Vapor Mass Research Articles

Three-Dimensional Numerical Study of a Fluid-Kinetic Model for Respiratory Aerosols with Variable Size and Temperature

In this paper, we extend to the three-dimensional case the numerical study previously performed in a two-dimensional framework for a complex coupled fluid-kinetic model describing respiratory aerosols. The specificity of this model lies in the fact that it takes into account the airway humidity and the resulting hygroscopic effects on the aerosol droplets, namely their size variation. The air is described through a system of partial differential equations: the incompressible Navier–Stokes equations for the air velocity, convection-diffusion equations on its temperature, and water vapor mass fraction. The aerosol distribution function obeys a Vlasov-type equation and depends on the standard kinetic variables, but also on radius and temperature variables. After discussing again the implementation strategy, we perform numerical experiments, mainly in a branched structure looking like the trachea and the first lung generation. This allows the presentation of various statistics on the aerosol behavior in terms of particle deposition, temperature, and size variation of the droplets. We observe that the outcome appears coherent with the two-dimensional case. Finally, we discuss several assumptions which may lead to model simplifications, such as the fact that the water vapor mass fraction in the air may be considered to be constant throughout the branched structure in standard breathing conditions.

A Model for Adsorption and Diffusion in Water Vapor Barrier Films

A model for describing the diffusion behavior of water vapor in barrier films is developed and applied to the cases of 1) pure polyethylene terephthalate (PET); 2) an inorganic thin film (ITF) with defects on a PET substrate (ITF/PET); and 3) PET/ITF/PET. The normalized concentration profile and the relative mass of water vapor in the ITF/PET and PET/ITF/PET barrier films are simulated as a function of diffusion time by considering the sorption and desorption of water vapor. The number of atoms penetrating the barrier films is quantitatively evaluated by the concentration gradient of water vapor, which is related to the water vapor transmission rate (WVTR). The simulated WVTR values in pure PET, PET/SiOx, and PET/SiOx/ORM layered structures are in good agreement with the experimental ones.

Filmwise Condensation From Humid Air on a Vertical Superhydrophilic Surface: Explicit Roles of the Humidity Ratio Difference and the Degree of Subcooling

Abstract The process involving heat and mass transfer during filmwise condensation (FWC) in the presence of noncondensable gases (NCG) has great significance in a large variety of engineering applications. Traditionally, the condensation heat transfer is expressed in the literature as a function of the degree of subcooling—reckoned as the difference between the ambient dry bulb temperature and the condenser wall temperature. However, in the presence of NCG, there exists a finite gradient of vapor mass fraction near the condenser plate, which directly influences the vapor mass flux to the condenser surface, thus limiting the condensation rate. The effects of both these influencing thermodynamic parameters, i.e., the degree of subcooling and the difference of humidity ratio (between the freestream environment and on the condenser plate), have been characterized in this work both experimentally and through a mechanistic model. The vapor mass flux during condensation on a subcooled vertical superhydrophilic surface under free convection regime is experimentally measured in a controlled environment (temperature and humidity) chamber. The mechanistic model, based on the similarity of energy and species transports, is formulated for the thermogravitational boundary layer over the condenser plate and tuned against the experimental results. Further, the model is used to obtain comprehensive data of the condensate mass flux and condensation heat transfer coefficient (CHTC) as functions of the salient thermal operating conditions over a wide parametric range. Results indicate that humidity ratio difference has a more pronounced influence on the condensation mass transfer rather than the degree of subcooling. Regime maps of condensate flux and CHTC show how these can be explicitly identified in terms of the degree of subcooling and humidity ratio difference, regardless of the prevailing thermal and humidity conditions at the freestream and the condenser plate. The mechanistic model thus lends to the development of empirical correlations of condensate mass flux and CHTC as explicit functions of these two parameters for easy use in practical FWC configurations.

Mathematical model describing the rate of evaporation of high-temperature petroleum products used in the oil and gas industry

Within the framework of the study, the process of evaporation of heated high-temperature oil products was studied, the results were used to determine the calculated values of the mass of vapors formed during the evaporation of spills of liquids heated above the design temperature. The result of the study was the development of a theoretical model based on the Stefan formula describing the rate of evaporation. This made it possible to establish that when heating high-temperature organic compounds form explosive vapor-air mixtures that pose a fire hazard.

