Small-scale Apparatus Research Articles

Influence of carbon fibre orientation and heat flux on the thermomechanical response of CFRP using small-scale apparatus

This study uses a small-scale apparatus to investigate the influence of carbon fibre orientation and heat flux on the thermomechanical response of carbon fibre reinforced polymer (CFRP). The proposed test apparatus allows the thermomechanical behaviour, relating to the mechanical performance degradation with particular surface temperature and temperature gradient of a CFRP, to be investigated. The motivation of this study is to understand the mechanical response of load-bearing CFRP materials during heating using a cone heater. Experiments were performed on CFRP specimens produced in four unique lay-ups to study their thermomechanical bending behaviour in terms of failure times, displacement, temperature distribution and failure modes. The results from this study show that different fibre orientations respond differently to thermomechanical loads. For example, it is observed that CFRP containing uni-directional [90°] fibres demonstrate the worst overall load-bearing response to thermomechanical loading conditions. In contrast, woven bi-directional [0°, 90°] fibres demonstrate the best. Uni-directional [0°] fibres and unwoven multi-directional [0°, ±45°, 90°] fibres present a modest overall load-bearing response to thermomechanical loading conditions. These results demonstrate that it is possible to systematically evaluate the performance of different fibre lay-ups and relate the failures to heating of the solid to the glass transition temperature and decomposition temperature of the polymer matrix.

Redox performance of trivalent iron iminodisuccinic acid in converting hydrogen sulfide to sulfur: A new complexed iron catalyst

A novel iron complex formed with tetrapotassium iminodisuccinate (IDSK4) was developed for catalytic conversion of hydrogen sulfide from industrial gases to monomeric sulfur, and a small-scale apparatus for the conversion of hydrogen sulfide in the laboratory was set up.The voltammetric curves of the system were generated with an electrochemical workstation, which indicated a quasireversible process. The catalytic capacity of the catalyst was saturated at 93.8% of the theoretical value for the trivalent iron complex.The open-circuit potential of the system was in the range −0.3 to −0.2 V, which provided full conversion of hydrogen sulfide, and after regeneration by air, it was restored to the initial potential.Full-cycle experiments showed that with increasing numbers of cycles, the open-circuit potential of the regenerated system was not fully restored to the initial value, thus requiring the design of a continuous absorption–regeneration system for industrial use. For safe treatment of hydrogen sulfide in industrial exhaust gases, a single-tower unit with absorption–regeneration cycles was used, and for safe treatment of hydrogen sulfide in combustible industrial gases, a double-tower unit with absorption–regeneration separation was used. The oxidation performance of the system was quickly monitored by measuring the open-circuit potential.

High pressure micromechanical force method to assess the non-plugging potential of crude oils and the detection of asphaltene-hydrate mixed agglomerates

A hydrate prevention strategy taking advantage of crude oil that exhibit hydrate non-plugging tendency is a viable option in oilfield production conditions, or during transient operations. For that reason, it is important to accurately evaluate crude oils for their potential as non-plugging oils in a small-scale apparatus, such as a High-Pressure Micromechanical Force (HP-MMF) system, before continuing to large-scale testing. HP-MMF is an interfacial method that has been applied to measure gas hydrate interparticle cohesive force to gain insight into the hydrate agglomeration tendencies of crude oils. Herein, methane/ethane hydrate cohesive force measurements in the presence of small concentrations of crude oil were performed in the HP-MMF. Direct observations from the HP-MMF revealed, for the first time, the appearance of asphaltene precipitates that interact with the gas hydrate particles to produce an asphaltene-hydrate mixed agglomerate. A new HP-MMF method has been developed that enables representative sampling and evaluation of the effect of crude oil samples on the cohesive force between two gas hydrate particles in the HP-MMF. The method has been tested with two crude oils, where lower cohesive force results are demonstrated by the presence of small concentrations (<5 vol% in model oil) of Crude A and C compared to the baseline system of pure model oil. Hence, indicating the presence of natural anti-agglomerants (AAs) that contribute to the non-plugging behavior of these crude oils. These studies show that the HP-MMF is a convenient tool to assess the non-plugging potential of crude oils at realistic (high pressure, low temperature) conditions, requiring only small oil sample volumes. The HP-MMF method developed in this work is demonstrated to be a unique tool that can be utilized for the detection of asphaltene-hydrate mixed agglomerates. These new findings provide important insights for asphaltene precipitation in the presence of gas hydrates, that can create catastrophic agglomeration in the flowlines.

