Multiple Inlets Research Articles

Enhancing Thermoelectric Efficiency Through Combined and Shunt Solar Chimneys: An Investigation of Vented Photovoltaic Panels with Multiple Inlets

Enhancing Thermoelectric Efficiency Through Combined and Shunt Solar Chimneys: An Investigation of Vented Photovoltaic Panels with Multiple Inlets

Direct MultiSearch optimization of TPMS scaffolds for bone tissue engineering

BackgroundScaffolds designed for tissue engineering must consider multiple parameters, namely the permeability of the design and the wall shear stress experienced by the cells on the scaffold surface. However, these parameters are not independent from each other, with changes that improve wall shear stress, negatively impacting permeability and vice versa. This study introduces a novel multi-objective optimization framework using Direct MultiSearch (DMS) to design triply periodic minimal surface (TPMS) scaffolds for bone tissue engineering. MethodThe optimization algorithm focused on maximizing the permeability of the scaffolds and obtaining a desired value of average wall shear stress (which ranges between the values that promote osteogenic differentiation of 0.1 mPa and 10 mPa). Multiple fluid inlet velocities and target wall shear stress were analyzed. The DMS method successfully generated Pareto fronts for each configuration, enabling the selection of optimized scaffolds based on specific structural requirements. ResultsThe findings reveal that increasing the target wall shear stress results in a greater number of non-dominated points on the Pareto front, highlighting a more robust optimization process. Additionally, it was also demonstrated that the tested Schwartz diamond scaffolds had a better permeability-wall shear stress relation when compared to Schoen gyroid geometries. ConclusionsDirect MultiSearch was proven as an effective tool to aid in the design of tissue engineering scaffolds. This adaptable optimization framework has potential applications beyond bone tissue engineering, including cartilage tissue differentiation.

Single channel sound source localization by using combinations of multiple tubes

A method for localizing the direction arrival of the sound source with a single channel is proposed with the configuration of system consists of a single channel acoustic sensor and multiple inlets with specific path length of tubes or pipes. The time delay of arrival at each inlet can be estimated from the autocorrelation function measured at the sensor and the positions of peak in autocorrelation function are changed according to the incidence angle. By using this concept, the basic configurations are considered and the related investigations are conducted as solutions to several problems that need to be solved. The proposed concept is validated experimentally in anechoic chamber and outdoor conditions. As a method to expand the range of observation angle, the configuration with difference length is investigated and it is confirmed that the unique solution for the whole direction can be obtained by a combination of tubes and inlets.

Predicting mixing degree of supersonic flow by a few target data using meta-learning

Predicting the mixing degree of supersonic flow is essential for designing compressible flow devices, such as scramjets, chemical lasers and ejectors. However, building appropriate predictive models of supersonic flow mixing degrees utilizing deep learning is challenging because the samples are expensive from computation or experiments. Herein, a meta-learning method is proposed to reduce the amount of target data required for training a mixing degree estimation by improving the pre-training performance. The datasets of multiple other inlet pressures are used as the pre-training datasets to allow the neural network to generalize to the target inlet pressure. A deep neural network pertained by a model-agnostic meta-learning algorithm estimates mixing degrees from the input information of a jet angle and an inlet temperature. The estimation accuracy is verified using the simulated dataset. Using 5 target data and 10 gradient steps, the meta-learning method achieves the averaged coefficient of determination of 0.95. Moreover, the meta-learning framework achieves mixing degree estimation more quickly and accurately than transfer learning and merged learning. This work provides a way to alleviate the required data usually insufficient for predicting the mixing performance for high-speed flow applications.

Experimental and numerical assessment and performance optimization of a novel T-arrow microfluidic device to mix two fluids with different thermophysical properties

Micromixers are critical parts of integrated microfluidic systems and their performance improvement has been a crucial problem for many investigators. Since the mixing enhancement in passive micromixers is hindered by the low-Reynolds number regime, multiple inlets have been recommended to create chaotic advection and improve the mixing quality. In this paper, a novel T-arrow micromixer is introduced to augment the mixing index (MI) of two liquids with different thermophysical properties. Numerical and experimental investigations are carried out by changing the distance between the inlets (a), the angle of the arrow-shaped inlet (α), the velocity ratio (VR), and the width-to-height aspect ratio (AR). Five optimization algorithms are also utilized to optimize the micromixer performance to achieve the most appropriate geometrical characteristics. It is found that MI is enhanced significantly by adding a Y-type inlet compared to a T-shaped mixer. The results demonstrate that while MI declines with a, there are optimal values for α, VR, and AR. Besides, parallel optimization of MI and pressure drop recommends two optimal micromixers with mixing energy cost (MEC) of 2841 Pa and 3370 Pa.