Experimental Study on Pressure Drop and Heat Transfer Characteristics of Wet Air with Ash Particles across Circular Finned Tube Bundles

In this paper, in order to provide guidance on the design and operation of waste heat recovery heat exchangers for the dryer exhaust of lignite pre-drying, pressure drop and heat transfer characteristics of wet air with ash particles across circular finned tube bundles were experimentally studied under different conditions. The experimental water vapor mass fraction ranged from 5% to 15%, ash particle concentration ranged from 0 to 12.8 g/m3 and mainstream flow velocity ranged from 1.73 m/s to 3.46 m/s, respectively. The pressure drop coefficient generally increases and Nusselt number decreases with time due to the gradual ash deposition. The pressure drop coefficient is sensitive to ash particle concentration, while Nusselt number is sensitive to water vapor mass fraction. Especially, Nusselt number for the ash particle concentration of 1.5 − 5.4 g/m3 is a bit larger than that for the wet air without ash particles. Based on the experimental data, a normalized empirical formula was proposed to calculate the heat transfer characteristics of wet air with ash particles across circular finned tube bundles, and the deviation between experimental data and predicted results is −16.5% to +27.0% for more than 90% of the data.

Modeling and Simulation of Distillation of a Binary Non-Reacting Mixture using Rate Based Approach in Packed Column under Total Reflux

Modeling and simulation of a distillation column are very important in many chemical industries where ever it requires separation or purification of a liquid mixture into its pure components. Particularly in the context of improving efficiency, process scale-up, intensification and control it requires a validated model. In this work, both experimental results and simulation results are obtained. A batch distillation equipment that consists of a reboiler, a packed column, and a top condenser is used to distill a mixture of benzene and toluene with various heat inputs to the reboiler. The distillation process in the column is modeled by an evaporation rate-based approach using Raoult’s law for driving force. This particular feature is different from the stage-wise equilibrium model. The evaporation mass transfer coefficients are obtained for benzene and toluene in lab-scale apparatus. The material balance equations for the two components are solved using a finite difference method. The distillate compositions at total reflux obtained from experiments and the simulations are compared for validating of model proportionally. Further insights are obtained in regard to throughput and distillation efficiency.

Transition region adaptive conduction (TRAC) in multidimensional magnetohydrodynamic simulations

Context. In solar physics, a severe numerical challenge for modern simulations is properly representing a transition region between the million-degree hot corona and a much cooler plasma of about 10 000 K (e.g., the upper chromosphere or a prominence). In previous 1D hydrodynamic simulations, the transition region adaptive conduction (TRAC) method has been proven to capture aspects better that are related to mass evaporation and energy exchange. Aims. We aim to extend this method to fully multidimensional magnetohydrodynamic (MHD) settings, as required for any realistic application in the solar atmosphere. Because modern MHD simulation tools efficiently exploit parallel supercomputers and can handle automated grid refinement, we design strategies for any-dimensional block grid-adaptive MHD simulations. Methods. We propose two different strategies and demonstrate their working with our open-source MPI-AMRVAC code. We benchmark both strategies on 2D prominence formation based on the evaporation–condensation scenario, where chromospheric plasma is evaporated through the transition region and then is collected and ultimately condenses in the corona. Results. A field-line-based TRACL method and a block-based TRACB method are introduced and compared in block grid-adaptive 2D MHD simulations. Both methods yield similar results and are shown to satisfactorily correct the underestimated chromospheric evaporation, which comes from a poor spatial resolution in the transition region. Conclusions. Because fully resolving the transition region in multidimensional MHD settings is virtually impossible, TRACB or TRACL methods will be needed in any 2D or 3D simulations involving transition region physics.

Validation of Ultrasonic Harmonic Scalpel for Real-Time Tissue Identification Using Rapid Evaporative Ionization Mass Spectrometry.

In this study, we integrate rapid evaporative ionization mass spectrometry (REIMS) with the Harmonic scalpel, an advanced laparoscopic surgical instrument that utilizes ultrasound energy to dissect and coagulate tissues. It provides unparalleled manipulation capability to surgeons and has superseded traditional electrosurgical tools particularly in abdominal surgery, but is yet to be validated with REIMS. The REIMS platform coupled with the Harmonic device was shown to produce tissue-specific lipid profiles through the analysis of porcine tissues in both negative and positive ionization modes. Comparison with other methods of electrosurgical dissection, such as monopolar electrosurgery and CO2 laser, showed spectral differences in the profile dependent on the energy device used. The Harmonic device demonstrated major spectral differences in the phospholipid region of m/z 600–1000 compared with the monopolar electrosurgical and CO2 laser-generated spectra. Within the Harmonic REIMS spectra, high intensities of diglycerides and triglycerides were observed. In contrast, monopolar electrosurgical and laser spectra demonstrated high abundances of glycerophospholipids. The Harmonic scalpel was able to differentiate between the liver, muscle, colon, and small intestine, demonstrating 100% diagnostic accuracy. The validation of the Harmonic device–mass spectrometry combination will allow the platform to be used safely and robustly for real-time in vivo surgical tissue identification in a variety of clinical applications.

