Critical Temperature Of Water Research Articles

A numerical model for the quantification of fluid inclusion property variations caused by heterogeneous entrapment and post-entrapment modifications in the H2O-NaCl system

The primary geological conditions for hydrothermal systems can be reconstructed using fluid inclusions, which generally requires that fluid inclusions trapped a single homogeneous phase and experienced no mass and volume changes after entrapment (Roedder's Rules). However, heterogeneous entrapment and post-entrapment modifications have been frequently identified in fluid inclusion studies, making the recovery of primary fluid properties from fluid inclusion data challenging or impossible. In this study, we constructed a specific tool, FlincPro, for the calculations of ideal and nonideal Fluid inclusion Properties in the H2O-NaCl system (ideal here refers to fluid inclusions that adhere to Roedder's Rules). Multiple modules have been developed to quantify the variations of fluid inclusion properties caused by heterogeneous entrapment, volume contraction/expansion, and water loss. The developed software illustrates possibilities in the variation of fluid inclusions in a specific assemblage with the input of a certain starting point.We found that compositions of the vapor endmember fluid are more significantly affected by heterogeneous entrapment than the liquid endmember, as the latter may have several orders of magnitude higher salinity and density. Homogenization pressure and temperature of halite-bearing fluid inclusions trapped on the halite liquidus will increase sharply with the addition of halite, but the homogenization behavior will not be changed. Volume contraction/expansion are effective ways to change the homogenization behaviors, especially for high salinity fluid inclusions. Water loss is not likely to cause the homogenization behavior change from total homogenization by vapor disappearance to total homogenization by halite dissolution for a halite-bearing fluid inclusion without additional volume contraction. Low-salinity and low-density fluid inclusions with total homogenization temperature around the critical temperature of water are least affected by post-entrapment modifications. Therefore, the interpretation of fluid inclusions formation depends on more parameters, e.g., petrographic observations, density and composition variations in fluid inclusion assemblages, and geological information, than only microthermometric data.

An investigation of the density of nano-confined subcritical/supercritical water

In various applications such as supercritical water gasification, oil and gas production, and energy harvesting and storage, subcritical/supercritical water is often confined within material pores. Investigating the density and critical parameters of high-temperature and high-pressure water in confined spaces can help us better understand the behavior of water within the pore space. In this study, a topological model consisting of two baths and a carbon nanotube (CNT) is built to examine the effect of temperature (300 K & 600–1173 K), pressure (1 atm & 20–30 MPa), and tube diameter (9.49–50.17Å) on confined density, and used machine learning (ML) to develop a predictive application (APP). The ML model demonstrates excellent predictive performance, achieving an R2 of 0.9962 on the test set. Furthermore, the mean impact value (MIV) is used to evaluate the impact of independent variables on confined density, and find that temperature has the most significant effect. The results indicate that the critical temperature and pressure of water confined within different CNTs are not significantly different from those of bulk water, but the confined critical density is slightly lower than the bulk critical density.

Deformation warning index for reinforced concrete dam based on structural health monitoring data and numerical simulation

The material mechanical parameters of the dam body and foundation will change when a dam is reinforced during the aging process. This causes significant changes in the structural state of the project and makes it difficult to ensure its structural safety. In this study, a new deformation warning index for reinforced concrete dams was developed according to the prototype monitoring data, statistical models, three-dimensional finite element model (FEM) numerical simulation, and the critical conditions of the dam structure. A statistical model was established to separate the water pressure component. Then, a three-dimensional FEM of the reinforced concrete dam was constructed to simulate the water pressure component. Furthermore, the deformation components that affected the mechanical parameters of the dam under the same amount of reservoir water level change were separated and quantified accurately. In addition, the method for inversion of comprehensive mechanical parameters after dam reinforcement was used. The influence mechanisms of the deformation behavior of concrete dams under the reservoir water level and temperature changes were investigated. A new deformation warning index was developed by combining the forward-simulated critical water pressure component and temperature component in the period of extreme temperature decrease with the aging component separated by the statistical model. The new deformation warning index considers the structural state of the dam before and after reinforcement and links the structural strength criterion and the deformation evolution mechanisms. It provides a theoretical foundation and decision support for long-term service and operation management of reinforced dams.