A theoretical and numerical analysis of solar chimney in multi-storey atrium building

Current research efforts on solar chimney are much on those configurations with single space or single vent, hampering its applications in complex buildings. To expand its implementation, the viability of solar chimney in multi-storey atrium buildings was explored numerically and theoretically. It was known that its natural ventilation performance can fulfil the WHO requirements (i.e., 6 air change per hour, ACH) even under low solar radiation of 200 W/m2 if it is appropriately designed, such as cavity gap (d), cavity height (Hc), solar radiation (Q), and window width (W). Its natural ventilation rate was found to be positively linear to the exponential form of the analyzed factors in this study, including cavity gap (d0.63∼0.69), cavity height (Hc0.59∼0.60), solar radiation (Q0.42∼0.43), and window width (W0.14∼0.20). The impacts of cavity gap and solar radiation are relatively weaker for big space such as atrium than those scenarios with single-space ventilation in the literature. The volume of the connected space was found to affect its natural ventilation performance, where the obtained ventilation rate of 4-storey is averagely 5.1 % lower than those of 3-storey buildings. A theoretical model was developed and experimentally validated, for the first time, to predict the natural ventilation rate of solar chimney when it is applied to the atrium with multiple air inlets. It was also noticed that the same theoretical model can be applied to the atrium buildings with odd and even storeys, but the area coefficients are different. The research outcomes of this study confirm the viability of solar chimney in complex buildings and offer a theoretical foundation for its implementation.

Modes of Weather System-Induced Flows through an Arctic Lagoon

With the increasing warming of the Arctic, the summertime ice-free period in the coastal Arctic becomes longer and the water exchange between arctic lagoons and coastal Beaufort Sea becomes more important for land–ocean interaction. This study examined the dynamics of water exchange between the arctic lagoons and the Arctic Ocean under the influence of weather systems (the transient arctic cyclones and hovering Beaufort High pressure system). We implemented rare observations, numerical modeling with the Finite Volume Community Ocean Model (FVCOM), and a forcing-response Empirical Orthogonal Function (fr-EOF) analysis to determine the weather-driven flow patterns and characteristics in the micro-tidal arctic lagoon (Elson Lagoon) with little freshwater discharge. The results were validated for both tidal and subtidal currents with in situ data. The inlets of the lagoon were significantly impacted by wind associated with the weather systems and the flows through the inlets were highly correlated with each other. The fr-EOF analysis for the 1.5-month FVCOM output indicated three significant modes of wind-driven flow. In the deepest (~16 m) northwestern-most inlet, a counter-wind flow occurred more than 96% of the time due to setup and set down of water level inside the lagoon and the vorticity balance related to the wind stress and water depth. For about 60–80% of the time, the exchange flow was out of the lagoon through the northwestern-most and deepest inlet due to the strong easterly winds dictated by the Beaufort High; this dominant flow is mainly caused by the persistent easterly wind as a limb of the Beaufort High pressure system, modified by the transient arctic cyclones with a westerly wind and inward flows at the westernmost inlet of Elson Lagoon. This study shows that the alternating influence from the cyclone-anticyclone weather systems produces a meteorological tide in the subtidal spectrum which dominates the water exchange in the region through the multiple inlets. With the observed increase in cyclone strength and frequency under the warming trend, this may imply a greater contribution from the westerly wind because of the increased cyclonic activities. If this is the case, the inward flow might increase and have an effect on sediment, larval, and nutrient transports through this system.