Investigation on lateral dispersion characteristics of fuel particles in dense phase zone of a large-scale circulating fluidized bed boiler under combustion conditions

The dispersion characteristics of fuel particles in the dense phase zone in circulating fluidized bed (CFB) boilers have an important influence on bed temperature distribution and pollutant emissions. However, previous research in literature was mostly on small-scale apparatus, whose results could not be applied directly to large-scale CFB with multiple dispersion sources. To help solve this problem, we proposed a novel method to estimate the lateral dispersion coefficient (Dx) of fuel particles under partial coal cut-off condition in a 350 MW supercritical CFB boiler based on combustion and dispersion models. Meanwhile, we carried out experiments to obtain the Dx in the range of 0.1218–0.1406 m2/s. Numerical simulations were performed and the influence of operating conditions and furnace structure on fuel dispersion characteristics was investigated, the simulation value of Dx was validated against experimental data. Results revealed that the distribution of bed temperature caused by the fuel dispersion was mainly formed by char combustion. Because of the presence of intermediate water-cooled partition wall, the mixing and dispersion of fuel and bed material particles between the left and right sides of the furnace were hindered, increasing the non-uniformity of the bed temperature near furnace front wall.

A study of the thermomechanical behaviour of CFRP laminate using small-scale apparatus

An approach for quantifying the thermomechanical bending behaviour of a CFRP laminate has been developed. The proposed test method allows the coupled thermomechanical behaviour, relating the mechanical performance degradation with the temperature gradient and hence the gradient in mechanical properties inside a composite material to be investigated. Furthermore, the data can extend its applicability to constitutive modelling of composite material under fire conditions and provide experimental results essential for numerical model verification. Drawing on material flammability, the thermal load is induced using radiant heat flux, which allows a systematic evaluation of the material response. By manipulating the applied heat flux, the process causing failure is shown to vary. At low heat fluxes, the failure is dominated by a large proportion of the specimen reaching the glass transition temperature. At higher heat fluxes, the failure is dominated by pyrolysis and oxidation of the CFRP at the locally exposed surface, resulting in a more brittle failure. Because the developed apparatus allows the systematic variation of the thermal and mechanical load, it is possible to utilise it to replace conventional uncoupled approaches where residual mechanical properties are often used to assess the performance of materials exposed to thermal loads.

Experimental characterization of CH4 and CO2 hydrates formation in presence of porous quartz and Cu gas-atomized particles: Thermodynamic analyses and evidences about the feasibility of CH4/CO2 reverse replacement

Methane and carbon dioxide hydrates were formed in a small-scale apparatus filled with pure quartz porous sand and Cu particles, produced via gas-atomization for applications in additive manufacturing. Three different concentrations were tested, of 4.23, 18.01 and 30.66 wt%. This additive was found to act as promoter for methane hydrates and as inhibitor for carbon dioxide hydrates. The effect increased with the concentrations and was associated to the chemical properties of particles. Results were compared validated with literature. For the first time, it was possible to add this material to the group of additives able to intervene on the process differently as a function of the guest compound involved. Results showed a thermodynamic area in which CO2 hydrates required more severe conditions than CH4 hydrates to form. This new configuration allowed to propose an innovative application based on the CH4/CO2 reverse replacement.

Construction and Calibration of a Unique Hot Box Apparatus

A variety of mathematical models are available to estimate the thermal performance of buildings. Nevertheless, mathematical models predict the thermal performance of buildings that might differ from the actual performance. The hot box is a widely-used test apparatus to assess the actual thermal performance of various building envelope components (walls, roofs, windows) in the laboratory. This paper presents the process of designing, constructing, and calibrating a unique small-scale hot box apparatus. Despite its smaller metering area (1.0 m × 1.0 m), this apparatus met the key requirements (below ±0.25 °C fluctuations in chambers’ air temperature, and below 2.0% variation from the point-to-point temperature in reference to the temperature difference across the specimen) as prescribed in the ASTM C1363 and ISO 8990 standards. The walls of this apparatus are uniquely constructed using vacuum insulation panels or VIPs. The efficient and novel use of VIPs and workmanship during the construction of the apparatus are demonstrated through the temperature stability within the chambers. The achieved range of temperature steadiness below ±0.05 °C and point-to-point temperature variation below 1.0% of the temperature difference across the specimen allow for this apparatus to be considered unique among the calibrated hot box categories reported in the literature. In addition, having an affordable, simple-to-operate, and high-accuracy facility offers a great opportunity for researchers and practitioners to investigate new ideas and solutions. The apparatus was calibrated using two extruded polystyrene foam (XPS) specimens with thicknesses of 2″ and 4″. The calibration exercise indicates small differences between results obtained numerically, theoretically, and experimentally (below 3.0%). Ultimately, the apparatus was employed to measure the thermal properties of a specimen representing a lightweight steel framing (LSF) wall system, which is commonly used in cold climates. The results obtained experimentally were then compared to the ones estimated numerically using a 3D finite element modelling tool. The difference between the results obtained by both methods was below 9.0%.

