High Relative Humidity Values Research Articles

Dependence on relative humidity in the formation of reactive oxygen species in water droplets

Water microdroplets (7 to 11 µm average diameter, depending on flow rate) are sprayed in a closed chamber at ambient temperature, whose relative humidity (RH) is controlled. The resulting concentration of ROS (reactive oxygen species) formed in the microdroplets, measured by the amount of hydrogen peroxide (H2O2), is determined by nuclear magnetic resonance (NMR) and by spectrofluorimetric assays after the droplets are collected. The results are found to agree closely with one another. In addition, hydrated hydroxyl radical cations (•OH-H3O+) are recorded from the droplets using mass spectrometry and superoxide radical anions (•O2-) and hydroxyl radicals (•OH) by electron paramagnetic resonance spectroscopy. As the RH varies from 15 to 95%, the concentration of H2O2 shows a marked rise by a factor of about 3.5 in going from 15 to 50%, then levels off. By replacing the H2O of the sprayed water with deuterium oxide (D2O) but keeping the gas surrounding droplets with H2O, mass spectrometric analysis of the hydrated hydroxyl radical cations demonstrates that the water in the air plays a dominant role in producing H2O2 and other ROS, which accounts for the variation with RH. As RH increases, the droplet evaporation rate decreases. These two facts help us understand why viruses in droplets both survive better at low RH values, as found in indoor air in the wintertime, and are disinfected more effectively at higher RH values, as found in indoor air in the summertime, thus explaining the recognized seasonality of airborne viral infections.

Optimization of the fan coil cooling system and the air source heat pump using a moderated mediation model

The data obtained from a heating and cooling system comprised of a fan coil unit integrated air source heat pump used in Istanbul, Turkey, as well as data on outdoor conditions, was analyzed in this study. The analysis was carried out with the help of the moderated mediation model, which is included as a process analysis in the ?Statistical Package for the Social Sciences? application. In this study, a mathematical model of the moderated mediation model was created and the efficiency coefficients of the parameters effecting performance were calculated. It was discovered that the effect of medium and high relative humidity values on the outdoor temperature was about 4.81%. The heat pump fails to transmit heat to the environment outside as a result of medium and high relative humidity values increasing the outdoor temperature. As a result of this it has been found that relative humidity values have a negative effect on the water temperature entering the fan coil unit by approximately -1.18%. This result of the study shows that the outlet water temperature of the fan coil unit does not adequately cool the rooms in the summer. It has been discovered that while wind velocity negatively affects performance affecting parameters, low relative humidity values have no effect on them.

НОВАЯ ПРОТИВОКОРРОЗИОННАЯ ПРИСАДКА «РОСОЙЛ-АКОР»

The paper contains the results of laboratory tests of a new Rosoil-Akor anticorrosive additive, designed to improve the protective properties of oils for various purposes and fuels in comparison with the similar AKOR-1 additive from two Russian manufacturers. The physicochemical characteristics of the additives are defined. The effect of additives on the protective and anti-wear properties of transformer oils, motor oils and diesel fuel are studied. It is shown that the physico-chemical parameters of Rosoil-Akor additive meets the requirements of GOST 15171-78 Additive AKOP-I. Specifications. It is found that when exposed to salt fog, the protective ability of oils and diesel fuel with Rosoil-Akor additive is 3-10 times higher than with AKOR-1 additives. At higher values of relative humidity and air temperature, the protective ability of oils and diesel fuel with Rosoil-Akor additive is up to 25 times better than with AKOR-1 additives. All the additives under study increase the anti-wear properties of transformer oils, while the diameter of the wear spot of oil with Rosoil-Akor additive is 1.2-1.4 times smaller than oils with AKOR-1 additives. The addition of the studied additives to engine oils does not significantly affect the anti-wear properties of oils. The wear index of diesel fuel decreases with the addition of Rosoil-Akor and AKOR-1 additives (sample No. 1), but increases with the addition of AKOR-1 additive (sample No. 2). Test results show that the new Rosoil-Akor additive has high anticorrosive and anti-wear properties and can be used to improve the protective properties of oils for various purposes and diesel fuel instead of AKOR-1 additive.

