Estimation Of Film Thickness Research Articles

Chemical engineering perspective of pyrolysis reactor and condenser system for biomass valorisation

The manuscript investigates the design, operating, and economic parameters of components in a biomass pyrolysis system. It covers two key components, the pyrolysis reactor and condenser, with plans to discuss other components in future publications. The study relies on experimental data from a fixed-bed reactor, bio-oil retention experiments using various vials, and computational modeling of the pyrolysis process using a lumped model. The experimental data were thoroughly analysed, considering different types of pyrolysis reactors and heating methods. Dimensionless numbers were employed to predict the impact of changing feed characteristics during pyrolysis. The second part of the study focuses on the operation of conventional condensers and how Bio-oil deposition on their surfaces affects efficiency and cost. Experimental estimation of Bio-oil film thickness on stainless steel and glass surfaces is presented, along with its effects. Finally, a hybrid condenser, combining stainless steel with a glass lining, is proposed to enhance efficiency and reduce costs based on operational requirements.

Application of x-ray energy dispersive spectroscopy to analyzing the thickness of diamond-like carbon film deposited on the surface of microparticles.

Depositing diamond-like carbon (DLC) film is considered to be more promising for surface modification of microparticles. The development of reliable and precise measurement techniques for DLC coatings on microparticles is crucial for advancing research in this field. This paper introduces a methodological approach for quantifying the thickness of the film on microparticles. The thickness of the film is obtained by establishing the quantitative relationship between the energy lost when electrons pass through the film and the thickness of the film. The proposed method allows for the estimation of film thickness by assessing solely the elemental abundance on the particle surfaces.

Numerical Study on the Impact Pressure of Droplets on Wind Turbine Blades Using a Whirling Arm Rain Erosion Tester

The leading-edge erosion of a wind turbine blade was tested using a whirling arm rain erosion tester, whose rotation rate is considerably higher than that of a full-scale wind turbine owing to the scale effect. In this study, we assessed the impact pressure of droplets on a wet surface of wind turbine blades using numerical simulation of liquid droplet impact by solving the Navier–Stokes equations combined with the volume-of-fluid method. This was conducted in combination with an estimation of liquid film thickness on the rotating blade using an approximate solution of Navier–Stokes equations considering the centrifugal and Coriolis forces. Our study revealed that the impact pressure on the rain erosion tester exceeded that on the wind turbine blade, attributed to the thinner liquid film on the rain erosion tester than on the wind turbine blade caused by the influence of centrifugal and Coriolis forces. This indicates the importance of correcting the influence of liquid-film thickness in estimating the impact velocity of droplets on the wind turbine blade. Furthermore, we demonstrated the correction procedure when estimating the impact velocity of droplets on the wind turbine blade.

Electrical Impedance Spectroscopy for Precise Film Thickness Assessment in Line Contacts

In this article, we focus on utilising electrical impedance spectroscopy (EIS) for the assessment of global and contact impedances in roller bearings. Our primary objective is to establish a quantitative prediction of lubricant film thickness in elasto-hydrodynamic lubrication (EHL) and investigate the impedance transition from ohmic to capacitive behaviour as the system shifts from boundary lubrication to EHL. To achieve this, we conduct measurements of electrical impedance, bearing and oil temperature, and frictional torque in a cylindrical roller thrust bearing (CRTB) subjected to pure axial loading across various rotational speeds and supply oil temperatures. The measured impedance data is analysed and translated into a quantitative measure of lubricant film thickness within the contacts using the impedance-based and capacitance-based methods. For EHL, we observe that the measured capacitance of the EHL contact deviates from the theoretical value based on a Hertzian contact shape by a factor ranging from 3 to 11, depending on rotational speed, load, and temperature. The translation of complex impedance values to film thickness, employing the impedance and capacitance method, is then compared with the analytically estimated film thickness using the Moes correlation, corrected for inlet shear heating effects. This comparison demonstrates a robust agreement within 2% for EHL film thickness measurement. Monitoring the bearing resistance and capacitance via EIS across rotational speeds clearly shows the transition from boundary to mixed lubrication as well as the transition from mixed lubrication to EHL. Finally, we have observed that monitoring the electrical impedance appears to have the potential to perform the run-in of bearings in a controlled way.

