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Densities of two synthetic biomethane-like mixtures were measured in the homogeneous liquid phase and the supercritical region using a low-temperature single-sinker magnetic-suspension densimeter. Both mixtures consist of methane, nitrogen, hydrogen and oxygen, whereas the second mixture additionally contains carbon dioxide. For the first mixture, four isotherms from (100 to 160) K were studied over the pressure range from (1.5 to 6.6) MPa. The second mixture was investigated along three isotherms from (140 to 180) K at pressures of (2.6 to 9.0) MPa, where only the densities at 180 K are usable due to solidification of the carbon dioxide at the lower temperatures. The relative expanded combined uncertainty (k = 2) of the experimental densities was estimated to be in the range of (0.022 to 0.027) % for the first mixture and (0.046 to 0.054) % for the second mixture, respectively. Due to a supercritical liquefaction procedure and the integration of a special VLE-cell, densities in the homogeneous liquid phase could be measured without changing the composition of the liquefied mixture. Moreover, saturated-liquid densities were determined by extrapolation of the experimental single-phase liquid densities to the vapor pressure, which was determined experimentally for the mixture without carbon dioxide and calculated with an equation of state (EOS) for the mixture containing carbon dioxide. The relative expanded combined uncertainty (k = 2) of the saturated-liquid densities is less than 0.08 % in most cases. The new experimental results were compared with the GERG-2008 equation of state; the deviations are less than 0.17 %. [ABSTRACT FROM AUTHOR]

We have determined the interfacial properties of short fully flexible chains formed from tangentially bonded Lennard-Jones monomeric units from direct simulation of the vapor-liquid interface. The results obtained are compared with those corresponding to rigid-linear chains formed from the same chain length, previously determined in the literature [F. J. Blas, A. I. M.-V. Bravo, J. M. Míguez, M. M. Piñeiro, and L. G. MacDowell, J. Chem. Phys. 137, 084706 (2012)]. The full long-range tails of the potential are accounted for by means of an improved version of the inhomogeneous long-range corrections of Janĕcek [J. Phys. Chem. B 129, 6264 (2006)] proposed recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2008)] valid for spherical as well as for rigid and flexible molecular systems. Three different model systems comprising of 3, 5, and 6 monomers per molecule are considered. The simulations are performed in the canonical ensemble, and the vapor-liquid interfacial tension is evaluated using the test-area method. In addition to the surface tension, we also obtained density profiles, coexistence densities, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the chain length and rigidity on these properties. According to our results, the main effect of increasing the chain length (at fixed temperature) is to sharpen the vapor-liquid interface and to increase the width of the biphasic coexistence region. As a result, the interfacial thickness decreases and the surface tension increases as the molecular chains get longer. Comparison between predictions for fully flexible and rigid-linear chains, formed by the same number of monomeric units, indicates that the main effects of increasing the flexibility, i.e., passing from a rigid-linear to a fully flexible chain, are: (a) to decrease the difference between the liquid and vapor densities; (b) to decrease the critical temperature and to increase the critical density; (c) to smooth the density profiles along the interfacial region; (d) to increase the interfacial thickness; and (e) to decrease the vapor-liquid surface tension. [ABSTRACT FROM AUTHOR]

The influences of GaI3, InI, and T1I on the evaporation characteristics of CeI3 have been studied over the temperature range 900K to 1400K using x-ray induced fluorescence. The total vapor densities, summed over all atomic and molecular species, of Ce, I, In, and T1 were obtained. Measurements of Ce were limited to temperatures above 1033K, the melting temperature of CeI3. This is the highest temperature range for which measurements of the vapor pressure of CeI3 have been made. The vapor pressure of the CeI3 monomer above the pure CeI3 salt for temperatures exceeding its melting point can be approximated by log10p=Pa 11.24(±0.03) - 10,690(±40) (T/K)-1 where the numbers in parentheses are standard uncertainties. InI and T1I were shown to modestly enhance the presence of Ce in the vapor phase, up to a factor of 5. GaI3 produced no enhancement in this temperature range. Numerical simulations of the thermochemical equilibrium suggest the importance of both liquid-phase and vapor-phase complexes. Significant improvement to the method of absolute calibration is discussed. [ABSTRACT FROM AUTHOR]

Fast-response infrared gas analyzers (IRGAs) have been widely used over 3 decades in many ecosystems for long-term monitoring of water vapor fluxes in the surface layer of the atmosphere. While some of the early IRGA sensors are still used in these national and/or regional eco-flux networks, optically improved IRGA sensors are newly employed in the same networks. The purpose of this study was to evaluate the performance of water vapor density and flux data from three generations of IRGAs – LI-7500, LI-7500A, and LI-7500RS (LI-COR Bioscience, Inc., Nebraska, USA) – over the course of a growing season in Bushland, Texas, USA, in an irrigated maize canopy for 90 d. Water vapor density measurements were in generally good agreement, but temporal drift occurred in different directions and magnitudes. Means exhibited mostly shift changes that did not impact the flux magnitudes, while their variances of water vapor density fluctuations were occasionally in poor agreement, especially following rainfall events. LI-7500 cospectra were largest compared to LI-7500RS and LI-7500A, especially under unstable and neutral static stability. Agreement among the sensors was best under the typical irrigation-cooled boundary layer, with a 14 % interinstrument coefficient of variability under advective conditions. Generally, the smallest variances occurred with the LI-7500RS, and high-frequency spectral corrections were larger for these measurements, resulting in similar fluxes between the LI-7500A and LI-7500RS. Fluxes from the LI-7500 were best representative of growing season ET based on a world-class lysimeter reference measurement, but using the energy balance ratio as an estimate of systematic bias corrected most of the differences among measured fluxes. [ABSTRACT FROM AUTHOR]

A fundamental understanding of the evaporation/condensation phenomena is vital to many fields of science and engineering, yet there is many discrepancies in the usage of phase-change models and associated coefficients. First, a brief review of the kinetic theory of phase change is provided, and the mass accommodation coefficient (MAC, α) and its inconsistent definitions are discussed. The discussion focuses on the departure from equilibrium; represented as a macroscopic "drift" velocity. Then, a continuous flow, phase change driven molecular-dynamics setup is used to investigate steady-state condensation at a flat liquid-vapor interface of argon at various phase-change rates and temperatures to elucidate the effect of equilibrium departure. MAC is computed directly from the kinetic theory-based Hertz–Knudsen (H-K) and Schrage (exact and approximate) expressions without the need for a priori physical definitions, ad-hoc particle injection/removal, or particle counting. MAC values determined from the approximate and exact Schrage expressions ( α a p p S c h r a g e and α e x a c t S c h r a g e ) are between 0.8 and 0.9, while MAC values from the H-K expression ( α H − K ) are above unity for all cases tested. α e x a c t S c h r a g e yield value closest to the results from transition state theory [J Chem Phys, 118, 1392–1399 (2003)]. The departure from equilibrium does not affect the value of α e x a c t S c h r a g e but causes α H − K to vary drastically emphasizing the importance of a drift velocity correction. Additionally, equilibrium departure causes a nonuniform distribution in vapor properties. At the condensing interface, a local rise in vapor temperature and a drop in vapor density is observed when compared with the corresponding bulk values. When the deviation from bulk values are taken into account, all values of MAC including α e x a c t S c h r a g e show a small yet noticeable difference that is both temperature and phase-change rate dependent. [ABSTRACT FROM AUTHOR]