Gravimetric analysis of water vapor adsorption kinetics on hydrophilic and hydrophobic Si surfaces using microcantilevers

Understanding the nature of the adsorption of water molecules on a Si surface is of great interest in basic sciences as well as in broad range of industrial processes. Traditional techniques such as Fourier transform infrared spectroscopy cannot capture the adsorption phenomena on a larger surface area of Si. Herein, we report the adsorption kinetics of water molecules on hydrophilic and hydrophobic Si surfaces by means of a precision gravimetric method using microcantilevers (MC). Si MCs with hydrophilic and hydrophobic surfaces were synthesized by chemical route, and their resonance frequency with increasing Relative Humidity (RH) was measured. Shift in resonance frequency of MCs due to adsorption of water molecules was used to estimate the added mass on their surface. In hydrophilic MCs, added mass Vs RH data revealed three distinctive slopes, indicating variation in the molecular configuration of water molecules with increasing RH as predicted by spectroscopic techniques. These results are independently validated by measuring the adhesion force on the MC surface using force-distance curves. In contrast to this, in hydrophobic MCs, added mass due to adsorption was very low and found to increase marginally at higher RH values. An increase in MC surface roughness leading to the clustering of water molecules was shown to be the reason for these observations.

How does humidity data impact land surface modeling of hydrothermal regimes at a permafrost site in Utqiaġvik, Alaska?

Humidity is a basic and crucial meteorological indicator commonly measured in several forms, including specific humidity, relative humidity, and absolute humidity. These different forms can be inter-derived based on the saturation vapor pressure (SVP). In past decades, dozens of formulae have been developed to calculate the SVP with respect to, and in equilibrium with, liquid water and solid ice surfaces, but many prior studies use a single function for all temperature ranges, without considering the distinction between over the liquid water and ice surfaces. These different approaches can result in humidity estimates that may impact our understanding of surface-subsurface thermal-hydrological dynamics in cold regions. In this study, we compared the relative humidity (RH) downloaded and calculated from four data sources in Alaska based on five commonly used SVP formulas. These RHs, along with other meteorological indicators, were then used to drive physics-rich land surface models at a permafrost-affected site. We found that higher values of RH (up to 40 %) were obtained if the SVP was calculated with the over-ice formulation when air temperatures were below freezing, which could lead to a 30 % maximum difference in snow depths. The choice of whether to separately calculate the SVP over an ice surface in winter also produced a significant range (up to 0.2 m) in simulated annual maximum thaw depths. The sensitivity of seasonal thaw depth to the formulation of SVP increases with the rainfall rate and the height of above-ground ponded water, while it diminishes with warmer air temperatures. These results show that RH variations based on the calculation of SVP with or without over-ice calculation meaningfully impact physically-based predictions of snow depth, sublimation, soil temperature, and active layer thickness. Under particular conditions, when severe flooding (inundation) and cool air temperatures are present, care should be taken to evaluate how humidity data is estimated for land surface and earth system modeling.

Variability of sulfur and oxygen isotope values within wet precipitation and its correlation with diminished anthropogenic sulfur dioxide (SO2) emission

