Laboratory-scale Tests Research Articles

Experimental studies on the effect of application methods on the lubricant performance during serial production in automotive industry

Lubricant breakdown and galling phenomena are widely observed at the tooling surface during the stamping of aluminium components for the automotive industry, which compromise the formed surface quality and reduce tool-life. The lubricant performance has been found to be significantly influenced by its method of application. In the present research, a dedicated lubricant was evaluated by utilizing an advanced lab-scale friction testing system, TriboMate, and the effects of lubricant application method and lubricant quantity on the coefficient of friction evolution were investigated. It has been found that lubricant performance was significantly improved when the lubricant was applied on the hot workpiece blank, compared to the cold tooling surface, and when the lubricant quantity was increased. The gradual increase of friction evolution despite lubricant application on the workpiece blank was found to be due to the formation of an aluminium transfer layer at the tooling surface.

Intricacies of CO2 removal from mixed gases and biogas using polysulfone/ZIF-8 mixed matrix membranes - part 1: experimental.

In this work, we explore the potential of polysulfone/ZIF-8 mixed matrix membranes (MMMs) for the enrichment of biogas to biomethane. To this end, we present data for these MMMs on permeability and selectivity as function of pressure and feed composition, at different loadings of ZIF-8. Specifically, we study dense polysulfone membranes prepared by solvent evaporation, with a ZIF-8 loading in the range 0.5-5 wt% for separation of CO2 from artificial mixtures of CO2 and CH4, and also biogas from an operating plant. The MMMs with 1 wt% filler loading gave the highest enhancement in permeability and selectivity, of 56.8% and 41% respectively, as compared to pure PSF membranes. At higher loadings, a tendency for the ZIF-8 particles to agglomerate was seen, which may compromise the ability of the filler to improve membrane performance. With mixed gases, increases in CO2 permeability of about 8 to 34% were observed depending on the gas composition, the enhancement being the higher, the lower the CO2 content. For biogas, permeability and selectivity of the 1% ZIF-8 loaded MMMs were found to be 14.6% and 39.64% lesser respectively than the pure gas values. The study thus throws light on the differences in membrane performance with mixtures as compared to ideal values obtained with pure gases and hence underlines the importance of lab-scale testing of the membranes with actual gas mixtures in the intended applications.

Denitrification Capacity of Volatile Fatty Acids from Sludge Fermentation: Lab-Scale Testing and Full-Scale Assessment

This work provides insights into the possibility of integrating recovered volatile fatty acids (VFAs) into biological nitrogen removal processes. VFAs are the main products of the acidogenic fermentation of waste sludge and are an effective carbon source for denitrification in activated sludge processes. The assessment of denitrification rates and the utilisation hierarchy of different VFAs are relevant to evaluating the possibility of replacing external carbon sources with the fermented liquid, FL, from acidogenic fermentation. To this scope, single VFAs, FL collected from a full-scale waste sludge fermenter, and commercial hydroalcoholic solutions have been tested with manometric lab-scale tests. Regarding single acids, acetic acid showed the highest denitrification rates, up to 4 mg N-NO3 g VSS−1 h−1, while more complex acids usually showed a lower denitrification rate. The synthetic VFA mixture and FL showed a higher denitrification rate than the sole acetate (up to 134% of the acetate denitrification rate). Mass balances across the full-scale wastewater treatment plant demonstrated the positive role of FL dosage in enhancing the denitrification process in the activated sludge treatment, with an average nitrogen removal equal to 57% and 78% without and with FL dosage, respectively. Batch manometric tests proved to be an efficient and reliable tool to assess the quality of the carbon sources as well as the activity of denitrifying bacteria in activated sludge samples.

