Medium Flow Rate Research Articles

Analysis of erosion and sealing characteristics of V-regulating ball valves for coal chemical industry

Purpose This study aims to research the erosion wear characteristics and sealing performance of V-regulating ball valve in coal chemical process pipelines, which provides a theoretical reference for improving its antiwear and sealing performance. Design/methodology/approach Taking the V-regulating ball valve as the research object, based on the computational fluid dynamics and the theory of erosion wear, the authors studied its erosion characteristics under different medium parameters and analyzed the sealing performance under the heat-fluid–solid coupling working condition. Findings The erosion wear mechanism of the valve sealing surface is the simultaneous action of cutting and deformation. When the medium flow velocity, particle mass flow rate and particle size increase, the maximum erosion rate and average erosion rate in the V-regulating valve increase. The inner diameter Mises contact stress of the sealing surface is symmetrically distributed in a “wing shape,” and the contact stress of the outer diameter is distributed in a “butterfly shape.” Due to the superposition of thermal stress and pressure stress in the contact transition zone to produce a significant stress concentration. Practical implications The findings will provide a theoretical basis for improving the erosion resistance and sealing performance of V-regulating ball valve in coal chemical industry. Social implications V-type regulating ball valve is widely favored by coal chemical enterprises and petrochemical enterprises because of its wide adjustment ratio and good erosion resistance. Originality/value The V-regulating ball valve wear mechanism for cutting and deformation simultaneously, and its wear rate is positively correlated with the medium flow rate, particle mass flow rate and particle size. After the valve is opened, there is a significant stress concentration occurs in the contact transition zone due to the superposition of thermal stress and compressive stress. The findings will provide a theoretical basis for improving the erosion resistance and sealing performance of V-regulating ball valve in coal chemical industry. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2024-0205/

Development of a Microbioreactor for Bacillus subtilis Biofilm Cultivation.

To improve our understanding of Bacillus subtilis growth and biofilm formation under different environmental conditions, two versions of a microfluidic reactor with two channels separated by a polydimethylsiloxane (PDMS) membrane were developed. The gas phase was introduced into the channel above the membrane, and oxygen transfer from the gas phase through the membrane was assessed by measuring the dissolved oxygen concentration in the liquid phase using a miniaturized optical sensor and oxygen-sensitive nanoparticles. B. subtilis biofilm formation was monitored in the growth channels of the microbioreactors, which were designed in two shapes: one with circular extensions and one without. The volumes of these microbioreactors were (17 ± 4) μL for the reactors without extensions and (28 ± 4) μL for those with extensions. The effect of microbioreactor geometry and aeration on B. subtilis biofilm growth was evaluated by digital image analysis. In both microbioreactor geometries, stable B. subtilis biofilm formation was achieved after 72 h of incubation at a growth medium flow rate of 1 μL/min. The amount of oxygen significantly influenced biofilm formation. When the culture was cultivated with a continuous air supply, biofilm surface coverage and biomass concentration were higher than in cultivations without aeration or with a 100% oxygen supply. The channel geometry with circular extensions did not lead to a higher total biomass in the microbioreactor compared to the geometry without extensions.

Dynamic modelling and optimal operation of the photovoltaic/thermal

This paper aims to introduce a dynamic model for a photovoltaic/thermal system, highlighting an approach and synthesis of existing dynamic models to depict the full photovoltaic/thermal system. The model was validated using data from an experimental setup at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor, under different weather conditions. The model's accuracy was assessed through normalized Root Mean Square Error, normalized Mean Bias Error, Correlation Coefficient, and the coefficient of determination error metrics, focusing on the temperature and electrical output power of the photovoltaic/thermal modules, as well as the temperature of the thermal energy storage tank. Furthermore, the paper also focuses on the optimal operation of the photovoltaic/thermal system under different mass flow rates of the working medium.