Study on hydrogenation of oxygenated aromatic hydrocarbons via water-gas shift reaction in a subcritical CO-H2O system

The hydrogenation properties of dibenzyl ether (an oxygenated model compound of lignite) via the water–gas shift reaction (WGSR) were studied in a subcritical CO-H2O system. The result showed during the hydrogenation process, the C-O bond was broken, and the fragments of dibenzyl ether were stabilized by the hydrogen generated by WGSR, generating benzene, toluene, benzyl alcohol and benzaldehyde. The presence of excess water inhibited the hydrogen transfer, largely reducing the conversion of dibenzyl ether. However, the inhibition effect was substantially reduced when the reaction environment reached the critical temperature and subcritical pressure of water. The hydrogen and deuterium generated by H2O and D2O via WGSR were utilized to label and analyze the hydrogenation position of the product, respectively. The results showed that the hydrogen generated by WGSR was added to the methylene after the break of dibenzyl ether, and this hydrogen appeared on the benzene ring structure via hydrogen transfer. The bond dissociation energy and energy required for the hydrogenation process of dibenzyl ether under aqueous condition were calculated by utilizing density functional theory (DFT). First, hydrides (H−) are formed by the WGSR under alkaline conditions. Then, the formation energy (140.81 kJ/mol) of hydrides and the energy (15.54 kJ/mol) of hydrides attacking the dibenzyl ether to form the transition state were lower than the bond dissociation energy (259.26 kJ/mol) of the dibenzyl ether. That is, the hydrogenation of dibenzyl ether via WGSR prefers to be a nucleophilic reaction rather than a pyrolysis reaction. In the coal liquefaction process, the hydrides produced by WGSR under the catalysis of alkali is conducive to the hydrocracking of oxygen containing functional groups.

The role mechanism of vapor-liquid behavior on boiling crisis triggering

Revealing the physical mechanism of critical heat flux (CHF) triggering is an essential basis for building accurate prediction models. Photographic observations assist in comprehending the physical mechanism of CHF during subcooled flow boiling. The vapor-liquid behavior obtained from experimental observations shows that, when heat fluxes extremely approaching CHF, a large amount of vapor condenses into a wavy vapor layer; simultaneously, a wavy liquid film layer forms beneath the vapor layer that propagates along the heating wall. The wavy vapor layer directly impedes liquid supplement from the liquid core to the liquid film adjacent to the heating wall. As the heat flux increases, the bubble departure diameter increases and the residual vapor phase in the detachment process directly leads to the formation of local dry spot, which prevents the rewetting of the adjacent liquid due to the vapor recoil effects. At approaching CHF conditions, dry patches are formed after the remaining wetted areas rapidly evaporate. Then, boiling crisis is postulated to be triggered when the dry spots initially form, grow and finally merge into dry patches. This observation sheds light on the triggering mechanism of the flow boiling crisis. The role mechanism for the CHF triggering is proposed through studying the boiling behavior of subcooled flow boiling near a heating wall, including just before CHF (CHF-), during CHF onset (CHF transient), and after CHF appearance (CHF+). Besides, a new correlation is presented for predicting critical heat flux temperature of water under a wide range of operating conditions with a mean absolute error of 3.81%. These results will provide guidance for developing mechanistic theoretical model and enhancing CHF.

Water deficit index to evaluate water stress status and drought tolerance of rainfed barley genotypes in cold semi-arid area of Iran

