Inlet Structure Research Articles

Structural and Heat Transfer Model Analysis of Wall-Mounted Solar Chimney Inlets and Outlets in Single-Story Buildings

Wall-mounted solar chimneys use solar radiation to heat the air inside the chimney cavity and use thermal pressure to create natural convection. Applying this principle allows for the indoor ventilation of a building without energy consumption. However, in wall-mounted solar chimney designs, different air inlet and outlet design dimensions can have varying degrees of impact on the effectiveness of wall-mounted solar chimney ventilation. In order to analyze the internal airflow state and airflow temperature field distribution of wall-mounted solar chimneys, physical models of wall-mounted solar chimneys with six different air outlet-to-inlet cross-sectional area ratios were developed in this research work. Before numerical simulation analysis, heat transfer analysis of the wall-mounted solar chimney’s structural components and airflow channels was carried out, and corresponding mathematical heat transfer models were established. The internal flow state and temperature distribution characteristics of a wall-mounted solar chimney were analyzed by steady-state simulations using the computational fluid dynamics software, Ansys Fluent. Finally, transient simulation calculation analysis was conducted under six different S-value models to investigate the variation in the natural ventilation of a single-story building’s wall-mounted solar chimney for a whole day. The study showed that under the same simulation conditions, 80% ≤ S < 100% effectively avoided the formation of vortices in the internal airflow of the wall-mounted solar chimneys and kept the ventilation effect of wall-mounted solar chimneys at a high level. The results of this study provide a reference for the optimization of research on the design of the air inlet and outlet structures of wall-mounted solar chimneys for single-story buildings.

Das ÖBB‐Kraftwerk Tauernmoos – Energiespeicher für die Bahn

AbstractIn 2004, ÖBB‐Infrastruktur AG started the first studies for the construction of a pumped‐storage hydro power plant between the two largest reservoirs of the existing Stubach Valley power plant group in Salzburg's Pinzgau region. Two reversible pump‐turbine units including a full converter with a total capacity of 170 MW and a maximum flow of 80 m3/s are planned. The construction of the 335 million. euro project started in 2020 and will be completed by autumn 2025. In addition to a 50,000 m3 cavern, an 11.5 km tunnel system including the access tunnels and the power water ways have been built. Most of the 11.5 km tunnel system is situated in stable gneiss. A greater challenge is the construction of the two inlet and outlet structures in the high mountain region during the winter season, when the lakes can be held on the lowest reservoir level. Since the remaining construction work is also carried out at an altitude of 1500 to 2250 m above sea level in alpine terrain, the construction company has been facing recurring problems such as snow, cold, wind, mudslides and the associated logistical difficulties. Despite these challenges, the excavation work was completed in summer 2022. The main focus is currently placed on the concrete works in the cavern, which is scheduled to be completed in autumn 2023. This will be followed by the installation of mechanical and electrical equipment as well as the control systems.

CFD Simulation Supported Development of Wind Catcher Shape Topology in a Passive Air Conduction System (PACS)

New studies and reports are published on a daily basis about the dangers of climate change and its main causes: humanity’s constantly growing population, the built environment and resource consumption. The built environment is responsible for approx. 40% of the total energy consumption, and a significant part comes from maintaining an appropriate indoor comfort environment by heating ventilation and air conditioning. Though contemporary studies have achieved a wide knowledge about natural ventilation and passive air conducting systems (PACS) and their applicability, further investigations are necessary to deepen the aerodynamic topology of air conducting building structures’ shape properties. Hence, in our current research we conducted a series of tests applying different wind catcher geometries. The methodology of this work is based on the authors’ previous work, where passive air conduction systems were compared with different airflow directions via computational fluid dynamic simulations (CFD). After finding the better performing PACS (a downdraught system), this research evaluates whether further improvements in ventilation efficiency are possible due to the aerodynamic shaping of the roof integrated inlet structures. Four different wind catcher geometries were examined to determine the most advantageous dimensional settings in the natural ventilation system’s given boundaries. After multiple series of basic and developed calculation runs, diverse shape designs of the passive air conduction inlet (PACI) were examined, including wind deflector geometries. The initial reference wind catcher’s air change rate was increased by approx. 11%. The results deliver the potential measure of improvements achievable in the aerodynamic shape design of structures under identic conditions of the same building domain. As a consequence, more sophisticated natural ventilation structural solutions will be possible in more operation cost- and performance-effective ways.