Electrochemical perspective on the applicability of electroosmosis for clay consolidation

There are three main electrochemical factors affecting the electroosmotic flow in clay soil: the voltage loss at the clay/electrode interface, the type of current carriers in the soil, and the ion composition change in the clay due to voltage application. Appropriate evaluation of these factors is important to cost effectively implement electroosmosis for in situ soil consolidation projects. In this study, three different experimental systems were developed and used to investigate electrochemical reactions occurring in reconstituted and natural marine clay during electroosmotic consolidation. The results of polarization tests show that the voltage loss at the clay/electrode interface is different depending on the combination of the clay material and electrode material. The results of electroosmotic element test also show that electroosmotic dehydration does not increase if large current–voltage value is applied and that an optimal current–voltage value for causing electroosmosis depends on the cohesive soil composition. If the clay contains a lot of oxidizable ions, such as sodium, these ions affect electrophoresis and chemical reactions that occur in the soil. Therefore, the optimal configuration to apply electric current also differs depending on the clay. The results of laboratory-scale electroosmotic dehydration tests, arranged in a realistic in situ layout, are performed to study the relationship between soil dehydration, consolidation, and surface crack generation.Graphical abstract

Cost-effective process development for sericin recovery from silk degumming wastewater

Sericin is a silk protein gum that draws attention due to recovery opportunity from textile effluents since it has anti-bacterial, anti-cancer, anti-UV and moisture absorption properties. This study investigates the development of a cost-effective process for the recovery of sericin from silk degumming effluents that would contribute to closing the technical and economical gaps in the field of resource recovery. The cost of sericin recovery was initially calculated by evaluation of capital and operational costs based on pilot and lab-scale tests. Eight alternatives from A1 to A8, covering combinations of pre-treatment (flocculation/sedimentation), volume reduction (nanofiltration-NF), solidification (ethanol precipitation + centrifugation) and drying (lyophilization, spray drying or oven drying) steps were considered to find the optimum recovery cost that would be competitive with the commercial price of sericin. Total costs were estimated to be between €140,000 and €2,600,000 for a plant lifetime of 15 years. The unit cost of recovered sericin was estimated to vary significantly from €89 to €1300 per kg. Alternatives A6 (pre-treatment + NF + oven drying), A7 (pre-treatment + oven drying), and A8 (pre-treatment + NF) enable competitiveness with market prices. For these alternatives, staff and energy expenditures were the main cost items. The payback period can be reduced from 15 years to 5 years by increasing the unit price of recovered sericin by 5%–30%. The developed cost-effective process would form a novel basis for a circular business model for the recovery of sericin as well as other resources such as nutrients, water, and energy.

Effect of Particle Size Ratio on Microstructure and Active Material Utilization in Argyrodyte All-Solid-State Composite Cathodes

Among next-generation batteries, all-solid-state batteries (ASSB) promise increased energy densities, fast charging properties, and higher safety compared to traditional liquid-based systems. To achieve the demanded high energy densities high mass loadings of the composite cathodes are necessary. These consist of active material (AM), solid electrolyte (SE), and conductive additive as well as binder. Volume changes of intercalation AM and insufficient ionic percolation at low SE contents lead to an increased interfacial resistance and capacity loss. In order to promote cathode AM utilization the particle size ratio of the AM and the SE within the composite cathode needs to be optimized.Theoretical calculations have shown that for high AM utilization at high AM loadings particle size ratio is a crucial parameter [1, 2]. Experimentally, the influence of particle size ratio has so far only been studied at laboratory scale. However, scalable process routes have not considered this important aspect. In this work, we present a solvent-based process route for the preparation of sulfide-based solid-state composite cathodes with NCM622 as AM, starting from the adjustment of the particle size of a commercially available Li6PS5Cl SE by planetary ball mill. Further process steps include the dispersion of SE with AM and conductive additive and doctor blade coating of cathode films. We analyzed the composite cathodes with regard to their internal resistance as well as their microstructure and conducted electrochemical tests in lab-scale test cells. Optimization of the particle size ratio results in an increase of AM utilization by a factor of 5 as well as an enhanced AM-SE-particle contact area and lower porosity.

