Liner Surface Research Articles

Temperature Rise on Liner Surfaces of Fuel Cell Electric Vehicle Tanks during Fueling Process

Herein, the temperature of the inner tank walls, or plastic liners, of composite pressure tanks in fuel cell electric vehicles during fueling using three‐dimensional computational fluid dynamics (CFD) models is evaluated. The liner materials are limited to 85.0 °C to prevent thermal stress causing material failure that would result in a hydrogen leak. Therefore, the temperature of hydrogen gas must be limited to below 85.0 °C during the fueling process as dictated by the current fueling protocol. However, there are limited experimental or simulation data confirming that the temperature changes do not exceed the threshold. Herein, the liner temperatures with CFD tank models for two sizes of type IV tanks representative of the upper and lower system bounds that are close to the SAE J2601 fueling protocol (36.0 and 244.0 L) are evaluated. First, each model's reliability is validated with experimental data and then analyzed, and the data are used to evaluate the maximum hydrogen and liner temperatures under real‐world fueling conditions. The evaluation shows that the maximum liner surface temperature of each tank model is at least 7 °C lower than that of the hydrogen. Additionally, there is at least 12 °C difference found between the upper limit and actual liner temperatures.

Effect of Ionic Liquids on Mechanical, Physical, and Antifungal Properties and Biocompatibility of a Soft Denture Lining Material.

This study aims to evaluate the effect of ionic liquids and their structure on the mechanical (tensile bond strength (TBS) and Shore A hardness), mass change, and antifungal properties of soft denture lining material. Butyl pyridinium chloride (BPCL) and octyl pyridinium chloride (OPCL) were synthesized, characterized, and mixed in concentrations ranging from 0.65-10% w/w with a soft denture liner (Molloplast-B) and were divided into seven groups (C, BPCL1-3, and OPCL1-3). The TBS of bar-shaped specimens was calculated on a Universal Testing Machine. For Shore A hardness, disc-shaped specimens were analyzed using a durometer. The mass change (%) of specimens was calculated by the weight loss method. The antifungal potential of ionic liquids and test specimens was measured using agar well and disc diffusion methods (p ≤ 0.05). The alamarBlue assay was performed to assess the biocompatibility of the samples. The mean TBS values of Molloplast-B samples were significantly lower (p ≤ 0.05) for all groups except for OPCL1. Compared with the control, the mean shore A hardness values were significantly higher (p ≤ 0.05) for samples in groups BPCL 2 and 3. After 6 weeks, the OPCL samples showed a significantly lower (p ≤ 0.05) mass change as compared to the control. Agar well diffusion methods demonstrated a maximum zone of inhibition for 2.5% OPCL (20.5 ± 0.05 mm) after 24 h. Disc diffusion methods showed no zones of inhibition. The biocompatibility of the ionic liquid-modified sample was comparable to that of the control. The addition of ionic liquids in Molloplast-B improved the liner's surface texture, increased its hardness, and decreased its % mass change and tensile strength. Ionic liquids exhibited potent antifungal activity.

Experimental and Numerical Study on the Combined Jet Impingement and Film Cooling of an Aero-Engine Afterburner Section

The recent advancement of cooling methodologies for critical components such as turbine blades, combustor liners, and afterburner liners has led to the development of a combination of impingement and film cooling. The present study proposes an efficient cooling technique for a modern aero-engine afterburner liner based on the combination of jet impingement and film cooling. To achieve this, a numerical model is devised to model the film flow over a corrugated liner with several jets impinging over it. The numerical model is validated in a set of in-house experiments as well as against experimental data available in the literature. The experiment is performed for a limited temperature range (i.e., with a low-density ratio). However, the numerical simulations are carried out by varying the blowing ratio from 0.3 to 0.6. The density ratio during the simulations is kept at 3.5. The minimum distance between the impinging plate and the liner is kept at h/D = 1. A detailed analysis of the numerical results indicates a significant drop in the temperature distribution over the liner surface because of the employed cooling technique. The present study also reveals that, under similar operating conditions, the combined jet impingement and film cooling system has the ability to achieve the targeted cooling effect at a lower bleed air flow rate due to its higher effectiveness than that of the standard film cooling arrangement.