CFD-DEM Simulation of Particle Fluidization Behavior and Glycerol Gasification in a Supercritical Water Fluidized Bed

In this study, a mathematical model of hydrogen production from glycerol gasification in supercritical water was established based on the CFD-DEM method. The fluidization process of a supercritical water fluidized bed and the effects of bed height and feed structure on particle distribution and residence time of feedstock were analyzed. Additionally, the temperature field in the fluidized bed, the reaction rate distribution of each reaction and the influence of wall temperature on gas yields were also studied. The simulation results show that the bubble channel is easy to form along the wall at one side of the feed inlet. When the initial bed height is high, and the double symmetric feed inlet structure is used, the residence time of the feedstock is prolonged. The pyrolysis of glycerol mainly occurs in the middle and lower part of the fluidized bed reactor, and the reaction rate of the water gas shift reaction and methanation reaction are highest near the outlet, and a high wall temperature is conducive to the glycerol gasification.

Analysis of nature based flood management in the Tisza River Valley, Hungary

Abstract The floodplains of the Tisza River, stretching across the eastern part of Hungary, are often affected by riverine and inland excess water flooding and draught. This paper investigates a possible solution to this problem utilizing the water retention capabilities of old floodplains. In this study, the effect of the position of the inlet structures of a floodplain, near Csongrád town, was examined with HEC-RAS 1D-2D coupled model. Based on the results, the rules of the deep floodplain selection were determined. On the extended model, the possibilities of a deep floodplain storage area chain have been explored. According to the estimate, more than 2.36 km3 potential storage capacity is available along the Hungarian section of the Tisza River.

Optimized design and key performance factors of a gas circulation filtration system in a metal 3D printer

To further improve the quality of parts in metal 3D printers, it is necessary to optimize the structure and study the performance of their gas circulation filtration systems. First, we used the parametric modeling method to complete the formed cavity modeling. We then optimized the design of the air inlet structure of the formed cavity using the moldflow simulation method, and finally, we evaluated the optimized design results through assembly experiments and measurements of the molded parts’ components. The combination of parametric modeling and moldflow simulation methods produced a high modeling efficiency and had a good effect on the optimized design of the gas circulation filtration systems. After optimizing the design, the turbulence intensities and distribution areas of the formed cavities were reduced. During the 3D printing of the curved guide plate, the plane of the guide plate holder was inclined 55° relative to the machining datum plane, which improved the form quality. The 3D printed curved guide plate closely matched the inlet end of the printer’s air duct, and the upper guide plate was fixed at a suitable position using screws. The niobium contents of the parts formed by the guide plate in Design 2 were low, which lays a foundation for the 3D printing of high-performance metal parts.

Counting DNA molecules on a microchannel surface for quantitative analysis

Microscopic visualization of DNA molecules is a simple, intuitive, and powerful method. Nonetheless, DNA-molecule quantification methods that employ microscopic visualization have not been reported so far. In this study, a new quantitative approach is presented that enables the counting of individual DNA molecules that have been rendered visible by fluorescence microscopy. Toward this, a microfluidic device was employed that directed DNA molecules into microchannels and deposited the molecules onto a positively charged surface. This microfluidic device had a vertically tapered channel inlet structure that prevented the accumulation of excess DNA molecules in the channel inlet while creating a tapering flow, thereby ensuring the even distribution of the DNA molecules in the microchannels. The channel heights and the density of positive charges on the surface were optimized for analysis. The linearity of this method with respect to the determination of the concentration of DNA in solutions was subsequently determined. The limit of detection was 0.48 fg/μL, which corresponds to 64 molecules of 7.25 kbp DNA in 1 μL of sample. This quantitative approach was finally used to count two types of plasmids co-transformed in an E. coli cell; a measurement that is typically considered challenging with gel electrophoresis.

