Small-scale Experimental Setup Research Articles

Development and Assessment of a Miniaturized Test Rig for Evaluating Noise Reduction in Serrated Blades Under Turbulent Flow Conditions

The implementation of serrated stator blades in axial compressor and fan stages offers significant advantages, such as enhanced performance and reduced noise levels, making it a practical and cost-effective solution. This study explores the impact of serrated blade design on noise reduction under specific engine operating conditions. A small-scale experimental test setup with a turbulence-inducing grid was designed for testing multiple grid sizes in order to identify the most promising configuration which replicates rotor–stator interaction. Numerical simulations and early experimental tests in an anechoic chamber using a four-blade cascade configuration at an airflow speed of 50 m/s revealed a small but notable noise reduction in the 1–6 kHz range for a partially matched grid–blade geometry. Serrated blades demonstrated an overall sound pressure level reduction of 1.5 dB and up to 12 dB in tonal noise, highlighting the potential of cascade configurations to improve acoustic performance in gas turbine applications.

Study on the Influence of Casing Surface Morphology on the Plugging Performance of Downhole CO2 Plugging with Sn58Bi

Aimed at the problem of gas flurries in carbon dioxide (CO2) geologic sequestration in the wellbore, this paper proposes a sealing method in which the downhole casing is processed with threaded grooves and then plugged with a low-melting-point alloy plug. Based on this method, a small-scale experimental setup was developed for alloy plug molding and gas sealing in this study. Molding and gas sealing experiments with Sn58Bi alloy plugs inside casings with different surface morphologies were carried out. The gas leakage pathway was determined. The microstructure of the interface between the alloy plug and casing was analyzed using an optical microscope. The influence of the inner surface roughness, threaded groove, length-to-diameter ratio, and ambient temperature on the gas sealing performance of the alloy plugs was analyzed. The experimental results show that, with an increase in ambient temperature, the gas sealing performance of the casing increases significantly; when the inner surface of the casing is processed through threaded grooves, the gas sealing performance is better than with smooth hole casing; the gas sealing performance of the alloy plug presents an obvious linear positive correlation with their length-to-diameter ratio. This research provides theoretical support for downhole CO2 plugging using Sn58Bi in the casing.

Effects of synthetic site water on bentonite-concrete system for a potential nuclear waste repository

In high-level nuclear waste (HLW) repositories, concrete and compacted bentonite are designed to be employed as buffer materials, which may raise a problem of interactions between concrete and bentonite. These interactions would lead to mineralogy transformation and buffer performance decay of bentonite under the near field environment conditions in a repository. A small-scale experimental setup was established to simulate the concrete-bentonite-site water interaction system from a potential nuclear waste repository in China. Three types of mortars were prepared to correspond to the concrete at different degradation states. The results permit the determination of the following: (1) The macro-properties of Gaomiaozi (GMZ) bentonite (e.g. swelling pressure, permeability, the final dry density, and water content of reacted samples); (2) The composition evolution of fluids from the synthetic site water-concrete-bentonite interaction systems; (3) The sample characterization including Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). Under the infiltration of the synthesis Beishan site water (BSW), the swelling pressure of bentonite decreases slowly with time after reaching its second swelling peak. The flux decreases with time during the infiltrations, and it tends to be stable after more than 120 d. Due to the cation exchange reactions in the BSW-concrete-bentonite systems, the divalent cations (Ca and Mg) were consumed, and the monovalent cations (Na and K) were released. The dissolution of minerals in the bentonite such as albite causes Si increasing in the pore water. It was concluded that the hydro-mechanical property degradation of bentonite takes place when it comes into contact with concrete mortar, even under low-pH groundwater conditions. The soil dispersion, the uneven water content, and the uneven dry density in bentonite samples may partly contribute to the swelling decay of bentonite. Therefore, the direct contact with concrete has an obvious effect on the performance of bentonite.