Atmospheric sulfate (SO42−) aerosols have the capacity to scatter solar radiation, thus exerting a cooling effect on the climate. It is widely acknowledged that SO42− deposition significantly contributes to ecosystem effect in aquatic and terrestrial environments worldwide. Over the course of several decades, considerable efforts have been undertaken to mitigate anthropogenic sulfur dioxide (SO2) emissions in China, leading to remarkably low SO2 concentrations. Nevertheless, the implications of reduced anthropogenic SO2 emission on atmospheric sulfate transformation and compositions of isotope values (δ34S-SO42–, δ18O-SO42–) remain inadequately understood. To address this knowledge gap, we conducted multiple rainfall sampling instances between 2010 and 2022 (n = 191), encompassing the period of transitioning anthropogenic SO2 emission from high to low levels. Remarkably, we observed a significant reduction in the volume-weighted mean value (VWMV) of SO42− concentrations, declining from 20.86 mg L−1 in 2010 to 2.41 mg L−1 in 2022, and the VWMV of SO42−/NO3− molar ratios also decreased from 12.90 in 2010 to 0.55 in 2022, reflecting the synchronously decreasing annual SO2 emissions and annual SO2 concentrations from 2010 to 2022. In contrast to the declining trends in VWMV of SO42− concentrations, the VWMV of δ34S-SO42– values exhibited a different pattern from 6.6‰ in 2010 to −0.1‰ in 2017 and slightly increased to 2.5‰ in 2022. Furthermore, the VWMV of δ18O-SO42– values demonstrated an increase from 8.8‰ in 2010 to 14.5‰ in 2018, but subsequently decreased to 5.4‰ in 2022. We attributed the sharply dropping VWMV of δ34S-SO42– values to the reduction in the input of primary sulfate with enriched δ34S-SO42– values. The strict desulfurization reduced SO2 emissions, leading to oxidation of these trace SO2 with negative δ34S values, resulting in low sulfate concentrations and negative δ34S-SO42– values. In addition, the monthly average δ18O-SO42– values exhibited a positive correlation with monthly mean δ18O-H2O values (p < 0.05), strongly indicating the water incorporation during SO2 heterogeneous oxidation. More importantly, during spring rainfall, positive δ18O-SO42– values but relatively negative δ34S-SO42– values were influenced by SO2 heterogeneous oxidation facilitated by air oxygen catalyzed under metal ions in dry weather condition, attributed to the low relative humidity (RH) coupled with high deuterium excess (dexcess) values. Conversely, in summer, negative δ18O-SO42– values but relatively positive δ34S-SO42– values resulted from the SO2 heterogeneous oxidation with H2O2 due to high RH and low dexcess values. Moreover, the VWMV of δ18O-H2O exhibited variations from −3.7‰ in 2019 to −9.7‰ in 2021, and displayed a positive correlation with annual temperature (p < 0.01) and a negative correlation with annual precipitation (p < 0.05), making it a valuable indicator of climate change alongside δ18O-SO42– values. Our findings underscore the importance of continued monitoring of atmospheric wet depositions in response to changes in anthropogenic SO2 emission activities. Furthermore, they highlight the substantial impact of variations in δ34S values of SO2 and primary sulfate on rainwater sulfate concentrations and isotope values.

Relationship between meteorological factors and the pituitary-thyroid axis in healthy men living in the Subarctic

BACKGROUND: The changing seasons in the subarctic region causes an adaptive restructuring of the inhabitants’ organisms. The most healthy individuals can adjust to the Northern climate without developing health disorders. However, a decrease in adaptive reserves may result in various pathological conditions. Extensive studies across different populations in various climatic zones have reported significant associations between meteorological factors and the fluctuations in thyroid hormones. AIM: To assess the influence of circannual dynamics of meteorological factors on the serum levels of thyroid hormones and thyroxin-binding globulin (TBG) in men living in subarctic environmental conditions. MATERIAL AND METHODS: An prospective analytical study was conducted in the city of Arkhangelsk (64°32´24.4˝ N). Twenty clinically healthy men comprised the sample. Blood samples were collected every 3 months over a 12-months period. Subjects with any factors affecting the hypothalamic-pituitary-thyroid axis were excluded. Circannual variation in the studied characteristics were analyzed using Wilcoxon signed-rank tests with Bonferroni correction. Associations between hormonal data and climatic data were assessed using Spearman’s correlation coefficients. RESULTS: The thyroid-stimulating hormone reached its peak, while T4 and TBG were at their lowest during the period of minimal daylight hours in December. This coincided with the highest values of relative humidity and atmospheric pressure. Furthermore, T4 and TBG positively correlated with the duration of daylight and outdoor temperature at the day of samples collection, while showing an inverse correlation with atmospheric pressure and average monthly relative humidity. Т3 and T4 inversely correlated with average monthly atmospheric pressure. T3 was positively associated with the duration of daylight. CONCLUSION: The key environmental factors affecting the health people living in Northern regions include are the duration of daylight, outdoor temperature, monthly atmospheric pressure, and relative humidity. It is important to note that the impact of these climatic conditions on human health varies across the regions. Thus, our findings cannot be generalized to other areas..

