Flux Values Research Articles

FEATURES OF THE FLOW STRUCTURE IN A RECTANGULAR TRENCH

The study of features of the flow structure in rectangular trenches in a wide range of Reynolds numbers was carried out by means of direct numerical simulation of the flow in the channel and on а plate. Both isothermal and non-isothermal formulations of the problem were considered. Water and air were used as the investigated fluids. The flow structure inside and around the trench in the rectangular channel in the range of Reynolds numbers based on the trench length Re<=9000 was studied in a three-dimensional setting. In the Reynolds numbers range Re>=10000, unsteady flow around a plate with a trench was considered in two-dimensional formulation of the problem. Depending on the Reynolds number, the flow structure in the trench, the influence of geometric parameters on the vortices scales in the trench, their localization and intensity were analyzed. The scale of inhomogeneity of the trench flow in the transverse direction was obtained. The features of non-stationary behavior and interaction of vortex formations with each other and with the external flow at higher Reynolds numbers are considered, development of instability of the vortex structure in the trench and its influence on characteristics of the external flow are shown: from regular oscillations at certain frequency to gradual chaosization of the flow around the trench as the Reynolds number increases, when fractional and multiple frequencies appear. A comparison was made with the vortex structure obtained by other researchers for similar geometric parameters of the trench. The contributions of frictional drag and shape drag to the overall hydraulic drag of the trench, as well as the streamlined surface downstream the trench, are considered. Intensity of heat exchange processes inside the trench, localization of the maximum values of heat fluxes, dependence of heat transfer on the oncoming flow speed were evaluated.

Features of Measurement and Presentation for Germicidal Lamps Parameters

The aspects of measurement and presentation of radiation parameters of germicidal lamps, including radiant flux within the set spectral range, are under consideration. Radiant flux is currently used as their main parameter. There are the following methods of measurement of this parameter: indirect, by means of irradiance from the lamps, goniometric, and the integrating sphere method. The goal of the work was to compare the results of measurement of germicidal lamps using different methods and to analyse the practice of presentation of germicidal lamp parameters. TUV, HNS, LTC, DB, DKB and DKBU germicidal lamps and irradiators with different power capacity and peak radiation in the mercury line 253.7 nm were selected as the measurement objects and such parameters as radiant flux, germicidal flux, and radiant flux stabilisation time were selected as assessed parameters. The measurements were made and the values of radiant flux and germicidal flux, using the indirect and goniometric methods, were obtained. The graphs of radiant flux stabilisation of different lamps are presented. The analysis of the measurements demonstrated necessity of modification of the approaches to measurement and presentation of the germicidal lamp parameters.

Daytime convective development over land: The role of surface forcing

AbstractWater availability at the Earth surface determines the portioning of the surface heat flux into its sensible and latent components, that is, the surface heat flux Bowen ratio. The two components affect differently the surface buoyancy flux and thus the development and growth of the convective boundary layer. As a result, the Bowen ratio has a strong impact on the daytime development of dry and moist convection over land. We use two canonical modeling test cases, one for the shallow convection and one for the shallow‐to‐deep convection transition, to document the impact of the surface Bowen ratio on daytime convection development. A simple approach is used where results from simulations featuring the original setup are contrasted with simulations where the surface‐sensible heat flux takes on values of the latent heat flux and vice versa. Such a change illustrates the key impact of the surface water availability without changing the total surface heat flux. Because of the larger surface buoyancy flux, simulations with the reversed surface heat fluxes feature faster deepening of the convective boundary layer and wider clouds once moist convection develops. Mean cloud‐base width of cumulus clouds increases with the boundary‐layer depth. For shallow‐to‐deep convection transition, comparison of simulations with the observed large‐scale flow that feature substantial lower‐tropospheric shear with simulations with no mean horizontal flow suggests that the organization of convective circulations within the boundary layer strongly affects initial size and organization of shallow convection, as well as the subsequent width increase once convection deepens and eventually transitions to deep precipitating convection. A simple explanation is provided of why a deeper well‐mixed convective subcloud layer results in wider clouds. The key is the larger width of boundary‐layer coherent updraft structures when the mixed layer is deeper.