Interfacial Dynamics Around a Swirling Roller in the Presence of Oppositely Imposed Horizontal Crossflows

Abstract The behavior of interfacial dynamics around a swirling circular drum is reported in the presence of horizontal crossflows of gaseous phase. A constant submergence ratio of the rotary drum is considered throughout this work. Forward and reverse crossflows are defined based on the direction of rotation of drum. A clockwise rotation is imposed on the drum and the rotation direction remains fixed throughout the present investigation. The pattern of film flow and cusp entrainment is observed thoroughly by considering rotational speed (ω) and strength of crossflow as influencing parameters. Strength of crossflow of gaseous phase is calibrated using flow Reynolds number based on roller diameter (Reflow=ρgUD/μg). Subsequently, we characterized the coated film thickness (h*=h/D) and cusp width (H*=H/D) by varying ω and Reflow. Furthermore, efforts are made to observe the influence of gravitational pull (calibrated using Archimedes number, Ar) and viscous drag (determined using Morton number, Mo) on interfacial morphology. The interfacial structures respond more to the rotational inertia compared to crossflow with the continuous increase of Mo. Again, the trailing end of cusp gets widened for the case of forward crossflow, whereas the cusp growth is obstructed in the presence of reverse crossflow, which is visualized using velocity vectors. We have also predicted appropriate correlations for film thickness (h*), cusp width (H*), and steady cusp length (θs*) in the presence of forward as well as reverse crossflow of air stream. Lastly, a theoretical framework is also developed to estimate film thickness and cusp width for both cases of crossflows and this framework agrees well with the simulated predictions.

Toward the truth of condensing-water membrane for efficient biogas purification: Experimental and modeling analyses

Facilitated transport membranes with high CO2/CH4 separation performance under humidified state have shown great prospects for biogas purification. The role of water might include the formation of condensed water film on membrane surface, but it was seldom verified and investigated. In this study, the condensation of water film on polyamide (PA) thin-film composite membrane was performed and regulated. Thanks to the absence of active carrier groups that can reversibly with CO2, the contribution of water to facilitated transport can be neglected, and the truth of condensing-water membrane was allowed to be explored. The PA layer was fabricated by interfacial polymerization with its hydrophilicity tuned by polyvinyl alcohol. The regulation of water film is based on three operational approaches: simple humidifying the feed gas, pre-wetting the membrane, or heating the humidifier. The remarkable increment of selectivity along with the improvement of water-condensing conditions implied the formation of condensed water film. Fortunately, the series of gas permeation data allowed the estimation of water film thickness according to the mass transfer resistance model for multilayer composite membranes. The decline of selectivity over time under elevated pressure was found effective to evaluate the stability of such condensing water membranes. The results show that a polyamide thin-film composite membrane with poor CO2/CH4 selectivity under dry state can achieve rather high performance (CO2 permeance 374 GPU and CO2/CH4 selectivity 31 for 16 days under 3.25 bar) with the aid of a simple condensed water layer. Hopefully, it provides a method to re-evaluate the effect of water on a given facilitated transport membrane, and possibilities of further enhancing its separation performance by fine tuning the condensed water film.

Machine learning approach to thickness prediction fromin situspectroscopic ellipsometry data for atomic layer deposition processes

A machine learning approach is applied to estimate film thickness from in situ spectroscopic ellipsometry data. Using the atomic layer deposition of ZnO as a model process, the ellipsometry spectra obtained contains polarization data (Ψ, Δ) as a function of wavelength. Within this dataset, 95% is used for training the machine learning algorithm, and 5% is used for thickness prediction. Five algorithms—logistic regression, support vector machine, decision tree, random forest, and k-nearest neighbors—are tested. Out of these, the k-nearest neighbor performs the best with an average thickness prediction accuracy of 88.7% to within ±1.5 nm. The prediction accuracy is found to be a function of ZnO thickness and degrades as the thickness increases. The average prediction accuracy to within ±1.5 nm remains remarkably robust even after 90% of the (Ψ, Δ) are randomly eliminated. Finally, by considering (Ψ, Δ) in a limited spectral range (271–741 nm), prediction accuracies approaching that obtained from the analysis of full spectra (271–1688 nm) can be realized. These results highlight the ability of machine learning algorithms, specifically the k-nearest neighbor, to successfully train and predict thickness from spectroscopic ellipsometry data.