Adsorption of Heavy Metals from Contaminated Water using Leachate Modular Tower

The heavy metals (HMs) and metalloids such as Cr(VI), As(Ill), and Pb(II) in contaminated water are toxic even at trace levels and have caused devastating negative health impacts on human beings. Hence, the effective adsorption of these heavy metals from contaminated water is important to protect biodiversity, hydrosphere ecosystems, and human beings. In this study, a leachate modular tower (LMT) was developed for the singular purpose of adsorbing HMs. The LMT contained nano-slag as a liner, which was synthesized from slag. The nano-slag was blended in different proportions of 90:10; 80:20, 70:30, 60:40, and 50:50 to the combined mass of clay and nano-slag, to evaluate the most efficient ratio of the blends capable of adsorbing HMs and metalloids with 100% efficiency. A series of leachate tests were performed to evaluate the adsorption capacity of LMT with different embedded liners. Attenuation periods of 2, 5, 7, and 10 days with a temperature of 500 °C were also selected to improve the sorption rate and uptake of HMs. Subsequently, the effluents were subjected to inductive coupled plasma mass spectrometry (ICP-MS) tests to evaluate the concentrations and percentages of adsorbed HMs, which were calculated using a pseudo-first-order adsorption model. The results revealed that the removal of 98%As, 99%Cd, and 99.9% Pb was achieved with a 50%:50% ratio of soil and nano-slag as the liner at 10 days equilibrium period. Furthermore, 98%Zn, 95.45%Cu, 93.3%Fe, 97%Ni, and 89% Hg were achieved upon further investigation using the same dosage of soil and nano-slag and equilibrium conditions. The scanning electron microscopy (SEM) tests demonstrated that some traces of the absorbed HMs and metalloids were found on the liner surfaces, indicating significant changes in microstructure. The results indicated the sorption rate increased significantly due to the elevated temperature, aluminosilicate structure, and prolonged attenuation period, which are also associated with an elevated pH level and higher cation exchange capacity (CEC), of the liner. Doi: 10.28991/CEJ-2023-09-06-017 Full Text: PDF

A geometric assessment method for estimating dimensional change of retrieved dual mobility liners for total hip arthroplasty.

Despite their emerging use, the current understanding of the in-vivo functional mechanisms of Dual Mobility (DM) Total Hip Replacements (THRs) is poor, and current characterisation methodologies are not suitable for the unique function and design of these types of devices. Therefore, the aim of this study was to develop a geometric characterisation methodology to estimate dimensional change across the articulating surfaces of retrieved DM polyethylene liners so that their invivo function may be better understood. The method involves the acquisition of three-dimensional coordinate data from the internal and external surfaces of DM liners. The data is processed using a bespoke MATLAB script which approximates the unworn reference geometry of each surface, calculates geometric variance at each point and produces surface deviation heatmaps so that areas of wear and/or deformation may be visualised across the implant. One as-manufactured and five retrieved DM liners were assessed, which demonstrated the efficacy, repeatability and sensitivity of the developed method. This study describes an automated and non-destructive approach for assessing retrieved DM liners of any size and from any manufacturer, which may be used in future research to improve our understanding of their in-vivo function and failure mechanisms.

A characterization method for the physical features of honed texture surface of engine cylinder liner

A machine vision method is proposed to characterize the physical features of the honed surface texture on the cylinder liner of internal combustion engines. According to the gray image information of the surface texture of the cylinder liner, the curvelet transform method is employed to extract the physical features of the multi-scale anisotropic surface topography image of the cylinder liner, and the partitioned iterated function system (PIFS) is constructed to calculate fractal dimension to describe the physical features of the surface texture of the cylinder liner. The proposed PIFS-based method is applied to the honed surface and dimple-textured surface of the cylinder liner, the effectiveness and the accuracy are verified by comparing with the other two methods.

