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The shape of elongated bubbles in upward inclined air-water slug flow was studied experimentally by quantitative measurements of the cross sectional distribution of the phases within the pipe, using a wire mesh sensor. Ensemble-averaged shapes of elongated bubbles were determined for a wide range of gas and liquid flow rates, as well as for different pipe inclination angles. The elongated bubble nose can be characterized by an annular domain where liquid is present above the gas. The effect of gas and liquid flow rates, as well as of the pipe inclination angle on the bubble shape (front and tail) is studied. A simplified theoretical model is proposed to determine the bubble front shape. The model predictions compare favorably with the experimental results.

Heat exchangers are widely used for heating, cooling, evaporation, and condensation. There are many types of heat exchangers, shell and tube, fin tube, and double tube heat exchangers. Double tube heat exchangers show high performance, and several modifications have been made with regard to their pipe geometry to further improve their performance. A petal-shaped double tube with a large wetted perimeter is one such example. The working fluid of a heat exchanger for the evaporator and condenser of an air-conditioner or boiler may become a gas-liquid two-phase flow with phase change. In this study, the flow and heat transfer characteristics of air-water bubbly flow through a petal-shaped double tube with a large wetted perimeter are examined experimentally and compared with those of a conventional circular double tube. The experiments employed two petal-shaped double tubes: one with six petals and another with five petals. This study explains for single-phase water and two-phase air-water bubbly flows. The heat transfer characteristics are studied by measuring the temperature distributions in the inner and outer pipes by a thermo couple. The study also clarifies the effects of air bubbles on heat transfer performance.

Protons play crucial roles in the interactions between heteropolyanions (HPAs) in aqueous solutions and solid acid salts. We report the aggregation behaviours of Keggin HPAs near the surfaces of heteropolyacid solutions. The structure of the aggregated HPA layer near the solution–vapour phase boundary closely resembles the solid-state crystal structure of the heteropolyacids in which the HPAs are connected by Zundel ions. The resemblance not only implicates the presence of protons in the form of planar Zundel ions near the air-water interface but, also, suggests that these align parallel to the interface. This study demonstrates an indirect means of assessing the impact of protons on HPA interactions near air-water interfaces and, in general, provides new insights about interfacial proton chemistry of heteropolyacids.

The present report studies on the flow pattern transitions during vertical air water downflow through millichannels (0.83 ≤ Eotvos no. ≤ 20.63). Four basic flow patterns namely falling film flow, slug flow, bubbly flow, and annular flow are observed in the range of experimental conditions studied and their range of existence has been noted to vary with tube diameter and phase velocities. Based on experimental observations, phenomenological models are proposed to predict the transition boundaries between adjacent patterns. These have been validated with experimental flow pattern maps from the present experiments. Thus the study formalizes procedure for developing a generalized flow pattern map for gas-liquid downflow in narrow tubes. © 2016 American Institute of Chemical Engineers AIChE J, 63: 792–800, 2017

Partition or distribution coefficients (and increasingly referred to as partition ratios) are widely used in environmental science to relate the concentration of a chemical solute in one phase to that in a second phase between which equilibrium applies or is approached. The solutes include organic and inorganic substances; the focus of this paper being on the former. The phases of interest include air, water, soils, sediments, aerosols, and biotic phases, such as lipids, blood, and various tissues. Availability of reliable partition coefficients for contaminants is essential for regulatory and scientific purposes, the general aim being to understand and predict the distribution of the substances in multimedia environmental and biological systems. The history of partition coefficients is reviewed, followed by a brief outline of their theoretical basis and a discussion of methods for determining partition coefficients both empirically and using a variety of predictive methods. It is suggested that ultimately a combination of empirical measurements, quantitative structure–property relationships, and computationally intensive quantum chemical molecular modeling techniques is required to provide accurate data for the large and increasing number of chemicals of commerce that may enter the environment.

We prepared a series of mesostructured Ni/TiO2–SiO2(Et) hybrid catalysts with highly dispersed Ni nanoparticles and incorporated ethane-bridged organosilica moieties. Ni/TiO2–SiO2(Et) showed high activity in the hydrogenation of nitrobenzene in water, and it could be recycled for several times with a constant activity and selectivity. It was confirmed that Ni/TiO2–SiO2(Et) catalyst is of hydrophobicity as the ethane-bridged organosilica fragments were incorporated into the mesoporous framework, and so the Ni active species was protected without contacting with water to form the inactive Ni species. In particularly, the Ni/TiO2–SiO2(Et) catalyst was air-stable, it could remain good activity after being exposed to air for a week. Accordingly, this work developed a kind of hydrophobic Ni catalyst with high stability to water and air, which is expected to have a wide application in the hydrogenation reactions.