A novel interferometric method for simultaneous measurement of film thickness and film interface temperature for a horizontal tube falling film evaporator for MED systems

Horizontal tube falling film evaporation spans a lot of applications, especially in multi-effect desalination application. Hence, the improvement of its gain output ratio is of prime importance, and for that, the studies on the characteristics associated with the flow, mainly falling film thickness and falling film interface temperature, are inevitable. As the falling film flow is a delicate fluid structure, non-intrusive measurement techniques have to be preferred for the experiment. In this work, we introduce a novel interferometric method to calculate film interface temperature and a shadowgraph approach to estimate film thickness simultaneously. A Mach-Zehnder interferometer with infinite fringe setting was used to capture the thermal fluctuations around the horizontal tube falling film evaporator. Interferometric method implemented in this work also serves as an image visualization technique and does the purpose of qualitative as well as quantitative analysis. An in house designed experimental setup was fabricated for producing a thin and uniform falling film with a fully wetted flow over the horizontal copper tube. A heater controller setup was incorporated into it for accurate temperature control. This method holds the advantage of scanning falling film thickness over circumferential angle for the range 5∘≤θ≤175∘, which is an improvement to state of the art. Furthermore, dynamic film thickness and instantaneous film interface temperature studies were also incorporated to prove the efficacy of the technique and to test the robustness of the algorithms implemented. CFD analysis was also carried out for the entire process by means of VOF scheme and was found to be in good agreement with the experimental results, which proves our technique to be a good one. A standard error of mean analysis was performed on every data set, which validates the reproducibility and the dynamic measurement capability of the technique used.

Comparison of the protective efficiency of polymethacrylates with different side chain length for AA2024 alloy

The protective properties of polymethacrylate coatings with different side chain lengths for 2024 aluminum alloys were studied, focusing on the chain length increase but also on the Ar-plasma pretreatment applied to the metal surface. The coatings were obtained by photopolymerization, obtaining reproducible molecular weight polymers during each process that were determined by high-performance liquid chromatography. AA2024 alloy were immersed into the polymethacrylate solution using methyl, butyl, and hexyl as monomers. Their roughness was then evaluated using atomic force microscopy. Surface hydrophobicity and contact angle hysteresis were analyzed in water and diiodomethane. Protective properties were evaluated by electrochemical impedance spectroscopy after 56 days of immersion in a 0.1 M Na2SO4. The alloy cross-sections were examined by field emission scanning electron microscopy and glow discharge optical emission spectroscopy, allowing the estimation of film thickness. Surface analysis revealed that the defect population densities in the coatings increased the monomer alkyl chain length. The immersion thickness increase was consistent with contact angle measurements taken over time, and independent from the chain length. Contradicting expectations, the results showed the protective efficacy was not related to the chain length, since after exposure, the PBMA film revealed the best anti-corrosive coating performance on the AA2024. This was possibly influenced by its polymeric film conformation, hydrophilicity, ordering and lower density of defects on the metal surface.

Applications of vibro-acoustic measurement and analysis in conjunction with tribological parameters to assess surface fatigue wear developed in the roller-bearing system

Rolling-element bearings are the most commonly used components in all rotating machinery. The variations in the operating conditions such as an increase in the number of operating cycles, load, speed, service temperature, and lubricant degradation result in the development of various defects such as pitting, spalling, scuffing, scoring, etc. The defects that appeared on rolling contact surfaces cause surface deterioration and change in the vibration and sound levels of the bearing system. The present experimental investigations are aimed at assessing the surface fatigue wear that appears on the contact surfaces of roller bearings. The studies considered the estimation of specific film thickness, analysis of surface fatigue wear developed on the rolling-element surfaces, surface roughness analysis, grease degradation analysis using Fourier transform infrared radiation, and vibration and sound signal measurement and analysis. The results obtained from the experimental investigation provide a good correlation between surface wear, vibration, and sound signals with a transition in the lubrication regimes in the Stribeck curve.