Observation of the Main Natural Parameters Influencing the Formation of Gas Hydrates

Chemical composition in seawater of marine sediments, as well as the physical properties and chemical composition of soils, influence the phase behavior of natural gas hydrate by disturbing the hydrogen bond network in the water-rich phase before hydrate formation. In this article, some marine sediments samples, collected in National Antarctic Museum in Trieste, were analyzed and properties such as pH, conductivity, salinity, and concentration of main elements of water present in the sediments are reported. The results, obtained by inductively coupled plasma-mass spectrometry (ICP-MS) and ion chromatography (IC) analysis, show that the more abundant cation is sodium and, present in smaller quantities, but not negligible, are calcium, potassium, and magnesium, while the more abundant anion is chloride and sulfate is also appreciable. These results were successively used to determine the thermodynamic parameters and the effect on salinity of water on hydrates’ formation. Then, hydrate formation was experimentally tested using a small-scale apparatus, in the presence of two different porous media: a pure silica sand and a silica-based natural sand, coming from the Mediterranean seafloor. The results proved how the presence of further compounds, rather than silicon, as well as the heterogeneous grainsize and porosity, made this sand a weak thermodynamic and a strong kinetic inhibitor for the hydrate formation process.

Ground loading from BLEVE through small scale experiments: Experiments and results

The ground force generated by a BLEVE is a hazard that has been seldom studied, even though BLEVE has been source of many research works in the past decades. However, emergency responders have been asking questions the risk and consequences of a BLEVE on a bridge and other critical infrastructures for a while, with no answer so far. Moreover, a tank truck accident in Bologna in August 2018 has shown that bridge collapse may result from such scenario.This paper presents the experimental work done with a small scale apparatus reproducing realistic BLEVE failure with a cylindrical tube. Load cells were placed under the base plate holding the tube to measure the local ground force generated by the explosion. Forces from 10 kN to 55 kN were measured for a 50 mm diameter tube with 300 mm length failing at pressures from 10 to 32 Bar. The ground force signals are interpreted together with the imaging and internal pressure signal. The synchronization between violent boiling, repressurization in the vessel and strong ground force is clear through this comparison. Different ground force signals were observed depending on the fill level and weakened length of the tube. The maximum ground force and impulse vary almost linearly with failure pressure and liquid fill level. It is less clear for the influence of weakened/opening length of the tube. More data is required to conclude on this parameter influence.

RETRACTED ARTICLE: Secondary treated wastewater of latex processing: reusing for irrigation or treatment by membrane filtration

Many technologies have been developed to treat the rubber effluent, but the quality of the treated effluent after the secondary treatment still does not meet the requirements for releasing it back to water bodies. This treated effluent becomes one of the most challenging problems for the Vietnamese rubber industry. Therefore, the present paper studied two applications as a potential solution for this issue. The first one is an advanced technology using membrane ultrafiltration, for a higher quality of the treated effluent that meets the disposal requirements. The second application is a direct reuse of the effluent for agricultural irrigation. For investigation of the effectiveness of the membrane filtration, a small-scale ultrafiltration apparatus with polyacrylonitrile membrane was used to conduct experiments on synthetic wastewater. The obtained results indicate that the membrane significantly reduced the COD concentration of the treated effluent to a level below the limit of 50 mg/L set by the Vietnamese Regulatory for discharge to water bodies. Kinetics of membrane ultrafiltration was also discussed. For the reuse of the treated effluent for irrigation, the effluent must have no negative impact on the groundwater. In order to investigate this aspect, a large-scale penetration test was conducted using a column filled with soil samples collected from rubber plantations in Binh Duong. The column penetration test results show that the irrigated effluent posed no harmful effect on groundwater. All COD, total nitrogen and phosphorous concentrations at a depth higher than groundwater were lower than the discharge limits for treated wastewater to water bodies.