Sand control screen selection for cased dual‐annulus gas offshore wells based on scaled laboratory tests

AbstractThis paper assessed and ranked several alternatives to control sand production in a well recompletion effort of offshore gas wells that have experienced massive sanding. The aim was to select an appropriate thru‐liner sand control system to increase well productivity. Four different screen types were evaluated, including a wire‐wrapped screen (WWS), slotted liner (SL), punched screen (PS), and a new multi‐layer open cell matrix polymer (OCMP) filter resembling gravel‐pack. The performance of screens regarding sand production and plugging was evaluated using a sand retention testing facility featuring a custom‐made device that mimics the unique well completion configuration. Further, a novel testing setup was constructed to assess the erosion potential of screens subject to high‐velocity gas and sand flow. All assessments were conducted under the representative actual well conditions. Laboratory tests indicate the superior performance of the OCMP filter compared to the other three options. Even though SL, WWS, and PS performed similarly in sanding, the WWS posed a higher erosion risk, with PS following in second place. The plugging tendency of the WWS was the least among all the options, whereas the PS had the highest tendency. Despite this, the WWS's sanding performance is expected to decline due to its vulnerability to erosion. Overall, the testing results indicated that the OCMP filter provides a promising solution to the issue of sand production in the gas wells being evaluated. However, the interaction of the OCMP filter with potential treatment chemicals in the wells should be tested before it can be used.

Protectiveness and stability of iron carbonate films on carbon steel in mildly alkaline aqueous alkanolamine CO2 environments

Carbon steel (CS) was pre-treated in CO2-saturated methyldiethanolamine(aq) to form FeCO3 surface films, the protectiveness of which against corrosion in monoethanolamine was studied using electrochemical impedance spectroscopy, open circuit potential measurements and ex situ surface characterisation. Only pure, dense FeCO3 films were found to provide protection in lab-scale tests. Dissolved O2 in pre-treatment solutions resulted in traces of iron (hydr)oxide within the films, exacerbating non-uniform corrosion. Impure films were compromised in pilot-scale experiments in the CO2 capture plant at Imperial College London. Therefore, pre-treating CS with methyldiethanolamine is not a robust corrosion control strategy for industrial CO2 capture plants.

Cuttings Transport With Oil- and Water-Based Drilling Fluids

Abstract Deviated well sections are common in most modern offshore well construction designs. In the North Sea region, which is a good example of mature areas, practically all producer or injector wells have highly deviated well sections. These wells must be constructed in an optimal manner with respect to functionality, drill time, risk, and all affiliated costs. Throughout the years, most hole-cleaning and hydraulic models have been developed based on experimental results from relatively small-scale laboratory tests with model fluids. Hole-cleaning properties and hydraulic behavior of practical drilling fluids intended for field application differ from those of most model fluids. Furthermore, results from small diameter tests may not always be relevant for or scalable to field applications because of the presence of a huge number of dimensional quantities like velocity, fluid properties, time, length, and other scale differences. Hence, studies using sufficient large-scale experimental facilities in controlled laboratory environments with the application of various field-designed drilling fluids are necessary to improve engineering models and operational practices. The current paper presents results from such laboratory tests where field-applied drilling fluids have been used. In comparison tests, the different drilling fluids have similar density and viscosity functions within the relevant field-applied shear rate range. This shear rate range is also assessed in the tests. One of the drilling fluids is oil-based, and the other one is an inhibitive water-based drilling fluid of the KCl/polymer type.

Design, Manufacturing, and Testing Process of a Lab Scale Test Bench Hybrid Rocket Engine

The current paper presents the architecture of a test bench for small (laboratory) scale hybrid rocket motors destined for teaching purposes. The sustainability of the proposed methodology is emphasized, as it addresses the development of small-scale hybrid rocket motor test benches, to be used either as didactic means for students or for research laboratories, by using low-cost materials, while preserving efficiency. In this regard, the entire development process is approached, from designing to manufacturing (including the casting of the fuel rod) and testing of the product. The developed product uses a mixture of 88% paraffin, 10% stearic acid, and 2% coal for the solid phase and liquid oxygen for the liquid phase. The testing of the hybrid rocket motor demonstrator was performed outdoors, in controlled conditions. The results showed a good correlation between the theoretical testing parameters with the obtained ones.

Shear strength and modulus of mine waste rock – Large scale laboratory testing results

This paper presents the sampling and laboratory testing results of mine waste rock consisting of limestone, siltstone, and intrusive materials collected from the Ok Tedi open pit mine in Papua New Guinea. The laboratory tests included specific gravity measurements, index testing, large-scale direct shear tests using a 720 mm square direct shear apparatus, large-scale consolidation tests using a 550 mm diameter consolidation apparatus, and shear wave velocity tests conducted on compressed waste rock samples. The obtained strength values, as well as small and larger strain modulus values, were subsequently compared with existing literature data from the literature. These findings can serve as a valuable reference for mine waste materials with similar lithology, particle size distribution, and stress condition, particularly in the context of static and seismic slope stability designs.

