Effect Of Water Vapor Research Articles

Sulphur poisoning, water vapour and nitrogen dilution effects on copper-based catalyst dynamics, stability and deactivation during CO2 reduction reactions to methanol

A model of methanol synthesis catalyst deactivation dependent on pressure, temperature and composition was developed to enable flexible process optimization in the era of the variable renewable supplies.

Effect of aging, temperature, and ambient gases on the complex impedance of As2Te13Ge8S3 glassy films

The work is focused on the application of the impedance spectroscopy method to provide evidence and study the effects of aging, temperature, and gas adsorption in chalcogenide-based thin films. The experiments are carried out with thin films of glassy quaternary composition As2Te13Ge8S3 in a wide frequency range at different temperatures under different environmental conditions, in particular, either dry or wet air or their mixtures with NO2 or CO2. It is found that aging has a significant effect on the impedance spectra of Pt–As2Te13Ge8S3–Pt functional structures, which make evidence for the presence of substantial spatial and compositional disordering. This effect can be stabilized by the post-preparation annealing of the sample. The effect of temperature on impedance spectra consists in a variation in the both real and imaginary parts of impedance that appear to be extremely sensitive to adsorptive processes. Adsorption of nitrogen dioxide results in a significant frequency-dependent decrease in the impedance parameters, which is attributed to an effective “strong” chemisorption process due to the interaction of "odd" electrons of NO2 molecules with lone pair electrons of chalcogen atoms. The effect of water vapors leads only to an increase in the real part of impedance, while the imaginary part abruptly decreases; this fact is attributed to a “weak” form of chemisorption. The effect of carbon dioxide on the impedance spectra is attributed to the physical adsorption of CO2 molecules. This effect is weak; however, it is reversible and clearly observed even at room temperature.

An isotopic strategy to investigate the role of water vapor in the oxidation of 1,2-dichloroethane over the Ru/WO3 or Ru/TiO2 catalyst

Electron paramagnetic resonance, in situ diffuse reflection infrared Fourier transform spectroscopy, and temperature-programmed techniques by means of the isotopic trace strategies were used to investigate the effects of water vapor on oxygen species, reaction pathways, byproducts distributions, and accumulation of the chlorine and carbon species on the catalyst surface for 1,2-dichloroethane oxidation over Ru/WO3 or Ru/TiO2 catalyst. The introduction of water vapor produced the OOH species that were converted into more active oxygen (O2– and O−) species. The mulliken population analysis indicates that βC and αC in VC are bonded with H and nucleophilic oxygen of −OH in sequence, respectively, which proved that water directly promoted the transformation of vinyl chloride to CH3COOH. Besides, water could be partially adsorbed at the hydroxyl groups on the Ru/WO3 sample surface, which were provided the adsorption sites for 1,2-dichloroethane molecules. However, the severe competitive adsorption on the surface of Ru/TiO2 resulted in insufficient oxygen adsorption to supplement the oxygen vacancy.

Water vapour characteristics and radiative effects at high-altitude Himalayan sites

We analyze long-term aerosol and precipitable water vapour (PWV) properties at two high-altitude sites (Nainital and Hanle) over the central Himalayan and western Trans-Himalayan region from 2008 to 2018. First-time assessment of the seasonality and variation in combined aerosol and water vapour radiative effects are also attempted, aiming to investigate the atmospheric effect on solar radiation over the Himalayan range that is especially important for the regional climate. A synergy of ground-based measurements from sun photometers, GPS (Global Positioning Systems) observations, radiosondes, along with satellite and reanalysis data was used to examine inter-annual and seasonal variability of PWV and specific humidity over both sites. The PWV is highest in monsoon and much lower during the dry winter season with slightly higher values at Nainital compared to Hanle. This is due to the lower altitude (∼2 km amsl) of Nainital, which is also directly affected by the Indian summer monsoon, compared to the Trans-Himalayan region. The vertical profiles of PWV from satellite and reanalysis data reveal a great consistency on a seasonal basis. The PWV is considered as one of the main greenhouse gases that exhibits a positive radiative effect at the Top of the Atmosphere (TOA) in the order of about 10 W m−2 at Nainital and 7.4 W m−2 at Hanle. The atmospheric radiative effect due to water vapour is about 3–4 times higher compared to aerosols, resulting in atmospheric heating rates of 0.94 and 0.96 K Day−1 at Nainital and Hanle, respectively. The results highlight the importance of water vapour and aerosol radiative effects in the climate sensitive Himalayan range.