Heat transfer characteristics during bottom-blown bubble coalescence

Bubble swarm evolution and behaviors are the key to study the heat transfer between a bubble swarm and its surrounding flow field, and are of significant and systematic theoretical guidance for exploring the process reinforcement technology and processes. In this study targeted at Therminol®66 and R245fa, we analyzed the three factors affecting gas-liquid two-phase flow. The results show that the flow rate of the dispersed phase has a significant effect on the heat transfer coefficient. When the flow rate of the working medium increases from 0.4 kg s-1 to 0.8 kg s-1, the heat transfer coefficient increases by about 1.25 times. The initial temperature difference is positively correlated with the heat transfer coefficient, but the continuous phase height increases the heat transfer coefficient first and then decreases. The heat transfer coefficient model is in good agreement with the results of Kwon, and the deviation is within 20 %, accounting for 92.464 %, which can be further used to describe the heat transfer process of heat exchanger or bottom-blown melting pool. Correlation equations for the Nusselt number (Nu) is developed, with average absolute deviation of 18.49 %.

Droplet Microfluidic Method for Estimating the Dynamic Interfacial Tension of Ion-Crosslinked Sodium Alginate Microspheres.

The research focuses on optimizing the production of hydrogel microspheres using droplet microfluidics for pharmaceutical and bioengineering applications. A semiempirical method has been developed to predict the dynamic interfacial tension at the interface of ion-cross-linked sodium alginate microsphere-sunflower oil modified with glacial acetic acid and Tween 80 surfactant. These microspheres are produced in a small-scale coaxial device that is manufactured using affordable DLP/LCD 3D printing technology with a transparent photopolymer. The method was tested to design the minireactor in the device, which allows for the production of fully cross-linked microspheres that are ready for use at the output of the reactor without additional cross-linking steps in the microsphere collector. The mathematical expression for estimating the interfacial tension at the moment of formation of a hydrogel microsphere includes the Reynolds number for a two-phase liquid, the Ohnesorge number, and the surface tension at the liquid-air interface for continuous medium flow (modified oil). The reliability of the prediction is confirmed for continuous medium and dispersed phase flow rates of 0.8-3.2 and 0.01-0.08 mL/min, respectively. The evolution of the interfacial tension from the moment the microspheres formed and the estimated ultimate interfacial tension in a cross-linked hydrogel-modified oil system contributed to the reliable determination of the linear size of a minireactor. The ultimate interfacial tension of 76.5 ± 0.3 mN/m was determined using the Young-Laplace equation, which is based on measuring the surface free energy of the hydrogel as soft matter using the Owens-Wendt method. Additionally, the equilibrium static contact angle of the fully cross-linked hydrogel surface wetted with oil is measured using the sessile drop method. From a practical perspective, a method for optimizing and streamlining the high-tech manufacturing of cross-linked polymer microspheres and mini- and microchannel devices for use in bioengineering and pharmaceutical applications is suggested.

Oxidation Study and Mechanism Analysis of Desulfurization Ash in Dense-Phase Tower

Dense-phase-tower desulfurization technology is an emerging semi-dry flue-gas desulfurization ash process, i.e., the flue gas is allowed to enter the desulfurization tower from the bottom up and, at the same time, is sprayed with a desulfurizing agent that undergoes an acid–base reaction with the flue gas in the ascent process. The calcium sulfite and calcium sulfate produced by the reaction and the part of the desulfurization agent that is not involved in the reaction will enter the subsequent dust removal system, and what is retained is the by-product desulfurization ash. This desulfurization ash contains a large amount of calcium sulfite, which leads to its unstable nature; it is easily oxidized and expands in volume, and, if used in the field of building materials, it will lead to cracking and other problems, so it is difficult to effectively use it. In order to solve this problem, XRF, XRD, and iodometric and other analytical methods were used to determine the specific composition of desulfurization ash, and the muffle furnace and vertical tube furnace were used to study the thermal oxidative modification of calcium sulfite in desulfurization ash, to investigate the effects of the oxygen content, reaction temperature, medium flow rate, and chloride content on the oxidation of calcium sulfite, and to analyze the thermodynamics in the high-temperature oxidation reaction. The results showed that the oxidation rate of calcium sulfite increased with higher reaction temperatures. Increased oxygen content promoted the oxidation rate, particularly at low oxygen levels. The oxidation rate of calcium sulfite correlated positively with the medium flow rate until a rate of 75 mL·min− was reached. At a reaction temperature of 420 °C and a gas flow rate of 85 mL·min−1, the oxidation conversion efficiency exceeded 89%. Chloride content significantly reduced the oxidation rate of calcium sulfite, although this inhibition weakened at temperatures above 500 °C. Kinetic analysis suggested that the oxidation reaction of calcium sulfite predominantly occurred below 500 °C. These findings have both theoretical and practical implications for the thermal oxidation treatment and disposal of desulfurization ash.