为实现发动机的水空两用，提出了一种新型的多涵道水空两用发动机概念设计。在建立了初步的三维有限元模型的基础上，重点对水中模式的工作情况进行了分析计算，初选金属钠作为水反应燃料，得到了燃料流量、燃烧室压强、推力的变化关系及燃料流量和比冲的变化关系，初步确定了燃料流量的适宜范围，肯定了水中工作条件下的推进效果。使用CFD软件对金属水反应冲压发动机的参数设计进行了模拟分析，确定了最有利于金属水反应和水冲压发动机推进效果的参数选择。初步评定新型水空两用发动机达到了设计目的。 In order to realize the air-water engine, a new multi-bypass amphibious engine conceptual design is proposed. The situation of air mode is analyzed briefly based on the establishment of a three dimensional finite element model. The situation of water mode is analyzed and calculated, and determines the metal sodium as the fuel of the reaction of metal and water. The relationships of fuel flow, combustion chamber pressure, thrust, fuel flow rate and specific impulse are obtained. The suitable range of fuel flow rate is preliminarily determined and the effect of propulsion of water mode is affirmed. The simulation of the design parameters of the metal-water reaction engine is conducted with CFD software. The parameter which is the most advantageous to metal- water reaction and the propulsion effect of the metal-water reaction engine is determined. Preliminarily evaluating the design goal of the new air-water engine is achieved.

Paper deals with the test procedure for evaluating performance parameters of the heat pump air water system. The objective of measurements was tuning errors and optimizes the work of the whole system. The main aim was to find the most acceptable evaporator with which the heat pump COP reached the best results. Choosing of the evaporator consisted of comparing the operating and performance characteristics of individual exchangers.

The single word that epitomises this collection is ‘rhapsodic’; rhapsodic not just in the contributors’ evident delight in their own chosen element, but in the way the essays, individually and as a...

This paper focuses on investigating the dynamic behaviour of foam flows, including flow regimes, their transitions and pressure profiles in relation to foam characteristics (foam holdup and wetness) at different surfactant concentrations (0–500 ppm). The experiments cover a wide range of gas and water flowrates in a 4.3 m long vertical acrylic pipe with 44 mm internal diameter. Flow regimes and their underlying mechanisms are characterised through Power Spectral Density analysis of the associated pressure fluctuation signals, collected at 100 Hz frequency. A flow map is developed for foam flow in a vertical pipe based on the gas and liquid Webber numbers, representing different flow regimes. The results from this study reveal that, even at small concentrations, the surfactant attenuates flow fluctuations, as observed in the pressure data, resulting a relatively uniform flow compared with air-water flows. The results also indicate the promoting effect of surfactant on the flow transition from churn to annular flow at much lower gas velocities compared to air-water flows. The flow transition from slug to churn and churn to annular in foam flows is shown to be associated with an increase in foam wetness. The lowering effect of surfactant on the pressure gradient is most pronounced at lower gas rates. Increasing the gas rate in the foam flow encourages bubble breakup, leading to the formation of a denser foam, composed of smaller bubbles carrying more liquid in the lamella of the foam network. This therefore leads to a higher pressure gradient at higher gas rates.

