Laboratory-scale Tests Research Articles

MEASUREMENT OF THE REGRESSION RATE IN A HYBRID ROCKET MOTOR BY ACQUIRING THE HELMHOLTZ FREQUENCY IN THE COMBUSTION CHAMBER

Low thrust values obtained with a hybrid rocket motor (HRM) are a consequence of the difficulty in quickly mixing the fuel and oxidizer, which is characterized by a low regression rate of the fuel grain. Therefore, the measurement of this parameter is of great importance in studies that aim at solutions for this deficiency in HRM. Several studies calculate a reliable value of the average regression rate over time by measuring the total mass of fuel before and after each burn. A method to measure instantaneous regression rate is by acquiring the Helmholtz resonance frequency in the combustion chamber. This work uses a piezoelectric pressure transducer to obtain the Helmholtz frequency mode of the combustion chamber in a laboratory scale test bench with high-density polyethylene (HDPE) and gaseous oxygen, and is based on the principle that this frequency is inversely proportional to the square-root of the chamber volume. With the chamber volume variation, the port diameter of the grain variation is obtained. In conclusion, the calculated variation of port diameter agreed well with the correlation for average regression rate, determined from mass loss during operation.

Separation characters of an axial-flow hydrocyclone with oil collecting pipe

In many offshore fields, water takes up 90 % of the produced fluid. The compact and efficient centrifugal pre-separation method is expected to replace the traditional sedimentation separator, which takes up a large area and is low in efficiency. The centrifugal separator can achieve rapid separation of produced fluids in the compact space of offshore platforms. However, conventional tangential inlet or axial hydrocyclone is poor-performed for high water content mixture due to droplet breakage caused by tangential inlet and unstable oil core in outlet section caused by axial inlet. In this paper, based on experiment and numerical simulation, a new type of efficient oil–water separator of high separation accuracy is constructed by the structural innovation of adding oil collecting pipe. In the treatment of 10 % oil mixture, when the inlet flow rate was 0.5 m/s, the volume fraction of oil at the oil outlet can reach 45 % and the volume fraction of oil at the water outlet can be reduced to 0.0724 %. According to the laboratory-scale tests, the novel separator shows great potential in oil field with high water content or offshore platforms.

Laser-based finite element model reconstruction for structural mechanics

It is imperative to know the health condition of a structure during its service life. The development of laser scanning technology has created new opportunities to leverage high-resolution 3D laser scanning (3DLS) as a non-destructive evaluation tool for detailed geometrical information extracted for the creation of precise computational models. However, the workflow associated with this integration is indirect and presents challenges. The existing scan-to-model strategies use completely scanning data to generate a new finite element model (FEM), leading to excessive computational costs, especially if nonlinear analysis is required. In view of this, this study creates a pathway for a direct scan-to-model strategy suitable for translating condition data derived from a 3D laser scanning system into a FEM capable of describing the mechanical response of the component. Then, based on the scan-to-model strategy, a localized pathway to automatically identify the damaged parts and locally update the FEM is proposed. Instead of generating a new FEM of the damaged component, only the damaged parts are updated, which can reduce the computation cost. After that, the pathways were validated through laboratory-scale tensile testing using 3D Digital Image Correlation (3D-DIC), which enabled full-field deformation characterization and correlation with numerical model prediction. Results of this study provide the foundation of a computational framework for establishing the fundamental link between visually observable geometric and numerical models that engineers use to understand the performance of engineered systems.

Arduino and IoT-based direct filter observation method monitoring the color change of water filter for safe drinking water

Globally, the red water crisis continues to occur because of aging water pipelines, excessive water system conversion, and inadequate water tank management. Therefore, in this study, we have developed a monitoring system for water tank filters in apartment buildings by using Arduino and Internet of Things (IoT) technology to realize efficient water tank management. The proposed system uses grayscale, RGB color, and pressure sensors, and these sensors are connected to an Arduino. In the performance evaluation of the direct filter monitoring system using a color sensor, the system could effectively detect the turbid water inflow by the signal-to-noise ratio of derivative of color change. Moreover, the representative turbidity-causing minerals such as iron (III) oxide-hydroxide (FeO(OH)), iron (III) oxide (Fe2O3), manganese oxide (MnO2) could be distinguished by a different color. A correlation analysis between pressure change and turbidity of filtered water yielded an R-square value of 0.9 or higher under most conditions. Based on the results obtained in the lab-scale test, a four-stage notification algorithm for safe filter operation was proposed. Finally, the developed direct filter monitoring system was installed in an apartment complex as a field demonstration, and it verified that the direct filter monitoring system can provide reliable notifications with high accuracy. Therefore, the direct filter monitoring system developed in this study can be widely used to manage water filter to ensure safe water supply in apartment complexes.