Study on the sliding wear map of cylinder liner − piston ring based on various operating parameters

The wear map can directly reflect the wear state and mechanism of the friction pair under different conditions and is widely used in wear prediction and fault diagnosis of steel materials. However, there are few reports on the wear map of the engine cylinder liner and its materials. In this study, the operating parameters were obtained through an engine bench test. The parameters near the cylinder liner's top dead center （TDC） were selected as wear test parameters. Thousands of hours of reciprocating lubrication wear tests were carried out on a multi-function wear tester. By analyzing the wear rate variation under different test parameters, the cylinder liner's wear state was divided into mild, medium, and severe wear. The morphology of the wear scar surface and cross-section of the cylinder liner was analyzed by scanning electron microscope (SEM) and then drawing the wear mechanism map. The results show that the primary wear mechanism under slight wear is spalling wear, accompanied by the plastic deformation phenomenon. Delamination wear is the primary mechanism in the medium wear state, accompanied by a small amount of massive spalling wear. The delamination wear is mainly caused by the crack generated by graphite in or below the deformation layer. The primary wear mechanism of the severe wear state is massive spalling. At this time, the graphite at the bottom of the deformation layer plays the role of primary cracks, which causes the plastic deformation layer to fall off.

Objective-level resilience assessment of circular roadway tunnels with reinforced concrete liners for vehicle fire hazards

A framework is presented to quantify the objective-level resilience of reinforced concrete liners of circular tunnels when exposed to enclosed vehicle fire hazards. By assessing the loss of functionality due to fire-induced damage, the framework enables a decision-basis evaluation of the efficiency of various fire mitigation methods for specific tunnel conditions. In this study, the fire-induced damage of concrete tunnel liners due to strength loss and spalling is stochastically simulated and classified based on typical post-fire repair procedures and damage evaluation. The resilience assessment is conducted using Monte Carlo Simulation in combination with a fast-running tool for calculating the thermal impact from vehicle fires on the inside surface of the tunnel liner (developed by the authors in previous work). The proposed approach accounts for uncertainties associated with both the vehicle fire (particularly the combustion energy) and the tunnel conditions (i.e., geometry, dimensions, and the presence of longitudinal ventilation and/or fixed fire-fighting systems (FFFS)). A parametric case study is used to quantitatively demonstrate the effectiveness of FFFS for reducing post-fire losses of tunnel functionality. Other parameters such as tunnel dimensions, traffic restrictions for vehicles with heavy fire hazard risk, and installation or upgrade of the tunnel ventilation system show somewhat less effectiveness for reducing fire-induced damage.

Surface topography characterization using a simple optical device and artificial neural networks

State-of-the-art methods for quantifying wear in cylinder liners of large internal combustion engines for stationary power generation require disassembly and cutting of the examined liner. This is followed by laboratory-based high-resolution microscopic surface depth measurement that quantitatively evaluates wear based on bearing load curves (also known as Abbott-Firestone curves). Such reference methods are destructive, time-consuming and costly. The goal of the research presented here is to develop nondestructive yet reliable methods for quantifying the surface topography. A novel machine learning framework is proposed that allows prediction of the bearing load curves representing the depth profiles from reflection RGB images of the liner surface. These images can be collected with a simple handheld microscope. A joint deep learning approach involving two neural network modules optimizes the prediction quality of surface roughness parameters as well. The network stack is trained using a custom-built database containing 422 perfectly aligned depth profile and reflection image pairs of liner surfaces of large gas engines. The observed success of the method suggests its great potential for on-site wear assessment of engines during service.

Experimental visualization of the wear and scuffing evolution of a flake graphite cast iron cylinder liner

Scuffing is a wear mechanism that can lead to catastrophic failure of various technical applications. Even though the mechanism has been researched in countless publications for decades, it is not fully understood yet. An experimental approach was used in this paper to investigate the origin and evolution of scuffing in a ring-on-liner contact. For this purpose, test runs in an application-oriented test rig were stopped at different points in time. A linear tribometer was used to transfer a reciprocating motion of a real piston ring segment to a specimen made from a real cylinder liner. Based on a comprehensive analysis, a four-stage scuffing hypothesis for a ring-on-liner contact was developed. In the first stage, smearing of the honing structure and the formation of surface cracks lead to the development of a scaly structure on the liner surface. Crack growth induced by adhesive shear forces leads to the formation of breakouts in the liner surface in the second stage. Both stages are stable and only the specific load increase of the used test strategy causes the transition to stage three. Here, large crack growth induced breakouts result in the local destruction of tribofilms and, subsequently in local metallic contact between the specimens. When this local destruction becomes rampant and expands to a macro scale, adhesive bonds lead to macroscopic scuffing. It can be deduced that the first occurring damage stage is a result of a surface fatigue process.

