Saturated Water Vapor Research Articles

THE ROLE OF SCANDIUM CHLORIDE AND HYDROXIDE COMPLEXES IN THE FORMATION OF SCANDIUM DEPOSITS: INSIGHTS FROM EXPERIMENTS AND MODELING

Abstract Although scandium is commonly concentrated to economic levels by magmatic processes, hydrothermal fluids also play an important role in its concentration. Indeed, the most important source of scandium is currently the Bayan Obo deposit in China, where scandium is extracted from hydrothermally produced aegirine. To know how and why scandium is concentrated by hydrothermal fluids, it is necessary to understand the speciation of scandium in hydrothermal fluids. In a recently published study, we showed that scandium forms stable species with fluoride ions and proposed that such species may have been responsible for the hydrothermal transport of scandium in deposits like Bayan Obo. Chloride ions, which have been shown to form stable complexes with the other rare earth elements (REEs), however, are much more abundant in most hydrothermal fluids than fluoride ions, as are hydroxide ions, particularly at high pH. We, therefore, conducted solubility experiments designed to investigate the stability of scandium chloride and hydroxide complexes in hydrothermal fluids. The experiments investigating the role of chloride species considered the solubility of Sc2O3(s) in the H2O-NaCl-HCl system at 100°, 150°, 300°, and 350°C and saturated water vapor pressure. These experiments showed that scandium concentration is independent of chloride concentration over the range of chlorinity investigated, i.e., up to 3.6 mol Cl– and that scandium, therefore, does not form stable complexes with chloride ions. To evaluate the role of hydroxide species in scandium transport and avoid the effect of chloride ions in the complexation, a second set of experiments was conducted that determined the solubility of Sc2O3(s) in H2O-NaClO4-HClO4 solutions at 100°, 150°, 200°, and 250°C, and saturated water vapor pressure. The results of these experiments showed that the solubility of Sc2O3(s) depends on pH and temperature. Based on the former dependence, two scandium hydroxide complexes, Sc(OH)2+ and Sc(OH)3°, were identified at low and higher pH, respectively. The formation constant (log β) determined for Sc(OH)2+ is 10.29 ± 0.07, 10.32 ± 0.07, 10.35 ± 0.19, and 10.91 ± 0.20 at 100°, 150°, 200°, and 250°C, respectively. That of Sc(OH)3° is 27.22 ± 0.68, 26.66 ± 1.35, 27.04 ± 0.13, and 28.02 ± 0.14 at the same temperatures, respectively. These results demonstrate that, unlike the case for the other rare earth elements, chloride plays a negligible role in transporting scandium in hydrothermal fluids. Instead, they show that scandium hydroxide complexes can be important in the transport of scandium and could have contributed significantly to the formation of deposits like those at Bayan Obo.

A dataset of carbon and water fluxes in the Changling alkali-saline paddy rice fields in the Songnen Plain, China (2018 –2020)

Compared with other terrestrial natural ecosystems, the land-atmosphere interaction in managed farmland ecosystem is more complex and changeable, due to the effect of crop types, cropping pattern, management practices, etc. As one of the most effective measures against the process of land alkalization and salinization in the Songnen Plain of Northeast China, paddy rice planting after desalination highly representative model for studying climate mitigation, water use and carbon balance. To support this approach effectively, it requires comprehensive field monitoring data. The eddy covariance method, grounded in micrometeorological theory, is widely recognized as the primary and direct approach for measuring CO2 and H2O exchanges in farmland ecosystems. This dataset comprises field measurements of Changling alkali-saline paddy rice during 2018–2020 subjected to rigorous quality control and gap filling in accordance with the ChinaFLUX data processing criteria. The dataset specifically includes half-hourly, daily, monthly and yearly scales of air temperature (Ta), air relative humidity (RH), water vapor pressure (e), saturated water vapor pressure (es), soil temperature (Ts), soil water content (SWC), net radiation (Rn) with four components, photosynthetically active radiation (PAR), rainfall (P), wind speed (Ws), wind direction (Wd), sensible heat flux (Hs), latent heat flux (LE), evapotranspiration (ET), net ecosystem CO2 exchange (NEE), ecosystem respiration (Re), gross ecosystem exchange (GEE), etc. The establishment and sharing of this dataset can offer valuable data support and a solid theoretical foundation for regional farmland ecosystem assessment and management.

