Fine Water Droplets Research Articles

Thermal Comfort In Recreational Facilities: Examining the Effect of Misting Systems

This paper delves into the significance of misting systems in enhancing thermal comfort in indoor and outdoor environments, particularly in recreational facilities. It explores how misting systems regulate temperature and humidity to create optimal thermal conditions for users. The evolution of misting-cooling systems as integrated design solutions for outdoor spaces is also discussed, highlighting their benefits in achieving and maintaining thermal comfort. Thermal comfort plays a crucial role in the overall experience of individuals in recreational facilities. Misting systems have emerged as effective tools for regulating temperature and humidity levels, thereby enhancing the comfort of users. These systems have evolved over time to become integral components of indoor and outdoor design, offering a range of benefits in creating ideal thermal conditions. Misting systems operate by releasing fine water droplets into the air, which evaporate quickly, absorbing heat and lowering the surrounding temperature. This process helps to cool the environment and maintain optimal humidity levels, contributing to a more comfortable experience for individuals in recreational spaces. The use of misting systems in recreational facilities offers several advantages, including improved thermal comfort, energy efficiency, and enhanced user experience. By creating a pleasant microclimate, these systems contribute to increased satisfaction among visitors and can help attract more patrons to the facility. Misting-cooling systems have undergone significant advancements in recent years, with a focus on integrating them seamlessly into outdoor spaces. By considering factors such as site topography, vegetation, and daily shade patterns, designers can optimize the effectiveness of misting systems in controlling microclimatic conditions. Keywords: Thermal Comfort, Recreational Facilities, Misting Systems, Droplets, Vegetation

Investigating the Impact of Wash Water Pump Rate on the Efficiency of Desalting Process of Crude Oil, a Case Study of X-Field in Iraq

Desalting is an essential process in the oil industry to remove salts from crude oil. These salts, which include fine saline water droplets and salt crystals, can have a significant impact on the crude refining process. If left untreated, they can foul heat exchangers, block pipelines, cause scales, corrosion, foaming, plugging and affect the overall performance of other equipment. To avoid these salt-related problems, it is crucial to remove salts from the crude oil, This paper presents a case study of the effect of wash water pump rate on the efficiency of the desalting process for crude oil in the X-field in Iraq. The desalting process was evaluated based on the wash water pump rate. Crude oil samples were collected downstream of the desalter at various wash water flow rates, on weekly basis for about ten weeks, and the average salinity were measured in parts per million (ppm). The results of the investigation show that there is an inverse relationship between the salinity of the crude oil and the wash water pump rate. As the salinity of the crude oil increases, the wash water pump rate decreases. At wash water pump rate of 6 m3/hr. and below, the salinity of the crude oil exceeds the 30-ppm export specification; implying that a lower wash water pump rate leads to inadequate desalting of the crude oil. The study also unraveled the causes and consequences of inadequate wash water pump rate such as: clogged inlet or outlet, insufficient power supply, passing valve, worn-out or damaged impellers, mechanical failure, piping issues, sealing problems, and increased operational costs. To optimize the wash water pump rate, a procedure was also developed in this study. This method addresses the identified causes and consequences of an inadequate wash water pump rate in effectively desalting crude oil. This study has unraveled the importance of the wash water pump rate in the desalting process and t highlights the need to maintain an optimal pump rate to effectively remove salts and avoid associated problems in the refining process.

Health Benefits of Airborne Terpenoids and Aeroanions: Insights from Thematic Review of Chinese-Language Research on Forest Sensory Experiences

Most research on air chemistry and human health has focused on negative consequences of air pollution from cities, rural dust, mining, or industrial sites. Research on nature tourism and nature therapy, in contrast, focuses on positive benefits of air quality for physical and mental health, e.g., via “clean air clean water” holidays. Aeroanions and terpenoids in forests have received particular attention, especially in China, Japan, and Korea. We review and analyse several hundred articles published in English and Chinese. With a few recent exceptions, English-language research has tested indoor negative ion generators, and concluded that they have no measurable health benefit. It has tested terpenoids in indoor aroma marketing. Chinese-language research, in contrast, has analysed fine-scale components of outdoor environments that affect concentrations of aeroanions and terpenoids: ecosystem, latitude, altitude, temperature, proximity to water, and individual plant species. Historically, health outcomes have been taken for granted, with little rigorous testing. Air quality research has shown that aeroanions can become attached to fine water droplets, e.g., after rain in forests, or in mists produced locally by waterfalls. We hypothesise that the health benefits of aeroanions in natural environments may arise through the scavenging of airborne particulates by negatively charged mists, creating especially clean, dust-free air. We propose that this particularly clean-tasting air, contrasting strongly with polluted urban air, creates positive effects on human mental health and perhaps, also on pulmonary physical health. Mechanisms and outcomes remain to be tested. We also propose testing psychological health effects of airborne terpenoid scents from forest trees.