Steam recovery from flue gas by organosilica membranes for simultaneous harvesting of water and energy

Steam recovery from the spent gases from flues could be a key step in addressing the water shortage issue while additionally benefiting energy saving. Herein, we propose a system that uses organosilica membranes consisting of a developed layered structure to recover steam and latent heat from waste. Proof-of-concept testing is conducted in a running incinerator plant. The proposed system eliminates the need for a water supply while simultaneously recovering latent heat from the waste stream. First, the long-term stability of an organosilica membrane is confirmed over the course of six months on a laboratory-scale under a simulated waste stream. Second, steam recovery is demonstrated in a running waste incinerator plant (bench-scale), which confirms the steady operation of this steam recovery system with a steam recovery rate comparable to that recorded in the laboratory-scale test. Third, process simulation reveals that this system enables water-self-reliance with energy recovery that approximates 70% of waste combustion energy.

Suspended particulate matter

Resuspended particulate matter in shallow lakes contributes remarkable phosphorus (P) concentrations to the water column that potentially support algal/cyanobacterial growth. However, only fine particulate matter can be retained in the water column for a long time after sediment resuspension events. The size at which fine particulate matter has ecological implications remains undefined. This research defined suspended particulate matter with a median grain size <2.5 μm (SPM2.5) in shallow lakes, which resists sedimentation and enriches bioavailable P. The relationship between the size of suspended particulate matter (SPM) and water disturbance was characterized by conducting a lab-scale jar test with sediments in a shallow lake. The sedimentation of completely resuspended particulate matter occurred under a series of turbulence shear rates (G) ranging from 0 to 50 s−1. When G was larger than 20 s−1, the SPM had a median grain size (D50) ranging from 9 μm to 11 μm for the three samples. When G was <10 s−1, only SPM <2.5 μm remained in suspension. The SPM larger than 2.5 μm settled when G was between 10 s−1 and 20 s−1, and the SPM remained in complete suspension when G was larger than 20 s−1. Furthermore, P fractionation was conducted on different size-grouped particles that were sorted using gravity sedimentation. The concentration of iron/aluminium bound-P (Fe/Al-P) decreased exponentially as the particle size increased. The concentration of Fe/Al-P in SPM2.5 ranged from 902.8 mg/kg to 1212.1 mg/kg, accounting for over 80 % of extractable total phosphorus. SPM2.5 contributed a remarkable amount of bioavailable P to the algal/cyanobacterial biomass in the shallow lake with frequent sediment resuspension.

Justification of an Energy-Efficient Air Purification System in Subways Based on Air Dust Content Studies

It is not uncommon that subways count as densely populated areas, so air quality standards, including fine dust concentration, have been established for them. As passengers and subway staff are exposed to potentially harmful airborne particles, addressing this issue is vital to ensuring a safe and healthy environment on the subway. To reduce the dust concentration in subway systems, the authors propose installing filters to capture dust in ventilation failures between subway tunnels near metro stations. A novel aspect of the proposed method is the fact that airflow will be moved through filters by using the piston action of trains passing through the tunnels. The result of this research provides empirical evidence regarding dust content and mass concentrations of PM2.5 and PM10 in subway environments. While some existing literature discusses air quality in subways, the inclusion of specific measurements and data from the experiment strengthens the understanding of the severity of dust-related air quality issues in such environments. The data for this study were collected in the Almaty subway (Republic of Kazakhstan) at four stations: Raiymbek Batyr, Almaty, Baikonur and Alatau. Measuring points were located on passenger platforms, in the halls and at the entrances to the station. The lab scale tests determined the percentage of particles by their diameters relative to the total volume of dust, the percentage of dust particles smaller than a certain diameter, the percentage of various metal oxides and the average dust density. A preliminary energy assessment has been done on the proposed method of air purification from dust. With a frequency of 24 pairs of trains per hour, the energy savings per ventilation failure will be 240.170 kWh.