Spatial variations and mechanisms for the stability of water use efficiency in China.

A clearer understanding of the stability of water use efficiency (WUE) and its driving factors contributes to improving water use efficiency and strengthening water resource management. However, the stability of WUE is unclear. Based on the EEMD method, this study analyses the spatial variations and mechanisms for the stability of WUE in China, especially in the National Forest Protection Project (NFPP) areas. It is found that the stable WUE was dominated by non-significant trends and increasing trends in China, accounting for 33.59% and 34.19%, respectively. The non-significant trend of stable WUE was mainly located in the Three-North shelterbelt program area, and the increasing trend of stable WUE was in Huaihe and Taihu, Taihang Mountains, and Pearl River shelterbelt program areas. Precipitation and soil moisture promoted the stable WUE in these project areas. The unstable WUE was dominated by positive reversals or negative reversals of WUE trends. The positive reversals of unstable WUE were mainly located in the Yellow River shelterbelt program areas, which was promoted by temperature and radiation, while the negative reversals of unstable WUE were mainly distributed in the Yangtze River and Liaohe shelterbelt program areas, which were mainly induced by saturation water vapor pressure difference (VPD). Our results highlight that some ecological restoration programs need to be improved to cope with the negative climate impact on the stability of WUE.

Significant Increases in Water Vapor Pressure Correspond with Climate Warming Globally

Global warming has become indisputable in recent years; however, the mechanisms by which water vapor, radiation, and greenhouse gases such as carbon dioxide contribute to driving global warming remain unclear, and it is becoming increasingly important to clarify their respective effects on temperature warming. In this study, we used the Global Land Data Assimilation System (GLDAS) datasets and National Oceanic and the Atmospheric Administration (NOAA) Global Monitoring Laboratory (GML) data to investigate the spatiotemporal variation characteristics of global warming and its driving mechanisms. The effects of water vapor, radiation (net longwave radiation), and CO2 on temperature rise are quantified from the perspective of the coupled land–atmosphere system, and water vapor is characterized in terms of the vapor pressure deficit (difference between saturated and actual water vapor pressures) to explicitly characterize its impact on the global water–heat cycle. The results show the following: (1) Under significant global warming, the vapor pressure deficit (VPD) exhibits an increasing trend, which is attributed to the rate of increase in actual water vapor being relatively slower than saturated water vapor. (2) Compared with the significant positive contribution of water vapor to global warming, CO2 is not, as generally expected, the most critical greenhouse gas causing global warming. (3) Water vapor and net longwave radiation (NLR) have significant mutual feedbacks on global warming. (4) A remarkable complementary mechanism of global warming that involves water vapor and NLR was identified, whereby the increased saturated water vapor induced by the rising temperature dominates the decrease in NLR. The results from this study have important theoretical value by enabling a more complete understanding of the contribution of VPD to global climate change and shedding light on the large-scale water vapor–climate change mutual feedback mechanism through research.

Carbon Deposition Mechanisms on Ni-Based Anode for SOFC: A Comparison Between Non-Discharge and Discharge Modes