Polycyclic aromatic hydrocarbons (PAHs) are semivolatile organic compounds of environmental concern. This study aims to investigate the influence of local sources of anthropogenic PAHs and their air–water exchange fluxes in an oligotrophic North–Patagonian lake in Chile. The monitoring was carried out in Panguipulli Lake during a six-month period during the autumn and winter seasons (March to August 2017) using a high–volume air sampler and a pump system for water samples. We detected and quantified fifteen PAHs in the gas phase (mean ∑PAHs = 11.6 ng m) and dissolved water phase (mean ∑PAHs = 961.8 pg L). Methylphenanthrenes and pyrene dominated the concentrations of PAHs in the studied phases. To determine sources of PAHs we used the PAH ratios of Light Molecular Weight/Heavy Molecular Weight (∑LMW/∑HMW) and Phenanthrene/Anthracene (Phe/Ant). The PAH ratio results revealed a pyrogenic source. We estimated the air–water diffusive exchange fluxes and fugacity ratios for the studied compounds. In general, air–water diffusive exchanges of PAHs showed a net volatilization for the less hydrophobic (log K < 4) and lighter PAHs (MW ≤ 170 g mol), and a net deposition trend for the more hydrophobic (log K 4–7) and higher molecular weight PAHs (MW ≥ 178 g mol). We found a significant correlation between log water/air fugacity ratios and log K of PAHs. Therefore, it is suggested that this oligotrophic lake acts as a sink by accumulating hydrophobic and mid-high molecular weight PAHs derived mainly from pyrogenic sources. This study is the first attempt to understand the sources and behavior of PAHs in oligotrophic lakes in the Southern Chile where information is scarce regarding the occurrence of PAHs., This study was funded by ANID FONDECYT 11150548, 1161504, ANID PCI REDI170292, ANID PIA Anillo INACH ACT192057, INACH REGULAR RT_12_17 (C. Galbán-Malagón) and ANID FONDECYT N° 3180159 (F. Tucca). Authors also thank the support of ANID FONDAP CRHIAM 15130015 (R. Barra and F. Tucca), ANID FONDECYT 1161673 (K. Pozo), “Universidad Andrés Bello” is thanked for funding a PhD scholarship awarded to Miss Thais Luarte. The “Universidad Austral de Chile” was highly acknowledged by their continuous logistic support on the lake. Kevin Ryan PhD(c) is thanked for language editing of the final version of the present manuscript.

A year-long field study of mercury (Hg) air/water exchange was conducted at a southern reservoir lake, Cane Creek Lake (Cookeville, TN, USA). The Hg air/water exchange fluxes and meteorological data including solar radiation (global solar radiation, Rg and ultraviolent radiation, UVA), water and air temperatures, relative humidity, and wind speed were collected to study the daily and seasonal trends of the Hg air/water exchange at the lake in relation to solar radiation and wind speed. The Hg exchange fluxes generally exhibited diurnal patterns with a rise in the morning, a peak around noontime, and a fall in the afternoon through the evening, closely following the change of solar radiation. There were cases that deviated from this general daily trend. The Hg emission fluxes were all below 3 ng m&minus, 2 h&minus, 1 with the daily mean fluxes &lt, 2 ng m&minus, 1. The fluxes in the summer (mean: 1.2 ng m&minus, 1) were higher than in the fall (mean: 0.6 ng m&minus, 1) and winter (mean: 0.7 ng m&minus, 1). The daily and seasonal trends of the Hg air/water exchange fluxes are similar to the trends of the changes of the dissolved gaseous mercury (DGM) concentrations in the lake observed in our previous study. Solar radiation was found to exert a primary control over the Hg air/water exchange, while wind speed appeared to have a secondary effect on the Hg exchange. The two-thin-film model was used to calculate Hg emission fluxes from the Cane Creek Lake water.

This paper designs an air intake device based on Peltier effect to solve the problems of insufficient per capita water use and difficult survival of living organisms in water-scarce areas in China. It uses semiconductor to refrigerate, takes water from the air in a cooling condensation way, uses wind power and solar energy to supply power for the refrigerator continuously. Through data analysis, the device can effectively collect air moisture and condense to produce liquid water, which has broad application prospects in arid areas in northwest China.

The aim of this study is to design and develop a dual-purpose integrated solar collector-storage device that can simultaneously provide hot water and hot air. The device can be used as a single purpose air or water heater, based on the requirement. A Simple mathematical model of the proposed dual-purpose heater is presented and validated for the climate of Raipur, Chhattisgarh, India (21.25oN, 81.62oE). The performance of the collector is numerically computed for the composite climate of Delhi, India (28.70oN, 77.10oE). The results reveal that about 19.9% of the heat energy can be conserved by covering the collector with an insulating cover at night. The dual collector performs well when a low mass flow rate of air flows through the upper compartment, in comparison to high mass flow rate. The maximum thermal efficiency during day time is about 82.8% at a mass flow rate of 0.020 kg/s. Thermal efficiency of the proposed dual-purpose heater is higher than that of conventional single purpose water heater. The maximum water and air temperatures in December (winter) where 56 °C and 50 °C, respectively, whereas those for May (summer) where 89.6 °C and 81.1 °C, respectively.