Raman spectroscopic analysis of encapsulants in aged photovoltaic modules

The aging of an encapsulation material of a random copolymer of ethylene and vinyl acetate (EVA), in outdoor-exposed (OE) crystalline-silicon (c-Si) photovoltaic (PV) modules was investigated through nondestructive Raman spectroscopy. The effect of water vapor (WV) on the Raman spectra of EVA encapsulants in c-Si PV modules was also investigated after long-term damp-heat (DH) tests at 85 °C and 85 % relative humidity. The EVA encapsulants in the long-term OE modules showed two different shapes and intensities of broad Raman spectra due to the increased intensity of the fluorescence background (FB). The encapsulants at the center of c-Si solar cells in the long-term OE modules showed a high intensity of FB, which increased with the exposure time. On the other hand, the Raman spectra of the encapsulant at the edge of the c-Si solar cells resembled those of the DH-exposed (DHE) modules, with a similar shape and lower intensity of FB than at the center. The spectral results indicate that the encapsulants at the edge were affected by WV, similar to the same as the DHE condition. The DHE-type Raman spectra for the EVA encapsulants at the edge of c-Si solar cells in OE modules show that the acetic acid may be formed from the EVA encapsulants by WV, resulting in corrosion of finger electrodes on c-Si solar cells and consequently diminishing the performance of the modules.

Amine-functionalized nano-Al2O3 adsorbent for CO2 separation from biogas: Efficient CO2 uptake and high anti-urea stability

Amine-functionalized adsorbents have become a hot topic in research on CO2 separation from biogas. However, developing superior adsorbents with high adsorption capacity and stable cyclic stability under a CO2 regeneration atmosphere remains difficult. In this study, azeotropic distillation, a green, recyclable method, was used to expand the pores of the nano-Al2O3 support. The pore volume of pore-expanded nano-Al2O3 reached 1.62 cm3 g−1, and the derived amine-functionalized nano-Al2O3 adsorbent (‘60%PEI@AD-Al2O3’) possessed a superior CO2 uptake of 199.4 mg·g−1adsorbent with rapid adsorption kinetics. ‘60%PEI@AD-Al2O3’ showed favourable cyclic stability under CO2 regeneration atmosphere with a final CO2 uptake of 133.8 mg·g−1adsorbent after 50 cycles, which possessed a competitive CO2 uptake compared with the reported amine-functionalized adsorbents with anti-urea stability. This superior performance is attributed to the large pore volume of the pore-expanded nano-Al2O3 support and the anti-urea stability for ‘60%PEI@AD-Al2O3’, which does not require active amine modification and avoids diluting the active amine content. Furthermore, the effect of water vapour in biogas on adsorption performance was studied. Water vapour could significantly promote CO2 adsorption at low temperatures (<90 °C), and it was accompanied by strong water vapour adsorption, which would potentially increase the regeneration energy consumption. Additionally, water vapour could effectively inhibit the formation of urea compounds, further improving the cyclic stability. Because of the facile, scalable preparation method, the synthesised amine-functionalized nano-Al2O3 adsorbent has broad application prospects for CO2 separation.