Acoustic-assisted centrifugal microfluidics for particle/cell separation

The process of microparticle manipulation using acoustic waves within microfluidic devices is called acoustophoresis. This research focuses on a new approach for concentrating and categorizing microparticles using an integrated acoustic centrifugal microfluidic system with standing surface acoustic waves (SSAWs) and centrifugal forces. The study employs a rectangular microchannel with multiple inlets and outlets placed on an electrified lab-on-a-disc (eLOD) device subjected to SSAWs, guiding microparticles radially. Various physical parameters such as distance from the center of rotation, lateral displacement, tilting angle, microchannel dimensions, microparticle size, disc rotation speed, and applied voltage to the piezoelectric were simulated to assess microparticle focusing. The results indicate that adjusting lateral displacement and tilting angle can direct microparticles toward desired outlets. Enhanced focusing is achievable at low rotation speeds with higher applied voltage and narrower microchannel widths. The system's potential for classifying circulating tumor cells (CTCs) and white blood cells (WBCs) based on volume and density differences was also demonstrated. This acoustic eLOD device offers an efficient means for manipulating micro- and bioparticles.

Mass transfer enhancement and flow field simulations for a Venturi bubble generator with multiple inlet tubes

The Venturi device plays a crucial role in the Filtered Containment Venting System (FCVS), effectively preventing the release of radioactive pollutants from nuclear reactor containment during overpressure events. Various configurations of the Venturi device yield different outcomes, with mass transfer efficiency being contingent on bubble size and overall gas holdup. This study examines the impact of varying numbers of inlet tubes on the Venturi device, while keeping the inlet area constant. Specifically looking at the gas–liquid flow field, bubble behavior, and mass transfer capacity in the diverging section. By comparing Single Inlet Tube Venturi Device (SITVD) and Double Inlet Tubes Venturi Device (DITVD), we have reached the following conclusions: (1) In SITVD, the liquid flow field is biased to one side, whereas in DITVD, the liquid flows along the axial direction, resulting in bubbles experiencing stronger shear forces. (2) DITVD exhibits a higher overall gas holdup compared to SITVD, with an average axial gas holdup of 0.0317, which is greater than SITVD's 0.0247. However, SITVD's gas holdup is more evenly distributed. (3) SITVD exhibits a higher turbulence dissipation rate of 545 m2/s3, while the bubble residence time in DITVD is comparatively longer. (4) The average bubble diameter of DITVD is 1.116 mm, which is higher than the 1.011 mm of SITVD. (5) DITVD has better mass transfer than SITVD. The proposed structure of the new Venturi scrubber in this study demonstrates a significant enhancement in mass transfer capacity and filtration efficiency. This discovery provides a solid basis for the design and optimization of FCVS, thereby ensuring the safe operation of nuclear reactors.

Numerical investigation on the effect of feed operating parameters and inlet structure on a cyclone utilizing flow splitting for performance enhancement

The shunting technique is regarded as one of the most crucial approaches for suppressing localized secondary flow within a cyclone. This study employs the Reynolds stress model and discrete phase model to investigate the impact of inlet structure and feed operating parameters on the performance of enhanced cyclone with split flow (ECSF), aiming to further enhance its efficiency. The findings demonstrate that the optimum feed velocity of ECSF is 29 m/s, which surpasses that of Lapple cyclone at 23 m/s. In addition, both a contracting inlet and multiple inlets contribute to enhancing the separation efficiency of ECSF. Specifically, ECSF with a contracting inlet exhibits a total separation efficiency of 86.8% for 2.5 μm particles, representing an improvement of 12.3% compared to ECSF with a straight inlet configuration. The enhancement in separation efficiency achieved through the implementation of the four-inlet design is even more pronounced. The segregated particles are directed into the discharge pipe via either underflow or bypass flow, and the trajectory of particle entry into the discharge pipe is closely associated with their cross-sectional positioning prior to entering the cylinder.