The Effect of Dust Deposition on the Performance of Photovoltaic Panels

Given the energy crisis and climate change due to pollution, and given that the largest emissions of greenhouse gases are produced by the energy industry, we must turn our attention to the efficient use of solar energy, which is the cleanest and most abundant of all renewable energies. In this paper, based on an analysis of the specialized literature, we studied the effect of dust accumulation on the surface of photovoltaic modules on some performance characteristics and on the efficiency of these panels and modules compared to the efficiency of clean modules. We analyzed the cause of dust accumulation and the influence of the tilt angles of the photovoltaic panels on the dust deposition rate. We highlighted the influence of atmospheric temperature, solar radiation, wind speed, and relative humidity depending on the density of the dust deposited on the surface of the photovoltaic panel, and we found a decrease in the efficiency of the panel based on the increase in dust density for slightly high values of solar radiation, wind speed, and relative humidity. We highlighted the reduction in CO2 emissions by replacing electricity from fossil fuels with solar energy. The efficient use of solar energy is a solution for the decarbonization of the energy sector.

The Effects of Fog on the Atmospheric Electrical Field Close to the Surface

Ground-based measurements of the atmospheric electric field have been recorded continuously since 2013 at the Wise Observatory, located in the Negev Desert Highland in southern Israel. The data have been used for defining the characteristics of fair weather and to identify the signatures of dust storms, lightning activity, and clouds. We report here on new results from observations of the variability of the electric field (transformed into the potential gradient, PG) during several foggy days, along with meteorological data on wind speed and relative humidity. The results show a substantial increase in the electric field (up to 400–650 V m−1) compared with the mean fair weather values observed at the site (180–190 V m−1). This increase is especially clear during times of high relative humidity values (95%+) and low wind speed (&lt;3 m s−1). This increase is likely a consequence of the reduction in the atmospheric conductivity at low levels, due to the attachment of charge carriers to fog droplets. Based on this discovery, it is suggested that continuously monitoring the electric field may offer an additional operational tool to alert for the onset and termination of fog at specific locations, such as airports and harbors, where this nowcasting capability is required.

Effect of habitat quality on the biodiversity of ant genera and functional groups in a riparian forest area of the Tauarizinho River in Eastern Amazonia

In view of the scenario of human disturbances and regional climate change, we intend to verify whether habitats that are structurally more heterogeneous, complex and of higher quality, such as riparian forests, support a higher biodiversity of ant genera and their respective functional groups, when compared to more homogeneous environments and of low habitat quality such as abandoned pasture areas, as well as the effects of seasonality. A total of 4,865 ants belonging to 7 subfamilies and 15 ant genera were collected. The subfamilies that showed the highest representativeness (abundance) were Myrmicinae (4,436), followed by Formicinae (282), Ectatomminae (97), Dolichoderinae (18), Pseudomyrmecinae (15), Dorylinae (9) and Ponerinae (8). The high-quality habitat, which corresponds to riparian forest, had the highest richness of genera, characterized by the genus Nylanderia, with a higher occurrence of the functional group Generalist Myrmecinae, with high values of relative humidity in both seasons. On the other hand, the low-quality habitat showed less richness of genera, being the genus that caracterizes this environment the Crematogaster, with higher occurrence of the functional group of Tropical Climate Specialists and low values of relative humidity. In view of the above, this study provides subsidies for conservation work in riparian forest areas in the humid tropical forest biome. Besides warning about the reduction in the richness of ant genera due to the conversion of natural areas into pasture.

Land Use Affects the Local Climate of a Tropical Mountain Landscape in Northern Ecuador

Changes in land use affect biodiversity and the biophysical structure of ecosystems, causing negative impacts on ecosystem services, such as climate regulation. However, few studies have evaluated the effect of land use changes on the local climate, particularly in tropical mountain systems such as the Andes. Therefore, this study compares 4 land use types (native forest, planted forest, maize monoculture, and pasture) in a mountain landscape in northern Ecuador as a proxy to assess the impact of land use change on local climate regulation. We estimated gap fraction with photographic techniques and recorded temperature and relative humidity using dataloggers set at 2 heights (0 m and 1 m) above ground level across the land use types. As we expected, native forests provided a more stable microclimate, demonstrating significantly lower temperatures and higher relative humidity values than the other land use types. This effect on microclimate was significantly explained with highest temperatures at intermediate gap fraction levels. In addition, we observed that native forests provided a buffer effect for the variations in mesoclimate; only native forests showed an evident reduction in local temperature over the range of mesoclimates. Local temperature variations registered in human-altered systems (planted forests and pastures) were significantly explained by the mesoclimate variation, with the exception of monocultures that exhibited a mismatch between the 2 scales of climate. These results highlight the importance of native forest for microclimate regulation, an ecosystem service that can act synergistically with other biodiversity and conservation goals to sustainably manage landscapes in Andean mountain systems.