In this study, the effect of crosslinking density of an acrylic-melamine clearcoat on water vapor transmission rate was evaluated. Four types of acrylic resins with different OH contents were used as the main polymeric backbone of the acrylic-melamine clearcoat. Also, three different acrylics to melamine–formaldehyde ratios were used in the coating formulations to obtain various crosslinking densities. It was observed that other film properties such as surface hydrophilicity and molecular homogeneity had a crucial impact on the clearcoat water vapor transmission rate together with the crosslinking density. Surprisingly, results showed that samples with acrylic resin with less OH content and lower melamine–formaldehyde crosslinker had the lowest water vapor transmission rate among other samples. These results were in agreement with the water contact angle and the data deduced from dynamic mechanical thermal analysis (DMTA) results of clearcoats. [ABSTRACT FROM AUTHOR]

The ground-based microwave radiometer (MWR) retrieves atmospheric profiles with a high temporal resolution for temperature and humidity up to a height of 10 km. Such profiles are critical for understanding the evolution of climate systems. To improve the accuracy of profile retrieval in MWR, we developed a deep learning approach called batch normalization and robust neural network (BRNN). In contrast to the traditional backpropagation neural network (BPNN), which has previously been applied for MWR profile retrieval, BRNN reduces overfitting and has a greater capacity to describe nonlinear relationships between MWR measurements and atmospheric structure information. Validation of BRNN with the radiosonde demonstrates a good retrieval capability, showing a root-mean-square error of 1.70 K for temperature, 11.72% for relative humidity (RH), and 0.256 g/m3 for water vapor density. A detailed comparison with various inversion methods (BPNN, extreme gradient boosting, support vector machine, ridge regression, and random forest) has also been conducted in this research, using the same training and test data sets. From the comparison, we demonstrated that BRNN significantly improves retrieval accuracy, particularly for the retrieval of temperature and RH near the surface. [ABSTRACT FROM AUTHOR]

The primary objective of this research study is to identify possible manifestations of local climate change in 13 micro-basins in Northern Colombia through statistical analyses of temperature, atmospheric humidity, vapor density, and potential evapotranspiration. The hydrological response area is estimated to infer the effect on water supply using the curve number method. The results show an average increase of 0.66°C in air temperature. Atmospheric water vapor density reached an increase close to 16%, whereas potential evapotranspiration shows an average increase of 30.9 mm. Curve numbers greater than 80 are found in eleven micro-basins in more than 85% of their territories. It is concluded that trends of potential local climate change are related to the area's physical state in terms of vegetation cover, as the main water and thermal regulator. [ABSTRACT FROM AUTHOR]

The article presents the research on the topic of system limit was first proposed by Tek in 1959 and the work extended the approach by Souders and Brown by incorporating concepts of drop stability developed by Hinze. Topics include the work by Hinze showed that there was a definite correlation between the maximum stable droplet size of liquid droplets entrained in vapor, and the Weber number relates the drag force on droplet in a vapor stream to the cohesive force that hold a droplet together.

• Flow boiling of R134a and R1234ze(E) in dimpled flat duct is investigated and compared experimentally. • Frictional pressure gradient of R1234ze(E) is 1.10–1.27 times that of R134a. • Heat transfer coefficient of R1234ze(E) is 0.89–1.20 times that of R134a. The low GWP (Global Warming Potential) refrigerant R1234ze(E) is a potential alternative of R134a. This study puts the emphasis on the comparison of the flow boiling pressure drop and heat transfer of R134a and R1234ze(E) in a dimpled flat duct. For the air-conditioning applications, the experiments are conducted at mass flux from 100 to 200 kg m−2 s−1, saturation temperature from 5 to 15 °C, heat flux from 2.5 to 10 kW m−2, and vapor quality from 0.1 to 0.95. The results show that the frictional pressure gradient of R1234ze(E) is 1.10 to 1.27 times that of R134a. The characteristics of the flow boiling heat transfer coefficient of R1234ze(E) are similar to R134a. The increasing flow boiling heat transfer coefficient with vapor quality in the tested range implies the convective evaporation dominates the heat transfer. It is also observed that the flow boiling heat transfer coefficient visibly increases with a rise in mass flux and decreases with the saturation temperature increment due to the increase in vapor to liquid density ratio. The enhancement effect of heat flux on the flow boiling heat transfer shows up at the highest value of 10 kW m−2 only. The heat transfer coefficient ratio of R1234ze(E) to R134a increases from 0.89 to 1.20 with an increase in vapor quality. The comparison of frictional pressure gradient and heat transfer characteristics between R1234ze(E) and R134a has been discussed from the viewpoint of fluid properties. [ABSTRACT FROM AUTHOR]

• A total of 87 (p, rho, T) data of R1123 were measured from 300 K to 430 K and up to 6.9 MPa. • A new equation of state was developed for R1123 based on the present data. • The new equation calculates all thermodynamic properties with reasonable accuracies. • The new equation shows good extrapolation at very high and low temperatures and high pressures. The (p, ρ, T) behavior of trifluoroethene (R1123) was investigated with the isochoric method. A total of 87 (p, ρ, T) data were measured along nine isochores (42, 98, 151, 197, 296, 493, 691, 790, and 888 kg · m − 3) at temperatures from 300 K to 430 K and pressures up to 6.9 MPa. The uncertainties in temperature are estimated to be within 10 mK below 380 K and 20 mK at higher temperatures, and the uncertainties in pressure are estimated to be within 1 kPa below 380 K and 2 kPa at higher temperatures. The estimated relative uncertainties in the density measurements are 0.15 % or less. A new Helmholtz energy equation of state was formulated based on the (p, ρ, T) data and recently published experimental data for the vapor pressure, liquid and vapor densities including those at saturation, vapor-phase sound speed, and ideal-gas isobaric heat capacity. The equation is applicable at temperatures from the triple-point temperature (195.15 K) to 480 K and pressures up to 20 MPa. Typical uncertainties in calculated properties are 0.1 % for vapor pressures, 0.1 % for liquid densities, and 0.2 % for vapor densities, except in the critical region where larger deviations up to about 1.5 % are sometimes observed in densities. The uncertainties in calculated vapor-phase sound speeds and ideal-gas isobaric heat capacities are 0.03 % and 1 %, respectively. The equation shows reasonable extrapolation behavior at extremely low and high temperatures, and at high pressures. [ABSTRACT FROM AUTHOR]