The nickel/yttria-stabilized zirconia (Ni/YSZ) and nickel/scandia-stabilized zirconia (Ni/ScSZ) have widely used as an anode for solid fuel cells (SOFCs). When hydrocarbon gas is supplied to the Ni-based fuel electrode of SOFCs, carbon is deposited on the anode, and it causes anode destruction. Therefore, carbon deposition control is required.The purpose of this study is to clarify carbon deposition mechanisms to understand how the carbon resistance appears on the Ni-based electrode in non-discharge and discharge modes. NiO/8XSZ powder with a binder was uniaxially pressed to form 0.7mm thick pellet (Ni : XSZ=50:50 vol%, X(dopant)=Y, Sc) which were subsequently sintered. After a reduction in H2 atmosphere, Ni/8XSZ sintered cells were heated in CH4/Ar (S/C ratio (Steam to Carbon) =0, CH4/Ar=0.25) and CH4/H2O/Ar atmosphere (S/C ratio=0.15, CH4/Ar=0.25) using a thermobalance, and the carbon deposition rates were measured from the weight change of the cell at 1173 K and 973 K. In this experiment, the S/C ratio was adjusted by bubbling CH4/Ar gas to set the saturated water vapor pressure at a given temperature. In addition, a power generation experiment of SOFC was conducted at 1073 K to investigate the effect of electrochemical reactions on the carbon deposition. The SOFC cells were prepared as follows. YSZ suspension was spin-coated on the NiO/8YSZ substrate. The electrolyte/electrode bilayer was co-sintered at 1673K. Then, a paste of LSM/YSZ was coated on electrolyte and sintered at 1473K. The cell was sealed to the alumina tube in the electric furnace. The anode side was fed with CH4/Ar/H2O (S/C ratio = 0.15) and the cathode side was exposed to O2. Current density was set to 126mA/cm2 for 30 min. After discharge, the anode surface was observed using SEM/EDS.As a result, the carbon deposition rate of Ni/ScSZ was lower than that of Ni/YSZ by 34 % at 1173 K and S/C=0 under non-discharge mode. This result indicated that the Ni/ScSZ exhibited superior carbon deposition tolerance than the Ni/YSZ at 1173 K. Steam reforming reaction was also different between the Ni/YSZ and Ni/ScSZ. Previous studies showed that carbon deposition tended to progress easily at the metal/solid electrolyte interface. The difference in carbon deposition behavior between Ni/YSZ and Ni/ScSZ was caused by the difference in the interface structure. On the other hand, the carbon deposition rate of Ni/ScSZ was higher than that of Ni/YSZ at 973 K which was opposite to that at 1173 K. Moreover, the rate of carbon reforming reaction (C+H2O→CO+H2) of Ni/YSZ was higher than that of Ni/ScSZ. In fact, the Ni/YSZ anode showed superior carbon tolerance than the Ni/ScSZ at lower temperature. XRD (X-ray Diffraction) analysis showed that the ScSZ with cubic structure was partially changed to the rhombohedral structure after the carbon deposition at high temperature while YSZ cubic structure was unchanged. This implied that the rhombohedral structure at the interface inhibited the carbon deposition reaction, suggesting that the electrolyte structure influenced the carbon deposition and steam reforming reactions. Therefore, it was shown that the electrolyte structure can control the carbon deposition while the same Ni was used. These findings give an useful hint to design the carbon tolerance electrode.Meanwhile, carbon deposition was not found on the Ni/YSZ surface after discharge at 1073 K. This indicated O2- ion improved the carbon tolerance during discharge. Comparison of carbon deposition between Ni/YSZ and Ni/ScSZ will be discussed using DFT (Density Functional Calculation).

New technology for ship bilge and oily water separation

AbstractBilge and oily water (BOW) during vessel's operation are the most large‐tonnage type of waste and for their treatment all ships, in accordance with international regulatory requirements, have to be equipped with special equipment—oily water separators. At sea vessel's operating conditions three main directions of BOW cleaning are now used: physical, chemical and biological. The analysis of BOW separation methods based on these three directions has shown that it is very difficult to obtain secondary petrochemical products. In the article authors offer a new method for BOW separation which is based on the use of a hydrodynamic process of supercavitation with artificial ventilation of the cavitational cavern. With local origin in the flow of a supercavitating cavern, there will always be saturated water vapor inside of it. The process of permanent water vapor selection from the cavern will ultimately contribute to the production of highly concentrated mixture of secondary petroleum products from initial mixture of BOW. During the study of BOW separation process it was found that decreasing of the working pressure inside the working chamber of the cavitation separator have to be always compensated by an increase in the temperature of the processed multiphase flow.

Real-time system for monitoring the water vapour concentration and temperature of air exhaled from human lungs

This article describes a fully optoelectronic system for measuring the H2O concentration and temperature of air exhaled from human lungs. A device consisting of both a laser hygrometer and an ultra-fast resistive thermometer. It was tested during an experiment with saturated water vapour, confirming its accuracy for measuring H2O concentration in air. Data, from a preliminary investigation of breath samples from anonymous adult volunteers, is presented.