Impact of design aspects on iron removal efficiencies from coal mine drainage in full-scale lagoons

In response to the potential ecological problems caused by coal mine drainage, passive Mine Water Treatment Schemes (MWTS), consisting of settlement lagoons and aerobic wetlands, are developed to remove iron and other contaminants prior to discharge into the environment. Existing research has examined individual design aspects separately, addressing the effect of lagoons' design on treatment performance. However, long-term research lacks data on the design aspects of full-scale mine drainage lagoons, to ensure consistent iron removal and optimal treatment of the mine drainage. This study analysed and assessed the design aspects of five full-scale lagoons, alongside monthly iron concentrations spanning over a period of twelve years, aiming to evaluate lagoon treatment performance based on different design aspects. Correlation and regression analyses were conducted to offer a better understanding of the potential relationships between iron removal efficiencies and the various design aspects of lagoons.Results indicated that the mean iron removal efficiencies of the lagoons studied, ranged from 25.12% to 92.85%, being impacted by the different design features. The correlation and multiple regression analysis results suggest that operational Water Levels, Surface Area, Aspect Ratio, layout and number of inlets and outlets, as well as shape of the lagoons affected iron removal (R2 0.78, p-value <0.05). Lagoons with larger aspect ratio were observed to have performed better in removing iron. In addition, a reduction in operational water level was observed to lead to increased iron removal. Furthermore, the result of the regression analysis demonstrated that the age of the lagoon significantly affects its treatment performance. Overall, lagoons with mid-mid configuration, multiple inlets and outlets and aspect ratio of 4 are found to allow for better flow and contaminant spread within the system, ensuring better adsorption and optimal removal of iron, although subject to regular ochre removal. This study offers valuable insights to lagoons design engineers, research scientists, policy makers and MWTS operators to optimize treatment performance.

Energy exergy and economic analysis of a multiple inlet solar air heater for augmented thermohydraulic performance

Solar air heaters typically feature a single inlet connected to the absorber section. This study explores a novel design for solar air heaters by introducing multiple inlets in the absorber section, creating a double-chamber system. The square test section incorporates inlets at each corner, facilitating increased air intake and inducing a swirling motion within the test section. Air exits through either a single central vent or multiple vents in the absorber plate, entering the upper chamber. The crossflow effect and localized disturbance generated by these vents enhance turbulence inside the test section. Numerical analysis carried out using ANSYS FLUENT by considering the variations in inlet duct width and vent diameters. Optimal thermo-hydraulic efficiencies of 80.32 % and 84.5 % are achieved for the Single central vent and Multiple vents configurations, respectively, with an inlet duct width ratio of 10.0 and 3.3. While the Multiple vent configuration demonstrates lower CO2 reduction potential than the Single central vent configuration, the energy payback period is approximately 4.5 months in energy calculations and around 4 years in exergy-based calculations. The average Enviro-economic parameter is determined to be $16/year, with the highest value observed in the Reynolds number range of 9000 to 12000.

Design and Development of Flow Fields with Multiple Inlets or Outlets in Vanadium Redox Flow Batteries

In vanadium redox flow batteries, the flow field geometry plays a dramatic role on the distribution of the electrolyte and its design results from the trade-off between high battery performance and low pressure drops. In the literature, it was demonstrated that electrolyte permeation through the porous electrode is mainly regulated by pressure difference between adjacent channels, leading to the presence of under-the-rib fluxes. With the support of a 3D computational fluid dynamic model, this work presents two novel flow field geometries that are designed to tune the direction of the pressure gradients between channels in order to promote the under-the-rib fluxes mechanism. The first geometry is named Two Outlets and exploits the splitting of the electrolyte flow into two adjacent interdigitated layouts with the aim to give to the pressure gradient a more transverse direction with respect to the channels, raising the intensity of under-the-rib fluxes and making their distribution more uniform throughout the electrode area. The second geometry is named Four Inlets and presents four inlets located at the corners of the distributor, with an interdigitated-like layout radially oriented from each inlet to one single central outlet, with the concept of reducing the heterogeneity of the flow velocity within the electrode. Subsequently, flow fields performance is verified experimentally adopting a segmented hardware in symmetric cell configuration with positive electrolyte, which permits the measurement of local current distribution and local electrochemical impedance spectroscopy. Compared to a conventional interdigitated geometry, both the developed configurations permit a significant decrease in the pressure drops without any reduction in battery performance. In the Four Inlets flow field the pressure drop reduction is more evident (up to 50%) due to the lower electrolyte velocities in the feeding channels, while the Two Outlets configuration guarantees a more homogeneous current density distribution.