Initial Rotor Position Estimation of SynRM Based on Pulsating Voltage Injection Combined With Finite Position Set Algorithm

Initial rotor position estimation is the basis of stable starting without reverse rotation; also initial position estimation directly affects the maximum starting torque. DC pulse voltage injection is one of the common methods for estimating the initial rotor position, which has low implementation complexity. However, the conventional DC voltage pulse injection methods, which works through injecting three DC voltage pulses, has low accuracy and slow response in estimating initial position. A rotor initial position estimation method based on pulsating voltage injection combined with an iteration algorithm is proposed in this paper. This method works by injecting only one DC voltage pulse to the motor and measuring the peak values of currents and fluxes of the motor; afterwards these values should be applied to an iterative algorithm. The iteration algorithm in the proposed method leads to increment of the accuracy of initial position estimation, and reduction of the number of injected dc pulses in comparison with the conventional methods. The performance of the proposed method is verified experimentally on a synchronous reluctance motor (SynRM). Also, a comparison between the two conventional methods and the proposed method is provided by this SynRM drive experimental setup.

CARMEN 2 and 3 LEO Electron Flux Measurements Linear Projection Onto RBSP Elliptical Orbit

CARMEN 2&3 (CARactérisation et Modélisation de l’Environnement ) CNES (Centre National d’ Études Spatiales) missions aim to measure particle fluxes in the radiation belts via ICARE-NG (Influence sur les Composants Avancés des Radiations de l’Espace-Nouvelle Génération) monitor embedded on Low Earth Orbit (LEO) satellites. In this paper we find a projection model of these data onto the elliptical orbit satellite RBSP (Radiation Belt Storm Probes) flux particles levels measurements. The projection is done with a machine learning algorithm. Trained with data from CARMEN missions, the algorithm aims to predict particle flux measured by RBSP. We obtain satisfying results we find a good projection model on a large L* interval (L* = 3.4 - 5.5 for CARMEN 2). While the global trend of the temporal variation of electron flux values is well predicted, the algorithm is not able to predict the suddenness of solar events which produces abrupt slope changes and maxima in the temporal evolution of fluxes.

Reflector Design for Simulating Varying Heat Flux on Nose Cap of a Re-entry Module

For thermo-structural tests of a nose cap for a re-entry module accurate simulation of time and space varying heat flux is essential for generating the actual temperature gradients as expected in flight. Temperature gradient simulations along with simulated structural loads are essential for testing the structural integrity of the C-C nose cap.
 Contoured reflectors are essential for obtaining spatial distribution of incident heat flux. For realizing the reflector for thermo-structural testing, it is important to design radiation reflectors that will generate required heat flux envelope along the nose cap geometry. Reflector design for simulating varying heat flux on re-entry nose cap has been carried out by estimating view factor between nose cap and for different geometries of reflector.
 Design could be accomplished by making use of view factor algebra. Elemental heat flux values were validated with literature data and methodology for reflector heat flux design was validated against test data. With single flat reflectors and multiple flat reflectors, the required spatial variation of incident radiative heat flux could be realized efficiently. View factor variation is compared with heat flux variation along the nose cap. It is recommended practice to have multiple reflectors for simulating required varying heat flux on the nose cap due to better flexibility.