Synthesis of graphite/rGO-modified fungal hyphae for chromium (VI) bioremediation process

ABSTRACT Bioremediation is a promising technology that can eliminate the drawbacks of conventional treatment methods in removing harmful toxic metals including chromium(VI). Therefore, in this study, fungal hyphae modified with graphite and reduced graphene oxide were synthesized and assessed for their potential to bioremediate heavy metals for the first time in the literature. The effects of the carbon-based materials on microbial structure were characterized using scanning electron microscopy analysis. Thermogravimetric, RAMAN, X-ray diffraction, and enzymatic analyzes were performed to determine the role of functional groups. In addition, batch adsorption experiments utilizing response surface methodology were conducted to optimize operating parameters such as time (1–11 h), chromium (10–50 mg/L), and graphite/reduced graphene oxide (0.1–1 g/L). The maximum adsorption capacity with the graphene fungal hyphae was determined to be 568 mg.g−1, which is 9.7 times that of the crude fungal hyphae. The Cr(VI) removal for fungal hyphae-graphite and fungal hyphae-reduced graphene oxide biocomposites was 98.25% and 98.49%, respectively. The isothermal and kinetic results perfectly matched the 2nd order pseudo-model and Langmuir model in terms of the nature of the adsorption process. The laboratory scale test results indicate that fungal hyphae modified with graphite and reduced graphene oxide have a high adsorption capacity, suitable for the removal of chromium (VI) from wastewater.

Durable and Versatile Immobilized Carbonic Anhydrase on Textile Structured Packing for CO2 Capture

High-performance carbon dioxide (CO2)-capture technologies with low environmental impact are necessary to combat the current climate change crisis. Durable and versatile “drop-in-ready” textile structured packings with covalently immobilized carbonic anhydrase (CA) were created as efficient, easy to handle catalysts for CO2 absorption in benign solvents. The hydrophilic textile structure itself contributed high surface area and superior liquid transport properties to promote gas-liquid reactions that were further enhanced by the presence of CA, leading to excellent CO2 absorption efficiencies in lab-scale tests. Mechanistic investigations revealed that CO2 capture efficiency depended primarily on immobilized enzymes at or near the surface, whereas polymer entrapped enzymes were more protected from external stressors than those exposed at the surface, providing strategies to optimize performance and durability. Textile packing with covalently attached enzyme aggregates retained 100% of the initial 66.7% CO2 capture efficiency over 71-day longevity testing and retained 85% of the initial capture efficiency after 1-year of ambient dry storage. Subsequent stable performance in a 500 h continuous liquid flow scrubber test emphasized the material robustness. Biocatalytic textile packings performed well with different desirable solvents and across wide CO2 concentration ranges that are critical for CO2 capture from coal and natural gas-fired power plants, from natural gas and biogas for fuel upgrading, and directly from air.