Optimizing the ITER NBI ion source by dedicated RF driver test stand

The experimental fusion reactor ITER will feature two (or three) heating neutral beam injectors (NBI) capable of delivering 33(or 50) MW of power into the plasma. A NBI consists of a plasma source for production of negative ions (extracted negative ion current up to 329 A/m2 in H and 285 A/m2 in D) then accelerated up to 1 MeV for one hour. The negative ion beam is neutralized, and the residual ions are electrostatically removed before injection. The beamline was designed for a beam divergence between 3 and 7 mrad.The ion source in ITER NBIs relies on RF-driven, Inductively-Coupled Plasmas (ICP), based on the prototypes developed at IPP Garching; RF-driven negative-ion beam sources have never been employed in fusion devices up to now. The recent results of SPIDER, the full size ITER NBI ion source operating at NBTF in Consorzio RFX, Padova, measure a beamlet divergence minimum of 12mrad and highlighted beam spatial non-uniformity. SPIDER results confirmed the experimental divergence found in smaller prototype sources, which is larger compared to filament-arc ion sources. Although prototype experiments have shown that the extracted current requirement can be achieved with minor design improvements, the beamlet divergence is expected to marginally achieve the design value of 7 mrad, which in multi-grid long accelerators results in unexpected heat loads over the accelerator grids. A contributor to the beam divergence is the energy/temperature of the extracted negative ions, so it is believed that plasma differences between the two source types play a role. Research is focused on the plasma parameters in the ion source.One RF driver, identical to the ones used in SPIDER, installed in a relatively small-scale experimental set-up, inherently more flexible than large devices, is starting operations devoted to the investigation of the properties of RF-generated plasmas, so as to contribute to the assessment of negative ion precursors, and of their relationship with the plasma parameters, particularly when enhancing plasma confinement. The scientific questions, that have arisen from the preliminary results of SPIDER, guided the design of the test stand, which are described in this contribution, together with the diagnostic systems and related simulation tools. The test stand, which shares with the larger experiment all the geometrical features and constraints, will allow technological developments and optimized engineering solutions related to the ICP design for the ITER NBIs.

Detection and Measurement System for Button Mushrooms Using Convolutional Neural Network

In Malaysia, the button mushroom is recognized as a vegetable with high nutritional value and is easy to cultivate. Monitoring mushroom growth requires farmers to regularly inspect their crops, which is time-consuming and inefficient. Hence, an automated detection and measurement system for button mushrooms has been developed using image processing techniques based on convolutional neural network (CNN) algorithm model known as YOLOv4. The algorithm was utilized to train the system using button mushroom images to create training models. The performance of the YOLOv4 models was evaluated across various iterations ranging from 1000 to 6000 iterations. The model with 2000 iterations demonstrated the most effective performance based on Recall, Precision, F1-score, Time and Mean Average Precision metrics. The model was used in a small-scale experimental setup to evaluate the button mushroom detection and measurement system’s performance. Based on the results obtained from the experiments, the detection and measurement system demonstrated high accuracy in locating the position of each button mushroom with only a 5% deviation error in predicting the size of each button mushroom.

A z-Axis-Tolerant Inductive Power Transfer System Using a Bipolar Double D Receiver Coil Structure

This paper presents a solution to a limitation of wireless power transfer that arises when using two D-shaped transmitter and receiver coils. Double D, or DD, coils are well known to have a polar, directional magnetic field, which increases the misalignment tolerance in one of the directions. The misalignment tolerance is nonsymmetric, and it is significantly better in one of the directions, which can also be considered a shortcoming. An additional shortcoming of the DD coil is that it is dependent on the rotation around the z-axis, due to the directional magnetic field. This is not a problem when using classic planar spiral coils, which do not generate a directional magnetic field. Therefore, DD coils are not suitable for applications in which the z-axis orientation is not determined and fixed to specific angle and direction. This paper presents a unique design of a transmitter coil, based on a double DD coil. The transmitter coil consists of two DD coils which are perpendicular to each other. The proposed transmitter structure can excite the receiver DD coil in a way that the efficiency of the power transfer is the highest, regardless of the orientation. The proposed transmitter structure can, therefore, solve the problem with rotation of a single DD coil. The proposed system structure was tested on the small-scale experimental setup.

