-Al coatings are discussed.

The Effect of Hydrogen Production Rate of the via Different Preparation of Co-Based Catalyst with Sodium Borohydride

This study processed the water vapor entrained in the NaBH4 hydrogen production reaction inside the primary hydrogen production tank through the secondary hydrogen production tank, in order to increase total hydrogen production. γ-Al2O3 was used as the carrier for the hydrolytic hydrogen production reaction in the primary hydrogen production tank. The reaction was chelated with metal catalyst Co2+ at different concentrations to produce the catalyst. Next, the adopted catalyst concentration and different catalyst bed temperatures were tested. The secondary hydrogen production tank was tested using NaBH4 powder and multiple NaBH4+ Co2+ mixed powders at different ratios. The powder was refined by ball milling with different steel ball ratios to enlarge the contact area between the water vapor and powder. The ball milling results from carriers at different concentrations, different catalyst bed temperatures, NaBH4+ Co2+ mixed powders in different ratios and different steel ball ratios were discussed as the hydrogen production rate and hydrogen production in relation to the hydrolytic hydrogen production reaction. The experimental results show that the hydrolytic hydrogen production reaction is good when 45 wt% Co2+/γ-Al2O3 catalyst is placed in the primary hydrogen production tank at a catalyst bed temperature of 55 °C. When the NaBH4+ Co2+ mixed powder in a ratio of 7:3 and steel balls in a ratio of 1:4 were placed in the secondary hydrogen production tank for 2 h of ball milling, the hydrogen production increased favorably. The hydrogen storage can be increased effectively without wasting the water vapor entrained in the hydrolytic hydrogen production reaction, and the water vapor effect on back-end storage can be reduced.

Mapping of thermal power plant emitted atmospheric carbon dioxide concentration using AVIRIS-NG data and atmospheric radiative transfer model simulations

Our study demonstrates the potential of Airborne Visible/Infrared Imaging Spectrometer Next Generation (AVIRIS-NG) hyperspectral data and radiative transfer modeling to retrieve the atmospheric carbon dioxide (CO2) concentration from point source emission of one of India’s major coal-fed super thermal power plants at Kota, Rajasthan, India. AVIRIS-NG data with synchronous in situ measurements were collected as a part of the first ISRO-NASA joint airborne hyperspectral science campaign in India. The method utilized in our study includes theoretical simulations of at-sensor radiance in AVIRIS-NG spectral bands through the atmospheric radiative transfer model MODTRAN. Simulations were performed for the specific scene-sensor-atmospheric conditions pertaining to AVIRIS-NG overpass over Kota site. To eliminate the interfering effect of atmospheric water vapor with CO2 concentrations, simulations pertaining to variable water vapor values varying from 0.25 to 4.5 g / cm2 were also carried out, which in turn were utilized to normalize the water vapor effects. Based upon the simulation results pertaining to the specific absorption bands of CO2 in the shortwave infrared spectral range of AVIRIS-NG radiance data, a theoretical model was established between continuum interpolated band ratio (CIBR) and CO2 concentration. The CIBR − CO2 model coefficients for each of the water vapor subranges were then applied to AVIRIS-NG L1 radiance data to obtain the CO2 concentration map of the study area. A distinct CO2 plume could be detected from the coal-fed Kota Super Thermal Power Station with the CO2 concentration (XCO2) of the order of more than 500 ppmv near the power plant stacks. A range of XCO2 from 400 to 550 ppmv was observed within the scene. Our study has provided promising results in mapping the atmospheric CO2 content from the point source using the high-resolution airborne hyperspectral AVIRIS-NG data.