Drought and heat are major stresses that adversely affect crop production in arid and semi-arid regions. This study assessed the water stress status of rainfed barley genotypes and identified their critical drought stress threshold in the cold semi-arid area of Iran. The field experiments were conducted at the Dryland Agricultural Research Institute, Maragheh, Iran in 2015–16 and 2017–18. The experimental design was a split-plot arrangement in a randomized complete block design with three replications. The main plots included two water regimes, rainfed (stress) and supplemental irrigation, and the subplots included 15 barley genotypes. Data were collected for grain yield, and its components, surface temperature (Ts) taken at six crop growth stages from flag leaf to soft dough, and normalized differences vegetative index (NDVI) at seven crop growth stages from the first node to the soft dough. The water deficit index (WDI) was determined using NDVI and the difference between Ts and air temperature (Ta). Based on the WDI, the critical water stress and temperature thresholds for genotypes were 0.59, and 24.3 °C, respectively. The identified temperature threshold was equivalent to 7.2 mm day−1 evapotranspiration (ET0) and 4.3 kPa vapor pressure deficient. The genotypes experienced a maximum drought stress when the WDI, Ts, and ET0 reached 1.01, 34.6 °C (upper limit), and 11.6 mm day−1, respectively. The critical drought threshold happened 254 days after the sowing date. WDI had strong negative correlation with both grain and biological yields. According to WDI, Ghara Arpa, Kuban-06, and Ansar genotypes were placed in the drought-tolerant group and are suitable for rainfed conditions, whereas ARM-ICB, Sahand, Sararood1, and Ste/Antares//YEA762 genotypes were more suitable for supplemental irrigation conditions. It can be concluded that WDI could effectively discriminate genotypes into tolerant and susceptible groups, and identify the starting time of water stress under rainfed conditions.

Mitsubishi Chemical is licensing the HydroPRS process of Mura Technology

In this chapter, the interaction of aqueous solutions with the materials of the experimental or production plants is discussed that can lead to major problems due to corrosion. The aqueous solutions contain many reactive compounds, for example, chloride ions, under oxidative or reductive conditions, that can cause corrosion. Corrosion includes all reactions of components of an aqueous reaction mixture with the walls of the equipment of experimental or production facilities, like pipes, valves, fittings, and autoclaves.Corrosion in hydrothermal and supercritical water processes depends on the properties of the reaction mixture, on the properties of the construction materials, and on the construction of the processing equipment. In general, no satisfying solution to corrosion problems can be achieved with addressing only one aspect. On the contrary, only a comprehensive adjustment of all aspects influencing corrosion can lead to a process configuration that can be operated successfully and for a reasonable extended time span.Various types of corrosion occur, such as general corrosion, intergranular corrosion, pitting corrosion, and stress corrosion cracking. General corrosion occurs mainly in the near critical and supercritical temperature range in a region, where the density is high. Corrosion rates below T = 320 °C are very low. At temperatures T > 320 °C and pressures higher than the critical pressure, corrosion rates increase considerably. At a pressure of P = 24 MPa, high corrosion rates drop down to the level observed at lower temperatures just around the critical temperature of water, while at a pressure of P = 38 MPa, corrosion rates remain high up to a temperature of about T = 450 °C, since at that temperature density reaches the limit for corrosion due to ionic processes.In this chapter, first corrosion phenomena are described as occurring in high-temperature aqueous systems. Then, the parameters influencing corrosion are discussed in some detail together with corrosion mechanisms. The effect of corrosion is illustrated by reporting on a number of detailed investigations on corrosion in aqueous systems. A detailed discussion of measures that can be used against corrosion follows and shows the necessity of combining several approaches and ends in a compilation of means against corrosion.

Water–Hydrocarbon Phase Equilibria with SAFT-VR Mie Equation of State

The study of water–hydrocarbon phase equilibria is very important for both scientific and industrial purposes. This work is a thorough investigation of the predictive capability of SAFT-VR Mie equation of state (EoS) for aqueous hydrocarbon phase equilibria, including n-alkanes, alkenes, cycloalkanes, branched alkanes, and aromatic hydrocarbons. For alkenes and alkyl benzenes, induced association (solvation) with water is considered. The model is able to capture the correct phase equilibrium topology for mixtures of n-alkanes and alkyl-benzenes with water as type III according to Van Konynenburg and Scott, but it is not able to predict the barometric shift for alkanes longer than n-hexacosane due to the overshoot of the critical temperature of water. Quantitative results for the solubility of water in light hydrocarbons such as methane, ethane, and ethylene, as well as the mutual solubility of hydrocarbons and water above the solubility minimum, are possible. The latter is not predicted with SAFT-VR Mie EoS similar to other EoSs in literature. Accurate predictions are also reported for the pressure of the three-phase equilibrium and the critical lines for the binary mixtures. Henry’s law constant is often used for the prediction of low-pressure vapor–liquid equilibrium due to the low mutual solubility of hydrocarbons and water. EoS calculations are in reasonable agreement with experimental data for Henry’s constant, especially at higher temperatures. Qualitatively, SAFT-VR Mie captures the maximum of Henry’s constant with temperature, as well as the shift with the carbon number at temperatures near critical to water. SAFT-VR Mie is shown to be overall capable of straightforward prediction of phase equilibria of aqueous hydrocarbon mixtures.

