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The focus of this paper is on the measurement and calculation model of void fraction for the vertical upward co-current air–water slug flow in a circular tube of 15 mm inner diameter. High-speed photography and optical probes were utilized, with water superficial velocity ranging from 0.089–0.65 m∙s–1 and gas superficial velocity ranging from 0.049–0.65 m∙s–1. A new void fraction model based on the local parameters was proposed, disposing the slug flow as a combination of Taylor bubbles and liquid slugs. In the Taylor bubble region, correction factors of liquid film thickness Cδ and nose shape CZ* were proposed to calculate αTB. In the liquid slug region, the radial void fraction distribution profiles were obtained to calculate αLS, by employing the image processing technique based on supervised machine learning. Results showed that the void fraction proportion in Taylor bubbles occupied crucial contribution to the overall void fraction. Multiple types of void fraction predictive correlations were assessed using the present data. The performance of the Schmidt model was optimal, while some models for slug flow performed not outstanding. Additionally, a predictive correlation was correlated between the central local void fraction and the cross-sectional averaged void fraction, as a straightforward form of the void fraction calculation model. The predictive correlation showed a good agreement with the present experimental data, as well as the data of Olerni et al., indicating that the new model was effective and applicable under the slug flow conditions.

An appropriate microenvironment for preserving cultural relics is essential, and the air-water direct contact technology is utilized to create the microenvironment recently. The influence of a deflector in a tank was numerically investigated based on uniform design method to improve the heat and mass transfer and pressure drop performance of the air-water direct tank. In this study, a simplified CFD-based model was established and validated between airstream and water surface within the tank, to analyze the heat and mass transfer and pressure drop processes. Meanwhile, regression models of the heat transfers rate, mass transfer rate and pressure drop were developed by uniform design method based on three parameters: installation position, tilt angle, and height of the deflector, in order to analyze the influences of these three parameters on the heat and mass transfer and pressure drop of the tank. Finally, all three optimal structural parameters of the deflector were obtained based on the proposed comprehensive evaluation index using a genetic algorithm. The results showed that the model established for air-water direct contact adopted well to predict the heat and mass transfer and pressure drop performance between airstream and still water surface. Furthermore, the results found that the flow field inside the water tank was affected by the deflector's structure, which affected the heat and mass transfer performance. The simulation results suggested that the deflector's optimal structural parameters are 8 mm of installation position, 88 ° of tilt angle and 19 mm of height, respectively, within a given extent in this study.

The 17th International Conference on Chemistry and the Environment (ICCE 2019) took place in the period 16–20 June 2019, in Thessaloniki, Greece. The Conference Centre of the Aristotle University of Thessaloniki, named KEDEA, was chosen as an appropriate venue for the conference. Through its lecture halls, foyer for posters and exhibition stands, food, and refreshment facilities, it offered a great conference environment. We appreciate the help of all people involved in the efficient and smooth organization (Organizing Committee, University personnel, Students) of ICCE 2019. The ICCE has been organized since 1980 by the Division of Chemistry and the Environment (DCE) of the European Chemical Society (EuChemS) as a biennial conference. The first meeting took place in Paris.

In the present study, using a quasi 3D analytical simulation, air concentration distribution in ski jump generated jet is calculated. A numerical simulation is also performed to verify the results of the analytical model in parallel with the available experimental and other analytical data. By solving continuity and momentum equations in the case of air-water flow for three different cases, it was confirmed that the air concentrations along the ski jet are uniquely linked to the relative black water core length. Results showed that the black water core length is also influenced by the approach flow depth, Froude number, geometrical parameters of ski jump and the chute bottom angle. Finally, an analytical equation is proposed to predict the air concentration distribution along the ski jump jet regarding different hydraulic and geometric parameters. By calculating the velocity profiles along the jet, it showed that increasing the air concentration reduces the jet velocity profile.