The behaviour of wood crib fires under free burning and fire whirl conditions

The dynamics of wood crib fires were investigated under fire whirl (FW) and free burning (FB) conditions in a small-scale apparatus. For open-packed cribs, the burning rates and fire spread rates of the FB and FW cribs were almost identical. However, as the number of sticks per layer (n) increased from 3 to 7, the burning rate for FW experiments increased 1.0–1.3 times that of the FB cribs and the spread rate for FW experiments was 0.92–1.66 times that of the FB cribs for the same geometric configuration. Likewise, for open-packed cribs the average flame height of the FB and FW cribs were very similar, but as n increased the average flame height for FW tests increased from 1.0 to 1.69 times that of FB cribs for the same configuration, which was almost the same increase as that for the fire spread rates. Temperature measurements along the centreline above the crib showed distinctly different profiles for FB and FW crib fires. The ratio of the absolute temperature in the continuous flame region of a FW to that of a FB crib of the same configuration increased from 0.99 to 1.2 as n increased.

Experimental Evaluation of Temperature and Concentration Effects on Heat of Dissociation of CO2-loaded MEA Solution in Strippers

Regeneration heat in strippers of CCS system is affected by operating temperature and concentration of amine solutions and accurate measurement, modelling and prediction of it are necessary to design the strippers with selecting new or blend amine solutions. This paper reports the heat of dissociation of CO2-loaded 30wt% monoethanolamine (MEA) solution quantified experimentally by a small-scale apparatus circulating the solution through absorber and stripper. This method can quantify total regeneration heat as well as breakdown of regeneration heat consisted of the heat of CO2 dissociation, the sensible heat of solution and the latent heat of condensed water simultaneously. The heat of CO2 dissociation agreed well with the heat of CO2 absorption at 120 degrees C in literatures. Aspen Plus offers an example file of rate-based CCS system using MEA, and the process flow diagram (PFD) was developed to simulate the apparatus by using it. The developed PFD with the original electrolyte NRTL model underestimated heat duty of the stripper. We modified temperature dependency of the specific heat capacity of protonated MEA. The modified model could predict accurately the heat of CO2 dissociation as well as mole fraction of chemical species, while effect of solution concentration on the heat of CO2 absorption was still not sufficiently simulated.

Study on the Behavior of Radiolytically Produced Hydrogen in a High-Level Liquid Waste Tank of a Reprocessing Plant: Comparison between Actual and Simulated Solutions

Experiments using a small-scale apparatus with 30 ml of actual high-level liquid waste from the Tokai Reprocessing Plant were carried out to show that the hydrogen concentration in the gas phase reaches a steady-state value of much less than 4% (lower explosive limit) in the absence of sweeping air. The H2 concentration reached a steady-state value as was expected, and it was compared with a value predicted from an equation with parameters that had been obtained using the simulated solution. Satisfactory agreement showed that the Pd-ion catalytic H2 consumption reaction previously found in the simulated solution proceeded equally well in the actual solution.

Measurement of bitumen–tyre adhesion temperatures at realistic loading rates

A small-scale apparatus was constructed to measure the ‘adhesion temperature’, at which bitumen ‘pick-up’ onto tyre rubber (and subsequent tracking) occurs. Loading frequencies equivalent to traffic speeds of over 100 km hr−1 and realistic tyre footprint pressures were used. The adhesion temperature increased with loading frequency, but all of the bitumens and polymer-modified bitumens studied had adhesion temperatures (i.e. the temperature at which the bitumen failed cohesively) at or below 60 °C, a temperature easily reached in the field. The results confirm the findings of an earlier slow-speed study (at 1.6 km hr−1) and indicate that the adhesion temperature under realistic loading conditions is governed by the properties of the bitumen, i.e. the bitumen yield stress is lower than that of the adhesive bond formed as the tyre traverses the bitumen.

Precise Optimization of Poultry Manure Composting Using an Experimental Small-Scale Apparatus

Precise Optimization of Poultry Manure Composting Using an Experimental Small-Scale Apparatus

A new simple approach for the scale-up of aerated stirred tanks

The scale-up of stirred tanks to very large size is challenging because measurements and correlations are mainly developed for small-scale apparatus. This paper presents the basic hydrodynamics of two-phase stirred tanks. The hydrodynamics in large-scale reactors are shown to be mainly a function of the superficial gas velocity in the system. For this reason scale-up by keeping the superficial gas velocity constant is suggested in comparison to scale-up by constant volumetric aeration per volume (vvm). It is shown that in order to achieve adequate mass transfer, large-scale stirred tanks, especially bioreactors, must operate mainly in the heterogeneous regime and therefore the correlations developed in small-scale and homogeneous regime are not directly applicable for scale-up. New simple ways to predict gas holdup, interfacial area and mass transfer in stirred tanks are presented and shown to follow experimental values. The model requires very little data as basis and can therefore be used in the initial stages of reactor design.