Direct and Indirect Climate Change Impacts on Brown Trout in Central Europe: How Thermal Regimes Reinforce Physiological Stress and Support the Emergence of Diseases

Water temperature is one of the most important abiotic parameters in rivers having direct and indirect effects on fish. Especially cold-water species like the brown trout (Salmo trutta) are limited by high temperatures. Beside direct physiological stress, higher water temperatures also reinforce the emergence of diseases. In this study we investigate thermal regimes of rivers based on a large-scale dataset covering Austria (approximately 70,000 km²). The analyses aim to clarify to what extent water temperatures support the emergence of proliferative kidney disease (PKD) and assemble physiological stress for brown trout under current and future climate conditions. Data from 274 gauging stations at 184 rivers were used to calibrate a water temperature model and to investigate critical water temperature thresholds. Therefore, we developed a risk assessment scheme to identify river reaches that already have or will develop critical thermal regimes for brown trout in respect of PKD emergence and thermal physiological stress. The results revealed severe changes in the thermal regimes of the investigated rivers under climate change. Furthermore, the variable characterising riparian vegetation played a vital role to explain cooling of the water in downstream direction. In respect of PKD, the amount of river reaches having unlikely outbreaks of PKD decreased from 72.6 % under current conditions to 37.7 % in the far future RCP8.5 scenario. Within small rivers that currently showed optimal thermal regimes over large extents (10,244 km), the habitat suitability will be reduced by combined effects of PKD and physiological stress to 6,554 km. In general, suitable habitats of S. trutta will shift upstream, thus to higher altitudes, and to smaller, alpine rivers in Austria. The warming leads to physiological stress that induces a diminished growth due to the non-positive transition of caloric values to growth as well as cardiac dysfunction in brown trout. These factors will further restrict the distribution of brown trout. However, the results also underline the enormous importance of the alpine region as a future refuge for brown trout in Central Europe. Thus, this study will help to inform managers to timely develop robust conservation strategies.

Гиперфорсированные воздушно-реактивные двигатели

This paper introduces a thrust augmentation method for super- and hypersonic jet engines by means of applying water at the engine intake. This method expands the use of jet engines with subsonic combustion, allowing velocities up to Mach 8 and altitude up to 45 km. At velocities higher than 3–4 Mach, stagnation temperature of the air is getting higher than the critical temperature of water, which makes the existence of water at the gas turbine engine intake impossible. Water vapour as a working medium of a jet engine creates the so-called inner thermodynamic circle. This phenomenon defines the physics of the thrust augmentation method proposed. The author discusses three variants of hyper afterburner application: hyper afterburner turbojet, hyper afterburner ramjet, and hyper afterburner turbo ejecting engine. The presented basic specifications of the hyper afterburner engines qualitatively differ from those of their prototypes (engines without the hyper afterburner thrust augmentation function). The proposed thrust augmentation method of jet engines is of a special interest for the aerospace field, particularly, for creating air launch systems. It is shown that the application of hyper afterburner in turbo ejecting engines can increase velocity and altitude of the launch aircraft up to Mach 7 and 40 km respectively, thus opening new avenues in space exploration.