A Multiscale Four-Dimensional Variational Data Assimilation Scheme: A Squall-Line Case Study

Abstract This study presents a multiscale four-dimensional variational data assimilation (MS-4DVar) scheme that aims to assimilate multiscale information from conventional and radar observations. The MS-4DVar scheme separately assimilates conventional and radar data in different outer loop iterations of an incremental 4DVar with varied resolutions in the tangent linear and adjoint models (TLM/ADM) and time window lengths in the 4DVar. The MS-4DVar scheme was evaluated through a series of single observation tests and several cycled assimilation and forecasting experiments for a real squall-line case. Our results indicated that different TLM/ADM resolutions and time window lengths applied to the conventional and radar observations improved the multiscale analysis. In addition, the MS-4DVar scheme was more efficient than the common 4DVar because of the low-resolution TLM/ADM used for conventional data and the shortened time window length for radar data. Verification of the squall-line forecasts suggested that the MS-4DVar scheme improved the hourly accumulated precipitation and radar reflectivity forecast skills and reduced the forecast errors of both large-scale environmental and convective-scale states. Further diagnosis revealed that the improvement of precipitation forecast skill was attributable to the stronger cold pool, deeper saturated water vapor layer, and stronger updraft of the simulated squall-line system, as well as a more favorable convective environment.

Disentangling day–night contributions toward altering atmospheric desiccation strength for US croplands

AbstractVapor pressure deficit (VPD) is the difference between saturation and actual water vapor pressures and is driven by interactions between air temperature and humidity. Globally, VPD observations indicate drying of the atmosphere, while air temperature (T) and relative humidity (RH) have changed asymmetrically during daytime versus nighttime. However, whether daytime or nighttime T (Tday and Tnight, respectively) and RH (RHday and RHnight, respectively) have been more important to VPD change is unknown, and so is the seasonal variation of this importance. This research determines the relative contribution of Tday, Tnight, RHday, and RHnight to VPD change observed during 1981–2021 across the conterminous United States. Tday contributed 41% to driving a VPD increase of 2.1 standard deviations (SD), followed by contributions of 25%, 22%, and 12% from RHday, RHnight, and Tnight, respectively. Regions with significant VPD increase have seen increase in Tday (by 1 SD) and Tnight (by 0.9 SD) and a decrease in RHday (by 1 SD) and RHnight (by 3.4 SD). Diurnal asymmetry in warming and drying trends was true for most months, with greater rates of change during the nighttime than daytime. Tday was the dominant driver of the annual mean VPD rise for 70% of the counties, followed by RHday (18%), RHnight (11%), and Tnight (1%). We conclude that warming and drying during the days and nights together explain increased VPD across the US croplands and that climate stressors during days and nights should be viewed independently due to their crop‐specific impacts that vary spatially and seasonally.

Moisture-driven CO2 pump for direct air capture

Direct Air Capture, the chemical separation of carbon dioxide (CO2) from air, is considered a necessary approach to generate negative carbon emissions and in turn limit global warming, though energetic and monetary costs must continue to decline to meet the needed gigaton scale. The promise of energy-efficient and continuous carbon dioxide membrane separation has only recently been investigated with the development of facilitated chemical transport and novel electrochemically driven methods. This work demonstrates the potential for continuous pumping of CO2 from air using commercial anion exchange membranes driven solely by a water vapor gradient. A reactive transport model that couples ionic transport with moisture sensitive bicarbonate chemistry in charged polymers, also termed moisture swing sorption, was developed alongside experimentally measured equilibrium and transport properties of CO2 and water vapor in Fumasep FAA-3 to determine the mass transport limits of such a system. The results show that the commercial membrane is kinetically limited by the moisture sensitive chemistry, enabling a CO2 current of 1.1 μmol/m2∙ s. In diffusion limited materials, a CO2 pumping flux can reach 11 μmol/m2∙ s in and peak performance is expected with a dry air relative humidity around 50% pumping into a saturated water vapor permeate. In all configurations, water loss becomes the major cost in such a separation and must be managed through optimal polymer design or water recovery mechanisms. The work demonstrates the applicability of a new driving force, the evaporation of water, to meet the energetic demand of CO2 separation from air.

Determination of Ce3+, Co2+, Mn2+ and Fe2+ diffusion coefficients in Nafion® membrane

Concentration gradient diffusion coefficients for Ce3+, Co2+, Mn2+ and Fe2+ cations are determined in Nafion®211 membranes over a wide range of environmental conditions. Measurements are made using finite-width cation-rich bands introduced to NR211 via a hot-pressing procedure. A robust method of accurate diffusion coefficient determination of the finite-width deposits is developed using a Fick's second law of diffusion solution for one-dimensional systems. The transition metal dications are found to have nearly identical NR211 diffusion coefficients under water saturated conditions over the 22–80 °C range. The powerful chemical mitigant, Ce3+, is about one-half as diffusive as the dications under identical conditions. Derived diffusion coefficients for Ce3+ and Co2+ are found to be independent of initial cation concentration over the range of 12.5–70 mol% exchange level. The diffusion behavior of Ce3+ in 80 °C liquid water and saturated water vapor is identical. The diffusion coefficients of Ce3+ are shown to have a strong dependence on membrane hydration level varying by a factor of more than 30 over the range of 95 to 40% RH. The implications of these new diffusion findings are applied to a discussion of potential guidelines for the development of highly durable fuel cell systems, which employ mobile metal cations as lifetime-extending redox stabilizers.