Characteristics of “Dust” Fluxes from the Surface of Copper and Lead Liners Exposed to One or Two Successive Shock Waves

Comparative experimental studies of the shock-induced particle ejection (“dusting”) from the free rough (Rz20) surface of copper and lead liners exposed to one or two successive shock waves separated in time by 0.2 μs have been carried out for the first time. This situation usually occurs in cumulative systems for the compression of the plasma by cylindrical or spherical liners shock or quasi-isentropically accelerated by explosion products. Using pulsed X-ray diffraction, laser optical recording, piezoelectric pressure sensors, and heterodyne interferometry, a qualitative picture has been studied and the quantitative characteristics of particle ejection from the free surface such as the velocities of the free surface and the particle flux front and the density (mass) distribution of particle flux in the direction of its motion, which are necessary for more accurate determination of features and the development of more appropriate models of the effect, have been evaluated.

Intermediate Cluster Disinfection: Which Disinfection Solution Is Most Effective on Milking Liners? A Comparison of Microorganism Reduction on Liner Inner Surfaces Using Quantitative Swab Sampling Technique.

During machine milking, pathogenic microorganisms can be transmitted from cow to cow through liners. Therefore, in Germany, a spray method for the intermediate disinfection of the milking cluster is often used for prevention. This method of cluster disinfection is easy to perform, requires little time and no extra materials, and the disinfection solution is safe from outside contamination in the spray bottle. Since no data on a systematic efficacy trial are available, the aim of this study was to determine the microbial reduction effect of intermediate disinfection. Therefore, laboratory and field trials were conducted. In both trials, two sprays of 0.85 mL per burst of different disinfectant solutions were sprayed into the contaminated liners. For sampling, a quantitative swabbing method using a modified wet-dry swab (WDS) technique based on DIN 10113-1: 1997-07 was applied. Thus, the effectiveness of disinfectants based on Peracetic Acid, Hydrogen Peroxide and Plasma-Activated Buffered Solution (PABS) was compared. In the laboratory trial, the inner surfaces of liners were contaminated with pure cultures of Escherichia (E.) coli, Staphylococcus (S.) aureus, Streptococcus (Sc.) uberis and Sc. agalactiae. The disinfection of the contaminated liners with the disinfectants resulted in a significant reduction in bacteria with values averaging 1 log for E. coli, 0.7 log for S. aureus, 0.7 log for Sc. uberis and 0.8 log for Sc. agalactiae. The highest reduction was obtained for contamination with E. coli (1.3 log) and Sc. uberis (0.8 log) when PABS was applied and for contamination with S. aureus (1.1 log) and Sc. agalactiae (1 log) when Peracetic Acid Solution (PAS) was used. Treatment with sterile water only led to an average reduction of 0.4 log. In the field trial, after the milking of 575 cows, the liners were disinfected and the total microorganism count from the liner surface was performed. The reduction was measured against an untreated liner within the cluster. Although a reduction in microorganisms was achieved in the field trial, it was not significant. When using PAS, a log reduction of 0.3 was achieved; when using PABS, a log reduction of 0.2 was obtained. The difference between the two disinfection methods was also not significant. Treatment with sterile water only led to a reduction of 0.1 log. The results show that spray disinfection under these circumstances does result in a reduction in the bacteria on the milking liner surface, but for effective disinfection a higher reduction would be preferred.

Analysis of contact pressure in a 3D model of dual-mobility hip joint prosthesis under a gait cycle