Geothermal In-Situ Heat Transfer Control Factor Simulation and Numerical Analysis

Geothermal energy, as a renewable and clean energy source, holds immense potential in meeting energy demands and reducing carbon emissions. Its unique sustainability and environmental friendliness make it an important complement to addressing today's energy challenges. Coaxial tubing in-situ heat exchange technology for geothermal wells, as a key extraction method for geothermal energy, is subject to control by multiple critical factors that directly relate to its efficiency and feasibility. This paper aims to delve into the technology of coaxial tubing in-situ heat exchange for geothermal wells through numerical simulation analysis, with a focus on studying the impacts of three key factors on its performance: heat transfer medium flow rate, inlet water temperature, and cement thermal conductivity. Through numerical analysis, this study aims to reveal the variations of these factors to provide more refined control methods and optimize the coaxial tubing in-situ heat exchange technology for geothermal wells. By conducting experimental simulations and numerical analysis on these key factors, this paper aims to provide strong support for optimizing the coaxial tubing in-situ heat exchange technology for geothermal wells, which will contribute to advancing geothermal energy technology and promoting the sustainable utilization of clean energy.

Unwinding the correlation between atmospheric pressure plasma jet operating parameters and variation in antibiotic wastewater characteristics

The influence of plasma operating parameters such as gas medium, electrode distance, applied voltage, gas flow rate, and their interdependency on reactive species generation was investigated. Full factorial design-based response surface methodology (RSM) was used to establish the correlation between the operating parameters. The optimization studies were carried out by taking energy yield and degradation efficiency as response parameters. The operating voltage of 9 kV, the airflow rate of 2 LPM, and the electrode distance of 5 mm are optimum for the system studied. The higher voltage of 9 kV and a flow rate of 2 LPM give maximum yield due to the increased rate of gas atoms undergoing ionization. However, at the low voltage (5 kV), the increase in air flow rate from 0.5 to 2 LPM, the energy yield decreases from 67.5 to 54.2 mg/kWh. These observations are further supported by measuring OH (A-X) intensity in an air medium using optical emission spectroscopy. The studies also reveal that the degradation efficiency is adversely affected by scavenges, with a maximum from isopropyl alcohol, followed by tert-butyl alcohol and methanol. TOC and LC-MS analyses established complete mineralization and its degradation pathway. Phytotoxicity studies suggest that treated effluent, rich in nitrates, is suitable for irrigation, promoting seed germination. In short, the studies provide a strategy to optimize the generation of reactive chemical species in a reactor and how such optimization would help attain optimum energy yield, especially when there is a fluctuation in target pollutant concentration.

CmpX overexpression in Pseudomonas aeruginosa affects biofilm formation and cell morphology in response to shear stress

Pseudomonas aeruginosa is an opportunistic pathogen causing chronic infections that are related to its ability to form biofilms. Mechanosensitive ion channels (Mcs) are cytoplasmic membrane proteins whose opening depends on a mechanical stress impacting the lipid bilayer. CmpX is a homologue of the small conductance MscS of Escherichia coli. The cmpX gene is part of a transcriptional cfrX-cmpX unit that is under the control of the cell envelope stress response ECF sigma factor SigX. CmpX was shown to regulate the activity of the hybrid sensor kinase PA1611 involved in the regulation of transition from a planktonic to a biofilm lifestyle. The deletion of cmpX leads to increased biofilm formation under static conditions. Herein, the effect of cmpX overexpression was investigated by confocal laser scanning microscopy in terms of biofilm formation and architecture, and matrix components production, in dynamic conditions. We show that overexpression of cmpX in P. aeruginosa leads to enhanced and altered biofilm architecture that seems to be associated to increased matrix components and the emergence of filamentous cells. These phenotypic alterations might occur potentially through a shear stress induced by the medium flow rate. ImportanceCmpX is involved in biofilm formation and cell filamentation with regards to the medium flow.

Impact of initial high flow nasal cannula flow rates on clinical outcomes in children with bronchiolitis.