Effects of inlet velocity and structure parameters on the performance of a rotary diesel particulate filter for truck diesel engine based on fuzzy grey relational analysis

In this paper, a three-dimensional mathematical model of the rotary diesel particulate filter (RDPF) for truck diesel engine is established according to the fluid mechanics and porous media theory. The effects of inlet velocity and structure parameters (diameter ratio, expansion angle and filter length) on the flow uniformity in the RDPF are investigated. Furthermore, the Fuzzy grey relational analysis (FGRA) is employed to make a weight analysis of the influences of structure parameters on the regeneration performance and pressure drop of the RDPF. The results show that the velocity uniformity in the RDPF can be improved by properly reducing the inlet velocity, diameter ratio or expansion angle θ1. The capture-regeneration volume ratio with 8–10 is appropriate range for the structural optimization. Finally, the expansion angle θ1 is the most important structure parameter for the filter regeneration performance (regeneration time R = 0.8467; regeneration efficiency R = 0.6849) and the diameter ratio is the most important structure parameter for the pressure drop at the capture-regeneration “balance point” (R = 0.9352).

Numerical study on heat transfer characteristics of heat exchange cell in an annular cross-wavy primary surface recuperator (annular CWPSR)

To eliminate the deficiency arising from the whole machine test with simplified cross-wavy (SCC) in investigating the impact of inlet and outlet structure and heat transfer characteristics of different channels, the heat exchange cell (HEC) is employed to explore the heat transfer and flow mechanism of the annular cross-wavy primary surface recuperator (CWPSR). In this work, we propose a complex physical model of HEC corresponding to the real geometric structure of the annular CWPSR, and establish the three-dimensional numerical simulation of fluid-thermal-structural coupling. By numerical simulation, we compare the thermodynamic characteristics between the HEC and SCC, and we analyze the temperature distribution of the HEC and the cross-wavy (CW) channel inlet section, as well as the heat transfer characteristics along flow direction for the different CW channels. The results show that there is a significant difference in thermodynamic characteristics between the HEC and SCC. Meanwhile, the heat transfer coefficient of CW channel structure is higher compared with the inlet and outlet structure for the HEC. In addition, the temperature of the air and gas CW channel inlet section increases gradually from the base circle R1 to the outer circle R2. Because of the existence of the air and gas inlet structure, the temperature of the CW channel increases from Channel-5 to Channel-30.

Numerical Investigation of Hot Helium Flow Homogenizer on Inter-Unit Flow Rate Uniformity of HTGR Once Through Steam Generator

High working temperature is a major feature of the high temperature gas-cooled reactor (HTGR). The helical tube once through steam generator (OTSG) should maintain appropriate temperature uniformity. The temperature non-uniformity of the HTGR OTSG includes the in-unit and inter-unit temperature non-uniformity, while the latter is mainly induced by the inter-unit flow rate non-uniformity of primary-side hot helium, which is significantly affected by the inlet structure. In this work, a new inlet structure with a hot helium flow homogenizer is designed, and its flow distribution characteristics are numerically investigated. Accordingly, the optimal geometrical parameters are determined, such as the circular hole diameter on the end wall, the square hole size, and arrangement on the cylinder wall. Increasing the resistance of the flow homogenizer with non-uniformly arranged square holes (NUASHs) can improve inter-unit flow rate uniformity because it decreases the effect of static pressure difference caused by dynamic pressure. Two design parameters (resistance coefficient and flow area ratio of the square hole on both sides) are introduced to evaluate the structure effect of the hot helium flow homogenizer on inter-unit flow rate distribution. They are recommended within the ranges of (7.81–22.42) and (0.53–1.64), respectively. In these recommended ranges, the suction phenomenon near the hot helium inlet can be effectively suppressed, with the critical resistance coefficient of 7.63. By coupling with 19 heat exchange units, the overall performance of the hot helium flow homogenizer is better than that of the current inlet structure with a baffle, with the maximum inter-unit flow rate deviation decreased from 2.97% to 0.30%. This one-magnitude enhancement indicates that the hot helium flow homogenizer with NUASHs is a promising solution to improve inter-unit flow rate uniformity of the HTGR OTSG.