In this paper, an Artificial Neural Network soft matrix correlation to estimate the pressure drop of air-water two-phase flow is developed. The applicability of the model is extended by using dimensionless physical numbers as inputs (Air-Reynolds number, Water-Reynolds number, and the ratio of Air Inertial Forces to Water Inertial Forces), so the model can be implemented for vertical pipes with the proper combination of diameter-velocity-density-viscosity allowing estimations of dimensional numbers within the range of: Air-Reynolds numbers (430–6100), Water-Reynolds number (2400–7200), and Air-Water-Inertial forces ratio (1.6–1834), including the diameter range from 3 to 28 mm. Experimental measurements of frictional pressure drop of water-air mixtures are determined at different conditions. A search of the most suitable density, viscosity, and friction models was conducted and used in the model. The performance of the proposed ANN correlation is compared against published expressions showing good approximation to experimental data; results indicate that the most used correlations are within a mean relative error ( mre) of 23.9–30.7%, while the proposed ANN has a mre = 0.9%. Two additional features are discussed: i) the applicability and generality of the ANN using untrained data, ii) the applicability in laminar, transitional, and turbulent flow regimen. To take the approach beyond a robust performance mapping, the methodology to translate the ANN into a programmable equation is presented.

Potential applications of functional liquid crystals such as biosensors strongly rely on control of the molecular orientation at interfaces. However, little knowledge regarding detailed molecular a...

A 3D computational fluid dynamics model based on a volume of fluid (VOF) approach is presented to simulate air-water interactions and transient pressures in T-junction pipes of urban stormwater dra...

The aggregative stability of nanosized particles of aluminum and magnesium oxides is considered, because they are common components of the environment. Air and water are chosen as the most probable contact media, and saline is chosen as a medium that imitates the internal human environment. It is found that, in all media, aluminum oxide particles have a lower aggregative stability and are more likely to form agglomerates than magnesium oxide particles. Nanosized particles of magnesium oxide and aluminum in the internal media of the human body tend to form nanosized clusters connected through liquid bridges; they are not stable; i.e., nanoscale particles can move in the form of a cluster and, in the medium of the target organ, they disintegrate into particles and act as a nanoscale material. The aggregative stability of nanosized particles is determined by the material of the particles, their size, and the distance between them, while it dynamically changes during the transition from the external environment to the internal environments of the body and at different stages of metabolism, which proves the need to take into account the physical interaction of particles in different environments to assess their toxicity.

Clean availability air used when coming from wells (air land) for the needs of everyday residents, air conditions are very murky, yellow, sour and post-idanan from the pollution of domestic waste air from waste air laundry, bathroom, toilet waste and the rest of the rice field irrigation system, although currently Kp. Sendal Kopo, Panenjoan Village has a unit of clean air water is the top thing to treat the surrounding residents Community-Based Sanitation (Sanimas) from the central government is limited only dipoman air waste household results to irrigate rice fields, not for air needs One way in processing ground air by designing air filters from PVC pipes using activated carbon media from coconut shells and additional media foam filter, injury, zeolite stone, activated carbon and sand silica for air to make the air good air. Simple air filter everywhere in Kp.Sendal Kopo, Panenjoan Village, Carenang District, Serang District, Banten Province. Any activity there provides favours throughout the community Kp. Sendal Kopo, Village Panenjoan RT / RW: 004/01 involved in the workshop of making simple air filters and counselling will maintain and manage clean air so that with the village Of Panenjoan will be murky and political air into air that has standard air through clean air design intalasi air

The current research focuses on the analysis of different dynamic effects of an air pocket located at mid-pipe length on transient pressures based on experimental data. Different flow rates and air...

Steels of various grades are ubiquitous in the modern economy. Cooling of steel during the production process is an important deciding factor about its final mechanical properties. This is dependent on the characteristics of the industrial setup and coolant used. Studies have been undertaken for analysis of their influence on the cooling rate, given specific parameters, for suitable industrial use and optimal production. The present study and experiments undertaken highlight the variation of the cooling rate of a Mild Steel Plate in a miniaturized Run Out Table (ROT), using air­water mist spray cooling under different initial plate temperatures and nozzle bank distances.