Our aim was to evaluate the impact of the initial high flow nasal cannula (HFNC) flow rate on clinical outcomes in children with bronchiolitis. This secondary analysis of retrospective data included children <2 years who required HFNC for bronchiolitis between 10/01/2018-04/20/2019, and following implementation of a revised institutional bronchiolitis pathway between 10/01/2021-04/30/2022. The new pathway recommended weight-based initiation of HFNC at 1.5-2 L/kg/min. We evaluated the effect of low (<1.0 L/kg/min), medium (1-1.5 L/kg/min) and high (>1.5 L/kg/min) HFNC flow rates on need for positive pressure ventilation (PPV), intensive care unit (ICU) transfer, HFNC treatment time, and hospital length of stay (LOS). The majority of the 885 included children had low initial flow rates (low [n = 450, 50.8%], medium [n = 332, 37.5%] and high [n = 103, 11.7%]). There were no significant differences in PPV (high: 7.8% vs. medium: 9.3% vs. low: 8.2%, p = 0.8) or ICU transfers (high: 4.9% vs. medium: 6.0% vs. low: 3.8%, p = 0.3). The low flow group had a significantly longer median HFNC treatment time (High: 29 [18, 45] vs. medium: 29 [16, 50] vs. low: 39 [25, 63], p < .001) and hospital LOS (High: 41 [27, 59] vs. medium: 42 [29, 66] vs. low: 50 (39, 75), p < .001). Logistic and linear regression models did not demonstrate any associations between HFNC flow rates and PPV or hospital LOS. Initial HFNC flow rates were not associated with significant changes in clinical outcomes in children in children with bronchiolitis.

IMPROVEMENT OF DIMENSIONS AND CHARACTERISTICS OF THE VORTEX CHAMBER PUMP FOR COAL-WATER MEDIUM DELIVERING

The vortex chamber pump combines the positive characteristics of the centrifugal pump and the jet pump, and its efficiency is much higher than that of the classical jet pump. This pump differs from the vortex injector by having the pump flow into the tangential outlet channel, which is not available in the vortex injector. The traditional bulk material pump in many aspects has certain shortcomings, these shortcomings limit its application scope and use effect, the traditional bulk material pumps mechanical parts and seals rapidly wear, resulting in short service life. Based on solving the Reynolds equations for water flow, the influence of the angle between the tangential channels of the pump on the energy characteristics is analyzed: an increase in the angle to 180° leads to a decrease in the relative efficiency by 30 %, the outlet pressure by 12 %, and the suction flow rate by 14 %. Thus, the design with a zero angle between the tangential active medium inlet and the tangential outlet channels is optimal in terms of energy-saving pumping performance. As the diameter of the vortex chamber increases, there is no significant trend in the efficiency of the pumped fluid be the vortex chamber pump. With the increase in the total supply pressure, the axial inlet flow rate increase is relatively slow, and the outlet flow rate increases in a parabolic trend. The wear of the pump vortex chamber wall depends on the mass flow rate of coal entering the vortex chamber. The larger the mass flow rate of the abrasive medium, the greater the erosion rate density and the mean volume fraction in the vortex chamber of the vortex chamber pump. The smaller the particle diameter of the coal, the larger the erosion rate density and mean volume fraction in the vortex chamber of the vortex chamber pump. Thus, an increase in particle size should be sought, which will result in less wear.

Characteristics of fungi formation in urban sewer at different flow conditions: Distribution, metabolism, and pathogenicity

Fungi are the significant components of the sewer ecology system which can consume substances and exhibit pathogenicity. However, the characteristics of fungi formation and metabolism in the complex sewer environment have not been revealed in depth. In this study, gradient flow conditions were conducted in a pilot sewer and the formation characteristics of fungi were synthetically investigated. The results showed that the low flow rate at 0.1–0.4 m/s led to the loose morphology of biofilms, while the overly loose environment did not allow fungi communities to thrive in sewer. The dense biofilms were found at the middle flow condition (0.4–0.6 m/s), and the fungal communities with degradation functions were exuberant at this condition (such as Tremellales with relative abundance of 6.18% and Talaromyces with relative abundance of 6.51%). In particular, eleven kinds of fungi with known pathogenicity of the sewer biofilm were found in this study, and it is worth noting that the abundance of pathogenic fungi at medium flow rates is significantly higher than that at other flow conditions (higher than 10 %). While, excessive flow shear force (0.8–1.2 m/s) led to biofilm shedding which caused hindering the proper generation of fungi. In summary, the pollutant transformation and pathogenic exposure conducted by fungi communities could affect the sewer management process significantly, and this study could provide research foundation for wastewater quality prediction and management of pathogenic risk in sewer systems.