Study on Inlet Flow Field Structure and End-Wall Effect of Axial Flow Pump Impeller under Design Condition

The existing experimental technology cannot accurately and quantitatively measure the flow field structure and the wall boundary layer displacement effect in the axial flow pump. Based on SST k-ω turbulence model, a three-dimensional unsteady numerical simulation of the whole flow field of an axial flow pump was presented at the designed operating point to overcome the weakness of traditional measurement methods in measuring the flow field of the axial flow pump. The flow field structure of the axial flow pump inlet was studied quantitatively and the result was compared with the theoretical design value. It was found that there is an obvious impeller rotation effect and end-wall effect in the flow field of the axial flow pump inlet. The distribution law of the impeller inlet flow field and the crowding coefficient caused by the wall boundary layer were obtained. The pump inlet measurement point in the experiment and calculation domain inlet in the simulation should be kept at a distance of more than 0.5 Ds away from the impeller inlet to eliminate the influence of the impeller rotation effect. Through contrastive analysis, it was found that there is an obvious difference between the calculated value and the design value of the flow field structure due to the end-wall effect. The crowding coefficient should be taken into account when designing an axial flow pump. This study has certain reference significance for further understanding the flow field structure at the inlet of the axial flow pump impeller and improving the design theory of the axial flow pump.

A Novel Technique Identifies Valve-Like Pathways Entering and Exiting Schlemm's Canal in Macaca nemestrina Primates With Similarities to Human Pathways.

Purpose: The aim of the study was 1) to describe a novel combination of techniques that permit immunohistochemistry imaging of Schlemm’s canal inlet (SIV) and outlet (SOV) valve-like structures, 2) to identify tissue-level SIV adhesive relationships linking the trabecular meshwork (TM) to hinged collagen leaflets at the Schlemm’s canal (SC) external wall, and 3) to determine whether the SIV lumen wall’s adhesive vascular markers are similar to those of the SC inner wall endothelium. Materials and Methods: Anterior segments of 16 M. nemestrina primates underwent immunohistochemistry (IHC) labeling. We perfused fluorescent microspheres into 12 of the eyes. Limbal tissues were divided into quadrants, viscoelastic introduced into SC, tissues fixed, immunohistochemistry performed, radial segments cut, tissues clarified, and confocal microscopy performed. Finally, we generated ImageJ 3D projections encompassing the TM, SC, and distal pathways. Results: IHC imaging identified 3D relationships between SIV, collector channel ostia, collector channels (CC), SOV, and intrascleral channels. Imaging depth increased 176.9%, following clarification (p < 0.0001). Imaging demonstrated CD31, collagen type 1 and 4 in the walls of the SIV lumen and more distal pathways. In eight eyes, 384 segments were examined, 447 SIV identified, and 15.4% contained microspheres. Conclusion: Our technique’s imaging depth permitted the identification of SIV linkage between the TM and SOV. We found comparable cell–cell adhesion molecules (CD31) and basement membrane components in the SC inner wall and SIV lumen walls. Recent OCT studies have suggested that SIV tensional relationships may control CC entrance dimensions that regulate distal resistance. Cellular adhesive properties sustain SIV tensional relationships. These SIV cell–cell and cell-basement membrane properties warrant further study because abnormalities could be a factor in the IOP elevation of glaucoma.