Sewage sludge conversion via hydrothermal liquefaction (HTL) – A preliminary study

Sewage sludge is regarded as a residue produced from municipal waste water treatment system. This waste is often used in low-value applications such as composting and incineration or disposed in landfills. Such practices posed many potential environmental hazards due to high levels of pollutants in the sludge. Sewage sludge is also a potential energy and currently received renewed attention for potential recovery of bio-oils and biochemicals through thermochemical conversion route. Hydrothermal liquefaction is a promising green method for conversion of sewage sludge. Hydrothermal liquefaction of sewage sludge were investigated at different temperatures (250°C, 300°C, 350°C and 400°C) and 1 hour reaction time. Experiments were carried out in a 10 ml stainless steel bomb reactor. The initial calorific value of sewage sludge was 12.36 MJ/kg. It was found that significant bio-oil yield of 52.23% and 48.25% were obtained at 350°C and 400°C respectively. Overall, the bio-oil yield increases with temperature up to critical temperature of water. It was clear that synergetic effect on the yield of liquid and solid were observed due to extended biomass fragmentations and depolymerization when reaction temperature was raised.The bio-oils produced from liquefaction of sewage sludge at 350°C contained an abundant number of ester based compounds, highlighting its potential as biofuel.

Pressure-Induced Miscibility Increase of CH4 in H2O: A Computational Study Using Classical Potentials.

Methane and water demix under normal (ambient) pressure and temperature conditions because of the polar nature of water and the apolar nature of methane. Recent experimental work has shown, though, that increasing the pressure to values between 1 and 2 GPa (10-20 kbar) leads to a marked increase of methane solubility in water, for temperatures which are well below the critical temperature for water. Here, we perform molecular dynamics simulations based on classical force fields-which are well-used and have been validated at ambient conditions-for different values of pressure and temperature. We find the expected increase in miscibility for mixtures of methane and supercritical water; however, our model fails to reproduce the experimentally observed increase in methane solubility at large pressures and below the critical temperature of water. This points to the need to develop more accurate force fields for methane and methane-water mixtures under pressure.

Sub- and supercritical water oxidation of anaerobic fermentation sludge for carbon and nitrogen recovery in a regenerative life support system

Sub- and supercritical water oxidation was applied to recover carbon as CO2, while maintaining nitrogen as NH4+ or NO3−, from sludge obtained from an anaerobic fermenter running on a model waste composed of plant residues and human fecal matter. The objective was to fully convert carbon in the organic waste to CO2 while maintaining nutrients (specifically N) in the liquid effluent. In regenerative life support systems, CO2 and nutrients could then be further used in plant production; thus creating a closed carbon and nutrient cycle. The effect of the operational parameters in water oxidation on carbon recovery (C-to-CO2) and nitrogen conversion (to NH4+, NO3−) was investigated. A batch micro-autoclave reactor was used, at pressures ranging between 110 and 300 bar and at temperatures of 300–500 °C using hydrogen peroxide as oxidizer. Residence times of 1, 5 and 10 min were tested. Oxidation efficiency increased as temperature increased, with marginal improvements beyond the critical temperature of water. Prolonging the residence time improved only slightly the carbon oxidation efficiency. Adequate oxygen supply, i.e., exceeding the stoichiometrically required amount, resulted in high carbon conversion efficiencies (>85%) and an odorless, clear liquid effluent. However, the corresponding oxidizer use efficiency was low, up to 50.2% of the supplied oxygen was recovered as O2 in the effluent gas and did not take part in the oxidation. Volatile fatty acids (VFAs) were found as the major soluble organic compounds remaining in the effluent liquid. Nitrogen recovery was high at 1 min residence time (>94.5%) and decreased for longer residence times (down to 36.4% at 10 min). Nitrogen in the liquid effluent was mostly in the form of ammonium.