A facile method for separating fine water droplets dispersed in oil through a pre-wetted mesh membrane

To achieve the successful separation of emulsions containing fine dispersed droplets and low volume fractions, a membrane with pore sizes comparable to or smaller than the droplet size is typically required. Although this approach is effective, its utilization is limited to the separation of emulsions with relatively large droplets. To overcome this limitation, a secondary membrane can be formed on the primary membrane to reduce pore size, but this can also be time-consuming and costly. Therefore, a facile and effective method is still required to be developed for separating emulsions with fine droplets. We introduce a pre-wetted mesh membrane with a pore size significantly larger than droplets, easily fabricated by wetting a hydrophilic stainless-steel mesh with water. Applying this membrane to emulsion separation via gravity-driven flow confirms a high efficiency greater than 98%, even with droplets approximately 10 times smaller than the pore size.

Steam containing fine water droplets as an effective binder for accelerated granulation of whey powders

Steam containing fine water droplets as an effective binder for accelerated granulation of whey powders

Effects of Interface Morphology between Nitrogen Plasma and Fine Water Droplet for Ammonia Production Efficiency

Effects of Interface Morphology between Nitrogen Plasma and Fine Water Droplet for Ammonia Production Efficiency

Facilitated encapsulation of a nonionic contrast agent for X-ray computed tomography into lipid vesicles by the multiple emulsification-solvent evaporation method

We studied the encapsulation of iohexol (Ihex), a nonionic contrast agent used for X-ray computational tomography, into lipid vesicles using the multiple emulsification-solvent evaporation method to formulate a nanosized contrast agent. This lipid vesicle preparation method consists of three steps: (1) primary emulsification for producing water-in-oil (W/O) emulsions containing fine water droplets that will be converted to the internal water phase of the lipid vesicles, (2) secondary emulsification for formulating multiple water-in-oil-in-water (W/O/W) emulsions encapsulating the fine water droplets containing Ihex, and (3) solvent evaporation to remove the oil phase solvent (n-hexane) and to form lipid bilayers surrounding the fine inner droplets, resulting in the formation of lipid vesicles encapsulating Ihex. As the diameter and Ihex concentration of the primary W/O emulsion droplets decreased, a higher Ihex encapsulation yield was obtained for the final lipid vesicles. The entrapment yield of Ihex in the final lipid vesicles varied significantly with the emulsifier (Pluronic® F-68) concentration in the external water phase of W/O/W emulsion, and the highest yield (65%) was obtained when the emulsifier concentration was 0.1 wt%. We also investigated the powderization of lipid vesicles encapsulating Ihex via lyophilization. The powderized vesicles were dispersed in water after rehydration and maintained their controlled diameters. The entrapment yield of Ihex in powderized lipid vesicles was maintained for over 1 month at 25 ˚C, while significant leakage of Ihex was observed in the lipid vesicles suspended in the aqueous phase.

미세 수액적을 가진 가스의 압축과정에 대한 이론적 연구

대기를 작동유체로 하는 유체기계의 효율은 등엔트로피식을 기반으로 계산된다. 이 방정식은 유입되는 대기의 온도만 알려지면 항상 일정한 값을 제공한다. 그러나 실제 압축 과정에서는 대기에 포함된 미세 수액적들이 주변 대기로부터 열을 빼앗아 증발하여, 대기의 온도를 낮춘다. 유입되는 대기의 온도가 일정하더라도 상대습도에 따라 대기에 포함된 미세 수액적의 양이 다르기 때문에 유체기계의 효율은 다르게 된다. 따라서 본 연구에서는 실제 압축 과정을 시뮬레이션하기 위하여 실린더-피스톤 시스템을 도입하였다. 이 시스템을 이용하여 압축 과정 동안 미세 수액적의 증발에 따른 열 · 유체역학적 상태량의 변화를 예측하는 이론 모델을 제안하였다. 또한 다양한 초기 변수들이 압축 과정 동안 실린더 내부의 열 · 유체역학적 상태량에 미치는 영향을 조사하였다.