The paper presents the study of experimental as well as the numerical study of air-water mist jet impingement cooling over a heated cylinder in the non-boiling region. The studies are conducted for various mist loading fraction, f = 0.0025, 0.0050, 0.0075 and 0.01; Reynolds number, Remix.=8000, 10,500, 13,000 and 15,500; and surface-to-nozzle spacing, H/d = 30, 40, 50 and 60. Enhancement in the heat transfer (η) for mist jet impingement as compared to air jet impingement is obtained from experimental and numerical analysis. The numerical study also helped in understanding the distribution and tracking of droplets in the computational domain. High enhancement in the heat transfer is observed with high mist loading fraction. Also, the lowest Reynolds number yielded the highest enhancement in heat transfer with comparison to the higher Reynolds number. At various surface-to-nozzle spacing, the enhancement in heat transfer is high for low surface-to-nozzle spacing near the stagnation zone to a certain point, after which point the enhancement reverses as higher enhancement in heat transfer is observed for high surface-to-nozzle spacing. As high as 408% and 775% enhancement in the heat transfer at the stagnation point is observed for f = 0.01, Remix.= 8000and H/d = 30 during experimental and numerical analysis respectively. The correlation has been proposed to estimate the enhancement in heat transfer at the stagnation point.

The article deals with theoretical and experimental studies of oily industrial wastewater flotation treatment using a saturator and vortex mixing devices (VMD) for preparing a water-air mixture. The use of VMD allows, in comparison with the saturator, to improve the efficiency of oil product removal on the flotator by 5-7% due to the greater gas saturation of the flotation volume. The energy consumption for preparing the water-air mixture in vortex mixers was on 8–10% lower than in flotation plants using a saturator.

Oligomers of amyloid-β (Aβ) peptides are known to be related to Alzheimer's disease, and their formation is accelerated at hydrophilic-hydrophobic interfaces, such as the cell membrane surface and air-water interface. Here, we report molecular dynamics simulations of aggregation of Aβ(16-22) peptides at air-water interfaces. First, 100 randomly distributed Aβ(16-22) peptides moved to the interface. The high concentration of peptides then accelerated their aggregation and formation of antiparallel β-sheets. Two layers of oligomers were observed near the interface. In the first layer from the interface, the oligomer with less β-bridges exposed the hydrophobic residues to the air. The second layer consisted of oligomers with more β-bridges that protruded into water. They are more soluble in water because the hydrophobic residues are covered by N- and C-terminal hydrophilic residues that are aligned well along the oligomer edge. These results indicate that amyloid protofibril formation mainly occurs in the second layer.

Annular flow with swirl induced by a swirler has been widely used in industry. Swirl decay which closely related to working performance and length of the flow is significantly important for its application in industry. Axial development of annular flow with and without swirl has been investigated in this work by means of experimentation and modelling. A vertical pipe system with 11 m long and 62 mm inner diameter was carried out to investigate axial development of flow pattern, void fraction and pressure drop in the annular flow with and without swirl. The experimental results show that a swirling annular flow with swirling streak and less disturbed waves is observed downstream of the swirler. Void fraction decreases, total pressure drop increases and the PDF (probability density function) of pressure drop becomes more concentrated in the annular flow with swirl, compared with these in the annular flow without swirl. However, swirling annular flow is gradually transformed to annular flow without swirl along the streamwise direction. To qualitatively predict the decay in an annular flow with swirl, a simplified theoretical model was developed here. The results calculated with the theoretical model were in agreements with experimental results. The obtained results can be used in predicting working performance and length of devices, such as separators and heat exchangers.

The present study focused on evaluating the heat transfer behavior and predicting the surface resulting status during air/water droplets two-phase flow. Transient heat transfer based on the lumped capacitance model (LCM) was investigated experimentally under a range of water droplets concentration, surface temperature, and varying Re number. Compared with a single-phase air cooling, the transient surface temperature decreased with the increase in water droplets concentration and Re number. At the same cooling time, the surface temperature decreases about 13.5%, 47%, and 53.2% for (j = 46.79 – 111.68 kg/m2 hr). It was also noticed that the heat transfer coefficient increased with the increase in water droplets concentration and reach its maximum value at (j = 111.68 kg/m2 hr). Based on the analysis of the experimental results, the heat transfer mechanism due to the impacting of water droplets on the sphere surface was classified into three important physical regimes. Clear convection heat transfer regime corresponds to the dry region (region I); Convection and evaporation regimes correspond to the dry-out and wet regions (region II and III).