Digital materials design by thermal-fluid science for multi-metal additive manufacturing

Metal additive manufacturing is promising for designing advanced metallic parts of complex geometries. The challenge lies in process control on melt flow dynamics, alloy mixing and vapour mass loss, which is significantly vital for the final quality. A high-fidelity thermal-solutal-fluid modelling approach including accurate tracking of surface shape, thermo-capillary dynamics and vaporisation has been developed. Multi-species formulations are also included for multi-metal simulation. Using this method, the physical link between metal vapour mass loss and melt flow process for 21 transition metals and 3 binary alloys is investigated. The mass loss rate is governed by a fluid dynamic parameter of Reynolds number with a simple proportional correlation linked with thermal-fluid behavior of the melt pool, and convective mixing further complicates the behaviour in in-situ binary alloying. The digital materials approach is effective in understanding complex interdependent thermal-fluid flow dynamics and can advance process-based materials design.

Experimental Study and Data Analysis of the Effects of Ions in Water on Evaporation Under Static Magnetic Conditions

In order to clarify and validate the effect of the magnetic treatment on physicochemical properties of water, a precise study is carried out in this paper. To reach our purpose, laboratory tests were carried out to obtain information on the effect of ionic water composition after magnetic treatment on the evaporation rate. The results showed that, whatever, the type of treated water (tap water and compound water), the presence of a static magnetic field increases the evaporation mass which reaches 24% as evaporation rate. It was concluded that water would be the receiver of the magnetic treatment, the possible presence of ions does not modify the effect of the treatment on water and the increase in mass evaporation depends on the magnetization, not on water composition.

Experimental research on heat and mass transfer characteristics of membrane energy accumulator used in solar refrigeration

• Hollow fiber and flat membrane energy accumulators are designed and tested. • Compared with HFMEAs, FMEAs have higher mass transfer efficiency. • The mass transfer mechanism in MEA is analyzed. • Effects of thermodynamic characters on solution mass transfer are obtained. An experimental platform was set up to test the heat and mass transfer performance inside the membrane energy accumulator (MEA). Hollow fiber MEAs (HFMEAs) and flat MEAs (FMEAs) were designed and tested. Compared with HFMEAs, FMEAs have higher mass transfer efficiency. The average mass transfer speed of the water vapor increased by 108.34% when the evaporation temperature increased from 4.5 °C to 12.3 °C for HFMEA. When the evaporation temperature increased from 7.88 °C to 19.51 °C, the change in mass fraction of lithium bromide (LiBr) in FMEA increased by 62.36%. Compared with a 60% solution, the average mass transfer rate of water vapor molecules in a 70% LiBr solution increased by 49.83% for FMEA. In addition, the water vapor absorbed by the 70% LiBr solution in 30 min increased by 18.63% compared to that of the 60% solution for FMEA. The effect of the initial solution temperature on the mass transfer rate is closely related to the mass fraction of LiBr. Both the mass transfer rate and crystallization melting process of the LiBr solution will accelerate by increasing the initial mass fraction and evaporation temperature.

Rapid Evaporative Ionization Mass Spectrometry: A Review on Its Application to the Red Meat Industry with an Australian Context.

The red meat supply chain is a complex network transferring product from producers to consumers in a safe and secure way. There can be times when fragmentation can arise within the supply chain, which could be exploited. This risk needs reduction so that meat products enter the market with the desired attributes. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) is a novel ambient mass spectrometry technique originally developed for rapid and accurate classification of biological tissue which is now being considered for use in a range of additional applications. It has subsequently shown promise for a range of food provenance, quality and safety applications with its ability to conduct ex vivo and in situ analysis. These are regarded as critical characteristics for technologies which can enable real-time decision making in meat processing plants and more broadly throughout the sector. This review presents an overview of the REIMS technology, and its application to the areas of provenance, quality and safety to the red meat industry, particularly in an Australian context.