PDA Laser Measurements of Droplet-Laden Flows in a Four-Stage Axial Compressor

Abstract Droplet-laden flows play a significant role in the development of turbomachinery. For example, fine water droplets are injected into the flow path of axial compressors to increase the power output of gas turbines by making use of evaporation cooling, often referred to as wet compression. Another example is the ingestion of rain droplets in aircraft engines. Therefore, thermodynamic and aerodynamic measurements of air and liquid are indispensable to better predict the following behavior of the droplets in the gas flow. This article presents a new PDA measurement setup for a droplet-laden four-stage axial compressor to analyze the droplet behavior in swirled flows. To reduce optical disturbances of the laser beam path, liquid films at the casing are suppressed by a boundary layer air injection. Supplementary investigations with this treatment show a negligible influence on the compressor behavior. To minimize refraction effects of the laser beams at the casing window, the laser device with the optical probes can be translated and rotated, thus having 4 degrees-of-freedom. Furthermore, the collected droplet data are compared with a mathematical description of velocity slip in superimposed air flows. For the first time, it can be shown experimentally that droplets smaller than 10 μm attain the velocity of air one stage after injection. For larger droplets, however, deviations from the air Mach number of up to 0.05 remain. In addition, detached liquid films behind the trailing edge of the stator blades with low velocities can be clearly detected.

Factors Impacting Atmospheric Pitting Morphologies

Stainless steels exposed to marine and near-marine environments can suffer from localized corrosion due to the appreciable amount of chloride aerosols present. In some cases, this localized corrosion, in the presence of sufficient tensile stress, can lead to stress corrosion cracking (SCC). Spent nuclear fuel (SNF) is currently stored in stainless steel canisters at independent spent fuel storage installation sites (ISFSI), many of which are located in near-marine environments. The possibility of localized corrosion features transitioning to SCC is a potential concern, particularly as the use of the SNF canisters at ISFSIs has been extended beyond their original licensing period.There is evidence that the likelihood of this transition occurring is dependent on the morphology of corrosion damage. Therefore, it is important to examine factors impacting the corrosion morphology. This work focuses on the effects of environment, surface finish, and stress state.304L stainless steel u-bends of various surface finishes were deposited with fine droplets of magnesium chloride solution or artificial sea water. They were divided among several exposure environments, cyclic or static in nature. Flat coupons of 304H, 304L, or 316L were finished to the same surface roughnesses and exposed in the cyclic environment. Static exposures were 75% or 40% RH at an elevated temperature while the cyclic environment varied both temperature and relative humidity. The cyclic environment is designed to mimic diurnal cycles experienced on a warm SNF canister after an initial storage (or cooling) period. In the flat coupons, the roughest surface finish developed elongated pits and microcracks formed along the edges of the pits, largely running perpendicular to the grind lines. When viewed in cross-section, pits on the roughest surface finish also appeared to have more severe under-cutting and to be more irregularly shaped. The results of the flat coupons will be compared to the u-bends exposed with various salt types and stress states. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. SAND2022-4056 A. PNNL-SA-171827

Clinical Trial for Evaluating the Effectiveness and Safety of a New Dental Plaque Removal Device: Microscale Mist Unit.

This study evaluates the effectiveness and safety of a microscale mist unit (MSM-UNIT) that sprays high-speed fine water droplets to remove dental plaque adhering to the oral mucosa (tongue and palate) and tooth surface. Fifteen patients who had difficulty self-managing sufficient oral care were included in this study. Effectiveness was evaluated for at least five patients’ tongues, palate mucosas, and tooth surfaces, and safety evaluation was conducted at all three sites for all patients. Effectiveness was evaluated using the rate of degree of dental plaque removal. Safety was evaluated using a numerical rating scale (NRS) for pain and symptoms of inflammation. An operator who performed treatment and an evaluator who evaluated effectiveness and safety were designated. In addition, an image judgment committee judged effectiveness. Although evaluation of the tongue varied between the evaluators and the image judgment committee, the rates of degree for all plaque removal increased in all regions. In addition, low pain NRS results and minimal symptoms of inflammation were observed and within an acceptable range. The MSM-UNIT can be used effectively and safely for removing oral plaque not only from teeth, but also from the oral mucosa.