Optical and electrical performance of an agrivoltaic field with spectral beam splitting

Solar photovoltaic power generation is a mature and competitive technology, but its high land area requirements conflict with other uses of available land. Agrivoltaics (APV) allows dual use of land, with photovoltaic panels installed over agricultural crops. However, the panels block a significant portion of the solar radiation, leading in many cases to a severe reduction in growth and productivity of the agricultural crop. Here, we present a novel type of collector to resolve this competition between electricity and crop yields by spectral splitting of the incident direct radiation using simple planar components. Photosynthetically active radiation (PAR) is transmitted to the crop while near-infrared radiation (NIR) is directed to the PV panels. The annual optical and electrical performance of a large-scale agrivoltaic field with these spectrum-splitting collectors is investigated in detail. The study is conducted using a computational model that includes optics, heat transfer, and electrical conversion. The reliability of the model was validated using experimental data obtained from a small-scale experimental setup. Results show that the electricity production per unit land area of the spectrum-splitting collectors can be similar to that of conventional APV fields and may reach even higher value by about 20% with optimized spectral splitters. According to the simulations, the loss of PAR on the ground due to the collectors may be significantly reduced, reaching only 10% compared to 21% in a conventional APV field.

Advanced electrochemical platform for simple and rapid quantification of tannic acid in beverages using batch injection analysis with amperometric detection

In this work, an advanced electrochemical platform was developed for the simple, rapid and sensitive determination of the polyphenolic compound tannic acid in various beverages using the combination of batch injection analysis with amperometric detection on a screen-printed carbon electrode. Several experimental parameters (pH of supporting electrolyte, detection potential, dispensing rate, injected volume, stirring) were consistently evaluated. The most favorable analytical performance in terms of sensitivity, selectivity, repeatability and sampling frequency was obtained in Britton-Robinson buffer pH 5.0 at a detection potential of +0.6 V vs. Ag/AgCl, a dispensing rate of 204 µL/s and an injected volume of 80 µL under stirring condition (1500 r.p.m.). The presented platform has advantages for routine analysis including portable and small-scale experimental setup, low sample consumption (∼100 µL), simple sample preparation (dilution in supporting electrolyte), high sampling frequency (180 injections per hour), low limit of detection (80 nM) and suitable precision (RSD = 4.2% for 10 μM tannic acid, n = 20). The applicability of the method was verified by analyzing several beverage samples (tea, wine) in spike-recovery assay with the recovery values for tannic acid ranging from 94 to 101 %.

A preliminary experimental study of a novel incorporation of chilled ceiling with phase change materials and transparent membrane cover

Abstract This study presents an experimental investigation into a novel incorporation of chilled ceiling with transparent membrane cover and phase-change material (PCM) to form a new type of PCM chilled ceiling panel. The membrane cover is infrared transparent to facilitate radiant cooling, but serves as a barrier of convection to avoid moisture condensation for applications in humid climate regions. As reliable electricity supply is still not accessible to millions of people, especially in sub-Saharan and South Asian countries where these countries also face the combined problems of high cooling demand and inadequate power supply, the use of solar energy would help to overcome these problems. To address such problems, the proposed PCM chilled ceiling can be applied along with a solar photovoltaic (PV) directly driven vapour-compression cooling system. Electricity generated by the photovoltaic (PV) panels drives the variable speed direct current (DC) compressor for cooling production, while excessive cooling is stored in the PCM packs for use at night. The variable speed compressor can adjust to match fluctuation in solar radiation and hence increases the utilization of solar energy. A small-scale experimental setup was prepared using a mini DC compressor refrigeration system. Integration of salt hydrate type PCM in chilled beam and chilled ceiling, respectively, and application of transparent membrane cover in chilled ceiling were tested to verify the proposed design.

Localization and Mechanical Transmission of Tomato Brown Rugose Fruit Virus in Tomato Seeds.