This paper presents results on the physicochemical properties of arsenic-containing substances—lewisite detoxification (destruction) products. Major attention is paid to the properties of hydrolytic sodium arsenite, a promising alternative industrial raw material for the production of high-purity arsenic and its compounds. Data are presented on the macro- and microcompositions of raw materials and temperature-dependent density and saturated vapor pressure of H3AsO4 solutions. The experimental data can be used in processing unconventional raw materials into extrapure arsenic-containing compounds. [ABSTRACT FROM AUTHOR]

The dynamics of a thin layer of liquid between a flat solid substrate and an infinitely thick layer of saturated vapor is examined. The liquid and vapor are two phases of the same fluid governed by the diffuse-interface model. The substrate is maintained at a fixed temperature, but in the bulk of the fluid, the temperature is allowed to vary. The slope ε of the liquid/vapor interface is assumed to be small, as is the ratio of its thickness to that of the film. Three asymptotic regimes are identified, depending on the vapor-to-liquid density ratio ρv/ρl . If ρv/ρl ∼ 1 (which implies that the temperature is comparable, but not necessarily close, to the critical value), the evolution of the interface is driven by the vertical flow due to liquid/vapor phase transition, with the horizontal flow being negligible. In the limit ρv/ρl → 0, it is the other way around, and there exists an intermediate regime, ρv/ρl ∼ ε 4/3, where the two effects are of the same order. Only the ρv/ρl → 0 limit is mathematically similar to the case of incompressible (Navier–Stokes) liquids, whereas the asymptotic equations governing the other two regimes are of different types. [ABSTRACT FROM AUTHOR]

The effect of electromagnetically induced transparency (EIT) in a three-level ladder system 5S1/2‒5P3/2 –5D5/2 of Rb atoms is investigated. The effect of spectral narrowing of a dark resonance (DR) as a function of atomic vapor density and thickness L of a spectroscopic cell containing Rb vapor is demonstrated. Thickness L was varied in the range of 390 nm to 4 mm, while atomic density N was increased up to ~1016 cm–3; in the process, high-intensity coupling radiation and weak probe radiation were used. The strongest effect, namely, a 22-fold spectral narrowing of the DR, was achieved in a cell of thickness L = 4 mm. The effect of spectral narrowing was decreasing with decrease in thickness L: a 2.4-fold spectral narrowing of the DR was observed at L = 2 μm. Spectral narrowing was nearly absent at L = 0.8 μm, and spectral broadening of the DR was observed with further decrease in the cell thickness down to L = 0.4 μm. A close to 100% DR contrast was achieved in nearly all cases at moderate atomic densities and high intensities of the coupling radiation. An interpretation of the effect of spectral narrowing and broadening of the DR is proposed. [ABSTRACT FROM AUTHOR]

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Fast-response infrared gas analyzers (IRGAs) have been widely used over three decades in many ecosystems for long-term monitoring of water vapor fluxes in the surface layer of the atmosphere. While some of the early IRGA sensors are still used in these national and/or regional eco-flux networks, optically-improved IRGA sensors are newly employed in the same networks. The purpose of this study was to evaluate the performance of water vapor density and flux data from three generations of IRGAs - LI-7500, LI-7500A, and LI-7500RS (LI-COR Bioscience, Inc., Nebraska, USA) - over the course of a growing season in Bushland, Texas, USA in an irrigated maize canopy for 90 days. The energy balance ratio, which is the sum of turbulent fluxes divided by the sum of surface available energy, was used to assess systematic biases of the IRGA sensors for evapotranspiration (ET). Water vapor density measurements were in generally good agreement, but temporal drift occurred in different directions and magnitudes. Means exhibited mostly shift changes that did not impact the flux magnitudes, while variances of water vapor density fluctuations were occasionally in poor agreement, especially following rainfall events. LI-7500 variances were largest compared to recent LI-7500RS and LI-7500A results manifesting in widened cospectra, especially under unstable and neutral static stability. Agreement among the sensors was best under the typical irrigation-cooled boundary layer, with a 14% interinstrument coefficient of variability under advective conditions. Generally, the smallest variances occurred with the LI-7500RS, and high-frequency spectral corrections were larger for these measurements resulting in similar fluxes between the LI-7500A and LI-7500RS. Fluxes from the LI-7500 were best representative of growing season ET based on a world-class lysimeter reference measurement but using the energy balance ratio as an estimate of systematic bias corrected most of the differences among measured fluxes. [ABSTRACT FROM AUTHOR]

Density effect corrections (DECs) are applied to adjust raw CO2 fluxes measured by eddy covariance (EC) systems with open‐path gas analyzers. DEC is also required for adjusting the measured CO2 concentration fluctuations to obtain the adjusted CO2 concentrations for analyzing turbulent statistics or quantifying fluxes. However, our data show that the power spectra of the DEC‐adjusted CO2 concentrations are distorted in the high‐frequency range, as compared with the corresponding spectra of temperature and water vapor density. This contradicts the similarity behavior of scalars, as suggested by Monin‐Obukhov similarity theory. It is demonstrated that such a distortion is caused by the DEC‐induced spikes in the DEC‐adjusted CO2, altering turbulent statistics of CO2 and scalar similarity between CO2 and other scalars. Our results suggest that CO2 fluxes are overestimated by applying DEC especially under high Bowen ratio conditions, potentially leading to substantial uncertainties in long‐term ecosystem carbon exchange in dry regions. Plain Language Summary: Eddy covariance (EC) systems are widely used to measure land‐surface fluxes. However, the measured water vapor densities and CO2 concentrations by open‐path CO2/H2O gas analyzers in EC systems are subjected to the density effects caused by heat and water transfer, the so‐called density effects. Density effect corrections (DECs) are required to adjust the measured raw CO2 concentrations to obtain the DEC‐adjusted CO2 concentrations. By comparing the power spectra of the DEC‐adjusted CO2 concentrations with those of temperature and water vapor density, it is found that the power spectra of the DEC‐adjusted CO2 are distorted in the high‐frequency range, contradicting the Monin‐Obukhov similarity theory that requires similar behaviors of different scalars. This distortion also causes an increase in the variances of CO2. CO2 fluxes are overestimated by about 5–35% under higher Bowen ratio conditions, potentially leading to substantial uncertainties in long‐term ecosystem carbon exchange in dry regions. Key Points: CO2 fluxes by applying density effect corrections (DECs) to time series of CO2 concentration fluctuations and to raw fluxes are equalPower spectra of the DEC‐adjusted CO2 concentration fluctuations are distorted in the high‐frequency range due to the DEC‐induced spikesUncertainties in turbulent statistics and CO2 fluxes caused by the DEC‐induced spikes are enlarged as Bowen ratio increases [ABSTRACT FROM AUTHOR]