One- and Three-Dimensional Hydrodynamic, Water Temperature, and Dissolved Oxygen Modeling Comparison

Understanding and modeling water quality in a lake/reservoir is important to the effective management of aquatic ecosystems. The advantages and disadvantages of different water quality models make it challenging to choose the most suitable model; however, direct comparison of 1-D and 3-D models for lake water quality modeling can reveal their relative performance and enable modelers and lake managers to make informed decisions. In this study, we compared the 1-D model MINLAKE and the 3-D model EFDC+ for water temperature, ice cover, and dissolved oxygen (DO) simulation in three Minnesota lakes (50-m Carlos Lake, 23.5-m Trout Lake, and 5.6-m Pearl Lake). EFDC+ performed well for water temperature and DO simulation in the open water seasons with an average root mean square error (RMSE) of 1.32 °C and 1.48 mg/L, respectively. After analyzing the ice thickness with relevant data, it was found that EFDC+ calculates a shorter ice cover period and smaller ice thickness. EFDC+ does not consider snowfall for ice thickness simulation. The results also revealed that EFDC+ considers spatial variance and allows the user to select inflow/outflow locations precisely. This is important for large lakes with complex bathymetry or lakes having multiple inlets and outlets. MINLAKE is computationally less intensive than EFDC+, allowing rapid simulation of water quality parameters over many years under a variety of climate scenarios.

Overview of Selected Serpentine Duct Simulations Using Computational Fluid Dynamics

Computational fluid dynamics (CFD) was used to perform simulations of multiple serpentine inlet ducts for comparison to experimental data. The simulations included two baseline duct geometries configured to match their respective wind tunnel tests. Each configuration was tested and simulated with and without flow control vanes. Some of the simulations included the geometric detail of the instrumentation probes at the aerodynamic interface plane. This paper highlights selected issues that impact robustness and accuracy. The topics include far-field boundary conditions and various methods of modeling the instrumentation probes. This paper summarizes discussion topics and recommendations for CFD practitioners preparing to simulate similar cases.

Needs of Extension Agents on Techniques for Climate-Smart Rice Production in North-Central, Nigeria

The study assessed the competency need of extension agents on Climate-Smart Agricultural Techniques (CSATs) for rice production in north-central, Nigeria. A multi-stage sampling procedure was used in selecting 88 respondents. Data collected with the aid of a questionnaire were analyzed with descriptive statistics and Borich needs model analysis. The result showed that their competencies in specific practices like the ability to promote index-based weather insurance ( = 1.00), operating alternate wet and dry technique (= 1.06), prime seeds with micronutrients (= 1.66) were low. Areas of competency upgrade as indicated by the mean weighted discrepancy scores were in teaching farmers about operating alternate wet and dry techniques (MWDS = 4.21), multiple inlet irrigation (MWDS = 2.98), site-specific nutrients managements (MWDS = 2.95), cropping calendar (MWDS= 2.42), climate information services (MWDS = 2.29). Training is needed in areas afore mentioned. Extension organizations should incorporate those areas discovered from the research into extension agents’ curriculum activities for adequate training. Extension agents should also be given opportunities to upgrade their competencies by attending intensive seminars and workshops in research institutions while in service.

Hydroelastic Responses of a Submersible Ring Structure for Offshore Seaweed Cultivation under Wave Action

This paper investigates the hydroelastic response of a submersible circular ring structure, designed for offshore seaweed cultivation, under wave action and during the submergence process. The ring structure comprises two circular HDPE pipes connected to each other by equally spaced brackets. The structure carries seaweed grow-out lines, and is kept in position by a mooring-line system used for fish pens. The HDPE collar is equipped with multiple inlet and outlet valves, allowing it to be submerged to avoid strong waves and to be raised to the water surface when the strong waves die down. The software AquaSim was used for the hydroelastic analysis of the moored structure. It is found that we can significantly reduce the von Mises stresses in the ring structure as well as the mooring-line forces by submerging. However, the structure can experience significant increase in stress during the submergence process due to bending from combined wave action and non-uniform distribution of filled water in the ring structure. This stress increase may cause structural damage or even failure. Therefore, it is important to submerge the ring structure in calm waves ahead of predicted storms and to control the distribution of seawater into the ring structure. For the latter, it is best to use at least two inlet valves and two outlet valves to minimize the likelihood of damage of the ring structure during the submergence process.