Experimental Study on Evaporation Characteristics of Light Cycle Oil Droplet under Various Ambient Conditions

The authors conducted droplet evaporation experiments of light cycle oil (LCO) at various ambient temperatures and pressures. Five kinds of LCO and three kinds of arranged fuels were used. We investigated the evaporation characteristics of LCO and the relationships between the evaporation characteristics and the cetane index. In addition to that, a surrogate fuel composed of four chemical species, which can simulate the droplet evaporation characteristics of LCO, was suggested. Experimental results show that the differences in droplet lifetime between fuel species become larger with decreasing ambient temperature. This is because the low volatile component made the evaporation rate outstandingly slow at a low ambient temperature. It was found that the relationship between droplet lifetime and the late-stage distillation temperature becomes stronger at low ambient temperature and high ambient pressure. By an analysis employing the properties of chemical species in LCO surrogate fuel, it is clarified that the mass evaporation rate becomes smaller than the internal diffusion, which is the condition similar to that in the distillation test. Finally, the relationship between the droplet lifetime and the cetane index was investigated. It can be concluded that the droplet lifetime is independent of the cetane index under all conditions tested in this study. The experimental data obtained by this research can be utilized for the validation of multicomponent fuel droplet evaporation models in the future.

Molecular dynamics simulation of sub/supercritical evaporation with n-butanol/n-heptane blended fuel

Sub/supercritical evaporations of single-component fuels have been developed well so far. In the last decade, dual fuels, even multiple fuels have received more attention. However, sub/supercritical evaporations of dual fuels are more complicated than that of single-component fuels, as dual fuels have uncertain critical points, and single-component fuels have exact critical points. Therefore, in this study, we focused on the functional relationship between the critical temperatures and the blending ratios (n-heptane to n-butanol) of the n-butanol/n-heptane blends by molecular dynamics simulations. A liquid film of the blends was constructed in nitrogen environment. The sub/supercritical evaporations processes of the blends were simulated in different ambient temperatures and pressures and in different blending ratios of the blends. The density profile, surface temperature, evaporation mass ratio and evaporation rate were estimated and compared under sub/supercritical states. The critical temperature of the blends was determined by the surface temperature and the surface tension. Results indicate that under ambient low supercritical condition, a transition from subcritical to supercritical state does not happen in the evaporation process of blends. The evaporation mass ratio is not always equal to the blending ratio as the way used in current evaporation model, but a function over time. A fitting formula for calculating the critical temperatures of the blends is provided.

Scalable High-Efficiency Bi-Facial Solar Evaporator with a Dendritic Copper Oxide Wick.

Solar thermal distillation is a promising way to harvest clean water due to its sustainability. However, the energy density of solar irradiation inevitably demands scalability of the systems. To realize practical applications, it is highly desirable to fabricate meter-scale solar evaporator panels with high capillary performance as well as optical absorptance using scalable and high-throughput fabrication methods. Here, we demonstrate a truly scalable fabrication process for a bi-facial solar evaporator with copper oxide dendrites via the hydrogen bubble templated electrochemical deposition technique. Furthermore, we construct a theoretical model combining capillarity and evaporative mass transfer, which leads to optimal operation conditions and wick characteristics, including superhydrophilicity, extreme capillary performance, and omni-angular high optical absorptance. The fabricated porous surfaces with excellent capillary performance and productivity provide a pathway toward a highly efficient bi-facial solar evaporator panel with meter-level scalability.

Improved treatment of dark matter capture in neutron stars II: leptonic targets

Neutron stars harbour matter under extreme conditions, providing a unique testing ground for fundamental interactions. We recently developed an improved treatment of dark matter (DM) capture in neutron stars that properly incorporates many of the important physical effects, and outlined useful analytic approximations that are valid when the scattering amplitude is independent of the centre of mass energy. We now extend that analysis to all interaction types. We also discuss the effect of going beyond the zero-temperature approximation, which provides a boost to the capture rate of low mass dark matter, and give approximations for the dark matter up-scattering rate and evaporation mass. We apply these results to scattering of dark matter from leptonic targets, for which a correct relativistic description is essential. We find that the potential neutron star sensitivity to DM-lepton scattering cross sections greatly exceeds electron-recoil experiments, particularly in the sub-GeV regime, with a sensitivity to sub-MeV DM well beyond the reach of future terrestrial experiments.