Cu-Co mixed oxide catalysts for the total oxidation of toluene and propane

Cu-Co mixed oxides were fabricated via co-precipitation, characterized by TG/DTA, FTIR, ICP, XRD, Raman and CO-TPR, and tested in the total oxidation of toluene and propane. Adding an appropriate amount of copper to cobalt oxide caused structural defects and weakened the CoO bond, thereby benefiting the activation of oxygen. Moreover, the reducibility of Co3O4 was greatly improved in the presence of copper. In terms of toluene oxidation, a promoting effect of Cu was observed in both activity and durability, which could be related to the enhanced redox ability induced by the strong Cu-Co interaction and the inhibitory effect of Cu on the accumulation of surface carbonaceous species, respectively. Cu0.2Co exhibited the best toluene oxidation performance (T90 = 240 °C) and excellent long-term durability. On the other hand, in propane oxidation, the activity of the Cu-Co catalysts decreased dramatically as the copper content increased, due to the extremely low intrinsic activity of CuO. The effects of CO2, water vapor and NO on propane oxidation over Co3O4 and Cu0.2Co were also examined.

Mechanical properties of graphene oxide\u2013silk fibroin bionanofilms via nanoindentation experiments and finite element analysis

Understanding the mechanical properties of bionanofilms is important in terms of identifying their durability. The primary focus of this study is to examine the effect of water vapor annealed silk fibroin on the indentation modulus and hardness of graphene oxide–silk fibroin (GO–SF) bionanofilms through nanoindentation experiments and finite element analysis (FEA). The GO–SF bionanofilms were fabricated using the layer-by-layer technique. The water vapor annealing process was employed to enhance the interfacial properties between the GO and SF layers, and the mechanical properties of the GO–SF bionanofilms were found to be affected by this process. By employing water vapor annealing, the indentation modulus and hardness of the GO–SF bionanofilms can be improved. Furthermore, the FEA models of the GO–SF bionanofilms were developed to simulate the details of the mechanical behaviors of the GO–SF bionanofilms. The difference in the stress and strain distribution inside the GO–SF bionanofilms before and after annealing was analyzed. In addition, the load-displacement curves that were obtained by the developed FEA model conformed well with the results from the nanoindentation tests. In summary, this study presents the mechanism of improving the indentation modulus and hardness of the GO–SF bionanofilms through the water vapor annealing process, which is established with the FEA simulation models.

The effect of water vapor containing hydrogenous atmospheres on the microstructure and tendency to brittle fracture of anode materials of YSZ–NiO(Ni) system

Purpose: The purpose of this work is to estimate the tendency to brittle fracture of the YSZ–NiO(Ni) anode cermet in a hydrogenous environment with various concentrations of water vapor. Design/methodology/approach: YSZ–NiO ceramic plates were fabricated by sintering in an argon atmosphere. The treatment of material was performed in a hydrogenous environment with various concentrations of water vapor. The strength test was performed under three-point bending at 20°C in air. The microstructure and morphology of the fracture surface of the specimens were studied using a scanning electron microscope (SEM) Carl Zeiss EVO-40XVP. The chemical composition was determined using an INCA ENERGY 350 spectrometer. Microhardness measurements were performed on a NOVOTEST TC-MKB1 microhardness tester. The configuration of the imprints and cracks formed was studied on an optical microscope Neophot-21. The porosity of the materials was investigated by analysing the SEM micrographs using the image processing technique. Findings: Peculiarities of changes in the microstructure, the morphology of specimens fracture surface, physical and mechanical characteristics of YSZ–NiO(Ni) material for solid oxide fuel cell (SOFC) anodes of different preconditioning modes aged under various partial pressures of water vapor in a hydrogenous environment are found. Research limitations/implications: To study the actual behaviour of the YSZ–NiO(Ni) anode material in the operating environment, it is necessary to evaluate its strength, Young’s modulus, microhardness, and fracture toughness by changing with a certain step the partial pressure of water vapor in the whole range noted in this work. Practical implications: Based on the developed approach to assessing the propensity to brittle fracture of the formed cermet microstructure, it is possible to obtain an anode material that will provide the necessary functional properties of a SOFC. Originality/value: An approach to estimating the propensity to brittle fracture of a formed cermet structure is proposed based on the microhardness and fracture toughness characteristics obtained by the Vickers indentation method.