Hydraulic fracturing and permeability enhancement in granite from subcritical/brittle to supercritical/ductile conditions

AbstractHydraulic fracturing experiments were conducted at 200–450°C by injecting water into cylindrical granite samples containing a borehole at an initial effective confining pressure of 40 MPa. Intensive fracturing was observed at all temperatures, but the fracturing characteristics varied with temperature, perhaps due to differences in the water viscosity. At the lowest considered temperature (200°C), fewer fractures propagated linearly from the borehole, and the breakdown pressure was twice the confining pressure. However, these characteristics disappeared with increasing temperature; the fracture pattern shifted toward the formation of a greater number of shorter fractures over the entire body of the sample, and the breakdown pressure decreased greatly. Hydraulic fracturing significantly increased the permeability at all temperatures, and this permeability enhancement was likely to form a productive geothermal reservoir even at the highest considered temperature, which exceeded both the brittle‐ductile transition temperature of granite and the critical temperature of water.

Effect of water properties on selectivity for 1-octene and 2-octanol reaction systems in sub- and supercritical water using a TiO2 catalyst

The effect of water properties on solid acid catalysis using TiO2 as the catalyst in sub- and supercritical water was elucidated using the reactions of 1-octene and 2-octanol as models. Kinetic data for these reactions at 290–410°C and 25MPa were analyzed, and relationships between reaction selectivities and water properties were evaluated quantitatively. The cis/trans selectivity for 2-octene produced in reactions of both 1-octene and 2-octanol drastically increased at around the critical temperature of water, and was quantitatively explained using the model of acid catalysis in sub- and supercritical water derived from kinetic analyses. The hydration selectivity of 1-octene conversion had a local maximum at around 330°C, which was explained by considering the change in reactivity of water as a reactant caused by changes in both water density and the degree of hydrogen bonding.

Thermal factors affecting egg development in the wandering glider dragonfly, Pantala flavescens (Odonata: Libellulidae)

The wandering glider dragonfly, Pantala flavescens (Fabricius), arrives in Japan from tropical regions every spring. The offspring colonize areas throughout Japan, with rapid increases in populations in the autumn, but all individuals die in the winter, suggesting low tolerance to low temperatures. However, few quantitative data on egg development and water temperature have been reported for this species. Females at the reproductive stage were collected from fields throughout the flying season and their eggs released using an artificial oviposition technique. Almost all of the eggs were fertilized. Egg size was stable throughout the seasons. Most eggs hatched within a period of 5 days at high water temperatures (35 and 30 °C), which were recorded in the shallow ponds and rice paddy fields from summer to early autumn. However, the egg-stage duration increased with declining water temperature. All eggs in water at 15 °C had failed to hatch by 90 days. The calculated critical temperature of water was determined to be approximately 14.3 °C; the total effective temperature for the egg stage was about 80 degree-days. Thus, low water temperatures in winter may prevent P. flavescens overwintering in Japan.

Cellular Uptake and Movement in 2D and 3D Multicellular Breast Cancer Models of Fructose-Based Cylindrical Micelles That Is Dependent on the Rod Length.

While the shape effect of nanoparticles on cellular uptake has been frequently studied, no consistent conclusions are available currently. The controversy mainly focuses on the cellular uptake of elongated (i.e., filaments or rod-like micelles) as compared to spherical (i.e., micelles and vesicles) nanoparticles. So far, there is no clear trend that proposes the superiority of spherical or nonspherical nanoparticles with conflicting reports available in the literature. One of the reasons is that these few reports available deal with nanoparticles of different shapes, surface chemistries, stabilities, and aspects ratios. Here, we investigated the effect of the aspect ratio of cylindrical micelles on the cellular uptake by breast cancer cell lines MCF-7 and MDA-MB-231. Cylindrical micelles, also coined rod-like micelles, of various length were prepared using fructose-based block copolymers poly(1-O-methacryloyl-β-d-fructopyranose)-b-poly(methyl methacrylate). The critical water content, temperature, and stirring rate that trigger the morphological transition from spheres to rods of various aspect ratios were identified, allowing the generation of different kinetically trapping morphologies. High shear force as they are found with high stirring rates was observed to inhibit the formation of long rods. Rod-like micelles with length of 500-2000 nm were subsequently investigated toward their ability to translocate in breast cancer cells and penetrate into MCF-7 multicellular spheroid models. It was found that shorter rods were taken up at a higher rate than longer rods.