Morphological, Structural, and Optical Bandgap Characterization of Extracted ZnO Nanoparticles from Commercial Paste

ZnO nanoparticles (NPs) were extracted from a commercial paste in both colloidal and precipitate forms. The Zetasizer analysis performed on the colloid showed ZnO NPs ranging from ∼30 nm to ∼100 nm. Thin films of ZnO were deposited on glass substrates by spin‐coating technique from a mixture of the extracted colloid and precipitate. The scanning electron microscope (SEM) images showed uniformly arranged, mesoporous, and nanostructured ZnO particles of different shapes, with an estimated film thickness of 0.67 μm. Analysis by energy dispersive X‐ray spectroscopy (EDS) and X‐ray diffraction analysis (XRD) confirmed the presence of ZnO in the films, with no impurities or remnants of other materials. The XRD analysis showed a polycrystalline nature of the films and identified a pure phase formation of the hexagonal wurtzite structure. The average crystallite size calculated from the diffraction peaks is ∼43.25 nm. The calculated crystal tensile strain is 1.954 × 10−3, which increases the crystal volume by 0.728% compared with the crystal volume of standard ZnO. The calculated crystal parameters are a = b = 3.258 Å and c = 5.217 Å. The calculated dislocation density (d) and bond length Zn–O (L) are 5.35 × 10−4 nm−2 and 2.695 Å, respectively. Ultraviolet‐visible absorption spectra showed an optical band gap of ∼3.80 eV.

Multibody Simulation for Gravity-Driven Falling Film Using Computational Fluid Dynamics

The annular flow two-phase regime appears in nuclear power plants cooling by water. On accidents with lost of cooling this regime determine the heat extraction conditions from the core. The experimental facility Gerador de Película Ondulatoria (GEPELON) was constructed at Universitat Politècnica de València to study this phenomenon. In this work, we use computational fluid dynamics techniques to simulate an air-water regime, specifically a gravity-driven falling liquid film in the GEPELON experimental facility. We consider a multibody geometry where the porous sintered of the input device is simulated in a realistic way. The Volume of Fluid (VOF) model was used in the resolution of the constitutive equations. We propose three geometric approximations to estimate film thickness, and simulation results were compared with experimental values. The simulation results show a good agreement with experimental measurements. Besides, no significant differences were observed between geometrical approximations for film thickness calculations.

FULL-SCALE STUDIES OF FLUORESCENCE FEATURES OF SURFACTANT FILMS ON EUTROPHIC WATER WAVY SURFACE

The current paper presents the results of a full-scale study of the fluorescence features of pollutants ( diesel fuel, Urals oil), as well as an alcoholic solution of oleic acid, which imitates oil by visco-elastic characteristics. The experiment was carried out on the Gorky Reservoir under conditions of wind waves. Local areas of artificial slicks were created for multiple intersections at different angles to the wind and waves with continuous lidar sounding of the upper water layer. Signals were recorded by the ninth generation UVL-9 laser ultraviolet fluorescent lidar developed by the Institute of Oceanology of the Russian Academy of Sciences. At signal analysis, spectral intensities and fluorescence features of the studied substances are determined, possibilities of slick detecting as well as film thickness estimation are made, examples of surfactant film detecting behind the oleic slick where visual observation of pollutants does not give a result are showed. The obtained results are useful for the further development of fluorescent methods and devices for operational remote sensing of surface pollution on wave water surface.