PURPOSE This study aimed to compare the wet bulb globe temperature (WBGT) index and other environmental parameters between early and late Boston Marathon race start times from 1995 to 2016. METHODS Environmental data from 1995 to 2016 (excluding 1996) were used to compare two identical time frames using the 0900-1300 h start versus the 1100-1500 h start. This included the WBGT, dry bulb (Tdb), black globe (Tbg), wet bulb (Twb), solar radiation, relative humidity, and air water vapor pressure. To make comparisons between start times, the difference in the area under the curve (AUC) for each environmental variable was compared within each year with a Wilcoxon signed rank test with a Holm-Bonferroni correction. RESULTS AUC exposures for WBGT (P = 0.027), Twb (P = 0.031), Tdb (P = 0.027), Tbg (P = 0.055), and solar radiation (P = 0.004) were reduced with an earlier start, whereas those for relative humidity and air water vapor pressure were not. Overall, an earlier race start time by 2 h (0900 vs 1100 h) reduced the odds of experiencing a higher flag category 1.42 times (β = 0.1744, P = 0.032). CONCLUSIONS The 2007 decision to make the Boston Marathon start time earlier by 2 h has reduced by ~1.4 times the odds that runners will be exposed to environmental conditions associated with exertional heat illness.

Heat pumps are mechanical devices that can be used for the sustainable generation of heating and cooling energy. However their construction generates also environmental burdens. The aim of this manuscript is the identification of the environmental hot spots of a air/water heat pump via means of life cycle assessment. Inventory data were collected by primary sources. The results indicate that the case of the heat pump, made of stainless steel, is the dominant contributor to the environmental impacts generated by the construction of the heat pump. Moreover, the main impact category affected by the heat pump components is that of human toxicity.

The prevalence of ions at the aqueous interface has been widely recognized, but their effect on the structure of interfacial water (e.g., hydrogen (H)-bonding) remains enigmatic. Using heterodyne-d...

A direct approach for determining the tray and point efficiencies of an industrial-scale distillation tray is proposed. The stripping of isobutyl acetate from an aqueous solution with air was used,...

The underwater world is still largely unexplored yet surveying and monitoring submerged sites is fundamental for many applications, including archaeology, biology, and disaster response [1, 2, 3]. One of the challenges for underwater autonomous deployments is limited communication between assets underwater and in the air. One conventional strategy is to periodically let the underwater vehicle surface to share data [4], which is inefficient due to time not being spent on the task. Another strategy is to deploy a network of buoys at the water surface [5], connected to both the underwater assets (via acoustic transducers) and the ground station (via Wi-Fi). This deployment configuration increases the cost and logistical overhead, limiting the overall scalability of the system.

Aims This study explores the microbial diversity of sources which may influence boat microbial communities. We investigated the impact of dock, air, and water microbial communities on the hull, transom, and bilge microbial communities over the span of 11 days. Methods and results Using source tracking software, we investigated the extent to which each of our potential sources (air, water, and dock) influenced the overall microbial community. This study concluded that the dock impacted 14-64% of the hull and transom microbial community. Microorganisms from the water were shown to impact 5.6% the bilge microbial community but had minimal impact on hull and transom microbial communities. Microorganisms from the air had minimal impact in all areas of the boat. Conclusions Our results demonstrate that microorganisms from sources other than water can influence the microbial community of a boat, suggesting that terrestrial microorganisms can impact the boat microbial community. Significance and impact of the study Outside of ballast tanks, microbial diversity on boats is largely unexplored. While ballast water is widely recognized as a route for dispersal of allochthonous microorganisms, comparatively little is known about the microbial diversity on other areas of the boat. If the organisms on a boat originate from sources other than water, there is potential that terrestrial microorganisms could be dispersed by shipping activity.

Air pollution throughout the world, in general, has been at a very alarming rate with the increase in industrial and human activities. In Indonesia, the level of air pollution caused by various industries, especially from motor vehicles, is no longer a secret. Particularly, in the province of Aceh, air, water, and air noise quality in recent years have resulted in deteriorating health for humans and living things. This research analyzed air quality, water odor, and air noise level in the Aceh Province. The results for air quality analysis show an increase in emissions. The noise level of the three regions analyzed is still below the thresholds set. Meanwhile, the results of water odor analysis show its level has exceeded the thresholds set by the Ministry of Environment. Therefore, industrial activities can have an impact on the environment when they are not managed appropriately.