The impact of meteorological factors on involuntary admission in Attica, Greece.

Few studies in the literature have examined the effect of meteorological factors, especially temperature, on psychiatric hospitalization and even less on their association with involuntary admission. This study aimed to investigate the potential association of meteorological factors with the involuntary psychiatric hospitalization in the region of Attica, Greece. The research was conducted at the Psychiatric Hospital of Attica "Dafni". This was a retrospective time series study of 8 consecutive years of data (2010 to 2017) and included 6887 involuntarily hospitalized patients. Data on daily meteorological parameters were provided from the National Observatory of Athens. Statistical analysis was based on Poisson or negative binomial regression models with adjusted standard errors. Analyses were initially based on univariable models for each meteorological factor separately. All meteorological factors were taken into account through factor analysis and then, through cluster analysis, an objective grouping of days with similar weather type was performed. The resulting types of days were examined for their effect on the daily number of involuntary hospitalizations. Increases in maximum temperature, in average wind speed and in minimum atmospheric pressure values were associated with an increase in the average number of involuntary hospitalizations per day. Increase of the maximum temperature above 23 °C at lag 6 days before admission did not affect significantly the frequency of involuntary hospitalizations. Low temperature and average relative humidity above 60% levels had a protective effect. The predominant day type at lag 1 to 5 days before admission showed the strongest correlation with the daily number of involuntary hospitalizations. The cold season day type, with lower temperatures and a small diurnal temperature range, northerly winds of moderate speed, high atmospheric pressure and almost no precipitation, was associated with the lowest frequency of involuntary hospitalizations, whereas the warm season day type, with low daily temperature and small daily temperature range during the warm season, high values of relative humidity and daily precipitation, moderate wind speed/gust and atmospheric pressure, was associated with the highest. As climate change increases the frequency of extreme weather events, it is necessary to develop a different organizational and administrative culture of mental health services.

Neighborhood environmental factors linked to hospitalizations of older people for viral lower respiratory tract infections in Spain: a case-crossover study

BackgroundLower respiratory tract viral infection (LRTI) is a significant cause of morbidity-mortality in older people worldwide. We analyzed the association between short-term exposure to environmental factors (climatic factors and outdoor air pollution) and hospital admissions with a viral LRTI diagnosis in older adults.MethodsWe conducted a bidirectional case-crossover study in 6367 patients over 65 years of age with viral LRTI and residential zip code in the Spanish Minimum Basic Data Set. Spain’s State Meteorological Agency was the source of environmental data. Associations were assessed using conditional logistic regression. P-values were corrected for false discovery rate (q-values).ResultsAlmost all were hospital emergency admissions (98.13%), 18.64% were admitted to the intensive care unit (ICU), and 7.44% died. The most frequent clinical discharge diagnosis was influenza (90.25%). LRTI hospital admissions were more frequent when there were lower values of temperature and O3 and higher values of relative humidity and NO2. The regression analysis adjusted by temperatures and relative humidity showed higher concentrations at the hospital admission for NO2 [compared to the lag time of 1-week (q-value< 0.001) and 2-weeks (q-value< 0.001)] and O3 [compared to the lag time of 3-days (q-value< 0.001), 1-week (q-value< 0.001), and 2-weeks (q-value< 0.001)] were related to a higher odds of hospital admissions due to viral LRTI. Moreover, higher concentrations of PM10 at the lag time of 1-week (q-value = 0.023) and 2-weeks (q-value = 0.002), and CO at the lag time of 3-days (q-value = 0.023), 1-week (q-value< 0.001) and 2-weeks (q-value< 0.001)], compared to the day of hospitalization, were related to a higher chances of hospital admissions with viral LRTI.ConclusionUnfavorable environmental factors (low temperatures, high relative humidity, and high concentrations of NO2, O3, PM10, and CO) increased the odds of hospital admissions with viral LRTI among older people, indicating they are potentially vulnerable to these environmental factors.Graphical

Microclimate under the Cup of Papaya Planted in the North-South and East-West Directions