Unmanned Aerial-Underwater Vehicles have been envisioned as a new kind of hybrid unmanned system capable of performing equally well in multiple mediums and seamlessly transitioning between them. Currently, bio inspired vehicles are leading the way in the development of such a vehicle, that can fly like an eagle and swim like a fish. This path-breaking amphibious aerial underwater vehicle is sought after because of its wide range of applications in military, commercial and civil environments. From aerial surveillance, deep water exploration to underwater non-destructive testing, this vehicle aims to do it all. However, the development of a fully functional version is hindered by the significantly different properties of air and water, considering the air water transition, different propulsion systems and stability underwater. We evaluate these available architectures that aim to accomplish the goal of creating a flawless multi-medium unmanned vehicle which has its limitations as one of the modes is dominant leaving the other to be at a lesser than expected measure. This paper presents a survey discussing the evolution of these systems by first looking at their parent systems and then evaluating the various existing types of UAUVs by understanding their working mechanisms. The paper aims to provide a comprehensive overview of the work done in the field so far which can provide direction to the further development of such vehicles.

The interaction between soyasaponin and soy β-conglycinin (7S) or glycinin (11S), adsorption of their mixtures at air-water interface, and foaming properties of the mixed system were investigated in this study. Fluorescence spectroscopy results showed that there was a weak binding of soyasaponin with 7S or 11S in bulk solutions, leading to the conformational changes of protein by nonspecific hydrophobic interactions. Dynamic surface properties of soyasaponin-7S/11S mixtures indicated that the composite layers formed via their weak interactions due to the synergy of reducing surface tension and the plateau of elasticity at the interface. Most mixtures represented high foam forming ability and stability except 0.2 % soyasaponin mixture, which could be a consequence that the surface behavior was dominated by soyasaponin under this concentration, and low surface elasticity lead to a less stable interfacial film. Overall, foamability of soyasaponin-7S mixtures were better than 11S ones. All data of this work was helpful to understand air-water behaviors of soyasaponin-7S/11S mixtures. This mixed system has shown good potential for further foam related industrial applications.

Within a remarkably short timespan the world population doubled and transitioned from an agrarian to an urban-industrial society. The transition was accompanied by the major expansion of industries that releases enormous amounts of toxicants into the air, water, and soil. Naturally occurring and synthetic chemicals compounds utilized the same signaling system as vertebrate internal cell signaling systems. The concept of environmental signals provides insights to address the impact of biochemically active toxicants on humans and the ecosystems that they share with other species. Disruption of the broad signaling systems has the potential for global change that transcends the biological systems of all organisms, including humans.

The complexation of corn protein hydrolyzate (CPH) with tannic acid (TA) was utilized to improve the foaming properties of CPH itself, and the air–water interfacial behavior of CPH–TA complex was also investigated. The results showed that the surface hydrophobicity of pure CPH was significantly decreased in bulk solution after the complexation with TA. Compared with pure CPH, the foams stabilized by CPH–TA complex showed higher interfacial thickness between the bubbles, which well explained the better long term stability of the corresponding foams. Therefore, the complexation maintained the good foaming capacity of CPH itself, but considerably increased its foam stability. Moreover, the air–water interfacial behavior study demonstrated that the complexation slightly decreased the interfacial activity of CPH itself, but considerably increased its interfacial viscoelasticity, suggesting more stable of the air–water interface stabilized by CPH–TA complex compared with that stabilized by CPH alone. These findings indicated that foaming properties of the surface active components were closely related with its air–water interfacial behavior. The study suggested that CPH–TA complex could be used as a stabilizer in constructing the peptides-based foams. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13197-018-03553-0) contains supplementary material, which is available to authorized users.