Sufficient air concentration on aerated spillway flows can mitigate the hazard of cavitation damages on concrete surfaces of spillways. In this study, a three-dimensional two-phase flow is modelled...

Linear and cyclic volatile methylsiloxanes (VMS) are Si and O containing organic compounds that are increasingly subject to scientific studies in recent years. They are used as solvents and coating materials in personal care products, cleaning materials and industrial applications. In this study, it was aimed to investigate the spatial variations of VMS levels in river water and ambient air in Kucuk Menderes Basin and their air-water exchange patterns. Grab river water samples and passive ambient air samples collected from 10 sites throughout Kucuk Menderes Basin located in Izmir region in Turkey, and they were analyzed for VMS. The concentrations of ΣVMS in river water and ambient air ranged from 48.4 to 148 ng L−1 and from 41.7 to 433 ng m−3, respectively. Among the VMS compounds, the predominant compounds were found to be D5 and D3 in ambient air and river water, respectively. In general, concentrations of all VMS congeners increased towards downstream of the river for both water and ambient air samples and there were substantial fluctuations between the sampling points. These fluctuations may be due to wastewater discharges at some sites (increase), followed by loss by volatilization along the river (decrease). VMS concentrations measured in air and river water samples were used to estimate the net air-water exchange fluxes. In all cases, fluxes were negative, ranging between −159 (L4) and −11100 (D3) ng m−2 day, indicating volatilization from water is a source for atmospheric VMS.

A computational analysis was carried out on the film cooling technique over the surfaces of eroded plates. The air–water mist coolant was injected through the slotted hole. A flat plate was patterned with various erosions. The loading fraction, f = 4–16%, and blowing ratio, M = 1–1.6, were simulated to understand their influence on the mist film cooling effectiveness. The coolant injection angle or the inclined angle of the secondary slot was kept at α = 35°. It can be observed that the increasing loading fraction raises the film cooling performance. Likewise, a higher blowing ratio can provide a better film cooling over the target surface. Again, it is found that the presence of erosion increases the cooling effectiveness at the particular surface of erosion. Simultaneously, a decrease in the effectiveness can also be noticed at the adjacent flat surfaces. Additionally, the erosions at the further downstream are more effective over the eroded surface compared to the upstream erosions. Considering the size of erosion as a crucial parameter, it was investigated for three different depth sizes. An increment in the mist film cooling performance is observed for the higher depth erosion.

Prediction of air-water two-phase flow frictional pressure loss in pressurized tunnels and pipelines is essentially in the design of proper hydraulic structures and pump systems. In the present study artificial neural networks (ANN) and adaptive neuro-fuzzy inference system (ANFIS) are employed to predict pressure loss in air-water two-phase slug flow. Adaptive particle swarm optimization (APSO) is also applied to optimize the results of the ANN and ANFIS models. To predict the pressure loss in two-phase flow, the frictional pressure loss coefficient needs to be determined with respect to the effective dimensionless parameters including two-phase flow Froude and Weber numbers and the air concentration. Laboratory test results are used to determine and validate the findings of this study. The performances of the ANN-APSO and ANFIS-APSO models are compared with those of the ANN and ANFIS models. Different comparison criteria are used to evaluate the performances of developed models, suggesting that all the models successfully determine the air-water two-phase slug flow pressure loss coefficient. However, the ANFIS-APSO performs better than other models. Good agreement is obtained between estimated and measured values, indicating that the APSO with a conjugated ANFIS model successfully estimates the air-water two-phase slug flow pressure loss coefficient as a complex hydraulic problem. Results suggest that the proposed models are more accurate compared to former empirical correlations in the literature.