The Spotlight Based on the Solid-State Laser Light Source

The spotlight development on the solid-state laser light source is considered in this scientific article. The light sources characteristics are as close as possible to the characteristics and parameters of modern LED light sources. The main aim is to reach the luminous flux value of 3000 lm. That is analogues with the luminous flux of modern LED searchlights. As well as the photometric and electrical parameters, values and determination of the measures to improve the design of the spotlight are of the interest. The spotlight sample has been tested. And the test results show that after the value of 3000 lm reached the main failing of light source is the low value of its luminous efficacy, equal to 57 lm/W. In order to increase the light output of the searchlight, there are the ways of modernization of its construction suggested in the article. The previous results show that the measures suggested will allow us to increase the value of luminous efficacy to 100 lm/W. Besides that, such parameters and characteristics of the spotlight as the correlated colour temperature (CCT), colour rendering index (CRI), wattage, luminous intensity and spectral light distribution are measured and submitted in the article. The obtained energetic characteristics of the sample allow us to conclude that application of such light sources is approved in special conditions. Absence of electronic components in the distant radiation source of white light allows increasing the light source reliability substantially. Therefore, the laser spotlights are acceptable for application in the hard-to-reach places for installation of the lighting equipment, for example, on high places where the equipment demount used for repairing works is too difficult. It is actually to use also the developed light sources at the explosive industrial facilities having the current-transmitting elements of construction, especially having the open contacts. That allows reducing the safety of facility operation significantly.

Self-consistent equilibrium models of prominence thin threads heated by Alfvén waves propagating from the photosphere

The fine structure of solar prominences is composed of thin threads that outline the prominence magnetic field lines. Observations have shown that transverse waves of Alfvénic nature are ubiquitous in prominence threads. These waves are driven at the photosphere and propagate to prominences suspended in the corona. Heating due to Alfvén wave dissipation could be a relevant mechanism in the cool and partially ionised prominence plasma. In this work, we explore the construction of 1D equilibrium models of prominence thin threads that satisfy an energy balance condition between radiative losses, thermal conduction, and Alfvén wave heating. We assumed the presence of a broadband driver at the photosphere that launches Alfvén waves towards the prominence. An iterative method was implemented in which the energy balance equation and the Alfvén wave equation are consecutively solved. From the energy balance equation and considering no wave heating initially, we computed the equilibrium profiles along the thread of the temperature, density, ionisation fraction, and other relevant parameters. On these equilibrium profiles, we used the Alfvén wave equation to compute the wave heating rate, which was then put back in the energy balance equation to obtain new equilibrium profiles, and so on. The process was repeated until convergence to a self-consistent thread model heated by Alfvén waves was achieved. We obtained equilibrium models composed of a cold and dense thread, an extremely thin prominence-corona transition region, and an extended coronal region. We found that the length of the cold thread decreases with the temperature at the prominence core and increases with the Alfvén wave energy flux injected at the photosphere. However, computed equilibrium models for large wave energy fluxes are not possible when the wave heating rate inside the cold thread becomes larger than the radiative losses. The maximum value of the wave energy flux that allows for an equilibrium depends on the prominence core temperature. This constrains the existence of thread equilibria in realistic conditions.

Study of the influence of the angle of inclination on the thermal resistance of glass light structures of agricultural buildings

The paper presents the results of studies of the influence of the angle of inclination on the thermal resistance of glass light structures of agricultural buildings. For experimental studies, a special refrigerating chamber was used, in which one of the walls is made in the form of a double-glazed window. The camera tilted towards the light structure. With the help of heat meters installed on the surface of the glass, the value of the heat flux was measured. Both single-chamber and double-glazed windows were tested. Based on the experimental data obtained, a calculated dependence is proposed for determining heat losses through external inclined light fences, including double-glazed windows.

Optical and thermal analysis of solar parabolic dish cavity receiver system for hydrogen production using deep learning