The thermal structure and temporal evolution of high-enthalpy geothermal systems

Numerical modeling is a powerful tool to investigate the response of high-enthalpy geothermal systems to production, yet few studies have examined the long-term evolution and thermal structure of these systems. Here we report a series of numerical simulations of fluid flow and heat transfer around magmatic intrusions which reveal key features of the natural thermal and hydraulic structures of high-enthalpy geothermal systems. We explore the effect of key geologic controls, such as host rock permeability, the emplacement depth and geometry of the intrusion, and temperature-dependent permeability near the intrusion, on the depth and extent of boiling zones, the number and spatial configuration of upflow plumes, and how these aspects evolve over the systems’ lifetime. Host rock permeability is a primary control on the general structure, temperature distribution and extent of boiling zones, as systems with high permeability (≥10−14m2) show shallow boiling zones restricted to ≤1km depth, while intermediate permeability (∼10−15m2) systems display vertically extensive boiling zones reaching from the surface to the intrusion. Intrusion emplacement depth is a further control, as intermediate permeability systems driven by an intrusion at ≥3km depth only show boiling above 1km. If a cooling intrusion becomes permeable at temperatures significantly in excess of the critical temperature of water, the enthalpy of the upflow becomes high enough that systems with high permeability show vertically extensive boiling zones, and intermediate permeability systems spatially extensive zones of supercritical water near the intrusion. The development of multiple, spatially separated upflow plumes above a single intrusive body is characteristic of systems with high permeability and deep emplacement depth. Depending on the primary geologic controls, systems exhibit characteristic lateral and vertical gradients in pressure, temperature and enthalpy relative to the intrusive heat source which may aid in geothermal exploration and interpretation of field measurements.

An experimental study of smelt-water interaction in the recovery boiler dissolving tank

A laboratory apparatus was constructed to simulate the operating conditions of recovery boiler smelt dissolving tanks and used to systematically study the interaction between molten smelt droplets and water. Experiments were performed on synthetic smelt made of 80 wt% Na2CO3 and 20 wt% NaCl at 800°C, 900°C, and 1000°C. The results show that upon contact with water, some smelt droplets explode immediately and break into small pieces, some require a delay time to explode, and others solidify without exploding. The probability of explosion strongly depends on water temperature and to some extent, smelt temperature. At a given smelt temperature, there exists a water temperature range below which explosion always occurs (the lower critical water temperature) and above which there is no explosion (the upper critical water temperature). The lower critical water temperature decreases with increasing smelt temperature, while the upper critical water temperature remains the same at 82°C in all cases. Up to this upper critical water temperature, both the explosion delay time and explosion intensity increase with increasing water temperature. The data was used to construct a Smelt-Water Interaction Temperature (SWIT) diagram that can predict if a molten synthetic smelt droplet will explode in water at different smelt and water temperatures.

The liquid-vapor equilibria of TIP4P/2005 and BLYPSP-4F water models determined through direct simulations of the liquid-vapor interface

In this paper, the surface tension and critical properties for the TIP4P/2005 and BLYPSP-4F models are reported. A clear dependence of surface tension on the van der Waals cutoff radius (rvdw) is shown when van der Waals interactions are modeled with a simple cutoff scheme. A linear extrapolation formula is proposed that can be used to determine the infinite rvdw surface tension through a few simulations with finite rvdw. A procedure for determining liquid and vapor densities is proposed that does not require fitting to a profile function. Although the critical temperature of water is also found to depend on the choice of rvdw, the dependence is weaker. We argue that a rvdw of 1.75 nm is a good compromise for water simulations when long-range van der Waals correction is not applied. Since the majority of computational programs do not support rigorous treatment of long-range dispersion, the establishment of a minimal acceptable rvdw is important for the simulation of a variety of inhomogeneous systems, such as water bubbles, and water in confined environments. The BLYPSP-4F model predicts room temperature surface tension marginally better than TIP4P/2005 but overestimates the critical temperature. This is expected since only liquid configurations were fit during the development of the BLYPSP-4F potential. The potential is expected to underestimate the stability of vapor and thus overestimate the region of stability for the liquid.