Predictions of salt solubility, brine vapor pressure and density are necessary to plan subsurface and surface operations. In this work, a comparative study was conducted to investigate prediction capabilities for salt solubility, equilibrium and volumetric properties of several minerals in "Formation" water by the Pitzer model (a commonly used industrial model) and by the ePC-SAFT equation of state (EOS). To achieve this, several validation and comparison steps were considered for reliable implementation of both models. Firstly, solubility, brine densities and vapor pressures for single-salt solutions were predicted. Afterward, the models' applications were extended to several mixtures of two salts to predict solubility compared to experimental data from available literature. ePC-SAFT shows promising accuracy. The average relative deviation for prediction of liquid density (which cannot be estimated with the Pitzer model) for single-salt solutions of NaBr, KCl, NaCl and Na2SO4 are 1.13%, 0.70%, 1.02% and 0.36%, respectively. The average relative deviation from experimental data of vapor pressure for mixtures of NaCl and KBr is 0.75% and for mixtures of NaBr and KCl is 0.74% for systems with different concentrations. Moreover, a stochastic regression procedure is presented to evaluate the ePC-SAFT parameters. This technique is used for strontium in different salt solutions. The average relative deviation for mean ionic activity coefficients calculated by ePC-SAFT from experimental data using the ePC-SAFT parameters of strontium from the work of Held et al. [1] for single-salt solutions of strontium chloride, strontium bromide, strontium iodide, strontium nitrate and strontium perchlorate are 19.73%, 19.96%, 15.15%, 14.95% and 25.70%, respectively. These values using the ePC-SAFT parameters of strontium regressed in this work are 6.98%, 10.13%, 8.33%, 9.59% and 10.08%, respectively. Finally, the solubility of different salts was studied for mixing of formation water (FW) and injection water (SW). [ABSTRACT FROM AUTHOR]

ShackHartmann-type laser wavefront sensors were utilized for the systematic investigation on Cr content dependence of 2D electron and metal vapor density distributions over vacuum arcs generated between CuCr electrodes, whose Cr content were 0 wt.%, 25 wt.%, 35 wt.%, 50 wt.% and 75 wt.%. The electron density was highest for the Cr25wt.% and Cr35wt.%, while the metal vapor density was lowest for the same CuCr electrode compositions. These experimental results demonstrated high consistency with previously reported CuCr composition dependence of electrode erosion rates, duration time of anode melting and residual charge after current zero. Furthermore, based on the present density data and previously proposed dielectric recovery processes, it was suggested that Cr25wt.% and Cr35wt.% are suitable for the interruption of intense-mode vacuum arcs; instead, Cr50wt.% and Cr75wt.% are useful for diffused arc interruption. The validity of this suggestion was supported by previous experimental studies reporting Cr content dependence of arc current interruption capacities and dielectric recovery speeds. [ABSTRACT FROM AUTHOR]

The Northern Great Plains (NGP) experienced a transition from a long drought cycle to a deluge cycle in the late 1900s. Embedded within this long‐term transition were shorter‐term decadal‐scale dry and wet periods. A recent NGP drought (1999–2004) was followed in 2005 by a wet period that continues to present day. However, how surface hydrology in a northern glaciated landscape responds to increased precipitation is poorly understood and a physically based modeling framework is needed to clarify the underlying processes. This study utilizes a physically based hydrologic model to investigate the impacts of increased precipitation on the water budget by examining its partition into intermediate processes from 2004–2017 in the Mauvais Coulee Basin (MCB). The MCB model evaluations against snow observations (2016–2017) and outlet streamflow observations (2004–2017) imply strong model performance. Simulated snow exhibits high spatiotemporal variation due to variability in precipitation, snow redistribution from stubble fields to wooded areas, and snow accumulation in small depressions. Our modeling results identify two major phases (before and after 2011) exhibiting different hydrologic responses. The period before 2011 is dominated by streamflow and evapotranspiration (ET), while extreme ET dominance is observed after 2011. This switch is due to climatic conditions involving changes in the vapor density difference and depressional and subsurface storage by intermediate processes. A clear contrast in the prewinter soil moisture‐streamflow relationship between before and after 2011 is reported. Our findings help illuminate the important influences of increased precipitation upon the intermediate processes in controlling streamflow in a northern glaciated prairie landscape. Key Points: A physically‐based model is used to investigate mechanisms of hydrologic change to recent wetting in a cold region agricultural basinDuring recent wetting, the hydrological system transitioned from a moderate ET‐controlled to an extreme ET‐dominated regimeInterannual streamflow variations are due to complex interaction of peak SWE, fall soil moisture, frozen soil conditions, and rain on snow [ABSTRACT FROM AUTHOR]

In this study, a fluidized bed graphite tube evaporator with an internal vapor-liquid-solid flow boiling in the tube was established and the signals of vibration acceleration of the tube were measured. The attractors of the fluctuations of flow induced vibration acceleration were investigated by applying the chaos theory, and the evolving mechanism of the chaotic attractors of vapor-liquid-solid flow induced vibration signals at varied solid holdup and steam pressure was analyzed. The results indicate that the multiphase flow induced vibration has a chaotic nature. The chaotic attractor of the vibration acceleration signals can display the multiphase flow vibration behavior. Higher fluid mixture density and turbulent vapor bubble number result in denser, bigger and more complex chaotic attractor. Fluidized solid particles have an obvious influence on the vibration behavior of the graphite tube with internal vapor-liquid flow boiling. Unlabelled Image • Vibration of tube with internal vapor-liquid-solid flow boiling is chaotic. • The attractor of vibration acceleration signal appears as a regular trajectory. • Attractor characters vary closely with the tube vibration behavior. • Time delay value doesn't change with solid holdup of vapor-liquid-solid flow. • Fluidized solid particles have an obvious influence on tube vibration behavior. [ABSTRACT FROM AUTHOR]