Critical condition and transient evolution of methane detonation extinction by fine water droplet curtains

Two-dimensional numerical simulations with Eulerian–Lagrangian method and reduced chemical reaction model are conducted to study the methane detonation propagation across a water curtain with finite thickness. The critical length of the water curtain with sprayed droplets is determined through parametric simulations with different water mass loadings and droplet sizes. The influence of water curtain length on the methane detonation is examined by the trajectories of peak pressure and time history of average heat release rate. The results indicate that the water curtain not only inhibit the incident detonation wave, but also prevent the detonation re-ignition after the incident wave is quenched. Moreover, unsteady response of gaseous methane detonation to water curtain are analyzed. The detonation re-initiation process behind the water curtain near the critical loading is also captured. In addition, mechanism of detonation inhibition with fine water droplets are discussed. It is found that energy and momentum exchanges start immediately when the detonation wave enters the water curtain area, but the mass transfer starts well behind the detonation wave due to the finitely long droplet heating duration. It is shown that the convective heat transfer by water droplets plays a significant role in quenching a detonation.

Mathematical and computational models for simulating transient nuclear criticality excursions within wetted fissile powder systems

This paper describes a novel methodology for the analysis of nuclear criticality excursions in fissile powder beds under wetting conditions. These potentially hazardous powder, slurry and sludge systems may be found in nuclear fuel manufacturing and fabrication facilities. A point neutron kinetics model was coupled with water infiltration, thermal–hydraulics and radiolysis models through the use of reactivity feedbacks. Good agreement in the water infiltration rate was found when comparing the water infiltration model used in this paper to experiments conducted by the French Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA). A case study was proposed whereby a sheet of fine water droplets from a sprinkler system came into contact with an open-topped bed of low enriched UO2 powder. Simulations indicate that the mean powder particle size had a strong effect on the time required for the water to percolate through the powder bed. Powder particle size was also predicted to have a moderate effect on the initial fission power spike. The fission energy released over the first 300 s of the nuclear criticality transient ranged from 65.28 MJ to 97.98 MJ depending on mean powder particle size. This is similar in magnitude to other simulated nuclear criticality excursions in powder beds. The model predicts that the initial fission power spike would be limited by the production of radiolytic gas and to a lesser extent the effects of Doppler broadening and thermal expansion. As expected, boiling and the associated steam production, was found to be an important phenomenon in the reduction of the fission rate through the negative void reactivity effect of the steam.

Extinction of incident hydrogen/air detonation in fine water sprays

Two-dimensional numerical simulations with Eulerian–Lagrangian method are conducted to study propagation and extinction of stoichiometric hydrogen/air detonations in fine water sprays. Parameterized by water mass loading and droplet size, a detonation extinction map is predicted. Detonation extinction occurs with larger mass loading and/or smaller droplet size. General features of water droplets and local detonation frontal structures are well captured. Numerical soot foils are used to characterize the influence of mass loading and droplet size on the detonation wave. The results also show that the detonation cell size increases with increased mass loading or decreased droplet size. Analysis on unsteady detonation extinction process is performed with the evolutions of detonation frontal structure, spatial distribution of thermochemical variables, and interphase transfer rates (mass, energy, and momentum). Moreover, the chemical explosive mode analysis reveals that for stable detonation, thermal runaway dominates behind the Mach stem, while chemical propensities of autoignition and thermal runaway appear alternately behind the incident wave. When the induction zone length increases as the reaction front (RF) and shock front (SF) are decoupled, localized burned pockets surrounded by the autoignition chemical explosive mixture can be observed. In addition, the interactions between detonation wave and water droplets demonstrate that the energy and momentum transfer have more direct interaction with SF and RF than the mass transfer. The interphase transfer rates increase with the water mass loading. Under the same mass loading, the smaller the droplet size, the larger the interphase transfer rates. However, the size of fine water droplets has a limited influence on the interphase momentum exchange. Moreover, high energy and mass transfer rates are observed at the onset of detonation extinction, and they gradually decrease when the reaction and detonation fronts are decoupled.