In hydraulic engineering, intense free surface breakups have been observed to develop in high-speed open channel flows, resulting in a mixed air-water layer near the free surface that grows with the development of self-aeration. This region is characterized by a substantial number of droplets coexisting with an induced air layer above. Little information about this droplet layer is currently available and no practicable approach has been proposed for predicting the parameters of the induced air layer based on the related flow structures in the droplet layer. In this research, laboratory experiments were accordingly conducted to observe the detailed droplet layer development in terms of layer thickness, droplet size, and frequency distributions under comparative flow conditions. Based on the simplified droplet layer roughness determined using the experimentally measured mean droplet size, the classical power-law of boundary layer theory was applied to provide an analytical solution for the air velocity profile inside the air layer. The relationship of air layer growth to droplet layer thickness, which is a key factor when determining the air velocity distribution, was also established, and the analytical results were proven to be in reasonable agreement with air velocity profiles presented in the literature. By determining the relationship between droplet layer properties and air velocity profiles, the study establishes a basis for the improved modeling of high-speed open channel flows.

Air water-harvesting systems are considered important technologies for overcoming the global water scarcity issue. Various relative humidity and cost considerations make sorbent-based air water-harvesting systems the most desirable technologies among current air water-harvesting systems. The limited availability of commercial instruments for air–water harvesting systems indicates a lack of fundamental studies on this field. In this regard, this review paper discusses and presents progress in the fields of sorbent materials and condensation and system design and future considerations in accelerating the commercialization of these technologies. Particularly, bio-inspired composition and design, mix design systems, use of renewable energy sources, modification of available sorbent materials according to functionalization, and composites are factors that require further attention. Fundamental studies of sorbent stability and life cycle, water absorbency, adsorption kinetics, heat and mass transport, regeneration condition, water-collecting surface design, and system design are essential.

It is important for estimating accurately the air-water transport of scalar such as heat and gas to understand turbulent characteristics close to the water surface. Near-surface turbulence in natural hydro-environments is influenced by the thermal stratification and the wind shear stress acting on the water surface. The purpose of this study is to numerically investigate how their factors influence the turbulent structure and the air-water scalar transport in an open channel flow by means of the direct numerical simulation, i.e., DNS. We reproduce the combined effects of the thermal stratification and the surface shear stress on the structure of the turbulent flow and the scalar transport on the water surface. The numerical results suggest that the scalar transport velocity is obviously changed by the combined effects of the thermal stratification and the surface shear stress.

Development of a robust self-cleaning oil-repellent surface in a cost-efficient and green manner is highly desirable, yet still difficult to realize. Herein, we develop a poly(vinyl alcohol) (denoted as PVA) composite hydrogel on which the oily contaminations can be removed efficiently by water merely. Owing to its high affinity to water and resistance to oils, the water-wetted hydrogel establishes a slippery oil-repellent state in air, displays underwater superoleophobicity with ultralow adhesion to all probe oils, and blocks oil from permeating when immersed into an oil surrounding. Oily contaminations on the PVA hydrogel surface are removed just by titling or water immersion, with no oil residue left behind. This enhanced oil repellency was retained after hand-bending, water-jetting, and even 1000 cycles of sand abrasion, demonstrating mechanical robustness. Application of the PVA hydrogel-coated copper mesh is demonstrated to separate oil/water and oil/oil mixtures, with separation efficiency being greater than 98%.

Fifteen years ago, polymeric hollow fibre heat exchangers were presented for the first time. Nowadays there are not only the shell-and-tube types as there were at the beginning. In this paper, six chaotised polymeric hollow fibre bundles with a different number of fibres were studied. The bundles presented varied in their fibre diameter, number and shape. These bundles were fixed into the module in such a way that the middle part serves as a cross-flow heat exchanger in an air tunnel. They were tested for air-water application with three different airflow rates. The overall heat transfer coefficients were determined, and the inner and outer heat transfer coefficients were derived. The modules presented achieved a heat transfer rate of up to 1309 W. The overall heat transfer coefficient reached a maximum of 339 Wm−2 K−1.