The colour difference of transparent surface finish on hydrothermally treated beech wood in the interior

The colour difference of transparent surface finish on hydrothermally treated beech wood in the interior. The paper deals with the influence of ageing of transparent surface finish in the dark and in the light in interior conditions. The colour difference of the tested samples with surface finishes (∆E*ab) was measured after the ageing of native wood and hydrothermally modified wood in the dark and in the light. In the experiment,European beech wood was hydrothermally treated at a temperature of 135 C under saturated water vapour for 6 hours. Three different types of surface finishes (acrylic-polyurethane, polyacrylic and aldehyde resin, alkyd resin) were applied on the wood surfaces. The colour parameters of the surfaces in the system CIE L*a*b*, chroma ΔC*,and hue angle Δh were measured immediately after surface finishing and after the ageing in the dark and in the light. The samples were placed behind windows glass in the interior for 60 days. The results of the colour difference ∆E*ab showed that the colour of wood and the colour of the surface finishes was changed after ageing in the dark as well as in the light. The colour difference ∆E*ab was bigger in the light than in the dark. The colour difference was bigger on native wood than on hydrothermally modified wood.

Применение автоматического парового стерилизатора для обеззараживания отходов иммунобиологического производства, контаминированных патогенными биологическими агентами

One of the ways to neutralize immunobiological production waste is their treatment in sterilizers with saturated water vapor under pressure. Currently, medical and pharmaceutical industries and laboratories use sterilizers with sterilization and disinfection programs preset by manufacturers. Decontamination modes are defined in Federal sanitary rules, norms and hygienic standards, SanPiN 3.3686-21, while the parameters of preliminary phases of the cycle must be tested experimentally and validated for specific conditions. Within the frames of this study, we have tested the modes of disinfection of an automatic steam sterilizer by the example of waste products from the production of cholera vaccine and anti-rabies immunoglobulin manufactured by the FSSI Russian Anti-Plague Institute «Microbe» of the Rospotrebnadzor. The wastes are used nutrient media, carcasses of laboratory animals (rabbits) and consumables. The chamber was loaded with «clean» objects in quantity and configuration, repeating the loading of material with pathogenic biological agents (PBA). The mode of inactivation inside the chamber and the objects was controlled by physical, chemical and biological methods. Based on the results of the experiments, corrective actions were taken to change the program and design of containers for autoclaving. It was concluded that the default disinfection programs set by manufacturers do not fully take into account specific conditions and need to be adjusted with further validation. It is necessary to develop standard operating procedures for personnel involved in the decontamination of pathogenic materials, in which should be stated the order of placement of objects and the means of control in the containers with PBA and the sterilizer chamber. Keywords: steam sterilizers, pathogenic biological agents, disinfection with saturated water vapor, phases of the steam disinfection cycle, validation.

The effect of time scales on the distribution of evapotranspiration and driving factors in desert grasslands

Promoting the reasonable allocation of evaporation (E) and transpiration (T) at a certain time scale is important for controlling the grassland desertification. Nevertheless, evapotranspiration (ET) and its components on a single time scale often cannot guarantee the dynamic and reasonable distribution of E and T. This study quantified ET and its component distribution in different time scales of the plant-growing season in desert grassland ecosystems to address this contradiction. Further the main driving factors of ET and its components at different time scales were clarified under multi-factor coupling. Results indicated that E was the leading component of ET in the ecosystem, with an average T/ET of 39.64%. The dominant factors of T/ET on different time scales were air temperature (Ta) and surface temperature (Ts), which showed significant negative correlations (p < 0.05). ET and its components showed obvious unimodal changes at the hourly scale. The peaks occurred at 12:00–14:00, and they all increased with increasing radiation (Ra), Ts, Ta, and saturated water vapor pressure difference (VPD). Ta was the dominant factor with a correlation coefficient of 0.76, followed by VPD> Ra>Ts. At the daily scale, ET and its components showed clear seasonal changes, ET was 1.94 mm d-1and T was 0.77 mm d-1. The dominant factors were soil moisture content (SWC) of the 0–10 cm soil layer and Ts. The dominant factors affecting ET and its components in the early, middle, and late stages of growth were relative humidity (RH), SWC, and Ts. At the monthly scale, the cumulative values of ET and its components were the largest in August and the lowest in October, mainly regulated by precipitation (P), whereas, T/ET had no significant correlation with P. The results from this study can provide a scientific basis for vegetation restoration and environmental protection in desert grassland ecological function areas.