Design of vortex-based cavitation devices/reactors: Influence of aspect ratio, number of inlets and shape

Vortex-based hydrodynamic cavitation devices are being used in a wide range of applications. However, adequate information on the design of such devices is not available. In this work, we have computationally investigated the influence of key design parameters such as the aspect ratio of the vortex chamber, the number of tangential inlets and the shape of the device on resulting flow characteristics and cavitation. Experiments were carried out to validate key findings from the computational studies. These investigations revealed that the aspect ratio of the vortex chamber as six may be considered as optimum. The performance of single and multiple inlet devices was found to be comparable at the same pressure drop (that is at same energy consumption per m3). Scale-up with a geometric similarity led to a reduction in the extent of cavitation for same energy consumption per m3. For facilitating scale-out option, an attempt was made to simplify the configuration of the vortex-based cavitation device. Computational results indicated that the cavitation performance of simplified configuration was not significantly inferior. A case of the formation of liquid–liquid emulsion was taken as a test case for evaluation of a modified cavitation device based on the present investigations. The droplet size distributions of emulsions generated by both the devices indicate that the proposed simplified configuration, which may facilitate fabrication and offer integrated scale-out options, performs almost at par with a complex configuration. The presented results will be useful for optimising designs of vortex-based hydrodynamic cavitation devices/ reactors.

Influence of different inlet modes on hot carrier gas flow in magnesium nitrate pyrolysis furnace

Spray pyrolysis of magnesium nitrate is a way to prepare magnesium oxide solid particles. The gas–solid flow process after the generation of solid particles inside the pyrolysis furnace was studied in this article. Six different inlet modes of hot-carrier gas were designed, and the hot-carrier gas enters the pyrolysis furnace at the same flow rate through the six different inlet modes. The influence of varying inlet methods on the actual running distance of gas flow and the particle sedimentation rate was deeply studied in this article. The longer the distance the hot-carrier gas runs in the pyrolysis furnace, the more conducive it is to full contact with the material. The higher the particle settling rate, the more magnesium oxide particles are collected in the pyrolysis furnace. ANSYS Fluent was used for numerical simulation in this study. The results indicate that when using a tangential inlet, the actual running distance of the hot-carrier gas in the pyrolysis furnace is longer than that of the normal inlet. The actual running distance of the thermal carrier gas at the three tangential inlets is 46.5 m, and that at a single normal inlet is 24.7 m. The former is 88% more than the latter. The sedimentation rate of solid particles at three tangential inlets is 32.24%, and that at a single normal inlet is 12.06%. The former is 167% higher than the latter. The three tangential inlet mode is the best way to increase the actual running distance of the hot-carrier gas and improve the solid particle settling rate in the pyrolysis furnace. The pyrolysis furnace with multiple tangential inlets has two advantages. On the one hand, increasing the running distance of the hot-carrier gas in the furnace is conducive, thereby making the contact between the hot-carrier gas and the material more sufficient. On the other hand, it can increase the capture rate of product particles, improve the product yield, and reduce the dust content of pyrolysis tail gas.

Small Unmanned Aircraft Systems and Agro-Terrestrial Surveys Comparison for Generating Digital Elevation Surfaces for Irrigation and Precision Grading

Advances in remote sensing and small unmanned aircraft systems (sUAS) have been applied to various precision agriculture applications. However, there has been limited research on the accuracy of real-time kinematic (RTK) sUAS photogrammetric elevation surveys, especially in preparation for precision agriculture practices that require precise topographic surfaces, such as increasing irrigation system efficiency. These practices include, but are not limited to, precision land grading, placement of levees, multiple inlet rice irrigation, and computerized hole size selection for furrow irrigation. All such practices rely, in some way, on the characterization of surface topography. While agro-terrestrial (ground-based) surveying is the dominant method of agricultural surveying, aerial surveying is emerging and attracting potential early adopters. This is the first study of its kind to assess the accuracy, precision, time, and cost efficiency of RTK sUAS surveying in comparison to traditional agro-terrestrial techniques. Our findings suggest sUAS are superior to ground survey methods in terms of relative elevation and produce much more precise raster surfaces than ground-based methods. We also showed that this emergent technology reduces costs and the time it takes to generate agricultural elevation surveys.