The solar thermochemical cycle, responsible for converting solar energy to chemical fuel, is an emerging clean hydrogen production technique. The distribution of the concentrated heat flux and temperature on the receiver is crucial in deciding solar-to-fuel conversion efficiency. Thus, the optimum configuration of a solar parabolic dish collector (PDC) is necessary for providing efficient thermal energy. The dish diameter, rim angle, and distance of the receiver aperture from the focal point of the dish characterize the optimization of the PDC. The non-uniform heat flux captured is coupled with a heat transfer model of a solar thermochemical reactor for a thermal dissociation of ZnO involved in a ZnO/Zn thermochemical cycle for hydrogen production. The directly irradiated rotating reactor comprises a cylindrical cavity packed with insulation layers and a quartz glass window. The rotating cavity is loaded with ZnO granular particles held by a centrifugal force. A 3D CFD numerical model is analyzed by coupling the Eulerian multiphase model for ZnO particle dynamics, fluid flow of gaseous mixture, RNG k-ԑ turbulence model, Energy and Discrete Ordinates (DO) radiation model, and Arrhenius reaction rate chemical reaction of ZnO dissociation. A numerical model with non-uniform heat flux input is validated for a cavity temperature, mass fraction of zinc and oxygen, and oxygen molar flow rate at the reactor outlet. An artificial neural network model is adopted to predict the heat flux and uniformity factor values of PDC. Correlation Coefficient (R2), Root Mean Square Error (RMSE), and Mean Absolute Percentage Error (MAPE) error metrices were used to evaluate the model's performance having the receiver diameter (d), the dish diameter (D), the rim angle (φ), and the distance between the focus and receiver (h) as input variables.

Fabrication of high-performance MeI and HPEI assembled PES/CPES hollow fiber nanofiltration membranes with high positive charges for efficient removal of salt/heavy metal ions

Environmental protection and resource recovery require efficient separation of salts and heavy metal ions from wastewater. A new hollow fiber nanofiltration membrane (HFNM) with a highly positive charge was developed via Hyperbranched polyethyleneimine (HPEI) self-assembly and methyl iodide (MeI) quaternization on a polyethersulfone (PES) with carboxylic-PES (CPES) substrate. Effects of different layers on surface charge and roughness, wettability, and mechanical stability were evaluated. MgCl2 and ZnCl2 as representative of salts and heavy-metal ions, respectively, were used to investigate separating properties of the membranes in terms of feed temperature and concentrations, operating pressures, antifouling properties, and long-term stability. The relationship between salt/ions rejection and water flux, pore size, and surface positive charge degree was explained by comparing the structures and properties of the membranes. The 1wt.% HPEI and 0.5 wt.% GA solutions for 30 min crosslinking at pH of 11 and then 5 wt.% MeI solution could lead to the formation of the optimum membrane. Based on high hydrophilicity, low surface roughness, Donnan exclusion, and steric hindrance, the membrane could effectively exhibit superb rejection rates of Zn2+ (99.8 %), and Mg2+ (98.6 %), while showing high flux values (24.47 and 33.54 Lm−2h−1). The high flux rate (around 25.41 Lm−2h−1) during 4 cycles of regeneration, and high ions rejection (>98 %) were retained even after an 8-hour consistent operation. The prepared membrane, with high durability and structural stability, can introduce an effective solution for water purification from divalent ions.

ON THE DETERMINATION OF THE SPECIFIC HEAT FLUX VALUE IN A PULSE DETONATION ENGINE’S CHAMBER

Abstract. The development of detonation engines (DE) is one of the most promising areas of rocket and space engine manufacturing. They are more efficient as compared to the liquid rocket engines and are structurally simpler. At the same time, the detonation engine chamber’s structure is subjected to much higher thermal loads. Therefore, at the development stage of the DEs, to create an efficient cooling system for the engine’s chamber, it is necessary to be able to determine the value of thermal energy, which is absorbed by the walls of the DE’s chamber. The goal of this research is to determine the specific heat flux from the detonation products towards the walls of the pulse detonation engine’s (PDE) chamber. The task of the work is to establish the methodology for calculating the values of the specific heat flux transmitted to the walls of the PDE’s chamber. The main tools for solving this problem are the method of mathematical simulation using computational fluid dynamics (CFD), and the method of regression analysis. The main results of this study: the possibility to utilize the well-known Ievlev methodology to determine the convective specific heat flux for the PDE’s chamber was analyzed; it was shown that for the conditions of the PDE’s chamber, the Ievlev methodology calculation results differ significantly from the experimental data, which can be explained by the presence of a clearly pronounced non-stationary nature of the detonation process; it was proven the utilization of the Viegas formula to obtain the values of the convective specific heat flux for the PDE’s chamber gives better results as compared to the known experimental data and the results of the mathematical simulations; it was also demonstrated that the average integral value of the specific heat flux, determined by the described methodology, can be used to calculate the thermal state of the PDE's chamber. Conclusion: a methodology for calculation of the specific heat flux value for the pulse detonation engine's chamber was proposed. The obtained calculation results are in good agreement with the results of mathematical simulations and known experimental data. The described methodology can be used in the design of cooling systems for the pulse detonation engine’s chambers.