Experimental and numerical analysis of the thermal performance of pebble solar thermal collector

In this work, pebbles of higher specific heat than the conventional absorber materials like aluminium or copper are proposed as a absorber in the solar flat plate collector. The proposed collector are integrated into the building design and constructed with masonry. Tests were conducted by varying the operating parameters which influence its performance, like the flow rate of the heat-absorbing medium, and the tilt of the collector using both coated and uncoated pebbles. The maximum temperature difference that could be measured for a conventional absorber was approximately 8 °C for a flow rate of 0.6 L/min. While for a coated and uncoated absorber, it was 7 °C and 5.5 °C respectively. This difference decreased with an increase in flow rates from 0.6 L/min to 1.2 L/min. For all the flow rates, it was observed that the average difference in efficiency between the coated and the conventional absorber collector is 5.82 %, while the difference between the coated and uncoated absorber collector is 15.68 %. Thus, it is very much evident that by replacing the conventional absorber with the proposed coated pebble absorber, the overall loss in efficiency is just 5.82 %, but the advantages are enormous. Along with the experimental study, numerical analysis was also carried out with CFD modeling. The numerical results agreed well with experimental results with the least error. Therefore, CFD simulation can be further used to optimize the design of the collector.

Transport of Antibiotics, Antibiotic Resistant Bacteria, and Antibiotic Resistance Genes Through Prairie Strips During Simulated Runoff

HighlightsA physical model system was used to track resistance contaminants through prairie strips.Resistance contaminants included antibiotics, antibiotic-resistant bacteria, and antibiotic resistance genes.Subsurface filtration caused the highest concentration reduction of resistance contaminants.Infiltration is highlighted as a key feature in concentration and mass load reductions.Abstract. Antibiotic use in production animals can drive the development and spread of antibiotic resistance within environmental systems. Transport pathways of resistance contaminants from animals to the environment are known, but there is no regulatory consensus on which specific contaminants should be monitored. Furthermore, there is a need for management practices to combat the transport of these resistance contaminants. The objective of this study was to evaluate Conservation Practice 43 prairie strips for their reduction of three resistance indicators: antibiotics, antibiotic-resistant bacteria, and antibiotic resistance genes, from manure-impacted overland flow under varying run-on flow rates. High, medium, and low run-on flow rates were tested with the use of a laboratory-scale flume containing a field-extracted section of prairie strip. Grab samples were collected immediately upstream, downstream, and beneath the prairie strip, representing run-on, runoff, and infiltrated flows, respectively. Percent reductions in the median concentration of each resistance contaminant were calculated for each flow experiment at both the runoff and infiltration sampling locations to demonstrate the impact of the prairie strip. However, in instances where an increase in the median concentration of a contaminant occurred between the run-on sampling location and either the runoff or infiltration sampling locations, a negative percent reduction is reported. Across all flows, the percent reductions in median concentrations at the runoff sampling location ranged from -11.4%–0.8% for antibiotics, 1.2%–28.2% for bacteria, and -4.2%–30.5% for genes. In comparison, the percent reductions in median concentrations at the infiltration sampling location ranged from -23.9%–43.6% for antibiotics, 12.9%–65.5% for bacteria, and -12.6%–43.5% for genes. The dataset from this study supports the use of appropriately designed prairie strips to decrease the concentrations and loads of resistance contaminants that are transported downstream from manured fields and can be used to inform in-field design parameters. Keywords: Antibiotic resistance, Flume, Swine manure, Water quality.