Real-time lipid patterns to classify viable and necrotic liver tumors

AbstractReal-time tissue classifiers based on molecular patterns are emerging tools for fast tumor diagnosis. Here, we used rapid evaporative ionization mass spectrometry (REIMS) and multivariate statistical analysis (principal component analysis–linear discriminant analysis) to classify tissues with subsequent comparison to gold standard histopathology. We explored whether REIMS lipid patterns can identify human liver tumors and improve the rapid characterization of their underlying metabolic features. REIMS-based classification of liver parenchyma (LP), hepatocellular carcinoma (HCC), and metastatic adenocarcinoma (MAC) reached an accuracy of 98.3%. Lipid patterns of LP were more similar to those of HCC than to those of MAC and allowed clear distinction between primary and metastatic liver tumors. HCC lipid patterns were more heterogeneous than those of MAC, which is consistent with the variation seen in the histopathological phenotype. A common ceramide pattern discriminated necrotic from viable tumor in MAC with 92.9% accuracy and in other human tumors. Targeted analysis of ceramide and related sphingolipid mass features in necrotic tissues may provide a new classification of tumor cell death based on metabolic shifts. Real-time lipid patterns may have a role in future clinical decision-making in cancer precision medicine.Real-time lipid patterns can identify liver tumors and their inter-tumor and intra-tumor heterogeneity. Ceramides and related sphingolipids are a common feature of necrotic tumors and can characterize the tumor phenotype based on metabolic shifts relevant for cell death pathways. Lipid patterns have the potential to improve clinical decision-making in the near future.

Electric Fuel Conversion by Multiphase Plasma at Ambient Pressure

Redefining the refinery for unconventional/heavy oils, significant emission reductions, and alternative/bio fuels, faces major technological challenges: conversion, energy efficiency, modularity and integration with renewable electricity. Here, we introduce a multi-phase non-thermal plasma reactor that uses electrical discharges to partially upgrade oils at ambient pressure. Normal hexadecane was treated to validate conversion chemistry, and quantify the pathways of vapor, condensate, liquid and residue mass conversion. Using 500 kJ/kg-hexadecane energy input (~1% of hexadecane’s energy content) this plasma process converts 9.36% of the hexadecane and 20% of the methane by mass. Distribution of products by mass are: 2.18% hydrogen, 45.9% C2-C4, 28.9% high octane gasoline (C5-C11), 16.4% diesel (C12-C18), 2.78% heavier hydrocarbons, and 3.88% soot. Lighter product yields (C5-C15) were ~9 molecules/100 eV, and modeled by a random scission mechanism. Hydrogen yield was 34.8 kWhr/kg-H2. Plasma-chemical conversion efficiency is ~30%. This conversion process has higher efficiency, and lower GHG emission than traditional technologies.

An Experimental Study of In-Tube Condensation and Evaporation Using Enhanced Heat Transfer (EHT) Tubes

A study was carried out to determine in-tube evaporation and condensation performance of enhanced heat transfer tubes (EHT) using R410A, with the results being compared to a plain tube. The test tubes considered in the evaluation include: plain, herringbone (HB) and spiral (HX) microgrooves, herringbone dimple (HB/D), and hydrophobic herringbone (HB/HY). Experiments to evaluate the condensation were conducted at a saturation of 318 K, and at 279 K for evaporation. Mass flux (G) ranged between 40 to 230 kg m−2s−1. Condensed vapor mass decreased from 0.8 to 0.2; and the mass of vaporized vapor increases from 0.2 to 0.8; heat flux increased with G. Inlet and outlet two-phase flow patterns at 200 kg m−2s−1 were recorded and analyzed. Enhanced tube heat transfer condensation performance (compared to a plain tube) increased in the range from 40% to 73%. The largest heat transfer increase is produced by the herringbone–dimple tube (HB/D). In addition to providing drainage, the herringbone groove also helps to lift the accumulated condensate to wet the surrounding wall. Evaporation thermal performance of the enhanced tubes are from 4% to 46% larger than that of smooth tube with the best performance being in the hydrophobic herringbone tube (HB/HY). This enhancement can be attributed to an increase in the number of nucleation sites and a larger heat transfer surface area. Evaporation and condensation correlations for heat transfer in smooth tubes is discussed and compared.

Dynamics of hygroscopic aqueous solution droplets undergoing evaporation or vapour absorption

Abstract