Room-temperature self-healing and self-growing of the exoskeleton with aligned structures in insects has few analogs in synthetic materials. Insect cuticle, such as elytra in beetles, with a typical lightweight lamellar structure, has shown this capability, which is attributed to the accumulation of phenol oxidase with polyphenol and amine-rich compounds in the hard cuticle. In this study, laminar-structure-based intelligence is imitated by incorporating adaptable and growable pyrogallol (PG)-borax dynamic-covalent bonds into a poly(acrylamide)-clay network. The events that lead to crack formation and water accumulation quickly trigger the deprotection of PG. Subsequently, atmospheric O2, as a regeneration source, activates PG oxidative self-polymerization. Multiple permanent and dynamic cross-links, with the involvement of the sacrificed borax, and initiation of a series of intelligent responses occur. The fabricated composites with an aligned lamellar structure exhibit outstanding characteristics, such as air/water-triggered superstrong adhesion, self-repairing, self-sealing and resealing, and reprocessing. Moreover, the strategy endows the composites with a self-growing capability, which leads to a 4- to 10-fold increase in its strength in an outdoor climate (up to 51 MPa). This study could lead to advances in the development of air/water-responsive composite materials for applications such as adaptive barriers.

The horizontal bubbly two-phase flow is preferably used in various industrial applications because it provides high interfacial areas which enhance the heat and mass transfer. In the present research, the phase distribution of controlled air-water flow in a horizontal acrylic round pipe with 60 mm inside diameter (D) has been investigated experimentally and modeled numerically. The modeled differential pressure and the mixture velocity profile at a distance of 33D from the mixing section (fully developed region) are computed numerically and compared with those obtained experimentally from the two-phase flow system established and maintained at the National Institute of Standards (NIS-Egypt). Furthermore, the numerical and the experimental data have been compared with previous correlations and models. Reasonable quantitative agreement between all data is found. An electronic device based on Arduino Uno board was designed and used with careful data manipulation for measuring the slug bubble velocity. The results point out that the air volume fraction has a maximum value at the upper pipe wall as the gas bubbles tend to migrate to the upper wall. A new correlation was obtained for bubble migration length to the upper pipe wall which is very important in chemical industrial processes and other engineering application.

In this project, the flow distribution for air and water, and the enhancement of the heattransfer coefficient are experimentally studied. Experimental studies have been performed totest the influence of discharge, pitch, the height of ribs at a constant heat flux on thetemperature and pressure distributions. Along the channel of the test and the heat transfercoefficient, the water volume flow rate was about (5-12 L/min), the air volume flow rate wasabout (5.83-16.66 L/min), and heat were (80, 100,120, watt). An experimental rig wasconstructed within the test whole system. On the other hands, the channel has a divergentsection with an angle =15o with vertical axis. The study included changing in the ribs heightby using three values (12, 15, 18 mm) and changing the ribs pitch into three values (5, 8, 10mm).The results indicated an increasing in the local heat transfer coefficient as a result ofincreasing the discharge. While there was an inverse influence for the temperature distributionalong the test channel which drops when the discharge rise. The results also confirm that theincreasing in the pitch distance leads to reduce the heat transfer coefficient. Increasing theribs height increases the coefficient of heat transfer. However, the experiment heat transfercoefficient improves about (15.6 %) when the water volume flow rate increased from (5 to 12L/min), and about (18.7%) when the air volume flow rate increased from (5.83 to 16.66L/min). The best heat transfer coefficient was about (35.6 %) which can be achieved whenthe pitch decreased from (10 to 5mm). The increasing of the height from (12 to 18) mmimproves the heat transfer coefficient about (11.2 %). The best rib dimension was 18 mmheight, and 5 mm pitch, which give a maximum heat transfer coefficient (1212.02 W/m2. oC).

Two-phase flow has been used in so many industrial processes, such as boilers, reactors, heat exchangers, geothermal and others. Some parameters which need to be studied include flow patterns, void fractions, and pressure changes. Research on void fractions aims to determine the composition of the gas and liquid phases that will affect the nature and value of the flow property. The purpose of this study is to find out the characteristics of the void fraction of various patterns that occurs and to determine the characteristics of the velocity, length, and frequency of bubbly and plug. Data acquisition was used to convert the data from analog to digital so that it can be recorded, stored, processed, and analyzed. High-speed camera Nikon type J4 was used to record the flow. The condition of the study was adiabatic with variation of superficial gas velocity (JG), superficial fluid velocity (JL), and also working fluid. To determine the void fraction by using the digital image processing method. The results of the study found that the flow patterns which occurred in this study were bubbly, plug, annular, slug-annular and churn flows. It also showed that the void fraction value is determined by the superficial velocity of the liquid and air. The higher the superficial velocity of the air, the lower the void fraction value.