Synergistic effect of xSi-TiO2 ceramic membrane on photocatalytic oxidation and water vapor recovery of high humidity NO

Photocatalytic membranes were prepared by hydrothermal method using in situ growth of silica-doped titanium dioxide nanorods with different molar ratios on the surface of hollow ceramic membranes. The removal of nitrogen oxides from high humidity flue gas at ppm level and the recovery of flue gas water vapor were investigated for the first time. The optimized 0.2Si-TiO2 photocatalytic membrane achieved complete conversion of 50 ppm NO carrying saturated water vapor in only 11 min under UV light source irradiation, and the generation of toxic intermediate product NO2 was significantly reduced to 4.2 ppm. Further studies have shown that the presence of water vapor can facilitate the conversion of the toxic intermediate NO2 to nitrate. Moreover, the water vapor recovery flux was 4.18 kg·m−2·h−1, and the water vapor recovery efficiency reached 7.04%. The main water vapor recovery method was membrane condensation. Mechanistic analysis showed that hydroxyl radicals and superoxide radicals are the main components of photocatalytic oxidation, and this work provides a reference for enhancing the photocatalytic conversion of NO and suppressing the emission of toxic intermediates NO2 in the process.

Comprehensive Effects of Atmosphere and Soil Drying on Stomatal Behavior of Different Plant Types

The soil water supply and atmospheric humidity conditions are crucial in controlling plants’ stomatal behavior and water use efficiency. When there is water stress caused by an increase in saturated water vapor pressure (VPD) and a decrease in soil water content (SWC), plants tend to close stomata to reduce water loss. This affects the gross primary productivity (GPP) and evapotranspiration (ET), subsequently leading to changes in water use efficiency (WUE) and carbon use efficiency (CUE) in plants. However, land–atmosphere interactions mean that water vapor in the atmosphere and soil moisture content causing water stress for plants are closely related. This study aims to compare and estimate the effects of VPD and SWC on the carbon cycle and water cycle for different plant functional types. Based on the fluxnet2015 dataset from around the world, the WUE and CUE of five plant functional types (PFTs) were estimated under varying levels of VPD and SWC. The results showed that high VPD and low SWC limit the stomatal conductance (Gs) and gross primary productivity (GPP) of plants. However, certain types of vegetation (crops, broad-leaved forests) could partially offset the negative effects of high VPD with higher SWC. Notably, higher SWC could even alleviate limitations and partially promote the increase in GPP and net primary production (NPP) with increasing VPD. WUE and CUE were directly affected by Gs and productivity. In general, the increase in VPD in the five PFTs was the dominant factor in changing WUE and CUE. The impact of SWC limitations on CUE was minimal, with an overall impact of only −0.05μmol/μmol on the four PFTs. However, the CUE of savanna plants changed differently from the other four PFTs. The rise in VPD dominated the changes in CUE, and there was an upward trend as SWC declined, indicating that the increase in VPD and decrease in SWC promote the increase in the CUE of savanna plants to some extent.

Effects of atmospheric and manure surface conditions on H2 S emissions from an in-ground finisher hog manure slurry tank.

Hydrogen sulfide (H2 S) emitted by livestock operations can be detrimental to human health. The storage of hog manure is a significant agricultural source of H2 S emissions. H2 S emissions from a ground-level Midwestern hog finisher manure tank were measured for 8-20 days each quarter over a 15-month period. After excluding 4 days with outlier emissions the mean daily emission was 1.89g H2 S m-2 day-1 . Mean daily emission was 1.39g H2 S m-2 day-1 when the slurry surface was liquid and 3.00g H2 S m-2 day-1 when crusted. Emissions however were not significantly different whether the surface was liquid or crusted when differences in temperature were considered. Diurnal variation in emissions was not correlated with air temperature, water vapor saturation deficit, or wind speed when the manure surface was crusted but was positively correlated with these variables when the surface was not crusted. Daily H2 S emissions were modeled according to two-film theory incorporating resistance approach with limited success. Additional emissions measurements with greater documentation of the manure liquid composition and crust characteristics are needed to assess the component transport resistances in the emissions model.