Ultrafiltration with in-line coagulation (FeCl3) to enhance arsenic removal and improve drinking water quality: From bench to pilot-scale

There is a growing interest in advanced technologies to guarantee drinking water safety in scenarios of increasingly polluted water sources. Based on that, this paper discusses the use of ultrafiltration membranes aided by in-line coagulation with FeCl3 (0.086 – 0.172 mg/L) to improve the resilience of drinking water treatment plants. The process was considered after the settling units and was first studied on a bench scale, later validated in a pilot plant that operated continuously for approximately 31 days. In experiments without an in-line dose of FeCl3, the average flux values corresponded to 189.9 ± 11.8 L/m2h, compared with 193.4 ± 5.3 L/m2h for experiments when the coagulant was considered. The flux decay was lower in experiments with an in-line dose of FeCl3 (J/J0 > 0.95) and analysis of particle sizes revealed that the average diameter increased from 24.1 to 29.2 µm after the coagulant was added. Consequences related to a greater particle size were a fouling layer more porous permeable, and with a lower hydraulic resistance. The additional coagulant dosage also acts on the residual natural organic matter, monitored by excitation-emission matrices. Furthermore, the results show that the concentrate recirculation to the beginning of the water treatment plant did not affect its overall performance. In fact, concentrate recycling would increase the recovery rate of ultrafiltration membranes and reduce losses during water treatment. Similar observations were obtained in pilot-scale operations, that validated the in-line dose on a more representative system that is closer to the full-scale treatment process.

Exploring the application of the hybrid nano-bioreactor technology based on the developed polyethersulfone mixed-matrix membrane for industrial effluent treatment

Due to the high concentration of various contaminants in the paper mill effluent, it must undergo an efficient treatment process before being discharged to the environment or being reused in the production cycle. In the present study, the submerged membrane adsorption bioreactor (SMABR) system was used for the treatment of the paper mill effluent. The modified polyethersulfone PES/MoS2 membrane was fabricated by incorporating exfoliated MoS2 nanosheets prepared in the laboratory, into the PES matrix. This membrane along with the powdered activated carbon (PAC) were utilized in the SMABR system for the paper mill effluent treatment. After the acclimation of the sludge with the target effluent, the optimum values of food to microorganism (F/M), hydraulic retention time (HRT), and adsorbent dosage were determined separately to be 0.451, 18 h, and 3 g/L by considering the maximum values of chemical oxygen demand (COD) removal and mixed liquor suspended solid MLSS concentration in each stage. In the final stage, the MBR and SMABR systems (using the pristine and modified membranes, separately) were prepared to separately investigate the effect of the presence of the PAC adsorbent and modified membrane, on the output parameters. In all systems, the values of pH and dissolved oxygen (DO) were maintained in the normal range (pH: 6.2–6.7, DO>2) to provide favorable conditions for the growth of microorganisms. Most importantly, best performance in this study was related to the SMABR system consisting the PES/MoS2 membrane and PAC adsorbent, with the highest values of COD removal (96%), MLSS concentration (15620 mg/L), and membrane permeation flux (110 L/m2.h). It is worth mentioning that the functionalized membrane exhibited better hydrophilicity compared with the pristine membrane, resulting in high water permeation flux, which is in accordance with the performance results.