The Effect of Oxygen and Water Vapor on the Electric Properties of (Co40Fe40B20)x(LiNbO3)100 – x Nanogranular Composites

The Effect of Oxygen and Water Vapor on the Electric Properties of (Co40Fe40B20)x(LiNbO3)100 – x Nanogranular Composites

Autonomous crack healing ability of SiC dispersed Yb2Si2O7 by oxidations in air and water vapor

Yb 2 Si 2 O 7 is a popular environmental barrier coating; however, it decomposes into Yb 2 SiO 5 in high-temperature steam environments. The thermal mismatch between Yb 2 Si 2 O 7 and Yb 2 SiO 5 leads to the cracking and failure of the disilicate coating via oxidation. Dispersing SiC nanofillers into the Yb 2 Si 2 O 7 matrix is suggested to maintain the Yb 2 Si 2 O 7 matrix and promote crack self-healing. This study is aimed at clarifying the effect of water vapor on the self-healing ability of such composites. X-ray diffraction analysis and scanning electron microscopy were used to monitor the surface composition and the crack formation, respectively, in 10 vol% SiC-dispersed Yb 2 Si 2 O 7 composites. Annealing at temperatures higher than 750 °C in air or in a water vapor rich atmosphere led to strength recovery and the self-healing of indentation-induced surface cracks owing to volume expansion during the oxidation of SiC. The self-healing effect was influenced by the oxidation time and temperature. Rapid diffusion of H 2 O as an oxidizer into the SiO 2 layer promoted self-healing in a water vapor rich atmosphere. However, accelerated oxidation at temperatures higher than 1150 °C formed bubbles on the surface. Fabricating composites with a small amount of Yb 2 SiO 5 will be a solution to these problems.

Influence of Water Vapor and Temperature on the Oxide Scale Growth and Alpha-Case Formation in Ti-6Al-4V Alloy

The Ti-6Al-4V alloy is extensively used in aerospace, automotive and biomaterial applications. In the aerospace industry, the service temperature of Ti-6Al-4V is currently limited to 350 °C due to its insufficient oxidation resistance. Oxidation at higher temperatures causes the formation of a fast-growing oxide scale and an oxygen-enriched subsurface layer, which is known as the “alpha-case.” Additionally, the effect of water vapor on the oxidation behavior is critical. In the present study, the oxidation behavior of Ti-6Al-4V in dry air and air containing 10 vol.% H2O at 500, 600 and 700 °C for up to 500 h has been investigated. The main focus of this study is the examination of the different oxide scale morphologies along with the oxygen enrichment in the subsurface zone. It has been observed that spallation of the oxide scale is more severe in a water vapor-containing environment. In dry air, the oxide morphology shows the typical layered TiO2/Al2O3 structure after exposure at 700 °C for 300 h, while Al2O3 precipitates are present in the outermost part of the TiO2 scale when oxidized in wet air. This indicates that the solubility and diffusivity of Al3+ ions in TiO2 are influenced by water vapor. In addition, the extent of oxygen enrichment in the subsurface zone (alpha-case) as a function of temperature and time is determined by nanoindentation profiles. It was shown that in contrast to the scale formation, the alpha-case thickness is not affected by the presence of water vapor in the atmosphere.

Reinforcement of Silk Microneedle Patches for Accurate Transdermal Delivery.

Microneedles (MNs) have attracted considerable attention in the pharmaceutical field as a minimally invasive delivery alternative to hypodermic needles. Current material systems of MNs have gradually shifted from metals, ceramics, and silicon to polymer in consideration of toughness and drug loading capacity. Silk fibroin (SF) is considered one of the most promising alternatives because it combines the ability to maintain the activity of biomolecules, adjustable mechanical strength, and excellent biocompatibility. However, the strength and hardness of SF MNs need to be carefully optimized to ensure skin epidermis penetration and controlled drug release, which are rarely explored in reported works. Here, the synergistic effect of glutaraldehyde-based cross-linking and water vapor annealing post-treatment is presented as an effective method to promote the formation of SF molecular networks and the mechanical strength of SF MNs. Moreover, the reinforced MN substrate is coated with a drug-loaded SF layer with low crystallinity. The drug release experiments demonstrate the successful controlled release of rhodamine B, horseradish peroxidase, and tetracycline, which suggests the great potential in the application of vaccine, antibiosis, cosmetology, and so forth.