Direct measurement of the resistance to ductile fracture propagation

The resistance to ductile fracture propagation remains a weak point in gas transmission pipelines’ safety since the emerging of this risk more than half a century ago. Full-scale burst tests of pressurized gas pipeline sections are performed to verify the ability of pipeline steel to arrest the crack propagation. However, motivated by the commitment to specific predictive models, the main outcome from full-scale burst tests (FSBT) has been in form of a binary “propagation/arrest” metric corresponding to each pipe in the test section. In the absence of a reliable laboratory-scale test demonstrating correlation with the full-scale resistance to ductile fracture propagation, such approach does not appear reasonable since it leaves line pipe manufacturers with very little clue regarding the preferential metallurgical designs. This work aims to better quantify the crack propagation resistance in FSBT providing metallurgists with a target property and facilitating the development of a new laboratory-scale mechanical test that shows reasonable correlation with FSBT. In order to improve FSBT testing methodologies, the pipe wall strain related to the crack propagation should be assessed along the entire test line. This can be implemented by means of modern 3D-measurement technologies that can digitize very large objects with high accuracy at a reasonably low cost. The method is demonstrated in the current work using the results of a recent FSBT carried out on X80 grade pipes. The results indicated that the plastic strain zone in FSBT can spread from the fracture surface over distances equivalent to tens of pipe wall thicknesses, while in the widely adopted drop weight tear test (DWTT) this spread hardly reaches one specimen thickness. Single-edge notched tensile (SENT) configuration provides much larger extent of the plastic zone into the specimen gauge when compared to DWTT whose major deformation mode is bending. Furthermore, the correlations between the strain parameters in different tests are discussed, and conclusions are drawn to promote a new laboratory test method for ductile fracture propagation resistance assessment in high strength steel pipe.

Spent-coffee grounds as a zero-burden material blended with bio-based poly(butylene succinate) for production of bio-composites: Findings from a Life Cycle Assessment application experience

This paper was conceived in consideration of the emerging trend of the composite industry's transition into organic filler application in materials and exploitation of organic wastes, to draw attention to the case of spent coffee grounds (SCG), namely the solid waste resulting from the popular beverage coffee. Life Cycle Assessment (LCA) analysis of SCG has been mainly focussed on oil extraction, which fails to address the value-added potential of solid waste and does not address the full life cycle of coffee. The study discussed in this paper aims at exploring the Carbon Footprint (CF) and the Cumulative Energy Demand (CED) of a set of composites through the application of LCA on a lab-scale dimension, which is comparable to small start-up production levels. Using the previously proven concept of the melt-blended SCG and bio-based poly (butylene succinate) (PBS) composites, the authors assessed a range from 20 to 60 wt% filler content suitable for a large variety of applications. Results from the study proved that the SCG/PBS ratio increased from 0.25 to 1.5 and reduced the whole-system related CED and CF by 7.4–8.4%. Overall, the study allowed to understand that, already in the phases of lab-scale design, testing, and assessment, it is possible to find material recovery paths that have the potential to lead to implementing sustainable circular models of the economy.

Lateral static stiffness of offshore monopile socketed in soft rock

Monopiles supporting offshore wind turbines (OWTs) sometimes need to be socketed in soft rocks. The lateral stiffness of piles plays a governing role on the fatigue limit state (FLS) and service limit state (SLS) of OWTs, so it needs to be further investigated. In this paper, laboratory-scale model tests and corresponding numerical analyses have been carried out to quantitatively evaluate the lateral static stiffness of monopiles in soft rocks under different scenarios. The results of pile responses, soil/rock resistance and the corresponding p-y curves are presented. Based on the experimental and numerical results, it is found that the load-sharing mechanisms of monopiles are significantly influenced by the rock-bearing layer. For modelling of rock-socked piles, p-y curves obtained by global curve fitting poorly describe the soil/rock resistance near the soil-rock interface, while p-y curves obtained by piecewise fitting for soil and rock layers or three-dimensional finite element model should be the preferred and recommended choices.

A laboratory-scale characterisation test for quantifying the size segregation of stockpiles

Most mine sites use large coarse ore stockpiles as a buffer between the mine and the processing plant. Stable operation of the downstream processes demands a uniform output from the stockpile with respect to particle size, however, particle size distributions of the product drawn from stockpiles can vary significantly over time due to various size segregation phenomena. Although quantifying size segregation occurring in industrial stockpiles would provide valuable information for operators, it is not practical due to the size of these piles which can exceed 100 kt. This research is focused on developing a laboratory test, which aims to quantify the propensity of an ore pile to segregate and to correlate these results to industrial stockpiles. The data generated by the laboratory-scale experiment could enable the modelling of size segregation for industrial-scale stockpiles. The results of the comprehensive laboratory tests indicate that it is possible to quantify size segregation in the laboratory and scale up the results.