Study of Quartz Crystal Microbalance Behavior with Viscous Sensing Film

Introduction In odor sensing based upon QCM[1] sensing film is crucial for both sensor sensitivity and selectivity. The viscoelastic property of the sensing film greatly influences the response of the QCM sensor. The shear wave generated from QCM cannot penetrate deeply into the viscous sensing film. However, many appropriate sensing films with interesting properties are viscous. We would like to understand the behavior of the viscous sensing film although the behavior of the rigid sensing film is well understood. Method A QCM has an equivalent circuit derived from Mason equivalent circuit[2] as shown in fig. 1. Equations (1) and (2) indicate the acoustic impedance (Z3e) due to acoustic loading as a function of film thickness (h) film density (ρA1) and complex wave velocity (νA1). To extract QCM equivalent circuit component, we used a network analyzer to measure conductance from a QCM. Then, we apply the curve fitting technique to extract R1, L1, and C1 from the conductance curve[3]. This technique was used instead of a conventional motional admittance method (measure the frequency of maximum conductance). Because all the data were used for fitting the curve, this method is more robust and less susceptible to noise than conventional motional admittance method.The dip-coating technique was used for coating viscous film on QCM (9MHz, AT-cut). The QCMs were immersed into glycerol solution and then pulled-up with various speeds, which results in different film thicknesses. Results and Conclusions To replicate odor deposition into sensing film. We were using a small-size dispenser to deposit droplets of liquid onto QCM. Water droplet was shot onto the glycerol film as on a QCM. The preliminary result is shown in fig.2. The frequency was increased after each vapor exposure, whereas the resistance was decreased, we sometimes encountered increase in frequency due to vapor exposure at the highly viscous environment. We tried to understand its mechanism using the following analysis.The study was firstly done with liquid loading which represents viscous film. Only a singles side of QCM should be in contact with liquid. We calculated resonance frequency shift and resistance change as a function of water film thickness as is shown in fig. 3. Our calculation result based upon Mason equivalent circuit roughly agreed with both Kanazawa’s equation[4] and the experiment when the film thickness became large.To estimate film thickness and dynamic viscosity of the film, Mason equivalent circuit was used. The optimization was performed to obtain the dynamic viscosity and film thickness using the experimental data obtained from various film thicknesses. Fig. 4 shows the experimental data points at estimated film thickness and calculated curve. The simulation of Mason circuit shows good agreement with experimental data. Moreover, the simulation result also suggests that the frequency increase occurs due to liquid loading at a certain condition.We will perform the experiment on depositing tiny liquid droplets into sensing film before the conference.

小型高光谱图谱仪与激光雷达及其海洋应用

Ocean is an important part of the earth's ecological environment. Exploration and exploitation of marine resources may easily cause serious damage to ocean, such as large-scale oil spill, pollution and red tide caused by oil and gas exploitation. Hyperspectral imaging technology can obtain both image information and spectral information at the same time, and has important applications in marine in-situ detection. In this paper, some recent works about hyperspectral imagers are reviewed, including a small-scale hyperspectral imager combined with fluorescence technology for the classification of oil spills and the estimation of oil film thickness, a multi-mode hyperspectral marine in-situ detection system (in three modes:common reflection or transmission imaging, telescopic imaging and microscopic imaging) for hyperspectral detection of different algae and spores of some fish infectious disease carriers. Hyperspectral technology combined with lidar technology has great potential in monitoring oil spill, red tide and other marine pollutants. An inelastic hyperspectral Scheimpflug lidar system and a ligh-sheet Scheimpflug lidar system are also reviewed. The former is for the type identification of oil spills through the fluorescence spectrum of oil spills, and the latter is for the detection of the 3D shapes of some manikin, shells and corals with the refraction correction at the air-water interface.

Lubrication characteristics and wear mechanism mapping for hybrid aluminium metal matrix composite sliding under surfactant functionalized MWCNT-oil

The friction-wear response of surfactant functionalized MWCNT-in-oil suspension under hybrid aluminium metal matrix composite/EN31 contact is presented. Composites were fabricated, characterized and tribological tests were performed with a pin-on-disc tribometer. Prior to tribological testing, thermophysical and stability analysis of the prepared lubricants were carried out. The operating regimes of the lubricants were predicted based on the estimated film thickness and friction responses. It is observed that the film thickness ratio for surfactant-MWCNT-oil is increased by 47% which helped in the shifting of lubrication towards the mixed regime. The findings of the study reveals that there is a remarkable enhancement in tribological behavior when surfactant functionalized MWCNT-in-oil is used. Finally, a wear map of the underlying wear mechanisms is also presented.