Interelectrode phenomena related to intense-mode vacuum arc interruption were systematically compared between CuCr and AgWC electrodes by using various optical techniques mainly including two-color pyrometry for anode temperature determination after current zero, optical emission spectroscopy for the plasma composition assessment, and a Shack–Hartmann method for simultaneous 2-D electron and metal vapor density imaging. At the current peak, the widths of the radial electron density distributions for CuCr were narrower than those for AgWC. The electron density for CuCr was 3–5 times higher than that for AgWC. At current zero, the metal vapor density for CuCr was slightly lower than that for AgWC, which was specifically demonstrated for CuCr by a locally reduced metal vapor density below the minimum detectable limit of 1020 m−3. During and after the arcing time, mixing ratios of the copper vapor existing in the CuCr gap was about two times higher than expected from the CuCr electrode composition. After current zero, the decaying time constants of the metal vapor densities on the anode surfaces were Cr < Cu < Ag. This order was consistent with the decaying time constants of the anode evaporation rates estimated from the anode temperature measurement. The consistency suggests that the supplying process of the metal vapor after the intense vacuum arc interruption was the evaporation of the anode surfaces. [ABSTRACT FROM AUTHOR]

In this paper, the breaking process of the vacuum circuit breakers is briefly described, and the main factors that influence the post-arc process are analyzed. Based on the detachable vacuum interrupter, the experimental platform of AC breaking is built, and the experiments of the post-arc current measurement and cathode spot observation are completed. The voltage and current during the period of current zero are measured, and the images of cathode spots during the arcing process are obtained. The experimental results show that at the same frequency, the post-arc current Ipac and the post-arc charge Qpac increase with the increase in d i d t cz ( d i d t at current zero). Under the same conditions of d i d t cz , Ipac and Qpac decrease with the increase in frequency, but both are unchanged with frequency when the frequency is high enough. With the increase in current frequency, the distribution diameter of cathode spots decreases under the condition of the same d i d t cz value. According to the characteristics of cathode spot distribution, the metal vapor density under different conditions is calculated. Comparing the calculation results of metal vapor with the experimental results of post-arc current, the concept of metal vapor ionization is put forward. An ionization process of metal vapor after the current zero crossing occurs. The ionization of metal vapor will cause an increase in the number of electrons after the current zero crossing, which affects Ipac, Qpac, and sheath growth. [ABSTRACT FROM AUTHOR]

Two groups of experimental data obtained in the vicinity of the critical point are discussed. Group I describes the level ht of the meniscus separating the two phases of the substance in the cell. The measurements were performed for SF6 under the condition (g = 9.8 m s–2) during an experiment conducted in a space laboratory. Group II includes data on the density of liquid and vapor measured for C6F6 along the saturation curve under terrestrial condition. In both cases, the studied two-phase sample is located in a horizontal cylindrical cell. In the second experiment, the gravitational effect was also measured along the isotherms as the dependence of the sample density on the height h measured from the bottom of the cell. An equation relating the ht level (experiment I) with such functions as the order parameter fs and the average diameter fd is derived in this work. The obtained equation describes the initial experimental data at relative temperatures τ = (T – Tc)/Tc = 2 × 10–6–0.01. An approach is considered that takes into account the influence under microgravity (g = gM ⪡ 9.8 m s–2) on the height h (experiment II). The dependences that represent fs and fd and the density of the liquid and gas phases along the saturation curve of these substances are obtained. These dependences agree satisfactorily with the results of experiments I and II in a wide temperature range and correspond to the scaling theory of critical phenomena. [ABSTRACT FROM AUTHOR]

In this study, the effect of copper nanoparticles on the interface properties of liquid–vapor argon is investigated by molecular dynamics simulation. Stoddard Ford potential function has been utilized to estimate the interactions of argon–argon and argon–copper particles. Simulation is done in the nanoscale computational domain to phase change of vapor to liquid at different saturated temperatures. Density values and surface tension for different cutoff radii are obtained. It is demonstrated that in the r c = 4 σ calculated values are acceptable. Simulation results show that nanoparticles change the interface properties of liquid–vapor argon. With addition of nanoparticles, liquid density decreases and vapor density increases. Nanoparticles displace density distribution and cause fluctuations in the density profile. Also, surface tension increases with increase in nanoparticle concentration. [ABSTRACT FROM AUTHOR]

The Euler model that attaches to the ANSYS CFX software is used to simulate the ethane shear and vaporizing flow on the shell-side of spiral wound heat exchanger (SWHE). The diameter of the disperse liquid particle that influences the phase interactions in the governing equations is investigated. Based on the energy conservation, formula for the average diameter of the disperse liquid particle is deduced. The heat ratio of phase change is proposed to compute simply the liquid particle average diameter so that the shear and vaporizing flow on the shell-side of SWHE could be simulated accurately and within the deviation of ±20%. The heat ratio of phase change is mainly influenced by the shell-side operating parameters including inlet quality and pressure, hence a formula of the heat ratio of phase change is fitted by both shell-side inlet quality and vapor density variables. The formula of the heat ratio of phase change is also applicable under different conditions such as mass velocity and heat flux variation. [ABSTRACT FROM AUTHOR]

Using the pseudo-boiling concept, supercritical heat transfer is analogized to the boiling at subcritical pressures. The proposed supercritical-boiling-number SBO represents the competition between the bubble expansion induced momentum force and the inertia force. Sudden changes between normal heat transfer and heat transfer deterioration are found when crossing critical SBO , which is experimentally determined for CO 2 , H 2 O, R134a and R22. The linear law of supercritical heat transfer is discovered. Our study supports the heterogeneous structure of supercritical fluids. • Supercritical-boiling-number SBO dominates supercritical heat transfer mechanism. • Sudden changes in heat transfer behaviors are found when crossing critical SBO. • Critical SBO values are experimentally determined for CO 2 , H 2 O, R134a and R22. • Our study supports the heterogeneous structure of supercritical fluids. Supercritical fluids such as CO 2 , water and organic fluids are frequently applied in power systems. The accurate prediction of heat transfer deterioration (HTD) is important to keep the safe operation of advanced power systems such as solar driven supercritical carbon dioxide Brayton cycle. As described in textbooks, it is impossible to identify liquid from gas beyond the critical point, thus supercritical fluid is assumed to have homogeneous structure with a single-phase. The single-phase assumption cannot explain and predict supercritical heat transfer (SHT). Instead, we investigate SHT by the pseudo-boiling concept. Heat transfer is analogized between supercritical pressure and subcritical pressure to create a new non-dimensional supercritical-boiling-number SBO , representing the bubble expansion induced momentum force against the inertia force when it is coupled with the ratio of liquid density with respect to vapor density. Our study reveals sudden changes from normal heat transfer (NHT) to heat transfer deterioration (HTD) with obvious temperature peak when crossing a critical SBO , which is 5.126 × 10−4, 2.018 × 10−4, 1.653 × 10−4 and 1.358 × 10−4 for CO 2 , H 2 O, R134a and R22, determined by a large quantity of database. Our work paves a new way to understand the SHT mechanism and supports the heterogeneous structure of liquid-like fluid and vapor-like fluid for supercritical fluids. [ABSTRACT FROM AUTHOR]