Improvement of Skin Permeation of Caffeine, a Hydrophilic Drug, by the Application of Water Droplets Provided by a Novel Humidifier Device.

Recently, a novel humidifier that sprays water fine droplets equipped with a copolymer, poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT/PSS) was developed. PEDOT/PSS in the humidifier absorbs water from the environment and releases fine water droplets by heating. In the present study, the effect of hydration on the skin barrier, stratum corneum, was first determined by the application of fine water droplets using the humidifier. The skin-penetration enhancement effect of a model hydrophilic drug, caffeine, was also investigated using the humidifier and compared with a conventional water-evaporative humidifier. More prolonged skin hydration effect was observed after application of the fine water droplet release humidifier using PEDOT/PSS than that using a conventional humidifier. In addition, markedly higher skin permeation of caffeine was observed in both infinite and finite dose conditions. Furthermore, higher skin permeation of caffeine from oil/water emulsion containing caffeine was observed in finite dose conditions by pretreatment with the humidifier using PEDOT/PSS. This device can provide water droplets without replenishing water, so it is more convenient for enhancing the skin permeation of chemical compounds from topical drugs and cosmetic formulations.

Effectiveness and safety of a new dental plaque removal device utilizing micro mist spray for removing oral biofilm in vitro

BackgroundRemoval of oral biofilm from the oral mucosa is essential for preventing risk of respiratory and gastrointestinal infection in elderly people. Currently, no device is available which can remove oral biofilm from oral mucosa effectively and safely. Therefore, the effectiveness and safety of the Micro Scale Mist UNIT (MSM-UNIT), a newly developed dental plaque removal device utilizing high speed sprays of fine water droplets, were evaluated for biofilm removal, including the rate and surface roughness for simulated tooth surface and mucous membrane.MethodsSimulated tooth and oral mucosa coated with an artificial biofilm of Streptococcus mutans were used for evaluation of effectiveness, with uncoated substrates as the controls. The MSM-UNIT and a conventional air ablation device were operated under recommended instructions. The effectiveness was evaluated from the rate of removal of the biofilm, and the safety was evaluated from the damage observed by scanning electron microscope and surface roughness.ResultsThe biofilm removal rate of the MSM-UNIT was significantly higher than that of AIRFLOW. Little damage was observed in the area treated by the MSM-UNIT. The surface roughness of the MSM-UNIT treated area on simulated tooth surface and oral mucosa showed no significant difference to the control area. In contrast, cracks and powder were observed in the area treated by AIRFLOW. In particular, the surface roughness of the AIRFLOW treated area for Toughsilon was significantly larger than that of the control.ConclusionsThe MSM-UNIT could be used safely and effectively for removing biofilm not only on simulated tooth surfaces but also simulated mucous membrane. The MSM-UNIT has no harmful effect on teeth or oral mucosa, and may be used for comprehensive oral care for patients during nursing care and the perioperative period.

Reprint of: Flow and Heat Transfer Characteristics of the Mist/Steam Two-Phase Flow Cooling the Rectangular Channel with Column-Row-Ribs

Using mist/steam two-phase flow by mixing a small amount of fine water droplets into steam as the working fluid for the internal cooling passages of blades and vanes is a promising cooling technology for future gas turbines. We proposed a new cooling channel roughed with the column-row-ribs to achieve higher cooling efficiency and better heat transfer uniformity. The heat transfer experiment was conducted to validate the effectiveness of our numerical method. Flow and heat transfer performance of mist/steam two-phase flow was investigated in channels of different gap ratios and in a column-row-ribbed channel with gap ratios of ε = 0.177 under different working conditions. Comparing to the solid ribbed channel, the column-row-ribbed channels sacrifice the heat transfer performance to achieve better heat transfer uniformity. As ε larger than 0.264, the column-row-ribs have better thermal enhancement performance than the solid ribs. For the column-row-ribbed channel with gap ratio ε = 0.177, the heat transfer effect increases with the Re number. But the thermal uniformity and the thermal enhancement of the channel decreases obviously. As the wall heat flux q rises from 3000W/m2 to 40000W/m2, the thermal enhancement factor F gradually increases. But the wall heat transfer becomes less even. Continuously increasing the mist/steam mass ratio will help to increase the heat transfer effect of the heated walls, so does the heat-transfer non-uniformity. Simply increasing the droplets diameter will decrease the thermal enhancement factor and increase the heat transfer non-uniformity at the same time.