Hip joint prostheses are used to replace hip joint function in the human body. The latest dual-mobility hip joint prosthesis has an additional component of an outer liner that acts as a cover for the liner component. Research on the contact pressure generated on the latest model of a dual-mobility hip joint prosthesis under a gait cycle has never been done before. The model is made of ultrahigh molecular weight polyethylene (UHMWPE) on the inner liner and 316L stainless steel (SS 316L) on the outer liner and acetabular cup. Simulation modeling using the finite element method is considered static loading with an implicit solver for studying the geometric parameter design of dual-mobility hip joint prostheses. In this study, simulation modeling was carried out by applying varying inclination angles of 30°, 40°, 45°, 50°, 60°, and 70° to the acetabular cup component. Three-dimensional loads were placed on femoral head reference points with variations of femoral head diameter used at 22 mm, 28 mm, and 32 mm. The results in the inner surface of the inner liner, the outer surface of the outer liner, and the inner surface of the acetabular cup showed that the variations in inclination angle do not have a major effect on the maximum contact pressure value on the liner component, where the acetabular cup with an inclination angle of 45° can reduce contact pressure more than the other studied inclination angle variations. In addition, it was found that the 22 mm diameter of the femoral head increases the contact pressure. The use of a larger diameter femoral head with an acetabular cup configuration at a 45° inclination can minimize the risk of implant failure due to wear.

Simulation of plateau-honed cylinder liner surface texture creation using superimposition approach

A novel procedure for the generation of cylinder liner surface texture during finish honing and plateau honing was presented. An idea of surface creation depends on superposition of one-process arbitrary oriented one-directional texture of Gaussian ordinate distribution on machined or modeled base surface. This iterative procedure depended on the type of honing process. In finish honing, in each iteration the vertical distance of the superimposed surface from the base surface increased in the defined step. In the plateau honing process, the mean plane of the superimposed surface was embedded at depth corresponding to the same material ratio of the base surface. The models presented were calibrated and validated by a honing experiment. The relative errors of predicting parameters Spq, Svq, Smq and Sal during plateau honing were less than 20%, in most cases they were smaller than 7%.

Effect of EVA-TiO2 composite interfacial buffer layer in improving the bond strength between PMMA denture base and PDMS liner

Polydimethylsiloxane (PDMS) is the most common dental liner that is used with acrylic dentures. A strong bond between the liner and the denture is a must, for the proper functioning and the longevity of the prosthesis. Debonding of the liner may occur due to an inefficient bond with the denture, or low cohesive strength due to wettablility/hydration and water/liquid storage-retention. The increased wettability/hydration pass on the moisture to the acrylic boundary surface causing initiation of debonding process. Hence, in order to prevent the debonding due to wettablility/hydration a novel method of introducing a hydrophobic polymer interfacial buffer layer between the acrylic denture surface and the PDMS liner surface is suggested. In, the present research work, ethylene vinylacetate (EVA) reinforced with titania (TiO2) polymer microfilm composite layer is prepared by solution casting method. The thin polymer film is placed between the acrylic denture surface and the PDMS liner surface and heat cured together to obtain a hydrophobic interfacial buffer layer. Wettability, fluid absorption and retention tests were performed to investigate the hydrophobic properties of the composite interfacial buffer layer. Mechanical strength properties on the prepared specimen (as per ISO 178) revealed that the EVA-TiO2 layer offered superior bonding and also improved the overall mechanical properties of the acrylic dentures without disturbing the mass and density of the denture.

Optimization of interfacial bonding properties between thermoplastic liners and carbon fiber‐reinforced composites by atmospheric‐pressure plasma and failure mechanism study

AbstractWeak interfacial bonding properties between thermoplastic liners and carbon fiber‐reinforced composites (CFRP) can easily lead to debonding failure, which is a major challenge in development of type IV composite hydrogen storage vessels. We optimized Box–Behnken design atmospheric‐pressure plasma process parameters for maximizing interfacial bonding properties between thermoplastic liner (PA11 liner) and CFRP using Design‐Expert software. From various designs, plasma process parameters, including time (t), nozzle‐to‐specimen distance (d) and gas flow rate (r) of treatment were selected for optimization to assess the effects of their interactions on climbing drum peel (CDP), flatwise tensile (FWT) and asymmetric double cantilever beams (ADCB). The CDP strength, FWT strength and strain energy release rate (GADCB) of untreated samples were 4.2 N·mm/mm, 0.26 MPa and 87.2 J/m2, respectively. After the plasma treatment, optimum process parameters of t = 200 s, d = 12.5 mm, and r = 700 L/h were used to achieve 33.8 N·mm/mm, 2.97 MPa and 1008.4 J/m2, respectively, which were 8.0, 11.4 and 11.6 times that of untreated PA11 surface, respectively. This method has the potential for guiding thermoplastic liner surface treatment of type IV hydrogen storage vessels before winding.