Tomato brown rugose fruit virus (ToBRFV), belonging to the genus Tobamovirus, is a highly virulent emerging virus, causing disease outbreaks and significant crop losses worldwide. The growing number of ToBRFV epidemic episodes prompted the investigation of the role of seeds in the dissemination of the virus as an important aspect in the overall disease management. Therefore, the objectives of this study were to determine the localization of ToBRFV within tomato seeds and to evaluate its seed transmission characteristics. Seeds extracted from naturally ToBRFV-infected tomato fruits were tested for the presence of the virus using serological, molecular, and biological assays. Three immunolocalization techniques were used to determine the localization and distribution of ToBRFV within the different tissues and parts of tomato seeds. To evaluate seed transmission of ToBRFV, two grow-out experiments were conducted to assess the rate of both vertical (seeds to progeny seedlings) and possible horizontal transmission (plant to plant) based on serological and molecular assays. Seeds extracted from ToBRFV-infected fruits had a 100% contamination rate. The localization of ToBRFV in tomato seeds is only external on the seed coat (testa). Seed transmission rate from seeds to their seedlings was very low (0.08%), while no transmission was recorded from plants to plants in a small-scale greenhouse experimental setup. In conclusion, ToBRFV is a seedborne virus located externally on tomato seed coat and transmitted mechanically from ToBRFV-contaminated tomato seeds to seedlings, which could initiate a disease foci and eventually drive further dissemination and spread of the disease in a new growing area.

Experimental analysis of fractional order PI λ D μ controller for improvement of power quality in smart grid environment

Power electronics load is considered to be a strengthening factor that leads the system operators more concerned about power quality issues. Poor power quality can lead to distinctive operation of electrical components and devices, which may cause heavy economic loss to the customers and power network operators. An application of fractional order PIλDμ (FOPIλDμ) controller for power quality improvement in smart power distribution systems is presented here. Analytical design steps are presented for the FOPIλDμ controller. A genetic algorithm is used for tuning the control parameters of the FOPIλDμ controller optimally. The FOPIλDμ controller is employed and evaluated for shunt active power filter (APF) to filter out harmonics and improve reactive power compensation for non-stationary, non-linear load conditions for a smart power distribution system. Effectiveness of FOPIλDμ controller for instantaneous reactive power theory based PQ control algorithm applied to shunt APF is validated using a small-scale laboratory experimental setup. The experimental results confirm the excellent performance of the FOPIλDμ controller in terms of its superior transient response, significant reduction in harmonic distortion, and improved reactive power compensation in a smart grid environment.

Experimental wildfire induced mobility of radiocesium in a boreal forest environment

Wildfires are expected to increase with warmer climate, which can contribute to the mobility and the resuspension of long-lived and potentially hazardous radionuclides. The release of 137Cs during combustion of dried litter, forest floor organic soil, and peat was investigated in a small-scale experimental set-up. Combustion conditions were varied to simulate different wildfire scenarios, and the fuels were dried organic material collected in a boreal environment of Sweden that was contaminated following the Chernobyl accident in 1986. The combustion-related release of 137Cs to the air was on average 29% of the initial fuel content, while 71% of the initial 137Cs remained in the ashes after the combustion. Peat and forest soil had the highest releases (39% and 37%, respectively), although these numbers should be viewed as potential releases since authentic wildfire combustion of these fuels are usually less effective than observed in these experiments. These results indicates that the 137Cs has migrated downwards in the organic material, which imply potentially significantly more 137Cs emissions in severe wildfires with intense combustion of the organic vertical profile in peatbogs and forests. More 137Cs tended to be released during intense and efficient combustion processes, although no significant differences among combustion intensities were observed.The generated experimental data was used in an emission scenario to investigate the possible range in 137Cs emissions from a wildfire. Our study shows that a severe wildfire in a contaminated area of 10,000 ha could potentially release up to 7 TBq of 137Cs. This is the first laboratory study to investigate 137Cs release upon varying combustion conditions using real fallout contaminated organic material obtained from a boreal environment.