Perancangan Sistem Fire Alarm Kebakaran Pada Gedung Laboratorium XXX

Abstract&#x0D; &#x0D; Fire is a phenomenon that occurs when a material reaches a critical temperature and reacts chemically with oxygen (for example) producing heat, flame, light, smoke, water vapor, carbon monoxide, carbon dioxide, or other products and effects. Fires can occur anywhere, be it in office buildings, residences or public facilities. As for other than in public areas, fires often occur, both in rooms and laboratories, the triggers are almost the same due to negligence and not being careful in using flammable tools. For this reason, the need for a fire detector with a detector system using an alarm so that once a fire occurs, all those in the building can find out through the detector with an alarm sound as a fire marker. In order to reduce casualties, the need for a sprinkler system to extinguish the fire, and can assist the officers or authorities in the building as soon as possible. From the above problems, this research will determine how many detectors and sprinklers are needed, as well as how much water volume, pump power, and ground water tank are needed. This type of research is quantitative research by direct observation of the object under study, then researchers measure the room one by one using a building meter. From the calculation results by taking a sample on the 1st floor, the number of detectors needed is 10 smoke detectors and 3 heat detectors, the number of sprinklers is 47, the volume of water needed is 846 m3, the pump power and ground water tank needed are hydraulic power. pump (HHP) 3,28621 kW, pump shaft power (BHP) 4.38 kW, pump electric power (P) 6 kW, diesel pump (PpD) 4 HP, jocky pump (PJk) 0.6 kW, capacity GWT ( QGWT) 44 m3.

Effect of Water Vapor on High-Temperature Oxidation Behavior of Fe–10 mass% Ni Alloy

Effect of Water Vapor on High-Temperature Oxidation Behavior of Fe–10 mass% Ni Alloy

Influence of water vapor and aerosols on downward longwave radiation in the high mountain region of Musala peak, Bulgaria

This study reveals the effect of aerosols and water vapor on downward longwave radiation in the high mountain region of Musala peak, Bulgaria. The investigated period is 01/01/2017 (Jan. 1st 2017) &amp;ndash; 30/09/2019 (Sep. 30th 2019). Statistical methods are the main tool for discovering the relationships between the different elements. The results indicate that air temperature is the leading factor for downward longwave radiation, specific humidity, and amount of aerosols in the air. That is why, in order to reveal the pure relationship between downward longwave radiation, specific humidity and amount of aerosols in the atmosphere, the air temperature was cleared from the data series. After this procedure, the results show that specific humidity has a significant influence on the downward longwave radiation flux, and an increase of 1% of the specific humidity results in an increase of about 12-15% in the values &amp;nbsp; of the downward longwave radiation. At air temperatures around 0&amp;ordm;C the influence of water vapor on the downward longwave flux is highest, which is due to the phase transitions of the water &amp;ndash; a process during which release/absorption of radiation in the longwave spectrum occurs. The amount of aerosols in the atmosphere also has a significant effect on this type of radiation, and an increase of 1% of the amount of aerosols in the air at air temperatures above &amp;ndash;5.5&amp;deg;C results in an increase of the downward longwave radiation of about 2-4%. The findings of this study show that coarser and opaque aerosol particles have a stronger effect on downward longwave radiation. In the area of Musala peak, as the air temperature rises, there is an increase in the amount of aerosols in the air, a decrease in their size, and a transition from transparent to opaque aerosols. The combination of these different tendencies causes the influence of aerosols on downward longwave radiation to be strongest in the middle temperature interval &amp;ndash; air temperatures between &amp;ndash;5.5&amp;deg;C and +5.5&amp;deg;C. Due to the increased total amount of aerosols and increased amount of opaque aerosols, their influence on downward longwave radiation is significant also at air temperatures above 5.5&amp;deg;C.