Ammonia measurement in exhaled human breath using PCF sensor for medical applications

Diagnosis of diseases through exhalation is a new, noninvasive method. In this study, a new photonic crystal fiber (PCF) has been proposed for detecting ammonia gas in breath. The spectroscopy system contains a tunable laser source, a monochromator that sets the wavelength at the absorption line of ammonia gas, a PCF used as a cell gas, a detector, and a computer to monitor and show the results. The gas sensing attributes of photonic crystal fiber are analyzed through the Finite Element Method (FEM). According to the simulated result, the high relative sensitivity of 63.18% is obtained when the core is filled by ammonia gas at 1.544 µm wavelength. The effect of water vapor on ammonia gas is investigated. It is shown that with the addition of respiratory moisture, the sensor still has high sensitivity and less confinement loss. Therefore, it is almost insensitive to moisture. These results illustrate the high performance of the sensor designed and that it can be helpful for medical applications, especially in diagnosing renal failure.

Experimental study of the effect of water vapor on dynamics of a high electric field non-equilibrium diffuse discharge in air

We report results on the influence of relative humidity (RH) on the propagation speed, the intensity of the emitted light, the energy and the gas temperature of a pin-to-plane nanosecond pulsed discharge at atmospheric pressure in synthetic air. The discharge is generated under very high overvoltage (several tens of kilovolts) so that it propagates with a voluminous, diffuse, and stable pattern. It is shown that the water vapor content has a strong impact on the discharge dynamics for gas mixtures with high RH and for the highest electric field values. In particular, for voltage pulse amplitudes higher than 65 kV and RH higher than 30%, the propagation abruptly slows down and the light intensity profiles show a stronger emission at the pin which weakens in the rest of the gap. The electric energy is slightly lower in humid air, independently of water vapor concentration. Also, time and spatially resolved gas temperature measurements carried out for different voltages show a late and significant heating at the pin whatever the water vapor content. An evaluation of the energy consumed in fast heating processes is proposed, showing an increased energy consumption at the pin in highly humid air. Besides, the hypotheses allowing for the consideration of the rotational temperature of the second positive system (SPS) of nitrogen (N2(SPS)) as the gas temperature under high electric field conditions are discussed.

Global Spatial and Temporal Variation of the Combined Effect of Aerosol and Water Vapour on Solar Radiation

This study aims to calculate the combined and individual effects of the optical thickness of aerosols (AOT) and precipitable water vapour (PWV) on the solar radiation reaching the Earth’s surface at a global scale and to analyse its spatial and temporal variation. For that purpose, a novel but validated methodology is applied to CERES SYN1deg products for the period 2000–2019. Spatial distributions of AOT and PWV effects, both individually and combined, show a close link with the spatial distributions of AOT and PWV. The spatially averaged combined effect results in a −13.9% reduction in irradiance, while the average AOT effect is −2.3%, and the PWV effect is −12.1%. The temporal analysis focuses on detecting trends in the anomalies. The results show overall positive trends for AOT and PWV. Consequently, significant negative overall trends are found for the effects. However, significant positive trends for the individual AOT and the combined AOT-PWV effects are found in specific regions, such as the eastern United States, Europe or Asia, indicating successful emission control policies in these areas. This study contributes to a better understanding of the individual and combined effects of aerosols and water vapour on solar radiation at a global scale.

Multi-Hollow Surface Dielectric Barrier Discharge for Bacterial Biofilm Decontamination

The plasma-activated gas is capable of decontaminating surfaces of different materials in remote distances. The effect of plasma-activated water vapor on Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli biofilm contamination was investigated on the polypropylene nonwoven textile surface. The robust and technically simple multi-hollow surface dielectric barrier discharge was used as a low-temperature atmospheric plasma source to activate the water-based medium. The germicidal efficiency of short and long-time exposure to plasma-activated water vapor was evaluated by standard microbiological cultivation and fluorescence analysis using a fluorescence multiwell plate reader. The test was repeated in different distances of the contaminated polypropylene nonwoven sample from the surface of the plasma source. The detection of reactive species in plasma-activated gas flow and condensed activated vapor, and thermal and electrical properties of the used plasma source, were measured. The bacterial biofilm decontamination efficiency increased with the exposure time and the plasma source power input. The log reduction of viable biofilm units decreased with the increasing distance from the dielectric surface.