Highly sensitive resistance spectroscopy technique for online monitoring of biofilm growth on metallic surfaces

Online techniques for monitoring biofilm formation and evolution are limited, especially as regards its application in flowing water systems. This is chiefly due to the absence of efficient non-destructive and non-invasive sensing methods. In this study, a sensitive electrical resistance spectroscopy technique is developed to monitor non-invasively and in real time the growth of biofilms over metallic surfaces inside water flow systems. To this aim, Pseudomonas fluorescens strain is used for biofilm development lasting 72 h in a laboratory-scale test channel of orthogonal cross section. Biofilm development corresponds to a progressively increasing coverage of the metallic surface area up to full coverage and a progressively increasing thickness. Biofilm development is registered by continuous recording of electrical impedance signals (time series). Proper configuration and tuning of the electronics promote the resistive contribution to the signal whereas careful grounding diminishes electrical interferences and yields superb sensing sensitivity. An increase of relative electrical resistance of around 15% is noticed in 72 h flow experiments which is attributed to both an increase of metallic surface area coverage and an increase of biofilm thickness. An independent estimation of these quantities using imaging tools and microscopy analysis, indicates that full coverage of the metallic surface occurs after only 48 h of the flow experiment, whereas biofilm thickness increases gradually along the entire 72 h of the experiment. Cross-examination of electrical signals with biofilm characteristics (metallic surface coverage and biofilm thickness) reveals that, qualitatively speaking, electrical signals are rather more sensitive to metallic surface coverage than biofilm thickness.

Enhancing TiO2 Precipitation Process through the Utilization of Solution-Gas-Solid Multiphase CFD Simulation and Experiments

Ensuring uniform particle size distribution is a crucial role in the precipitation process of manufacturing white pigment. This study presents a comprehensive investigation that combines multiphase computational fluid dynamics (CFD) simulations with experimental research to effectively address the challenge of achieving uniform particle distribution during TiO2 precipitation. The objective of this study was to enhance three-phase CFD simulations involving the mixing process of TIOSO₄ solution, steam as a gas phase, and solid seed particles. By analyzing the trajectories of the seed particles using CFD, the optimal injection position for the seed particles within the mixing process was determined. Subsequently, a lab scale test and real field test were conducted based on the insights gained from the CFD simulations. The particle size distribution of two different types of seed inlets was analyzed and compared using Transmission Electron Microscopy (TEM) and Scanning Electron Microscope (SEM). The findings of this study demonstrate that the developed multiphase CFD simulation can effectively enhance the precipitation process for the production of anatase titanium dioxide particles. Additionally, using the developed multiphase CFD solver, the real physics involved in the precipitation process were identified, leading to a better understanding of the process itself. Furthermore, TiO2 particles with uniform particle size had a positive impact on the washing and bleaching processes following the precipitation process, resulting in a significant reduction in the annual defect production rate.

Lactococcus lactis subsp. lactis bv. diacetylactis Q5C6 strain as debittering adjunct culture for vegetable clotted cheese

One of the main challenges associated to the use of vegetable coagulants in cheesemaking is represented by the bitter taste conferred to the final product. In this context, the use of aminopeptidases positive strains could lead the hydrolysis of bitter peptides. The present study aimed to setup an experimental cheese clotted by using a kiwifruit enzymatic extract and inoculated with the Lactococcus lactis subsp. lactis bv. diacetylactis Q5C6 strain as debittering adjunct culture. The optimal amount of kiwifruit enzymatic extract, to be used in cheesemaking, was determined by performing laboratory-scale coagulation tests. Two experimental cheesemaking trials (A and B) were performed and the obtained cheeses were subjected to physico-chemical, microbiological, and sensory analysis. Results showed that, compared to cheeses clotted by animal rennet, the use of the kiwifruit enzymatic extract determined changes in fat, ash, and protein content. The L. lactis subsp. lactis bv. diacetylactis Q5C6 strain, inoculated at 1%, was able to reduce the bitter taste obtaining a final product with a sensory profile comparable to cheese clotted by animal rennet.