Macro-meso dynamic fracture behaviors of Xinjiang marble exposed to freeze thaw and frequent impact disturbance loads: a lab-scale testing

Macro-meso dynamic fracture behaviors of Xinjiang marble exposed to freeze thaw and frequent impact disturbance loads: a lab-scale testing

A Novel Method for Smart Fire Detection Using Acoustic Measurements and Machine Learning: Proof of Concept

Fires are a major hazard resulting in high monetary costs, personal suffering, and irreplaceable losses. The consequences of a fire can be mitigated by early detection systems which increase the potential for successful intervention. The number of false alarms in current systems can for some applications be very high, but could be reduced by increasing the reliability of the detection system by using complementary signals from multiple sensors. The current study investigates the novel use of machine learning for fire event detection based on acoustic sensor measurements. Many materials exposed to heat give rise to acoustic emissions during heating, pyrolysis and burning phases. Further, sound is generated by the heat flow associated with the flame itself. The acoustic data collected in this study is used to define an acoustic sound event detection task, and the proposed machine learning method is trained to detect the presence of a fire event based on the emitted acoustic signal. The method is able to detect the presence of fire events from the examined material types with an overall F-score of 98.4%. The method has been developed using laboratory scale tests as a proof of concept and needs further development using realistic scenarios in the future.

Desilication of Sodium Aluminate Solutions from the Alkaline Leaching of Calcium-Aluminate Slags

The desilication of sodium aluminate solutions prior to precipitation of aluminum tri-hydroxides is an essential step in the production of high purity alumina for aluminum production. This study evaluates the desilication of sodium aluminate solutions derived from the leaching of calcium-aluminate slags with sodium carbonate, using CaO, Ca(OH)2, and MgO fine particles. The influence of the amount of CaO used, temperature, and comparisons with Ca(OH)2 and MgO were explored. Laboratory scale test work showed that the optimal conditions for this process were using 6 g/L of CaO at 90 °C for 90 min. This resulted in 92% of the Si being removed with as little as 7% co-precipitation of Al. The other desilicating agents, namely Ca(OH)2 and MgO, also proved effective in removing Si but at slower rates and higher amounts of Al co-precipitated. The characteristics of solid residue obtained after the process indicated that the desilication is via the formation of hydrogarnet, Grossular, and hydrotalcite dominant phases for CaO, Ca(OH)2 and MgO agents, respectively.

Exploring PCDD/Fs and potentially toxic elements in sewage sludge during smouldering treatment.

Potentially toxic elements (PTEs), persistent organic pollutants, and emerging contaminants make sewage sludge management challenging. There is significant interest in thermal treatment technologies that can destroy these compounds. The most common thermal treatment, incineration, poses risks due to formation and/or release of hazardous substances in process emissions such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and PTEs. Smouldering has been introduced recently as a potential treatment for managing sewage sludge. Smouldering systems present several advantages over traditional incinerators; however, there are still uncertainties regarding process by-products. This key question was investigated in three laboratory-scale tests (0.08m radius) and five oil drum-scale tests (0.3m radius) that were evaluated for PCDD/Fs and PTEs in the mixture before and after treatment as well as in process emissions. Volatile organic compounds (VOCs) were also measured. These experiments represent a broad spectrum of conditions to evaluate process emissions, from robust self-sustaining to extinction of smouldering. Robust smouldering had negligible PCDD/Fs in process emissions. Weak smouldering had low levels of PCDD/Fs (emissions factor: 3.3±0.3μg TEQ/Mg dried sludge destroyed), levels less than uncontrolled emissions from commercial incinerators. Overall, smouldering acted as a sink for PCDD/Fs, as only 0-3% of the PCDD/Fs originally present in the sludge were released in the emissions, and >99% of the remainder were destroyed with <1% remaining in post-treatment ash. No evidence was found to support de novo synthesis or precursor reactions forming new PCDD/Fs. In addition, 94-100% of all the PTEs analyzed were retained in the post-smouldered material. These results indicate that only minimal emissions treatment for PTEs, PCDD/Fs, and VOCs may be necessary for future sewage sludge smouldering systems. These low emissions risks combined with its unique ability to handle high moisture content waste, indicate that smouldering has significant potential as a valuable waste management technique.