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The paper presents research results of the pyrrole oxidation in stoichiometric, rich, and lean mixtures of C 4 H 4 NH/O 2 (ρ Py = 0.15 mol/dm3, ρ O2 = 0.61−0.91 mol/dm3), diluted with argon and water vapor (x D = 46−62%mol), at the uniform heating (1 K/min) of a tubular reactor made of stainless steel. It was revealed that pyrrole oxidation proceeds through the heterogeneous and homogeneous oxidation mechanisms. The contribution of heterogeneous oxidation increases with the accumulation of corrosion products on the reactor wall and a decrease in the density of water vapor. Based on the time dependences of the temperature of the reaction mixtures, it was revealed that in the presence of corrosion products, the ignition temperature of pyrrole in argon medium is about 50 K below than that in water vapor (varies within the range 608−619 K). From the results of mass spectrometric analysis, it follows that pyrrole oxidation occurs mainly through the formation of NH 3. Along with N 2 and NH 3 , N 2 O was detected in volatile oxidation products. It is shown that the increase in water vapor density inhibits pyrrole oxidation. The degree of nitrogen removal from the pyrrole in the form of N 2 is changed from 9.9 to 90.1%mol. The composition and morphology of corrosion products are determined by X-ray diffraction analysis and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

• A new model of a thermosiphon desorber under sub-atmosphere was established. • The known correlations were checked to the validities of the model. • The heat transfer and mass flow rate behaviors have been investigated in the model. The thermosiphon desorber or bubble pump is advantageous in absorption cooling devices, since the processes of refrigerant desorption and solution pumping is combined in one hermetical unit. This supersedes the necessity of a mechanical solution pump. In the application with NH 3 /H 2 O the thermosiphon desorber typically operates at a pressure of around 15 bar with a liquid vapor density ratio in the range of 102, which is in a well-known regime of two phase flow. Nevertheless, for the application of thermosiphon desorbers in H 2 O/LiBr absorption chillers, which are commonly operated at a pressure below 0.1 bar with the liquid vapor density ratio in the range of 104, there is a lack of heat transfer correlations for two-phase flow. First attempts to fill this gap of flow boiling heat transfer correlations in the thermosiphon desorber at sub-atmospheric pressures is presented in this paper. A model is formed by solving simultaneously the mass, energy, and momentum equations. The well-known correlations for predicting single-phase and two-phase flow heat transfer coefficient and frictional pressure drop have been reviewed to find a possibility for applying them to the thermosiphon desorber. The mass flow rate and heat transfer behavior with the different flow length of the riser tube and with changing the pressure has been theoretically studied in the model. For verification, the model has been compared to experimental data using pure water. This will be presented in the second part of the paper. [ABSTRACT FROM AUTHOR]

A pure theoretical investigation of convective rain formation processes and formation efficiency (FE) is performed using a kinematic one‐dimensional time‐dependent model with warm rain microphysics. FE is defined as the ratio of total cloud‐to‐rainwater conversion to total condensation. FE is a component of precipitation efficiency, which is an important but poorly understood parameter in idealized climate models. This model represents a cloud by a cylindrical thermal bubble rising at constant velocity. The model focuses on the interaction between auto‐conversion, collection, and lateral mixing about which no theory has been proposed. Taking the auto‐conversion threshold into account, a criterion for rain formation and a semianalytical approximate solution of FE are found. The auto‐conversion threshold limits the temporal and spatial extent of the "vigorous rain formation region" where most of the rain is produced. The collection and auto‐conversion compete with lateral mixing to determine the strength of rain formation within this region. The FE is predicted to be most sensitive to auto‐conversion threshold, fractional entrainment rate, and initial bubble water vapor density. Plain Language Summary: A theory is proposed to understand how much rain a convective cloud can produce. The subsequent evaporation of raindrops after they fall out of the cloud is a separate problem and is not considered here. The rain formation depends on two competing factors: One is how fast it is for floating small droplets to grow into falling large droplets, and the other is how much water is thrusted out of the cloud by turbulent flow before they are converted to rain. The cloud is modeled as a cylindrical hot air blob moving upward at a given uniform speed. The result shows that the cloud radius, initial water vapor content, and a cloud water conversion threshold governed by aerosol concentration are the most influential factors for the in‐cloud rain formation process. Key Points: A semianalytical kinematic one‐dimensional cloud model for understanding rain formation efficiency (FE) is derivedThe auto‐conversion threshold controls FE through controlling the temporal and spatial size of vigorous rain formation regionFE is predicted to be most sensitive to auto‐conversion threshold, fractional entrainment rate, and initial bubble vapor density [ABSTRACT FROM AUTHOR]

A new force field for dimethyl ether (DME) based on the Lennard-Jones (LJ) 12-6 plus point charge functional form is presented in this work. This force field reproduces experimental saturated liquid and vapor densities, vapor pressures, heats of vaporization, and critical properties to within the statistical uncertainty of the combined experimental and simulation measurements for temperatures between the normal boiling and critical point. Critical parameters and normal boiling point are predicted to within 0.1% of experiment. This force field is used in grand canonical histogram reweighting Monte Carlo simulations to predict the pressure composition diagrams for the binary mixtures DME + SO2 at 363.15 K and DME + CO2 at 335.15 and 308.15 K. For the DME + SO2 mixture, simulation is able to qualitatively reproduce the minimum pressure azeotropy observed experimentally for this mixture, but quantitative errors exist, suggesting that multibody effects may be important in this system. For the DME + CO2 mixture, simulation is able to predict the pressure-composition behavior within 1% of experimental data. Simulations in the isobaric-isothermal ensemble are used to determine the microstructure of DME + SO2 and DME + CO2 mixtures. The DME + SO2 shows weak pairing between DME and SO2 molecules, while no specific pairing or aggregation is observed for mixtures of DME + CO2. [ABSTRACT FROM AUTHOR]

In situ uniform growth of ZnO nanowires was realized and monitored at real time by heating zinc film in an environmental scanning electron microscope. Better controllability and repeatability were obtained by using zinc film as source material compared to traditionally used zinc powder. Morphology of the as-grown ZnO nanowires was found to depend on both the growth temperature and holding time. Low temperature (500 °C) and short growth time (∼20 min) favor one-dimensional nanowire growth, whereas longer holding time (>40 min) or higher temperature (700 °C) lead to nanosheet growth. The results suggest that the zinc vapor partial pressure is vital in determining the final morphology. These results help to give more insights into the mechanism of ZnO nanowire synthesis. [ABSTRACT FROM AUTHOR]