A series of N-alkyl-N,N-dimethyl-N-(2,3-epoxy propyl) ammonium chloride (CnEAC, n = 10, 12, 14, 16) with alkyl of decyl, dodecyl, tetradecyl, and hexadecyl were synthesized. The adsorption properties of CnEAC under the different temperatures, concentrations, interfacial oscillation frequencies as well as the inorganic salts (NaCl and Na2CO3) at air/water interface were investigated by interfacial dilatational rheology. The dilatational properties of CnEAC solutions including complex moduli, elastic moduli and viscosity moduli increased with oscillation frequency. The elastic moduli were higher than those of viscosity ones. With different hydrogen carbon length, the complex moduli of CnEAC showed different changing role with their concentration and temperature. Inorganic salts compressed the oppositely charges on CnEAC micelle surface and induced the decrease of both complex and viscosity moduli.

본 연구는 공기-물 이젝터를 이용하여 수중에서 수평으로 주입되는 2상 분류의 유입 및 분류 거동에 대한 실험적 연구를 목적으로 한다. 이젝터의 구동 노즐 면적비를 변수로 유입율 및 유출 계수를 산출하였으며, 수조 내의 주유동 방향 속도 분포를 측정하여 분류의 정량적 거동을 분석하였다. 면적비가 커지면 유입률은 감소하였으며, 유출 계수는 약간 증가하였다. 구동 노즐 면적비가 작고 출구 속도가 감소하면 디퓨저 출구 부근을 제외하고 부력 분류의 특성이 나타나며, 면적비가 커지고 출구 속도가 증가하면 수평 분류에서 부력 분류로 천이되는 거리가 길어지고, 분류 중심선 부근의 주유동 방향 속도가 증가하였다.

The simple geometry configuration of T-junctions and their capability to act as partial phase separators, especially on offshore platforms, made them common pipeline system components in power and process industries. Moreover, in the pursuit of achieving better phase separation by controlling the maldistribution occurred in the component phases of a mixture at the junction, industries often utilise reduced T-junctions. Nevertheless, most of the published data in which industries was based on to adopt the previous configuration was relating on fully horizontal T-junctions with large main pipe diameters although T-junctions are rarely placed in a horizontal position in such industries, whilst the usage of small main pipe diameters could also lead to scaling down their size. In this regard, the present paper aimed to extend the available data by performing numerical analysis and studying both regular and reduced T-junctions with a small main pipe diameter, and upward inclination angles. It was observed that reduced Tjunctions performed worse in terms of phase separation compared to regular T-junctions for all inlet conditions applied and irrespective of the side arm inclination, whereas in case of regular T-junctions a superior separation performance was ensured for the inclined side arm at 30°.

In this research, the overall system performance of the solar air heater integrated with air–water heat exchanger (SAH-IAWHE) was investigated experimentally in Iraq-Samarra. V-corrugated absorber ...

For the determination of heat transfer coefficients in air-water spray cooling, two methods are presented that are capable of characterizing multi-nozzle cooling set-ups. The methods are based on the quenching of thin-walled tubes or massive cylinders on which cooling curves are recorded at given positions with thermocouples. The temperature dependent heat transfer coefficients were calculated by an inverse calculation and the measured temperature-time-curves could be reproduced with these data in numerical cooling simulations. Next, the determined heat transfer coefficients were used for the calculation of an air-water-spray quenching process of a forging part with more challenging geometry. The calculated results were compared with thermocouple measurements. Different calculation variants for the heat transfer on component surfaces not directly exposed to the air-water spray are shown and discussed. ◼

This study presents a novel and simple morphology approach to generate two-dimensional air–water distribution in porous media considering Or and Tuller’s cavitation mechanism (published in 2002). The connectedness condition for the nonwetting phase is replaced by the Laplace equation. An algorithm is developed to detect the ruptured water spaces that are incorrectly formed in the throat by the morphology approach, but cannot exist in a real thermodynamic equilibrium system. The distributions of soil moisture, water retention curve, and air–liquid interface area at different saturations predicted by this method are in a good quantitative agreement with the experimental observations on glass beads and Ottawa sand from micro X-raycomputed tomography (microXCT). Compared to Lu et al.’s Monte Carlo lattice-gas approach (published in 2010), another computational method to generate the soil moisture distribution, the proposed approach provides better results with significantly less computational power.