Effects of scale on internal blast measurements

This paper presents a comparative study between large and small-scale internal blast experiments with the goal of using the small-scale analog for energetic performance evaluation. In the small-scale experiment, highly confined explosive samples <0.5 g were subjected to the output from a PETN detonator while enclosed in a 3-liter chamber. Large-scale tests up to 23 kg were unconfined and released in a chamber with a factor of 60,000 increase in volume. The comparative metric in these experiments is peak quasi-static overpressure, with the explosive sample expressed as sample energy/chamber volume, which normalizes measured pressures across scale. Small-scale measured pressures were always lower than the large-scale measurements, because of heat-loss to the high confinement inherent in the small-scale apparatus. This heat-loss can be quantified and used to correct the small-scale pressure measurements. In some cases the heat-loss was large enough to quench reaction of lower energy samples. These results suggest that small-scale internal blast tests do correlate with their large-scale counterparts, provided that heat-loss to confinement can be measured, and that less reactive or lower energy samples are not quenched by heat-loss.

An experimental system for the recovery, accumulation, and utilization of heat generated by bamboo chip biodegradation using a small-scale apparatus

We performed experiments using a small, laboratory-scale apparatus for validating a system of recovery, accumulation, and utilization of the heat generated by bamboo chip biodegradation. This system is based on the effective use of biomass resources and is needed to support industrial progress in low population regions such as Noto, Ishikawa Prefecture, Japan. This paper is the first attempt at quantifying the use of heat to warm an aquaculture pond. Although conduction is the main heat transfer mechanism in the bamboo chip pile, physical models of heat conduction are mathematically complex. Therefore, we considered the heat conduction effects concentrated around the heat extraction pipe embedded in the bamboo chip pile, and obtained relatively simple analytical solutions for the temperature in the bamboo chip pile, water reservoir for heat accumulation, and conceptual fishpond (i.e., a heat utilization subsystem). Based on the experiment's results and the simplified model, we discussed the validity of the comprehensible heat transfer model and the feasibility of the proposed system.

Macro-Scale Direct Shear Test Device for Assessing Soil-Solid Interface Friction Under Low Effective Normal Stresses

Abstract The paper describes a new macro-scale direct shear test device for assessing the large-displacement soil/solid interface drained shear strength at low effective normal stresses. The testing method arises from a need to obtain the interface friction between soils and pipelines under low effective normal stress levels, which is an important consideration in the design of pipelines laid on the sea bed. The test device is fundamentally similar to the conventional small-scale direct shear box device except for its large footprint that provides a plan interface shear area of 3 m2 (1.72 m by 1.75 m). The device is designed to impart displacement-controlled interface-shearing at displacement rates ranging from 0.0001 mm/s to 1 mm/s and with the ability to reach a maximum interface shear displacement of 1.2 m. The desired normal stress at the soil/solid interface is obtained using surcharge loads externally applied by means of bulk sand or water masses, or both in certain cases. The device is instrumented with transducers mounted flush with the top of the solid surface for the measurement of pore-water pressure at the shear interface. As a result, the device allows for accurate determination of the effective normal stress at the soil/solid interface during interface shear testing. The key features of this device are described, and the device capabilities are demonstrated using tests conducted on Fraser-River-sand/mild-steel, plastic-silt/epoxy-coated-mild-steel, non-plastic-silt/epoxy-coated-mild-steel, and kaolinite/epoxy-coated-mild-steel interfaces at effective normal stresses between 3 and 7 kPa. The results can be also used as benchmarks to justify possible modifications of the currently available small-scale apparatus to reliably measure interface shear strength at such low effective normal stresses.

Postcombustion CO2 Capture by Chemical Absorption: Screening of Aqueous Amine(s)-based solvents

The purpose of our work was to evaluate separately the absorption and regeneration performances of different types of amine(s) based solvents (primary, secondary and tertiary alkanolamines, sterically hindered amines, non-cyclical tetramine and cyclical absorption activators) by carrying out screening tests using small scale apparatus: a gas-liquid contactor for absorption, namely a double-stirred cell, and a regeneration cell. Absorption and regeneration performances of the solvents were compared thanks to calculated absorption and regeneration efficiencies. Concerning the absorption results, the positive effect of an activator, and especially the cyclical di-amine piperazine (PZ), on the absorption performances of the different simple amine solutions was clearly highlighted. The activation of the secondary amine MMEA by PZ gives also higher absorption efficiencies.Regarding the regeneration tests, the better regeneration performances of tertiary and sterically hindered amines(MDEA and AMP) were confirmed. For the amines blends, higher regeneration performances were observed with PZ activated solutions than with PIP activated solutions.These absorption and regeneration results will be taken into account in the solvent selection for future combined absorption-regeneration tests.