Electric Field-Induced Water Condensation Visualized by Vapor-Phase Transmission Electron Microscopy.

Understanding the nanoscale water condensation dynamics in strong electric fields is important for improving the atmospheric modeling of cloud dynamics and emerging technologies utilizing electric fields for direct air moisture capture. Here, we use vapor-phase transmission electron microscopy (VPTEM) to directly image nanoscale condensation dynamics of sessile water droplets in electric fields. VPTEM imaging of saturated water vapor stimulated condensation of sessile water nanodroplets that grew to a size of ∼500 nm before evaporating over a time scale of a minute. Simulations showed that electron beam charging of the silicon nitride microfluidic channel windows generated electric fields of ∼108 V/m, which depressed the water vapor pressure and effected rapid nucleation of nanosized liquid water droplets. A mass balance model showed that droplet growth was consistent with electric field-induced condensation, while droplet evaporation was consistent with radiolysis-induced evaporation via conversion of water to hydrogen gas. The model quantified several electron beam-sample interactions and vapor transport properties, showed that electron beam heating was insignificant, and demonstrated that literature values significantly underestimated radiolytic hydrogen production and overestimated water vapor diffusivity. This work demonstrates a method for investigating water condensation in strong electric fields and under supersaturated conditions, which is relevant to vapor-liquid equilibrium in the troposphere. While this work identifies several electron beam-sample interactions that impact condensation dynamics, quantification of these phenomena here is expected to enable delineating these artifacts from the physics of interest and accounting for them when imaging more complex vapor-liquid equilibrium phenomena with VPTEM.

Computing the Thermal Efficiency of Autoclaves during Steaming of Frozen Prisms for Veneer Production at Changing Operational Conditions

A methodology for the computation of the thermal energy efficiency of modes for the heat treatment of frozen wooden prisms in an autoclave with saturated water vapor at changing operational conditions has been proposed. The methodology includes computer simulations with two own-coupled unsteady models: one to calculate the 2D temperature distribution in the cross-section of prismatic wood materials during their heat treatment, and the second to determine the heat balance of industrial autoclaves for such wood treatment. Simulations were carried out in order to determine the duration, energy consumption, and thermal efficiency of different modes, caused by changed operational conditions, for the autoclave steaming of frozen beech prisms with industrial parameters in the absence and presence of dispatcher intervention. The influence of nine combinations between the time of dispatcher intervention and the degree of reduction of the constant maximum temperature from the 130 °C of the basic mode on the thermal efficiency of the autoclave was investigated. The results show that all studied dispatching interventions cause an increase in both the duration and the thermal efficiency of the modes. This efficiency in the modes at changing operational conditions has values between 68.7% and 74.6%, while the efficiency in the basic steaming mode is equal to 68.0%.

Consistency of Water Vapour Pressure and Specific Heat Capacity Values for Modelling Clay-Based Engineered Barriers

The aim of this study is to assess the consistency in the modelling of thermo-hydraulic problems in clay-based engineered barriers. This study focuses on two aspects: the modelling of vapour pressure as a function of temperature, and the specific heat capacities of liquid water and water vapour in relation to the enthalpy of vaporisation and the internal energy of liquid water and water vapour. Regarding the first aspect, several formulations of the saturated vapour pressure have been inspected, evaluating their accuracy and information provided in the temperature range from 0 to 150 °C. Regarding the second aspect, the enthalpy of vaporisation and the internal energy of water were used to assess the consistency of pairs of specific heat capacity values in the same temperature range. Values from the literature were also inspected. An accurate and simple enough expression for the saturated water vapour pressure with temperature has been identified as the optimal option for modelling. Recommendations on specific heat capacity constant values for liquid water and vapour are suggested to maximise consistency in the studied temperature range. However, the loss of accuracy in the enthalpy or internal energy of vaporisation associated with the inspected specific heat capacity pairs is limited.