Fan Noise Reduction by Acoustic Liners Combined with Fine-Perforated-Film: Noise Tests by a Small Turbofan Engine DGEN 380

Resonant-type liner panels are one the primary countermeasures for the fan noise of aircraft engines, though the sound absorption performances of the liners are known to be tolerated by the grazing flow streaming on their surface. Therefore, suppressing the effect of the flow on the liners is greatly important for higher sound absorption efficiency. In this study, liner panels with special surface structures were manufactured and applied to an outdoor test using a small turbofan engine, DGEN 380. A special thin film, Fine-Perforated-Film (FPF), was applied to two liner samples. In the first sample, FPF was applied directly to the surface of a typical liner. In the second sample, a gap was fixed between the FPF and liner surface. In addition, a rigid wall and a typical liner were used for comparison, to investigate the effect of the structures. During the test, the samples were installed to the exhaust bypass duct of the DGEN engine. The acoustic pressure inside the duct and in far field was measured. Analysis and comparison of the results showed that the new structures suppressed the effect of the grazing flow and caused a larger amount of noise reduction, compared to the typical liner sample.

Friction Reduction by Dimple Type Textured Cylinder Liners-An Experimental Investigation.

Applying texture to a surface in a tribological interface will influence frictional performance, which has been investigated in several previous studies. However, since varying operating conditions heavily affect the frictional performance and optimum texture dimensions, more work in this field is required. There are few experimental studies concerning the influence of texture on friction especially under sliding lubricated conditions and even fewer at high sliding speeds. In this work, the effect of texture on frictional losses between the piston ring and cylinder liner is studied experimentally. The texture is of the dimple type, with a diameter and depth of 300 µm and 3 µm, respectively, applied to the cylinder liner surface. Experiments are performed with sliding speeds close to real piston sliding speeds. A clear reduction in frictional losses is observed with the textured cylinder liner. Moreover, qualitatively comparing the experimental results to a numerical model shows a good correlation.

Service life predicting of the piston ring with laser-hardened cylinder liner

The article considers the issues associated with the evaluation of hardening treatments influence on the service life of the piston ring in the cylinder of a heavy-duty diesel engine. The statement about the high efficiency of laser hardening of cylinder liners made of cast iron is substantiated. Model experiments on a laboratory friction machine investigate the wear resistance of the friction surfaces of the coupling piston ring-cylinder liner. The effect of piston ring wear on the loss of elasticity and the service life of the coupling is analyzed. The calculation method determines the service life of the coupling and analyzes the efficiency factor of the laser hardening treatment. On the basis of the study, it was found that laser hardening of the friction surfaces of cast-iron cylinder liners has a positive effect on the coupling wear resistance, but increases the wear of the piston rings. To eliminate the increase in wear resistance of piston rings, it is proposed to make them from steel and apply laser treatment of a wear-resistant coating from a high-entropy alloy of the Fe-Cr-W-Mo-Co-Ni system, which can significantly increase the service life of the piston ring-cylinder liner coupling in heavy diesel engines.

Corrosion of a chimney liner operated for 130,000 hours

The tests were carried out for a coal-fired boiler heating a single-family house with a usable area of 220 m2. The tests covered the chimney liner (structure and surface layer - produced oxides/deposits), hard coal (eco-pea coal) and furnace ash. The chimney liner was located in a chimney made of bricks joined with concrete. A chimney liner made of austenitic steel was tested. The chimney liner was operated for 130,000 hours. The chimney insert was studied on the inner and outer side the respective cross-section. Coal with a grain size of 50-210 mm was analyzed. The bottom ash consisted of both loose ash and a mass of glassy sintered ash, the so-called slag. Thorough examinations of the researches materials comprised: microscopic examinations using an digital microscope VHX-7000 and scanning electron microscopes Jeol JSM-6610LV. Analysis of the chemical composition using Energy dispersive X-ray spectroscopy (EDS) in conjunction with the scanning electron microscopy (SEM). The surface topography (roughness) was measured using a VHX microscope using a Gaussian filter. The following parameters were determined on the basis of the tests: arithmetic mean height, maximum height, height of the highest peak, depth of the lowest depression, root mean square height, skewness, kurtosis.