Root response and phosphorus uptake with enhancement in available phosphorus level in soil in the presence of water-soluble organic matter deriving from organic material

Understanding the available phosphorus (P) levels in the presence of water-soluble organic matter (WSOM) deriving from organic materials can be important for the improvement of the P use efficiency. This study aimed to: (i) determine which types of WSOM (deriving from the organic material) can suppress P immobilization, and (ii) understand whether plants can uptake P that the immobilization is suppressed by the presence of WSOM, as well as how the plant roots response depending on the available P levels. The P sorption test revealed that the presence of WSOM deriving from cattle manure compost (CM), sewage sludge compost (SSC), and hydrothermal decomposed liquid fertilizer (HDLF) can suppress the P sorption by 44, 44, and 24%, respectively, as compared to single P. In the incubation test, the percentage of the available P to that added as P fertilizer was found to be >21% higher in the presence of a CM- or a SSC-derived WSOM than those of single P, but the effect of the HDLF-derived WSOM was not. In the cultivation test, P uptake was found to be improved in the CM-, the SSC-, and the HDLF-deriving WSOM by 17, 13, and 11%, respectively, as compared to single P. Moreover, the root weight was found to decrease along with an increase in the amount of P uptaken by the plant. These findings provide the first experimental evidence that the presence of the WSOM deriving from CM, SSC, and HDLF simultaneously enhance the available P level in the soil and P uptake by the plant at the lab-scale test. In addition, the higher the available P levels in the presence of WSOM, the lower the root developments. The presence of WSOM, particularly of one of high maturity, can suppress the P sorption by 24–44%; as a result, >20% of the P added remains as the available P depending on the type of organic material used.

An Accurate and Convenient Method of Vehicle Spatiotemporal Distribution Recognition Based on Computer Vision.

The Convenient and accurate identification of the traffic load of passing vehicles is of great significance to bridge health monitoring. The existing identification approaches often require prior environment knowledge to determine the location of the vehicle load, i.e., prior information of the road, which is inconvenient in practice and therefore limits its application. Moreover, camera disturbance usually reduces the measurement accuracy in case of long-term monitoring. In this study, a novel approach to identify the spatiotemporal information of passing vehicles is proposed based on computer vision. The position relationship between the camera and the passing vehicle is established, and then the location of the passing vehicle can be calculated by setting the camera shooting point as the origin. Since the angle information of the camera is pre-determined, the identification result is robust to camera disturbance. Lab-scale test and field measurement have been conducted to validate the reliability and accuracy of the proposed method.

Lab-scale and on-field industrial composting of biodegradable plastic blends for packaging

Background: The acceptance of compostable plastic packaging in industrial composting plants is not universal despite available certification for compostability due to the persistence of compostable plastic residues reported by some industrial plants. This study aims to better understand this discrepancy by comparing the disintegration rate of two compostable plastic blends designed for rigid packaging (polylactic acid based) and soft packaging (polybutylene succinate based) between a controlled lab-scale test and an on-field test in an industrial composting plant. Methods: The thermophilic lab-scale disintegration test was conducted according to ISO 20200 in triplicates for 4, 8 and 12 weeks while the on-field test was conducted by exposing duplicate test material in the compost pile of an industrial composting plant in northern Germany, for three weeks. The mass change of the remaining test material &gt;2mm was used as an indicator of disintegration. Results: The rigid packaging blend (1 mm thickness) retained on average 76.4%, 59.0% and 55.7% of its mass after 4, 8 and 12 weeks respectively in the lab-scale test. After exposure to industrial composting on-field, the remaining mass was 97.2% and 99.5%. The soft packaging blend (109±9 µm sample thickness) retained on average 45.4%, 10.9% and 0.3% of its mass after 4, 8 and 12 weeks respectively and 94.0% and 93.8% after exposure to industrial composting on-field. Conclusions: The results show a substantial difference in disintegration rates between the lab-scale and the on-field test after three to four weeks. The difference between the tests that might contribute significantly to the differing disintegration rates is the composition of the composting substrate. Besides the design and characteristics of the packaging itself, the composting substrate and thermophilic composting duration of individual plants are important to determine the suitability of treating compostable plastic packaging in industrial composting plants as well as inform potential solutions.