The slug flow phenomena are often encountered in various industrial applications such as petroleum, process, and power plant. The presence of slug flow should be avoided as it causes structural damage due to resonance, corrosion and pipes blast. From the view point of multiphase flow, the understanding of the slug initiation mechanism is very important in pipeline design. This research is conducted using horizontal transparent acrylic pipes with diameters of 50 mm with a variation on the superficial velocity of water between 0,1 m/s and 0,77 m/s and superficial velocity of air between 0,31 m/s and 6,2 m/s. In the present experimental study, the slug initiation mechanisms was explained by visual observation by using high speed video cameras. As the results, the slug flow initiation mechanism were clarified. Furthermore, the proposed of flow initiation map was introduced.

Stratified gas–liquid flow is a flow regime typically encountered in multiphase pipelines. The understanding and modeling of this regime is of engineering importance especially for the oil and gas industry. In this work, simulations have been conducted for stratified air–water flow in pipes. We solved the Reynolds-averaged Navier–Stokes (RANS) equations with the volume of fluid (VOF) method. The aim of this work was to evaluate the performance of the k–ω shear stress transport (SST) turbulence model with and without damping of the turbulence at the gas–liquid interface. Simulation results were compared with some of the latest experimental results found in the literature. A comparison between the simulated velocity and kinetic energy profiles and the experimental results obtained with the particle image velocimetry (PIV) technique was conducted. The characteristics of the interfacial waves were also extracted and compared with the experiments. It is shown that a proper damping of the turbulence close to the interface is needed to obtain agreement with the experimental pressure drop and liquid hold-up. In its current form, however, RANS with the k–ω turbulence model is still not able to give an accurate prediction of the velocity profiles and of the interface waves.

Gas cell stabilization in dough by its aqueous phase constituents is arguably more important in non-wheat than in wheat dough due to weaker protein networks in the former. Dough liquor (DL), a model for the dough aqueous phase, was isolated from fermented wheat, rye, barley, and oat doughs by ultracentrifugation. DL composition (protein, lipid, arabinoxylan, β-glucan) and air/water interfacial functionality [foaming, viscosity, surface tension, surface dilatational modulus (E)] were related to bread quality. Poor foaming and low E of wheat DL were ascribed to lipids and proteins co-occurring at the interface. Nonetheless, the presence of a gluten network resulted in high-quality wheaten breads. Homogeneous and heterogeneous crumb structures of rye and barley breads, respectively, were attributed to high and low E values of their respective DLs. High lipid content and low surface tension of oat DL indicated a lipid-dominated interface, which may explain the heterogeneous crumb structure of oat breads. ispartof: FOOD CHEMISTRY vol:264 pages:126-134 ispartof: location:England status: published

Solar Energy has enormous potential to fulfill the energy requirements of the world and can be extracted using solar cells. However, the solar cells are affected by poor efficiency and further affected by wind speed, orientation of the panel, temperature and dust deposition. There are different cleaning technologies devised by many industry experts to clean the solar panels. However, they are facing drawbacks when deployed in the solar farm. An efficient cleaning system, along with an added cooling system must be devised, so that the solar panels must be cleaned and cooled often to maximize the energy production. This paper presents a low-cost, energy-efficient, smart and innovative dust cleaning and cooling system for Photovoltaic (PV) Panels. The system is designed, fabricated, fully-automated using Programmable Logic Controller (PLC) and tested successfully. A battery-charging kiosk, capable of charging two, 24V Lead Acid Batteries embedded within this prototype, shall provide clean-energy in a sustainable manner to the rural communities of the developing nations. The user can check the status of the battery such as battery voltage, battery temperature, and state of charge on the Human Machine Interface (HMI) panel while charging the batteries

The original technical solution and the actual testing of the experimental installation based on the technology of the vapor-compression "air-water" heat pump for the complex modernization of the typical radiator heat supply system of social /administrative building are described. The expediency of the heat pump using in the heating period under different connection schemes is analyzed and the corresponding heat pump energy conversion factors is calculated, Представлено опис технічного рішення та апробація експериментальної установки на основі технології з використанням парокомпресійного теплового насосу типу «повітря-вода» для комплексної модернізації типової радіаторної системи теплопостачання будівлі соціально-адміністративного призначення. Проаналізована доцільність використання теплового насоса в опалювальний період при різних схемах підключення та розраховані відповідні коефіцієнти перетворення енергії теплового насосу

This Feature addresses the analysis of the reactive species generated by nonthermal atmospheric pressure plasmas, which are widely employed in industrial and biomedical research, as well as first clinical applications. We summarize the progress in detection of plasma-generated short-lived reactive oxygen and nitrogen species in aqueous solutions, discuss the potential and limitations of various analytical methods in plasma-liquid systems, and provide an outlook on the possible future research goals in development of short-lived reactive species analysis methods for a general nonspecialist audience.