Antirelaxation surface coatings allow long spin relaxation times in alkali-metal cells without buffer gas, enabling faster diffusion of the alkali atoms throughout the cell and giving larger signals due to narrower optical linewidths. Effective coatings were previously unavailable for operation at temperatures above 80 °C. We demonstrate that octadecyltrichlorosilane (OTS) can allow potassium or rubidium atoms to experience hundreds of collisions with the cell surface before depolarizing, and that an OTS coating remains effective up to about 170 °C for both potassium and rubidium. We consider the experimental concerns of operating without buffer gas and with minimal quenching gas at high vapor density, studying the stricter need for effective quenching of excited atoms and deriving the optical rotation signal shape for atoms with resolved hyperfine structure in the spin-temperature regime. As an example of a high-temperature application of antirelaxation coated alkali vapor cells, we operate a spin-exchange relaxation-free atomic magnetometer with sensitivity of 6 fT/Hz and magnetic linewidth as narrow as 2 Hz. [ABSTRACT FROM AUTHOR]

Atomic spin polarization of alkali atoms in the ground-state can survive thousands of collisions with paraffin-coated cell walls. The resulting long spin-relaxation times achieved in evacuated, paraffin-coated cells enable precise measurement of atomic spin precession and energy shifts of ground-state Zeeman sublevels. In the present work, nonlinear magneto-optical rotation with frequency-modulated light (FM NMOR) is used to measure magnetic field-induced spin precession for rubidium atoms contained in a paraffin-coated cell. The magnetometric sensitivity of FM NMOR for the rubidium D2 line is studied as a function of light power, detuning, frequency-modulation amplitude, and rubidium vapor density. For a 5-cm-diameter cell at temperature T≈35 °C, the optimal shot-noise-projected magnetometric sensitivity is found to be 2×10-11 G/Hz (corresponding to a sensitivity to spin precession frequency of ≈10 μHz/Hz or a sensitivity to Zeeman sublevel shifts of ≈4×10-20 eV/Hz). [ABSTRACT FROM AUTHOR]

The homogeneous nucleation of water was studied experimentally in this work using a thermal diffusion cloud chamber; droplets were counted by the photomultiplier method and helium was used as a carrier gas. The nucleation rates range from 3×10-2 to 3×101 cm-3 s-1 and six isotherms from 295 to 320 K with step of 5 K are measured. The experimental setup and obtained data are mutually compared to our previous publication [Brus et al., J. Chem. Phys. 129, 174501 (2008)], where the droplets were counted using digital photography and image processing. The molecular content of the critical clusters was estimated from the slopes of experimental data. The measured isothermal dependencies of the nucleation rate of water on the saturation ratio were compared with previously published data of others, several theoretical predictions, and the former nucleation onset data. The aim of the present investigation was to show for the first time that nucleation results can be quantitatively reproduced with two different experimental setups operated in different ways. [ABSTRACT FROM AUTHOR]

Atomic clocks that fly on global-navigation satellites such as global positioning system (GPS) and Galileo employ light from low-temperature, inductively coupled plasmas (ICPs) for atomic signal generation and detection (i.e., alkali/noble-gas rf-discharge lamps). In this application, the performance of the atomic clock and the capabilities of the navigation system depend sensitively on the stability of the ICP's optical emission. In order to better understand the mechanisms that might lead to instability in these rf-discharge lamps, and hence the satellite atomic clocks, we studied the optical emission from a Rb/Xe ICP as a function of the rf power driving the plasma. Surprisingly, we found that the electron density in the plasma was essentially independent of increases in rf power above its nominal value (i.e., "rf-power gain") and that the electron temperature was only a slowly varying function of rf-power gain. The primary effect of rf power was to increase the temperature of the neutrals in the plasma, which was manifested by an increase in Rb vapor density. Interestingly, we also found evidence for electron temperature fluctuations (i.e., fluctuations in the plasma's high-energy electron content). The variance of these fluctuations scaled inversely with the plasma's mean electron temperature and was consistent with a simple model that assumed that the total electron density in the discharge was independent of rf power. Taken as a whole, our results indicate that the electrons in alkali/noble-gas ICPs are little affected by slight changes in rf power and that the primary effect of such changes is to heat the plasma's neutral species. [ABSTRACT FROM AUTHOR]

We have performed molecular dynamics simulations of Lennard-Jones argon clusters in equilibrium with a surrounding vapor and combined them with simulations of nucleation events in supersaturated vapor to investigate the dependence of critical cluster size on the vapor density in the cluster size range of 20–300 atoms. The simulations are performed at reduced temperature T′=0.662, which with the parameter values of Lennard-Jones argon corresponds to 80 K. We obtain bulk equilibrium values by simulating a planar liquid-vapor interface. In the studied cluster size range, we find a linear relation between critical size ΔN* and Δμ-3, where Δμ is the chemical potential difference between supersaturated vapor and saturated vapor, but the slope of the line is not given by the Kelvin relation of classical nucleation theory. With this relation, along with the known formation energy of the small critical cluster of the nucleation simulations, we proceed to calculate the formation energies for larger critical sizes by integrating the nucleation theorem. We compare the molecular dynamics results to results from Monte Carlo simulations and both perturbative density functional theory and square gradient theory calculations. We find that the molecular dynamics results are in excellent agreement with the density functional and square gradient values. However, the Monte Carlo critical sizes and formation energies are somewhat lower than the molecular dynamics ones. [ABSTRACT FROM AUTHOR]

We examine the propagation of shaped (amplitude- and frequency-modulated) ultrafast laser pulses through optically dense rubidium vapor. Pulse reshaping, stimulated emission dynamics, and residual electronic excitation all strongly depend on the laser pulse shape. For example, frequency swept pulses, which produce adiabatic passage in the optically thin limit (independent of the sign of the frequency sweep), behave unexpectedly in optically dense samples. Paraxial Maxwell optical Bloch equations can model our ultrafast pulse propagation results well and provide insight. [ABSTRACT FROM AUTHOR]

We examine two free-energy-based methods for studying the wetting properties of a fluid in contact with a solid substrate. Application of the first approach involves examination of the adsorption behavior of a fluid at a single substrate, while the second technique requires investigation of the properties of a system confined between two parallel substrates. Both of the techniques rely upon computation and analysis of the density dependence of a system’s surface free energy and provide the contact angle and solid-vapor and solid-liquid interfacial tensions for substrate-fluid combinations within the partial wetting regime. Grand canonical transition matrix Monte Carlo simulation is used to obtain the required free-energy curves. The methods examined within this work are general and are applicable to a wide range of molecular systems. We probe the performance of the methods by computing the interfacial properties for two systems in which an atomistic fluid interacts with a fcc crystal. For both of the systems studied we find good agreement between our results and those obtained via the mechanical definition of the interfacial tension. [ABSTRACT FROM AUTHOR]