The application of TiO2 nanofluids in photovoltaic thermal collector systems

Solar energy may be transformed into several types of energy, including electrical energy. Solar cell efficiency is low because some of the thermal energy that solar panels collect is not used. A solar panel’s relative efficiency and heat transmission decrease as it heats up. By collecting thermal energy and cooling it, photovoltaic systems may operate more efficiently. In this study, a thermal photovoltaic collector (PVT) system with a working fluid is used to cool PV panels. Laboratory-scale testing and simulation using the ANSYS Software were applied in the analysis. The simulation outcomes confirm the experimental values. Nanofluid serves as the working fluid because it has strong heat transmission qualities and has the characteristics of titanium dioxide (TiO 2). Average PV operating temperatures may be reduced by using TiO 2-based PVT systems. This can be explained by the fact that the fluid makes it easier for heat to be transferred. In comparison to PV-ground cells, photovoltaic solar cells now have a 2.11% higher efficiency. When utilizing TiO 2-based PVT systems, an average photovoltaic temperature of 58.5 °C is generated, with a 13.04% photovoltaic efficiency.

Study on microbial community of "green-covering" Tuqu and the effect of fortified autochthonous Monascus purpureus on the flavor components of light-aroma-type Baijiu.

"Green-covering" Tuqu (TQ), as one of Xiaoqu, is a special fermentative starter (also known as Jiuqu in Chinese) that originated in southern China and is characterized by a layer of green mold covering (Aspergillus clavatus) the surface and (sometimes) with a red heart. It plays a vital role in producing light-aroma-type Baijiu (LATB). However, to date, the microbiota that causes red heart of TQ remain largely unexplored, and it is still unclear how these microbiota influence on the quality of LATB. In this study, two types of TQ, one with a red heart (RH) and another with a non-red heart (NRH), were investigated by high throughput sequencing (HTS) and directional screening of culture-dependent methods. The obtained results revealed the differences in the microbial communities of different TQ and led to the isolation of two species of Monascus. Interestingly, the results of high performance liquid chromatography (HPLC) detection showed that citrinin was not detected, indicating that Monascus isolated from TQ was no safety risk, and the contents of gamma-aminobutyric acid in the fermented grains of RH were higher than that of NRH during the fermentation. Selecting the superior autochthonous Monascus (M1) isolated from the TQ to reinoculate into the TQ-making process, established a stable method for producing the experimental "red heart" Tuqu (ERH), which confirmed that the cause of "red heart" was the growth of Monascus strains. After the lab-scale production test, ERH increased ethyl ester production and reduced higher alcohols production. In addition, Monascus had an inhibitory effect on the growth of Saccharomyces and Aspergillus. This study provides the safe, health-beneficial, and superior fermentation strains and strategies for improving the quality of TQ and LATB.

Adsorption of Heavy Metals from Small-Scale Gold Processing in Baguio Mining District, Philippines

Small-scale mining in the Philippines lacks research and technologies for the application of an inexpensive and environmentally sound treatment of its wastewaters. Hence, laboratory-scale fixed-bed column tests were carried out to test and evaluate the sorbent adsorption performance of the Philippine Natural Bentonite (PNB) and the Philippine Natural Zeolite (PNZ) against the heavy metals present in the ball mill facilities within the Baguio Mining District. Results showed that removal percentages of PNB and PNZ in terms of lead (Pb) concentrations are 50.43% and 26.90%, respectively. Moreover, the dynamic uptake capacity and maximum adsorption capacity values of PNB showed greater values than PNZ and the sorption models, Bohart-Adams, Wolborska, Thomas, and Yoon-Nelson models, displayed good fit for the breakthrough curves. Furthermore, varying the flow rate and bed height manifested that an increase in flow rate yields a lesser saturation time while the rise in bed height increases uptake capacity, saturation time, and removal percentage of the system. Regarding the cost efficiencies of the sorbents, the study revealed that PNB is more cost-efficient than PNZ since only 1.13 Philippine pesos of PNB is required to remove a gram of Pb compared to PNZ, which costs 3.5 pesos. Therefore, this research concluded that PNB could be a better sorbent of Pb in terms of removal percentage and cost-efficiency. The study recommends further regeneration studies for the reusability of the sorbents after exhaustion and hopes that this research will be a springboard for further environmental studies.