Experimental Study of Heat Transfer Enhancement by Turbulence Generator in Side Pipe

The enhancement of heat transfer exchangers is an important matter of concern for achieving more efficient thermal energy conversion systems. The use of modified twisted tape (TT) inserts as a passive heat transfer augmentation technique is an efficient way of improving heat transfer. Twisted tape insert is one of the passive heat transfer enhancement techniques that are widely used in various applications for heat transfer, such as air conditioning and cooling systems, heat recovery systems, Processes, procedures for food and milk, plants for chemical processes. To increase the heat transfer rate of the tubular heat exchanger, in this study a small-scale experimental setup was performed. The heat improvement of the heat exchanger is done using twisted tape inserts with a twist ratio (y=5.5). The effects of two-dimensional parameters namely Nusselt number & friction factor on tubular heat exchanger effectiveness are studied. The turbulent flow was generated by the insertion into the test pipe of the twisted tape inserts, producing a high turbulence rate in the pipe, resulting in an increase in turbulence. And hence the enhancement of heat transfer and drop in pressure. The length and width of the insert were 1000 mm and 21.5 mm respectively. The diameter of the test pipe outside & inside is 23 mm and 22 mm respectively. The length of the test section is 2000 mm. The study is carried out for the Reynold number regime (500-6500). The results show that The maximum enhancement for Nu number at Re 500 was 32% that of the plain tube.

Experimental-theoretical approach to calculating the partial density of hydrogen cyanide during fires at energy facilities

It is made analysis of toxic effect of hydrogen cyanide on people during fire evacuation at energy facilities premises. The critical value of the partial density of hydrogen cyanide is substantiated. An experimental and theoretical approach is proposed for calculating the partial density of hydrogen cyanide indoor fire. The proposed approach is based on the analytical dependence of the average volumetric partial density of HCN on the change in the volumetric average partial density of oxygen in the premises. The results of experiments on measuring the partial density of HCN in the case of combustion of modern cable products used at energy facilities are presented. The results of experimental and theoretical studies make it possible to determine the time variation of the average volumetric partial density of hydrogen cyanide in a fire in a full-scale premises using the experimental values of the specific coefficients of formation of hydrogen cyanide and oxygen absorption obtained in a small-scale experimental setup, and the change of the volumetric average partial density of oxygen obtained from the solution of the conservation law equation mass of oxygen. It is substantiated that the calculation can also be made without solving the differential equation of the law of conservation of the mass of hydrogen cyanide using only the experimental dependence of the HCN density on the change in O2 density.

Cryogenic two-phase natural circulation loop

This paper presents the application of cryogenic natural circulation loop for engine cooling of launch vehicles, and the experimental measurements of the natural circulation system. The experimental results indicate that the circulation flow rate increases with an increase in heat input and a decrease in system pressure, on varying them. The study includes the temperature and pressure profiles of the natural circulation loop. The steady-state flow rate calculation was developed with two-phase models: the homogeneous equilibrium model (HEM) and thermal equilibrium drift-flux model (TEDFM). The TEDFM revealed a 5% error in the experimental circulation flow rate, and it is agreeable with the experimental results. The small-scale experimental setup verified the two-phase flow pattern in the cryogenic natural circulation loop. A fully liquid flow was observed in the downward section. The horizontal section had a bubbly flow, where the speed of the gas and liquid were similar. The slug and churn flows were present in the vertically upward section, where gas velocities were faster than liquid. Both HEM and TEDFM can be applied in the horizontal heated section. However, it is more appropriate to apply TEDFM in the vertically upward section during the pressure drop calculation for the cryogenic natural circulation loop.

Experimental assessment of a small scale hybrid liquid desiccant dehumidification incorporated vapor compression refrigeration system: An energy saving approach

This work investigates a small-scale hybrid experimental setup developed combining the two technologies of liquid desiccant dehumidification and vapour compression refrigeration. A hybrid system of 5 kW capacity is designed and developed for energy saving analysis. The experiments are designed with central-composite design scheme using three variables namely air mass flow rate, desiccant inlet temperature, and desiccant inlet concentration. Three responses namely specific humidity change in the dehumidifier, dehumidifier heat load and hybrid system performance coefficient are considered for the investigation. The regression correlations for all three responses are developed and presented. Further, the performance comparison of the hybrid system with the standalone vapour compression refrigeration unit is also carried out. The comparative results reveal that the maximum improvement of 27.54% is observed in the coefficient of performance at which 54.93% of the total latent heat load is being covered by the dehumidifier. Finally, the energy saving analysis reveals that the hybrid system is having payback duration of 4 years compared to the standalone vapour compression refrigeration system of same cooling capacity.