Hierarchical porous structure formation mechanism in food waste component derived N-doped biochar: Application in VOCs removal

Nitrogen-doped (N-doped) hierarchical porous carbon was widely utilized as an efficient volatile organic compounds (VOCs) adsorbent. In this work, a series of N-doped hierarchical porous carbons were successfully prepared from the direct pyrolysis process of three food waste components. The porous biochar that derived from bone showed a high specific surface area (1405.06 m2/g) and sizable total pore volume (0.97 cm3/g). The developed hierarchical porous structure was fabricated by the combined effect of self-activation (Carbon dioxide (CO2) and water vapor (H2O)) and self-template. The emission characteristics of activation gas analyzed by Thermogravimetric-Fourier transform infrared spectrometer (TG-FTIR) and the transformation of ash composition in the biochar help to illustrate the pore-forming mechanism. Calcium oxide (CaO) and hydroxylapatite were confirmed as the major templates for mesopores, while the decomposition processes of calcium carbonate (CaCO3) and hydroxylapatite provided a large amount of activation gas (CO2 and H2O) to form micropores. The materials also obtained abundant N-containing surface functional groups (up to 7.84 atomic%) from pyrolysis of protein and chitin. Finally, the porous biochar showed excellent performance for VOCs adsorption with a promising uptake of 288 mg/g for toluene and a high adsorption rate of 0.189 min−1. Aplenty of mesopores distributed in the materials effectively improved the mass transfer behaviors, the adsorption rate got a noticeable improvement (from 0.118 min−1 to 0.189 min−1) benefited from mesopores. Reusable potentials of the hierarchical porous carbons were also satisfying. After four thermal regeneration cycles, the materials still occupied 84.8%–87.4% of the original adsorption capacities.

Effect of Water Vapor on the Accelerated Deterioration Treatment of Cu-SSZ-13 as Catalysts for Selective Catalytic Reduction

Effect of Water Vapor on the Accelerated Deterioration Treatment of Cu-SSZ-13 as Catalysts for Selective Catalytic Reduction

Experimental and numerical investigation of iC8H18 laminar combustion characteristics based on hydrogen – water complementary regulation

The present study examines using water dilution and hydrogen as control measures to regulate the laminar burning velocity of iso-octane/air mixtures in a constant volume combustion bomb. Experimental results are obtained by processing schlieren photographs and simulation results are calculated by Chemkin software. The water dilution rates of the mixtures were between 0 and 5% and the hydrogen addition ratio was between 5 and 55%. The initial pressure was set at 101.3 kPa with the preheating temperature ranging from 400 K to 500 K. According to the results, laminar burning velocity varied almost linearly with the dilution of water and the addition of hydrogen, respectively. This study also distinguishes the thermal and kinetic effects of water on the combustion processes. The thermodynamic effect of water vapour on laminar burning velocity was higher than the kinetic effect. In kinetics, O, H, and OH were the most affected free radicals by the addition of water vapour. The main free radical change affected the rate of the elementary reaction. Besides, the kinetic effect of water vapour promoted combustion. However, this effect was offset by the thermodynamic effect. The introduced hydrogens of premixed mixtures did not lead to measurable improvements in laminar burning velocity. Additionally, the change in the reaction rate of the elementary reaction was not obvious, which was inconsistent with the change of laminar burning velocity. Lastly, a laminar burning velocity model using hydrogen and water vapor content as control parameters was proposed. Accordingly, the designated laminar burning velocity of the iso-octane/air mixture was achieved by altering hydrogen and water vapour ratios in the mixture. BP (Back-Propagation) neural network algorithm (a multi-layer feed forward neural network trained by error back propagation algorithm) and empirical data were used to verify the model, and the model’s maximum error was less than 5%.