In this paper, we used the Molecular Dynamics method to simulate the equilibrium vapor–liquid methane in contact with a solid quartz substrate and study the condensation process and momentum exchange at the atomic level. A large potential cutoff radius is used to determine the vapor and liquid densities at good accuracy. By tracking the motions of fluid molecules exchanged between the vapor and liquid phases and carrying out statistical analysis of residence time, penetration depth and especially velocity correlation, the mass and the velocity accommodation coefficients can be determined at the same time. The latter is based on the assumption that the reflected events take place over a short time, near the interface and thus atoms velocities are correlated while the condensation/evaporation events are not. The calculated coefficients are sensitive to the film thickness due to the presence of the quartz substrate and the layering effects. As temperature increases, atoms condense less and reflect more and the reflection is more diffusive due to increasing collision rate. Near the critical temperature, both the condensation and momentum accommodation coefficients vary significantly. [ABSTRACT FROM AUTHOR]

• The liquid and vapor branches of the coexistence curve of nitrogen, ethylene and sulfur hexafluoride are obtained in analytically closed form. • The critical exponents of the order parameter and reduced coexistence-curve diameter are regressed from high-precision data and compared with scaling predictions. • Index functions (effective exponents) defined by the Log–Log slope of the order parameter and diameter indicate the onset of the critical scaling regime. • The crossover from the ideal power-law scaling regime of the coexistence curve to the triple point is modeled with Index functions. Analytic closed-form expressions are obtained for the liquid and vapor saturation densities defining the coexistence curve. The densities are modeled with broken power laws and Weibull distributions. Specifically, the coexistence curves of nitrogen, ethene and sulfur hexafluoride are derived, without the use of perturbative expansions, based on high-precision data extending from the triple point into the critical regime. The analytic continuation of the vapor branch below the triple point decays exponentially at low temperature. The order parameter and coexistence-curve diameter of the fluids are assembled from the regressed liquid and vapor branches of the coexistence curve, and the critical power-law scaling of these quantities is examined. The scaling exponents of the order parameter and the reduced diameter are regressed and compared with the calculated critical exponents of the 3D Ising universality class. Index functions representing the Log−Log slopes (temperature-dependent effective exponents) of the liquid and vapor densities, order parameter and diameter are used to determine the onset of the ideal power-law scaling regime and to illustrate the slope evolution of these quantities in the subcritical regime. [Display omitted] [ABSTRACT FROM AUTHOR]

• Radiative impact of biases in tropical atmospheric parameters was investigated. • Standard tropical parameters deviate from the instantaneous atmosphere state. • Radiative impact is highly susceptible to water vapor and temperature changes. • Longwave component significantly influenced the net ARF and HR. • Emphasizes the usage of instantaneous atmosphere state for estimating ARF and HRs in the tropics. Many studies highlight the importance of water vapor in tropical atmospheric radiative transfer calculations. However, limited research focuses on understanding the effects of biases in different atmospheric factors, such as pressure, temperature, water vapor, and ozone densities. These biases stem from various sources, including satellites, reanalysis data, and the standard TROPICAL atmosphere. This study explores how these biases influence estimates of two key things: atmospheric radiative forcing (ARF) and heating rate (HR) profiles over the tropical region. The study is undertaken at Gadanki, a rural background site in the tropics. It considers different situations - clear skies and those with aerosols - across different parts of the electromagnetic spectrum and throughout the seasons. Additionally, this study investigates how sensitive ARF and HR profiles are to biases in each of these atmospheric factors within specific spectral ranges. The study results show that the standard TROPICAL atmosphere often differs significantly from real-time measurements, leading to varied effects on radiation. Among the various factors, biases in water vapor density have the most substantial impact on ARF and HR, followed by biases in temperature. Moreover, longwave radiation is more sensitive to water vapor and temperature changes. This study emphasizes the importance of considering the exact state of the atmosphere, especially in tropical regions, when estimating ARF and HR. To improve estimates when real-time data isn't available, the study suggests combining data from the Microwave Limb Sounder (MLS) and the Atmospheric Infrared Sounder (AIRS), and using reanalysis data for broader assessments. It's also important to be cautious when using the TROPICAL atmosphere to analyze the radiative effects of aerosols. [Display omitted] [ABSTRACT FROM AUTHOR]

• Near-critical CO 2 heat transfer experiments were conducted at low mass fluxes. • DNB type boiling crisis occurred under vapor quality below 20%. • Heat transfer deterioration propagated to inlet side within 3500 s under small power increase. • A phenomenological model was established for self-propagation of heat transfer deterioration. • Larger power increase resulted in higher movement speed of dry/wet interface. Near-critical CO 2 exhibits unique boiling heat transfer behavior due to its high saturated vapor density, low latent heat, and extremely low surface tension. In this study, an experimental investigation was conducted to study the heat transfer deterioration of near-critical CO 2 inside a vertical circular channel at low mass fluxes. The experimental results show a rapid rise in wall temperature at the outlet side with minimal power increase (∆ power = 33 W), and the wall temperature rise continuously self-propagates toward the inlet side. The heat transfer deterioration mechanism responsible for the wall temperature rise was considered to be a departure from nucleate boiling type boiling crisis based on the low vapor quality of the bulk fluid. In addition, the evolution of the axial heat transfer deterioration was analyzed in detail. And a phenomenological model was developed to explain the axial self-propagation of heat transfer deterioration based on the low mass fluxes and unique bubble behavior resulting from the low surface tension, high vapor density and low latent heat of the near-critical CO 2. The model was validated using different dry/wet interface movement speeds. [ABSTRACT FROM AUTHOR]

A corollary of the nucleation theorem due to Kashchiev [Nucleation: Basic Theory with Applications (Butterworth-Heinemann, Oxford, 2000)] allows the volume V* of a critical bubble to be determined from nucleation rate measurements. The original derivation was limited to one-component, ideal gas bubbles with a vapor density much smaller than that of the ambient liquid. Here, an exact result is found for multicomponent, nonideal gas bubbles. Provided a weak density inequality holds, this result reduces to Kashchiev’s simple form which thus has a much broader range of applicability than originally expected. Limited applications to droplets are also mentioned, and the utility of the pT,x form of the nucleation theorem as a sum rule is noted. [ABSTRACT FROM AUTHOR]