Scale-up of Vertical Wet Stirred Media Mill (HIGmill) via Signature Plots, Stress Analyses and Energy Equations

HIGmill, which is a type of vertical wet operated stirred media mill, has found applications in mineral industry requiring fine grinding stage. As the technology has recently been developed, knowledge regarding to its operation is scarce. This study aims to fulfill this gap with its focus on scale-up of the mill from laboratory scale tests. Within the scope of the work, a HIGmill operated at copper regrind circuit was sampled at different operating conditions, i.e., tip speeds, solids contents and media filling. In parallel, laboratory scale tests using the identical HIGmill feed were run in a dry batch operated vertical stirred mill and ball mill. The two results were initially calibrated by changing the operating parameters of the laboratory mills. Afterwards, the feed samples were processed with the optimal condition of stirred mill and the results of both scales were compared. In this study, the applicability of three different scale-up methodologies, signature plot, energy equations and stress analyses were examined. The investigations showed that the procedures can be utilized to predict both the required energy and volume required for the milling application. The developed methodologies may be helpful for basic engineering purposes requiring sizing the mill.

Stability of Filled PDMS Pervaporation Membranes in Bio-Ethanol Recovery from a Real Fermentation Broth.

Mixed matrix membranes (MMMs) have shown great potential in pervaporation (PV). As for many novel membrane materials however, lab-scale testing often involves synthetic feed solutions composed of mixed pure components, overlooking the possibly complex interactions and effects caused by the numerous other components in a real PV feed. This work studies the performance of MMMs with two different types of fillers, a core-shell material consisting of ZIF-8 coated on mesoporous silica and a hollow sphere of silicalite-1, in the PV of a real fermented wheat/hay straw hydrolysate broth for the production of bio-ethanol. All membranes, including a reference unfilled PDMS, show a declining permeability over time. Interestingly, the unfilled PDMS membrane maintains a stable separation factor, whereas the filled PDMS membranes rapidly lose selectivity to levels below that of the reference PDMS membrane. A membrane autopsy using XRD and SEM-EDX revealed an almost complete degradation of the crystalline ZIF-8 in the MMMs. Reference experiments with ZIF-8 nanoparticles in the fermentation broth demonstrated the influence of the broth on the ZIF-8 particles. However, the observed effects from the membrane autopsy could not exactly be replicated, likely due to distinct differences in conditions between the in-situ pervaporation process and the ex-situ reference experiments. These findings raise significant questions regarding the potential applicability of MOF-filled MMMs in real-feed pervaporation processes and, potentially, in harsh condition membrane separations in general. This study clearly confirms the importance of testing membranes in realistic conditions.

Synergy of random balance design method and intelligent optimization technique for model updating of the 4 MW offshore wind turbine benchmark

The technical challenges for model updating of real marine engineering structures include the extraction of modal parameters associated with incomplete measurement information and the correction of a large number of structural parameters. As it is difficult to verify the effectiveness of model updating methods for engineering applications, the representative models have to be adopted in finite element (FE) analysis or lab-scale tests, leading to the incomplete reflection of actual structural performances. Based on these factors, a practical model updating method is developed in this study to make full use of field measurement data from a 4 MW offshore wind turbine for the accurate estimation of structural parameters using the random balance designs-Fourier amplitude sensitivity test (RBD-FAST) strategy and an improved particle swarm optimization (IPSO). Leveraging the measured acceleration signals from offshore wind turbines under the conditions including operation, shutdown, collision and typhoon scenarios, the complex exponential decomposition method is applied to accurately extract the time-varying acceleration components (TVAC) for the construction of the frequency response function (FRF). Following that, RBD-FAST is implemented into IPSO with adaptive inertia weights and asynchronously varying learning factors to enable efficient selection of numerous updated physical parameters, thus improving time cost and computational accuracy. The correctness of the proposed method is verified by a numerical jacket platform model. Furthermore, the 4 MW offshore wind turbine benchmark is developed to assess the feasibility of the proposed model updating method using field measured data from different scenarios. Results show that the synergy of RBD-FAST and IPSO in the proposed method can accurately update parameters and minimize a maximum discrepancy of 0.8970% for the first-three orders of natural frequencies between the benchmark and the updated models in the collision scenario. Summarily, the present work provides a potential technique and practical engineering references for model updating of offshore wind turbines subject to harsh marine environments.