The Effect of Water Vapor Originating from Land on the 2018 Drought Development in Europe

The 2018 summer drought in Europe was particularly extreme in terms of intensity and impact due to the combination of low rainfall and high temperatures. However, it remains unclear how this drought developed in time and space in such an extreme way. In this study we aimed to get a better understanding of the role of land–atmosphere interactions. More specifically, we investigated whether there was a change in water vapor originating from land, if that caused a reduction in rainfall, and by this mechanism possibly the propagation and intensification of the drought in Europe. Our first step was to use remote sensing products for soil moisture content (SMC) and the normalized difference vegetation index (NDVI) to see where the 2018 drought started and how it developed in time and space. Our SMC and NDVI analysis showed that the 2018 drought started to impact the soil and vegetation state in June in Scandinavia and the British Isles. After that it moved towards the west of Europe where it intensified in July and August. In September, it started to decay. In October, drought was observed in Southeast Europe as well. Based on the observed patterns we divided Europe into six regions of similar spatiotemporal characteristics of SMC and NDVI. Then, we used a global gridded dataset of the fate of land evaporation (i.e., where it ends up as precipitation) to investigate whether the drought intensification and propagation was impacted by the reduction in water vapor transported from the regions that first experienced the drought. This impact was investigated by identifying the anomalies in the water vapor originating from land recycling, imports, and exports within Europe during the spring, summer, and autumn seasons. From these regions we identified four drought regions and investigated the changes in water vapor originating from source regions on the development of drought in those regions. It was found that during the onset phase of the 2018 drought in Europe that the water vapor originating from land played an important role in mitigating the precipitation anomalies as, for example, the share of land evaporation contributing to precipitation increased from 27% (normal years) to 38% (2018) during July in the west of Europe. Land evaporation played a minor role in amplifying it during the intensification phase of the drought as the share of land evaporation contribution to precipitation decreased from 23% (normal years) to 21% (2018) during August in the west of Europe. These findings are somewhat in contrast to similar studies in other continents that found the land surface to play a strong amplifying role for drought development. Subsequently, we found that the relative increase in the amount of land water vapor originating from eastern half of Europe played a role in delaying the onset and accelerating the decay of the 2018 drought in the west of Europe.

Modelling of effects of water vapor and temperature gradient on moisture and gas transfer in unsaturated landfill cover

Modelling of effects of water vapor and temperature gradient on moisture and gas transfer in unsaturated landfill cover

Water‐CaO‐Al2O3 Join Interaction: Crystallization Behavior Investigation Using the Single Hot Thermocouple Technique (SHTT)

AbstractCalcium aluminate system is widely used in several ceramic and metallurgical materials and processes such as tundish and mold slags for continuous casting process. In the case of mold powders, they play significant role during the steel solidification process and knowing its physicochemical properties is crucial in the study of slag behavior. In this context, the crystallization tendency of the mold powders plays a significant role in essential properties such as viscosity—which is fundamental to the efficiency of the casting process. In the present study, the effect of a water vapor atmosphere on the crystallization behavior of the CaO‐Al2O3 join is investigated using the single hot thermocouple technique. Distinct crystallization behaviors in presence of water vapor atmosphere are observed, according to the temperature range. Hindering of crystallization onset occurs at a temperature range above 1150 °C. For the temperature range below 1150 °C, crystallization improvement can be observed. The resulting time–transformation–temperature diagrams show the influence of temperature on the effect of water vapor upon crystallization, denoting the amphoteric nature of water.

Combined effects of hot water vapor, sodium chlorite, and PVC film on postharvest decay and browning of trimmed aromatic coconut

ISHS V International Symposium on Postharvest Pathology: From Consumer to Laboratory-Sustainable Approaches to Managing Postharvest Pathogens Combined effects of hot water vapor, sodium chlorite, and PVC film on postharvest decay and browning of trimmed aromatic coconut