Solusi Persamaan Difusi Neutron Pada PWR (Pressurized Water Reactor) Berbentuk Heksagonal dengan Bahan Bakar Uranium Daur Ulang

The Research on solution of the neutron diffusion equation with a PWR reactor using recycled uranium fuel at 1⁄6 section of the reactor core with a hexagonal IGT-6 geometry. The purpose of this research is to determine the distribution of the neutron flux in the PWR of recycled uranium fuel. The solution is done by computational simulation using the Dev-C++ programming. The parameters used in this study determine the specifications of the reactor core, determine the volume fraction, determine the atomic density, calculate the macroscopic cross-section with the PIJ module, calculate the neutron diffusion equation, calculate ϕ (x,y) using the Gauss Seidel method. The results obtained in this study are the neutron diffusion equation without a source obtaining the highest relative neutron flux value in group 1 of 4,5729×〖10〗^(-2), with a fission source obtaining the highest relative neutron flux value in group 3 of 7,3327×〖10〗^(-4), with fission and scattering sources obtaining the highest relative neutron flux value found in group 2 of 1,5157×〖10〗^(-3), and 3,200 MW of power is added to the source fission, the value of the neutron flux does not change. This is because the addition of power does not affect the value of the neutron flux.

Experimental and numerical investigation of pool boiling heat transfer from finned surfaces

An experimental study of the pool boiling process on three test surfaces, namely, Plain surface, Rectangular finned surface, and Trapezoidal finned surface, was carried out using distilled water as the working fluid at atmospheric pressure. A parametric study of finned surfaces was performed to understand the effect of fin spacing and fin height on the pool boiling performance. A high-speed camera was employed to capture the pool boiling process. A numerical investigation was also performed using the Eulerian multiphase model associated with the RPI wall boiling model. A 2-D rectangular boiling chamber filled with distilled water was considered for the numerical study. The numerical results with default models were validated with the experimental results. A correction was proposed for the Bubble Waiting Time coefficient (Cw) of the quenching heat flux to improve the numerical results. Experimental results showed that using rectangular and trapezoidal finned surfaces improved the heat flux values by 52.3% and 101.5%, respectively, compared to the plain surface. The heat transfer coefficient (HTC) depends upon the area availability and type of boiling surface used. Increasing the height of the fins was beneficial, whereas increasing the fin spacing adversely affected the fin performance.

Effects of the Applied Potential on the Performance of Polysulfone Membranes Functionalized with Sulfonated Polyether Ether Ketone Polymers.

The global water crisis growth has led to a tremendous increase in membrane technology research. Membranes are favored over many other technologies for water treatment because, in principle, they require no chemical additives and can be used isothermally at low temperatures. Membranes that can reject contaminants and salts, produce adequate permeate flux values, and require minimal cleaning are highly demanded. However, most synthesized membranes on the market have associated problems, such as membrane fouling; inverse relationships between flux and solute rejection; and the high cost of synthesis, operation, and maintenance. Therefore, there is a continuied need to produce membranes with properties that make them able to sustain flux and selectivity over time. This research study focused on increasing the surface charge and hydrophilicity of polysulfone (PSf) membranes by incorporating sulfonate-functionalized poly-ether-ether-ketone (SPEEK) into PSf/N-Methyl-2-pyrrolidone (PSf/NMP) membranes. The sulfonation of the PEEK provided a net increase in negative charge on the surface of the membranes that enabled charge repulsion to take place, thus increasing the rejection of ions. In this project, the effect of the applied potential on the performance of SPEEK: PSf/NMP membranes was evaluated. The characterization of the as-synthesized membranes was carried out using the surface's structure and morphology, contact angle, and zeta potential. Furthermore, a voltage of 1.5 V was applied to the membranes in the presence of various salts (sodium chloride, calcium chloride, and potassium chloride salts) to evaluate the effects of the applied potential on solute rejection. It was found that both the permeability and the selectivity of the membranes increased when the voltage was applied. The obtained results indicate that incorporating SPEEK into PSf/NMP membranes increased the hydrophilicity of the membranes, and under the applied voltage, the incorporation allowed it to function as an electrodialysis process that is capable of removing ions from water bodies by utilizing the charge repulsion of ions.