Fabrication and estimation of optical constants of hydrophobic Ta2O5 thin films

Present study investigates the optical properties and film thickness estimation of tantalum oxide (Ta2O5) thin films of various thicknesses, deposited by physical evaporation technique. The optical constants and thickness of deposited films were estimated by using envelope method. The thickness value obtained from this method has been compared with in-situ (quartz crystal thickness monitor) as well as Ex-situ (Coherence Correlation Interferometry) thickness estimation techniques. Refractive index calculated by envelope method was also validated using Reflectometer. These thickness values were used for the estimation of other optical constants such as refractive index, absorption and extinction coefficients. Contact angle measurement studies are also performed on uncoated as well as Ta2O5 coated glass substrates, which indicate the hydrophobic nature of these films.

The Role of Grease Composition and Rheology in Elastohydrodynamic Lubrication

Grease lubrication is inherently complicated due to its non-Newtonian flow dynamics. The flow behavior of grease is difficult to determine under tribological shear rates as these shear rates are often extremely high, and therefore, are not accessible on a regular rheometer. In this work, we demonstrate the use of shear rate-concentration superposition method to extrapolate the data measured with a rheometer to tribologically relevant shear rates. This method is similar to the other superposition methods routinely employed by rheologists for predicting flow behavior beyond the measurement range of rheometer. In this method, a data master curve, which extends over a broad range of shear rates, is constructed by superposing individual flow curves for greases with different thickener concentrations. The master curve is utilized to determine infinite shear viscosity of grease which is then used for the film thickness estimation. Furthermore, the grease samples are tribologically tested using a four-ball tester to identify the individual and interactive roles of the thickener type, concentration and base oil in lubrication behavior. A change in thickener concentration or type influences frictional torque and wear scar size through modification in infinite shear viscosity and structural stability of grease. The SEM images show deposition of thickener particles on the contact surface, which also apparently affect friction and wear during the test. The lubrication performance is strongly influenced by base oil, which points towards the importance of its role in dictating flow resistance and film-forming behavior of grease inside elastohydrodynamic contact.

Numerical Study of Power Loss and Lubrication of Connecting Rod Big-End

A hydrodynamic lubrication analysis for connecting rod big-end bearing is conducted. The effects of engine speed, operating condition, lubricant viscosity and oil temperature on tribological performance of big-end bearing have been examined. Force equilibrium is solved to define instantaneous eccentricity between journal and bearing to have accurate estimation of oil film thickness at interface of connecting rod big-end bearing and crankpin. Connecting rod big-end is treated as π film hydrodynamic journal bearing and finite difference scheme is applied to calculate generated hydrodynamic pressure and frictional power loss at each crank angle. Beside the development of analytical formulation, well-known Mobility model introduced by Booker has been employed to be compared with the analytical model. The presented analytical model reduces the complexity and the numerical effort with respect to Mobility method, thus shortening the computation time. The simulation results show good agreement between analytical model, Mobility approach and experimental data.

Film Thickness and Shape Evaluation in a Cam-Follower Line Contact with Digital Image Processing

Film thickness is the most important parameter of a lubricated contact. Its evaluation in a cam-follower contact is not easy due to the continuous variations of speed, load and geometry during the camshaft rotation. In this work, experimental apparatus with a system for film thickness and shape estimation using optical interferometry, is described. The basic principles of the interferometric techniques and the color spaces used to describe the color components of the fringes of the interference images are reported. Programs for calibration and image analysis, previously developed for point contacts, have been improved and specifically modified for line contacts. The essential steps of the calibration procedure are illustrated. Some experimental interference images obtained with both Hertzian and elastohydrodynamic lubricated cam-follower line contacts are analyzed. The results show program is capable of being used in very different conditions. The methodology developed seems to be promising for a quasi-automatic analysis of large numbers of interference images recorded during camshaft rotation.