The objective of this work was to evaluate the variations of environmental factors under the canopy of papaya planted in a north-south and east-west orientation. Two areas were studied, one oriented north-south and the other east-west, both planted with a spacing of 3.20 mx 2.40 m, planted in April 2015. The distances from the papaya line (levels of shading) and a place in full sun, where it was evaluated, in the North-South direction: in the papaya planting line, at 40 cm west side, 40 cm east side and in full sun; in the East-West direction: In the papaya planting line, at 40 cm on the north side, 40 cm on the south side and in the planting line in full sun. The following atmospheric variables were determined: temperature, irradiance and relative humidity. Tukey's test was used to compare means at a confidence level of 95%. Papaya planted in the east-west direction, under the conditions studied, provided lower incident irradiation, reduced temperature and higher values ​​of relative humidity under its canopy, compared to papaya planted in the north-south direction. It is possible to intercrop papaya planted in the east-west direction with other agricultural crops, including conilon coffee.

Study of the process of tea moisture sorption

The article presents studies of the sorption characteristics of green and black tea. The obtained experimental data indicate that tea is a hygroscopic product, so with an increase in the relative humidity of the environment, the sorption rate and the amount of moisture absorbed by tea increase. It was found that small-leaf black tea is more susceptible to intense moisture than large-leaf tea. At high values of relative humidity of the environment, molds of the species Aspergillus and Penicillium most often develop. When the moisture content of tea does not exceed the norms of the standard, the microflora does not have a significant impact on the quality indicators of the product. To preserve the quality of the product, it is necessary to use packaging materials with high barrier properties and maintain a relative humidity of less than 65% in warehouses.

Cuticle – Designed by nature for the sake of the hair

The cuticle of human hair has been examined, via a range of analytical methods, in order to reveal previously unknown information about its structure and to deepen understanding of its contribution to fibre properties. Cross-sections of hair fibre have been examined with X-ray microdiffraction oriented perpendicular to the surface of the cross-sections. AFM investigations were carried out for further investigating and deciphering the structure of the cuticle. Moisture sorption analytics of cuticle separated from fibre and mechanical tests of decuticled fibres against virgin fibres were used for understanding the role of the cuticle in the economy of hair fibre. Previously unknown swelling behaviour of the hair cuticle during moisture sorption has been revealed, as has an increased significance of the cuticle's role in moisture management at higher values of relative humidity. Through AFM investigation, the reaction of hair cuticles with chlorine water has further strengthened the idea that the Allwörden membrane does not exist, and is actually an artefact of the delamination of the A-layer and exocuticle from the underlying endocuticle. Using decuticled fibres for stress-strain tests, and by comparing the results with those of virgin fibres, the effect of the cuticle on the post-yield area of the hair fibre stress-strain diagram has also been demonstrated. Finally, X-ray microdiffraction and AFM investigations suggest that the cuticle possesses a small-scale ordered structure, based on possibly not fully crystalline and irregularly arranged α-helices oriented almost perpendicular to the growth axis of the fibre and enhancing the general description of cuticle as the protective layer of the fibre. The role of the cuticle for the hair fibre is more complex than previously thought. The cuticle is demonstrated not only to possess a hidden rod-matrix structure, that supports its protective nature, but also to play specific roles in the fibre's response to moisture, and in fibre mechanical behaviour.

Quantification of shedding of leaves in yerba mate and determination of associated hormonal levels

In recent years, leaf shedding in the yerba mate crop has been a phenomenon of important economic incidence, the cause of which is still unknown but has been attributed to various factors. The objective of the present study was to establish a methodology to quantify leaves shedding in yerba mate and to determine whether the high leaf shedding is due to a biotic or abiotic effect. In both plantations, high shedding of leaves was significant only when the lowest values of heliophany and the highest values of relative humidity were recorded. Coincidentally, a high percentage of green leaf detachment was recorded with the characteristic symptomatology of the fungus Cylindrocladium sp. An accumulation of ABA, JA and SA hormones was detected in yerba mate plants with high shedding of leaves, which was associated with the attack of the necrotrophic fungus Cylindrocladium sp. With predisposing climatic conditions for the manifestation of Cylindrocladium, an early harvest would reduce the loss of green leaves. The differences found among plants Cylindrocladium attack could be due to a genetic condition. The JA pathway may be the most important line of defense activated by Cylindrocladium infection. A high accumulation of JA and ABA has been detected in plants with high leaf shedding that could suppress the SA signaling pathway responsible for SAR establishment.