Because of the antioxidant activity of vitamin C (Vit C) polar heads, they can be used as a protective agent for fatty acids. Hence, the study on the growth of Vit C/stearic acid (SA) mixed binary films at air–water interface (known as Langmuir monolayer) and air–solid interface (known as Langmuir–Blodgett films) is of paramount interest. Although Vit C is situated at subsurface beneath SA molecules and interacts via hydrogen bonding between the hydroxyl groups of Vit C and SA, several Vit C molecules may infiltrate within SA two-dimensional matrix at the air–water interface. The increased mole fraction of Vit C (0.125–0.5) and the reduction of temperature (from 22 to 10 °C) of the subphase water result in an increase in the amount of adsorbed Vit C at the air–water interface. The surface pressure (π)–area (A) isotherms illustrate that such inclusion of Vit C provokes a spreading out of Vit C/SA binary monolayers, which leads to an alteration of different physicochemical parameters such as elasticity, Gibbs free energy of mixing, enthalpy, entropy, interaction energy parameter, and activity coefficient. However, being polar in nature, the transfer of pure Vit C on substrates gets affected. It can be transferred onto substrate by mixing suitably with SA as confirmed by infrared spectra. Their structures, extracted X-ray reflectivity, and atomic force microscopy (topography and phase imaging) are found to be strongly dependent on the nature of the substrate (hydrophilic and hydrophobic).

Dry-out and rewetting phenomenon may occur on a fuel rod surface during anticipated operational occurrences (AOOs) for a boiling water reactor (BWR). The conventional rewetting model included in the current system code tends to underestimate the rewetting propagation velocity due to the absence of an appropriate precursory cooling model. The present research aims at the development of a mechanistic model for the precursory cooling in the annular mist flow regime typical of AOO and anticipated transition without scrum (ATWS). Rewetting experiments were carried out using a single heater rod in the circular glass pipe with air-water flow at atmospheric pressure to visualize the rewetting behavior and obtain mechanistic understanding on the phenomena. This paper summarizes the experimental results and discusses the liquid film flow characteristics including roll wave formation and spattering at the rewetting front.

In support of a header/feeder phenomena study, an adiabatic, near-atmospheric, air-water flow loop was commissioned simulating a single feeder of a Pressurized Heavy Water Reactor’s primary heat transport system under a postulated Loss of Coolant Accident scenario. An extensive database in representative two-phase flow conditions was collected, 750 tests in total, in order to create a two-phase flow map to be used in the more complex geometries such as header/feeder systems. The flow loop consists of two vertical test sections, for upwards and downwards flow, and one horizontal test section, each with an inner diameter of 32 mm and at least 120 diameters in length. Superficial velocities extended up to 6 m/s for the water and 10 m/s for the air. Void fraction was measured by means of quick-closing valves and a pair of wire-mesh sensors (WMS) in each test section. Two-phase repeatability tests showed that the liquid and gas superficial velocities varied by 1.1% and 0.6% at reference conditions of 2.0 and 2.8 m/s, respectively. The corresponding void fraction measurements varied for the quick-closing valves by at most 6.8%, which indicates a low sensitivity to the closure time of the valves and an appropriate axial distance between them, and 2.3% for the WMS. For both measurement techniques, the largest variations occurred in the vertical downwards test section. For the formal two-phase tests, over 600 distinct flow conditions were performed. The results showed that the two measurement techniques agreed within 5% at high void fractions and low liquid flow rates in vertical flow. For all other cases corresponding to the transitional or dispersed bubbly flow regime, the WMS over-estimated the void fraction by a consistent bias. An empirical correction is proposed, with a root-mean-square error of 6.6% across all tests. The void fraction map resulting from this database provides validation for the WMS measurements, a quantitative assessment of its uncertainty and range of applicability, and will be used as a reference in future tests under similar scale and flow conditions.

Laboratorio de Estudo de Bacias Departamento de Geologia Universidade Estadual Paulista - UNESP