The importance of photovoltaic-thermal (PV / T) collector systems in renewable energy technologies is increasing for combined hybrid electrical heat applications. The efficiency of photovoltaic (PV) systems varies between 5-20%. On average, 15% of the solar radiation coming to the PV panel surface is converted to electrical energy and the remainder is lost. In this study, a PV/T collector was designed using two different fluids simultaneously and its efficiency was calculated numerically. PV/T collector systems are specifically designed for agricultural production and their advantages are discussed. In this study, numerical calculations of PV/T collector with a different design have been made. The results were compared with reference to another experimental study. Two different working fluids (air and water) were used in the calculations. The system where air is used as working fluid is called Mode 1 and the system where water is used is called Mode 2. It is aimed to achieve high heat transfer by using water pipes, air ducts and fins placed under PV panels. In this way, it is aimed to produce a more stable hot air and water. In addition, in order to investigate the effect of flow on the yield, different flow rates were calculated. As a result of the theoretical analyses and calculations made in consideration of literature, the total efficiencies of air flow mode (Mode 1) were calculated as 43.2%, 46,2% and 48.7% at 0.0067 kg/s, 0.0072 kg/s and 0.0077 kg/s mass flow rates, respectively. For water flow mode (Mode 2), these values computed as 52.81%, 53.83% and 55.04% at 0.023 kg/s, 0.036 kg/s and 0.054 kg/s mass flow rates, respectively. It was found that PV / T collector efficiency increased with increasing end flow. Designed collector system is preferable in terms of effective use of energy and it can be easily applicable in processes such as hot air-water preparation, drying and greenhouse heating.

A novel fluidization backwash method by the air-water bubbly flow with air bubbles of various sizes has been proposed for rapid filters. The backwash efficiency is closely related to the bubble wake motion. Bubble coalescence, bed contraction and jet generation caused by the motion of air bubble wakes strikingly enhance the discharge of retained sludge. The effect of the bubble wakes on the backwash efficiency is ensured by controlling the fluidizing condition which is easily identified visually. The size of air bubbles should be controlled properly, and the air bubble size at the dense bed surface must be within several centimeters to prevent the loss of filter media particles from filter beds. The backwash efficiency of the filter bed achieved 94% in average by optimizing the air bubble size in the air-water bubbly flow. The air-water bubbly flow backwash method was also applied to a self-backwash filter where the backwash flow rate depends on an elevated water tank, and the backwash efficiency was as high as that for the constant flow rate backwash method.

Understanding the interactions between viruses and surfaces or interfaces is important, as they provide the principles underpinning the cleaning and disinfection of contaminated surfaces. Yet, the physics of such interactions is currently poorly understood. For instance, there are longstanding experimental observations suggesting that the presence of air-water interfaces can generically inactivate and kill viruses, yet the mechanism underlying this phenomenon remains unknown. Here we use theory and simulations to show that electrostatics may provide one such mechanism, and that this is very general. Thus, we predict that the electrostatic free energy of an RNA virus should increase by several thousands of kBT as the virion breaches an air-water interface. We also show that the fate of a virus approaching a generic liquid-liquid interface depends strongly on the detailed balance between interfacial and electrostatic forces, which can be tuned, for instance, by choosing different media to contact a virus-laden respiratory droplet. Tunability arises because both the electrostatic and interfacial forces scale similarly with viral size. We propose that these results can be used to design effective strategies for surface disinfection., We know that air-water interfaces can generically inactivate viruses, but the mechanisms behind this observation are unclear. Here the authors use simulations to uncover those mechanisms and find that the electrostatic repulsive free energy of an RNA virus increases by several thousands of kBT as it approaches an air-water interface, providing a mechanism for viral destabilization which may induce inactivation.