Impact of thermal desorption tubes on the variability of exhaled breath data

Due to the overall low abundance of volatile compounds in exhaled breath, it is necessary to preconcentrate the sample prior to traditional thermal desorption (TD) gas chromatography mass spectrometry analysis. While certain aspects of TD tubes, such as volatile storage, have been evaluated, many aspects remain uncharacterized. Two common TD tubes, Tenax TA and Biomonitoring 5TD tubes, were evaluated for background content and flow rate variability. The data illustrate that the Biomonitoring 5TD tubes have the highest number (23) and abundance of background contamination greater than 3x the mean noise when compared to Tenax TA (13) and empty tubes (9). Tentative identifications of the compounds in the background contamination experiment show that greater than 59% (16/27) of the compounds identified have been reported in the breath literature. The data illustrate the TD tube background abundance could account for more than 70% of the chromatographic signal from exhaled breath for these select compounds. Flow rate measurements of 200 Tenax TA and 200 Biomonitoring 5TD tubes show a large range in measured flow rates among the TD tubes (Tenax: 252.9–284.0 ml min−1, 5TD: 220.6–255.1 ml min−1). Finally, TD tubes of each type, Tenax TA and Biomonitoring 5TD, previously established to have high, medium, and low flow rates, show insignificant differences (p > 0.05) among the tubes of different flow rates, using both gas standards and an exhaled breath from a peppermint experiment. Collectively, these results establish overall background compounds attributed to each TD tube type tested. Additionally, while measured flow rate variability is present and plausibly impacts exhaled breath results, the data demonstrate no statistically significant difference was observed between tubes showing high, medium, and low flow rates from two separate sample types.

Study on performance of carbon nanotube composite phase change cold storage sphere with annular fins

Aiming at the poor phase change material thermal conductivity, high shell layer thermal resistance and low cold storage efficiency in encapsulated cold storage sphere systems, we adopt computational fluid dynamics to numerically investigate the cold storage process after adding carbon nanotubes to phase change paraffin cold storage spheres. The heat transfer model of a new type of annular-finned cold storage sphere and cold storage device is established, and the effects of sphere diameter, shell material, fins and refrigerating medium flow rate on the cold storage process are investigated. The results show that the optimum fin length of the sphere is 11 mm and the optimum fin spacing is 8 mm at a sphere diameter of 50 mm. The completion time of the carbon nanotube-added annular finned sphere is 48 min shorter than that of the traditional pure paraffin sphere without fins, and the cooling efficiency increases by 61.7 %, which is better than those of adding either fins or carbon nanotubes; carbon nanotube additions are better than fin additions to the single-variable factors to enhance the cooling effect. The convective heat transfer coefficients at 4 m/s and 5 m/s refrigerating medium flow rates increase by 20.1 % and 42.3 %, respectively, compared with those at 3 m/s. We provide a theoretical basis and reference value for the optimal design of an accumulator sphere and its devices.

Lab Investigation Using a Box Model and Image Analysis of a Contaminant Back-Diffusion Process from Low-Permeability Layers

Contaminants stored in low-permeability soils can continue to threaten the adjacent groundwater system even after the aquifer is considered remediated. The redistribution of contaminants from low-to-high-permeability aquifer zones (Back-Diffusion) can generate a long-term plume tail, commonly considered one of the main obstacles to effective groundwater remediation. In this paper, a laboratory test was performed to reproduce the redistribution process from low-permeability silt lenses (k ≈ 1 × 10−7 m/s) to high-permeability sand aquifers (k ≈ 1 × 10−3 m/s). The target of the experimental and numerical approach was finalized to verify what influence the shape and position of the lenses could have, with respect to the bulk flow, on the time necessary to complete the depletion of the dissolved substances present in the lenses. For this purpose, an image analysis procedure was used to estimate the diffusive flux of contaminants released by these low-permeability zones in different boundary conditions. The results obtained in the laboratory test were used to calibrate a numerical model implemented to simulate the Back-Diffusion process. Once calibrated, the numerical model was used to simulate further scenarios to evaluate the influence of the location and shape of the low-permeability lenses on the time necessary to diminish its contaminant content when subjected to a steady-state flow. The numerical model was also used to investigate the effect of different groundwater velocities on the depletion time of the process. The results show that the shape and position of the lens have an important impact on the time necessary to empty the lens, and an increase in the velocity field in the bulk medium (flow rate rising from 1.6 l/h to 2.5 l/h) does not correspond to diminishing total depletion times, as the process is mainly governed by diffusive transport inside the lens. This appears to be significant when the remediation approach relies on pumping technology. Future research will verify the behavior of the released plume in a strongly heterogeneous porous medium.