A THREE INPUT DC-DC CONVERTER FOR HYBRID ENERGY APPLICATION

Power electronic converters are so crucial in the integration of different energy sources in the concept of Hybrid Energy System (HES). A three input DC-DC converter with buck-boost operating capability is introduced in this paper. The converter is capable of integrating energy sources which have different V-I characteristics. The output equation of the DIDC converter is derived from different working states using voltage - second principle. Also, the converter which has been presented in this paper can incorporate a single source or multiple sources with a small modification in the converter structure. This converter topology is designed and simulated in MATLAB / SIMULINK platform. Three input sources with different voltage levels such as 30 V, 20 V and 10 V are used for the performance evaluation of the converter. A small scale experimental setup has been developed to check the performance evaluation of the converter in real time condition and the results are incorporated. Also the efficiency profile of the converter under various loading condition has been analyzed which clearly shows that the presented converter has a good efficiency level.

Experimental Study to Investigate the Effect of Backfilling Materials on Thermal Performance of Ground Air Heat Exchanger System

Abstract In ground air heat exchanger (GAHE) system, the heat transfer between air and underground soil largely depends on soil thermal properties and therefore, any improvement in soil thermal properties will shorten the pipe length required and the land area needed for its installation. The objective of the present study is to investigate the effect of different backfilling materials (low cost and locally available) on the thermal performance of GAHE system using a small-scale laboratory experimental setup. Seven different backfilling materials have been considered for the study and it was observed that after 6 h of continuous operation, the drop in air temperature was 6.2 °C at outlet section of pipe (2.4 m away from inlet) for the native soil. However, for sand–bentonite with graphite as a backfilling material (BFM), the drop in air temperature of 6.2 °C was obtained at a pipe length of 1.15 m only. Therefore, the use of sand–bentonite with graphite as a BFM reduces the pipe length of GAHE system by more than 50%. The study establishes the fact that the length of pipe and land area requirement for GAHE system can be substantially reduced by using thermally enhanced backfilling materials at the close vicinity of GAHE pipes.

Non-Invasive Magnet Temperature Estimation of IPMSM Based on High-Frequency Inductance With a Pulsating High-Frequency Voltage Signal Injection

In this paper, a method to estimate the temperature of a permanent magnet of a traction motor for automotive applications is derived by analyzing the high-frequency inductance of an interior permanent-magnet synchronous motor. The derived method exploits the high-frequency inductance as an indicator of the magnet temperature, and it does not require a temperature sensor not only on the rotor side but also on the stator side. Hence, the method is truly noninvasive. The proposed method has been verified in a small-scale experimental setup. The performance of the method has been evaluated at various torques, speeds, and magnet temperatures ranging from -24 to 82 °C. Through testing at various operating conditions, it has been confirmed that the maximum error is less than 2.9 °C even when the speed and torque vary.

Analysis of underwater gas release and dispersion behavior to assess subsea safety risk.

Underwater gas release and dispersion characteristics are important to assess and manage potential risks. This paper presents an experimental and numerical investigation of underwater gas release and dispersion behavior. A small-scale experimental setup is designed and developed for underwater gas release and dispersion study. A series of release scenarios are carried out to study the effect of release size, leak pressure, and leak direction on dispersion behavior. The underwater gas dispersion behavior is analyzed from the risk assessment perspective. The considered parameters included plume offset, plume radius and fountain height for different scenarios. The experimental results are used to test and verify numerical computational fluid dynamics model using Eulerian-Lagrangian approach. The developed numerical model is subsequently used to analyze the gas plume in a full-scale scenario. The developed model would help to support risk assessment and response planning of potential subsea gas release accidents.