Flow and Heat Transfer Characteristics of the Mist/Steam Two-Phase Flow Cooling the Rectangular Channel with Column-Row-Ribs

Using mist/steam two-phase flow by mixing a small amount of fine water droplets into steam as the working fluid for the internal cooling passages of blades and vanes is a promising cooling technology for future gas turbines. We proposed a new cooling channel roughed with the column-row-ribs to achieve higher cooling efficiency and better heat transfer uniformity. The heat transfer experiment was conducted to validate the effectiveness of our numerical method. Flow and heat transfer performance of mist/steam two-phase flow was investigated in channels of different gap ratios and in a column-row-ribbed channel with gap ratios of ε=0.177 under different working conditions. Comparing to the solid ribbed channel, the column-row-ribbed channels sacrifice the heat transfer performance to achieve better heat transfer uniformity. As ε larger than 0.264, the column-row-ribs have better thermal enhancement performance than the solid ribs. For the column-row-ribbed channel with gap ratio ε=0.177, the heat transfer effect increases with the Re number. But the thermal uniformity and the thermal enhancement of the channel decreases obviously. As the wall heat flux q rises from 3000W/m2 to 40000W/m2, the thermal enhancement factor F gradually increases. But the wall heat transfer becomes less even. Continuously increasing the mist/steam mass ratio will help to increase the heat transfer effect of the heated walls, so does the heat-transfer non-uniformity. Simply increasing the droplets diameter will decrease the thermal enhancement factor and increase the heat transfer non-uniformity at the same time.

Experimental Study of the Effect of Water Spray in the Air on Thermal Transfers Along a Plate of an Exchanger

Abstract This study is an experimental investigation of the oceanic environment effect on a plate heat exchanger performance. Indeed, an experiment was carried out on a single plate of the exchanger to generate a turbulent airflow in which fine water droplets were injected into a horizontal vein where a heated plate was placed. The experimental tests were conducted for different air velocities and various water concentrations of freshwater and saltwater. In fact, two plate forms were considered: The first one is flat while the second is corrugated. Three main facts were observed in this work: (i) the correlations linking the heat transfer rate to the operating conditions, (ii) the effect of fog addition and the plate form on convective heat transfers, and (iii) the impact of the formation of a salt layer on the surface of the plate in the case of salt water.

Monodisperse macroporous microspheres prepared by microfluidic methods and their oil adsorption performance

Monodisperse macroporous poly(methyl methacrylate- hydroxyethyl methacrylate) (poly(MMA-HEMA)) microspheres have been successfully prepared by microfluidic methods. In our experiment, numerous fine water droplets were at first fabricated by homogeneous emulsification method and were then evenly dispersed inside monodisperse poly(MMA-HEMA) microspheres as porogens by using a combination of the microfluidic emulsification and the free-radical polymerization method. The embedded fine water droplets within the poly(MMA-HEMA) microspheres resulted in highly controllable uniform porous structures. Fourier transform infrared (FT-IR) spectrometer and scanning electron microscopy (SEM) were employed to examine the chemical compositions and microstructures of the microspheres. The effects of porogen quantity on the macroporous structures have been investigated systematically. The macroporous microspheres samples showed superior adsorption performance. With a water-in-oil type emulsion (water-to-oil volume ratio = 40%) used as the porogen, the microporous microspheres adsorbed 3.18 and 2.80 times their own weight of oil in diesel and in ethylene glycol dimethacrylate (EGDMA), respectively, and the adsorption capacity of microspheres remained unchanged by repeating the process five times. The large adsorption capacity for oil and good reusability of the macroporous microspheres make them attractive when applied in the separation of water and oil.