Gas storage of peat in autumn and early winter in permafrost peatland

The carbon (C) balance of permafrost peatlands in autumn and winter, which affects the annual C budget estimation, has become a hotspot of studies on peatlands C cycle. This study combined the static chamber method, in situ soil profile measurements, and incubation experiments to investigate release and storage of C during autumn and early winter in a permafrost peatland in the Da Xing'an Mountains, Northeast China. Our results showed that the peak values of CH4 fluxes (30 August 2016) lagged behind those of CO2 fluxes (24 July 2016). At the onset of soil freezing, CH4 fluxes slightly increased, while CO2 fluxes decreased. During soil freezing in autumn, gases were found to be mainly stored in the soil as dissolved CH4 and CO2 and dissolved C concentrations (CH4, CO2, and DOC (dissolved organic carbon)) increased with depth. DOC concentrations were closely related to dissolved C gases, implying that the stored dissolved C gases might be derived from DOC decomposition. The CO2: CH4 ratio decreased sharply from the freezing of the surface layer to the total freezing of the soil, indicating larger CH4 storage in totally frozen soil. The incubation experiments also showed larger CH4 storage in the frozen soils and the stored C gases could influence the assessment of C emissions during thawing. These findings have important implications for clarifying the gas storage of permafrost peatland in autumn and early winter. The results may also clarify the key link of C emissions between the growing season and the nongrowing season.

Device‐Scale Nanochannel Evaporator for High Heat Flux Dissipation

AbstractHigh heat flux values in thin film evaporation experiments are typically attained based on short wicking distance, ranging from tens to hundreds of micrometers between the meniscus and the liquid reservoir, thus making such devices vulnerable to quick drying out while also limiting their real‐world applicability. Here, the performance of a nanochannel (122 nm depth and 10 µm width) based evaporator with FC72 is demonstrated as working fluid. FC72 is an ideal fluid for electronics cooling as it is nonpolar and dielectric with a low boiling point. The 1 mm thick evaporator consists of more than 1000 nanochannels connecting two micro‐reservoirs 4.8 cm apart. Thin film evaporation experiments are conducted for four different power inputs, and the steady‐state wicking distance varied from 21 to 8 mm depending on the evaporator's working temperature. Direct weight measurement of evaporated FC72 is used to estimate the interfacial evaporative heat flux. Such a technique mitigates the need for contact angle measurement in micro/nano confined space, a methodology commonly used in literature studies that is prone to error and uncertainties. The maximum evaporative heat flux is 0.93 kW cm−2 at ≈65 °C hot spot temperature. Interestingly, the product of wicking distance and evaporative heat flux remain constant for all power inputs. Numerical simulations are performed to quantify heat loss and effectiveness of the evaporator.

Exploration of the performance of iron-based superhydrophilic meshes for oil-water separation

This study investigates the oil-water separation capability of iron-based superhydrophilic meshes. It also intends to provide an optimistic view of their potential for industrial application. Oil-water separation performance of the 150 mesh, 300 mesh, and 400 mesh is primarily examined by analyzing the efficiency and speediness of separation as well as the limit of oil intrusion using petroleum based oils. The superhydrophilic meshes are further applied for oil-water separation of locomotive wash effluent. The superhydrophilic meshes showed good oil-water separation behavior. The 300 mesh is observed to have superior separation performance. It is also tested to have good reusability and resistance in harsh conditions. The separation effectiveness of 94.7%, reduced turbidity of 21.8 NTU, and chemical oxygen demand of around 70 ppm, along with reasonable flux and intrusion pressure values of 73.28 Lm−2min−1 and 0.848 kPa, respectively, are noticed for the separation study conducted for locomotive wash effluent using the designated superhydrophilic mesh. This study hence as well demonstrates a prospective future of superhydrophilic mesh for practical utility.