Experimental study of the effect of load and rotational speed on the electrical power of a high-speed ORC microturbogenerator

The article presents the results of the study conducted on a microturbogenerator with a nominal power of 1 kWe. One of the primary objectives of the study was to determine the maximum power of the microturbogenerator for several preset and constant flow rates of the HFE-7100 working medium. During the tests, the variable parameters were the power of the heat source and the electrical load of the microturbine generator. Such a methodological approach made it possible to determine the experimental mechanical and electrical characteristics of the high-speed microturbogenerator, which are practically absent in the subject literature at present.The study shows that, at a preset working medium flow rate, there exists an optimum heat source power level at which the microturbogenerator's power output is maximum. It was determined that the maximum electrical power also depends on the load value of the microturbine generator. At the minimum tested working medium flow rate value of 30 g/s, a maximum power of approx. 210 We was obtained with a heat source power of 12 kWt and a resistive load of approx. 6.4 Ω. On the other hand, at the same flow rate value of the HFE-7100 and a heat source power of 14 kWt, the maximum electrical power of the microturbogenerator was approximately 205 W. On the other hand, for an HFE-7100 flow rate of 60 g/s, the maximum electrical power of approximately 625 W was achieved with a heat source power of 18 kWt. It was found that the load current of the generator had a major influence on the maximum electrical power of the microturbogenerator.

Mathematical model of controlled vane hydraulic shock absorber

Introduction. Modern technologies, as well as various methods and schemes currently used in technology, have made it possible to automatically control the damping properties of shock absorbers, which increases the energy intensity of the entire suspension system. However, in order to use these solutions in practice, it is necessary to develop mathematical models of these damping elements. Such models serve as a theoretical tool for studying the described processes in order to implement the correct control action. As for such units as controlled (adjustable) vane shock absorbers, the studies carried out earlier on them are clearly not enough to ensure their effective operation in various conditions.The object of this study is a controlled vane hydraulic shock absorber.The purpose of this work is to carry out theoretical studies and improve the methodology for calculating controlled (adjustable) bladed hydraulic shock absorbers, in which magnetorheological fluid is used as the working fluid of the shock absorber.Research methods. The design and principle of operation of controlled vane hydraulic shock absorber with magnetorheological (MR) throttles are considered. Method of calculation is proposed and theoretical studies are performed on influence of change of volume flow rate of working medium of shock absorber in MR throttle on forces of resistance to rotation on shaft of shock absorber blade.The results of theoretical research. 1) Results of theoretical studies of change of volume flow rate of working medium of controlled hydraulic blade shock absorber are presented. 2) An adequate mathematical model is obtained that is suitable for calculating the characteristics of controlled (adjustable) hydraulic vane shock absorbers, where magnetorheological fluid is used as the working medium of the shock absorber, as well as for selecting control action in the control system. Conclusion. The results of the study are intended for organizations and enterprises engaged in the development and production of heavy high-speed tracked vehicles.The results of the studies can be used to refine the methodology for estimating the smoothness of the heavy high-speed tracked vehicles.

Solving Innovative Problems of Thrust Vector Control Based on Euler's Scientific Legacy

This study aims to develop an interdisciplinary approach to solving innovative thrust vector control problems. The methodology involves the development of a working hypothesis about the ejection process when using a controlled nozzle to deflect the thrust vector (velocity vector) in any direction within a complete geometric sphere. When developing the working hypothesis, a multilateral analysis of individual facts and scientific and technical information is performed using tools in the "big data" area, assessing opportunities to apply the "Foresight" methodology for predicting the development of fluidics. The authors propose new mathematical models to describe the thrust vector in the distribution of the mass flow rate of the fluid medium between flow channels. Patents for inventions support the novelty of scientific results that reveal new opportunities for more active development of fluidics as applied to simple and complex jet systems with low and extremely high energy density in flows. The proposed methodology rests on a modern computer base and is a logical continuation and development of well-known Euler’s works. The computer simulation of multiflow jet devices mainly focuses on power engineering, production, and processing of hydrocarbons. Some results of this research work, including patented design developments and calculation methods, also apply to developing robotics, unmanned vehicles, and programable jet systems. The authors attribute further development of the interdisciplinary approach for solving inventive problems to the use of different AI options. Doi: 10.28991/CEJ-2023-09-11-017 Full Text: PDF