Modeling the effect of humidity and temperature on VOC removal efficiency in a multistage fluidized bed adsorber

The competitive adsorption of volatile organic compounds (VOCs) and water vapor onto beaded activated carbon (BAC) in a fluidized bed adsorber is developed in the form of a two-phase model using the Manes method. The Manes method uses as input single component adsorption isotherms described by the Langmuir model for adsorption of VOCs and the Qi-Hay-Rood (QHR) model for adsorption of water vapor. The effect of temperature is accounted for using the linear van’t Hoff relationship for Langmuir affinity coefficient. The effects of relative humidity (RH) and temperature in the simulations are validated using experimental data, with very good agreement observed (e.g. R2 = 0.98 comparing overall removal efficiencies). Humidity begins to have an effect on the adsorption of 1,2,4-trimethylbenzene (TMB) on BAC starting at 70% RH in the form of a reduction in overall removal efficiency due to fewer available adsorption sites. The overall removal efficiency decreases from 93.0% at 70% RH to 85.4% at 90% RH, and then plateaus with further increase in RH up to 100%. In dry air, temperature variation has a small effect on removal efficiency, showing a reduction in modeled overall removal efficiency from 93.0% to 90.2% when the adsorption temperature increases from 22 to 50 ˚C. On the other hand, at high RH values, temperature has a larger and positive effect on removal efficiency due to RH change. Increasing the temperature of a stream of humid air (RH = 95%) from 22 to 27 °C increases the TMB removal efficiency by 6.9% from 85.3% to 92.2%. Taking into account the effect of humidity and temperature, the model can be used to help optimize fluidized bed adsorber operations in industrial applications.

Observed Climatology and Trend in Relative Humidity, CAPE, and CIN over India

Water vapor is the most dominant greenhouse gas in the atmosphere and plays a critical role in Earth’s energy budget and hydrological cycle. This study aims to characterize the long-term seasonal variation of relative humidity (RH), convective available potential energy (CAPE), and convective inhibition (CIN) from surface and radiosonde observations from 1980–2020. The results show that during the monsoon season, very high RH values are depicted while low values are depicted during the pre-monsoon season. West Coast stations represent large RH values compared to other stations throughout the year. Irrespective of the season, the coastal regions show higher RH values during monsoon season. Regardless of season, the coastal regions have higher RH values during the monsoon season. During the pre-monsoon season, the coastal region has high RH values, whereas other regions have high RH values during the monsoon season. The rate of increase in RH in North-West India is 5.4%, followed by the West Coast, Central, and Southern parts of India. An increase in water vapor leads to raised temperature, which alters the instability conditions. In terms of seasonal variation, our findings show that CAPE follows a similar RH pattern. CAPE increases sharply in Central India and the West Coast region, while it declines in South India. Opposite features are observed in CIN with respect to CAPE variability over India. The results of the study provide additional evidence with respect to the role of RH as an influencing factor for an increase in CAPE over India.

Assessing the impacts of meteorological factors on freshwater consumption in arid regions and forecasting the freshwater demand

The continuously increasing consumption and scarcity of natural freshwater resources impose threats on different aspects of human life. This study investigated the possible influences of meteorological factors, e.g., relative humidity, temperature, and wind speed, on net freshwater consumption (NFWC). Additionally, we determined the seasonal variations in these factors and forecasted the consumption rate over five years. We took Kuwait as an example and analyzed daily readings obtained from 2014 to 2018 by the Directorate General of Civil Aviation and Ministry of Electricity and Water. The results showed that the consumption rate was affected positively by temperature and negatively by relative humidity. In the seasonality results, two groups characterizing the summer (May to October) and winter (November to April) seasons were obtained regarding the corresponding meteorological factors and net freshwater production (NFWP) and NFWC. The summer season showed high temperature, NFWC, and NFWP and low relative humidity values. In contrast, the winter season revealed high relative humidity and low temperature, NFWC, and NFWP values. The forecasting model is highly accurate and estimated that NFWC will reach 171,919 million imperial gallons/year by 2024. Thus, the obtained results and performed analyses assist in the future management and performance of installed desalination processes.