Numerical investigation for CO2/N2 mixture gas - liquid Taylor flow in microchannel by CFD simulation

Taking CO2/N2 and water as a system, the influence of microchannel inlet structure on the hydrodynamics of gas-liquid two-phase Taylor flow is numerically simulated by using VOF and species transport model. The flow properties of Taylor flow in perpendicular inlet structure are firstly explored, and the simulation results are compared with the inlet structures with different angles. The microchannel inlet structure has an obvious effect on the flow properties of Taylor flow. The simulation results provide some guidance for the design of micro reactor.

Valve-Like Outflow System Behavior With Motion Slowing in Glaucoma Eyes: Findings Using a Minimally Invasive Glaucoma Surgery-MIGS-Like Platform and Optical Coherence Tomography Imaging.

PurposeThis study aimed to investigate anatomic relationships and biomechanics of pressure-dependent trabecular meshwork and distal valve-like structure deformation in normal and glaucoma eyes using high-resolution optical coherence tomography (HR-OCT).MethodsWe controlled Schlemm’s canal (SC) pressure during imaging with HR-OCT in segments of three normal (NL) and five glaucomatous (GL) ex vivo eyes. The dissected limbal wedges were studied from 15 locations (5 NL and 10 GL). A minimally invasive glaucoma surgery (MIGS)-like cannula was inserted into the SC lumen, whereas the other end was attached to a switch between two reservoirs, one at 0, the other at 30 mm Hg. A steady-state pressure of 30 mm Hg was maintained to dilate SC and collector channels (CC) during 3D volume imaging. The resulting 3D lumen surface relationships were correlated with internal structural features using an image mask that excluded tissues surrounding SC and CC. While imaging with HR-OCT, real-time motion responses in SC and CC areas were captured by switching pressure from 0 to 30 or 30 to 0 mm Hg. NL vs. GL motion differences were compared.ResultsLumen surface and internal relationships were successfully imaged. We identified SC inlet and outlet valve-like structures. In NL and GL, the mean SC areas measured at the steady-state of 0 and 30 mm Hg were each significantly different (p < 0.0001). Synchronous changes in SC and CC lumen areas occurred in <200 ms. Measured SC area differences at the steady-state 0 and 30 mmHg, respectively, were larger in NL than GL eyes (p < 0.0001). The SC motion curves rose significantly more slowly in GL than NL (p < 0.001). Pressure waves traveled from the cannula end along the SC lumen to CC and deep intrascleral channels.ConclusionHR-OCT provided simultaneous measurements of outflow pathway lumen surfaces, internal structures, and biomechanics of real-time pressure-dependent dimension changes. We identified SC inlet and outlet valve-like structures. GL tissues underwent less motion and responded more slowly than NL, consistent with increased tissue stiffness. A MIGS-like shunt to SC permitted pulse waves to travel distally along SC lumen and into CC.

Prototype of electrical generator development based on water flow pressure

Electric potential energy or kinetic energy produces electrical energy. The integration of electrical current and potential yields the energy that is deliverable to the end user via electrical circuitries. There are various techniques used to produce electric energy. Typically, electricity is generated by using fossil fuels or natural gas. However, these resources are facing the extinction problem. Thus, another established method to generate electricity is by using water flow pressure in hydroelectric station. This work presents a model of small electrical generator developed based on the theory of pressure yielded by water stream. The development of conventional hydroelectric generator station destroyed the nature environment and caused the death of animal, especially in the water. Therefore, a turbine in a spherical shape that is integrated with microcontroller is suggested in this work with external passage that is attached to the turbine to reduce the catastrophic effect to the aquamarine and nature. The analysis is conducted on the different material while designing the basin, size of basin radius and the structure of model outlet inlet. The results show that the turbine that is designed by using polyvinyl chloride (PVC) with 10 cm radius produced higher voltage at 5.8 V compared to the other types of basin material and radius

Comparative Study of Inlet Structure and Obstacle Plate Designs Affecting the Temperature Stratification Characteristics

Temperature stratification between outgoing hot water and incoming cold water is a key factor in diminishing energy loss during the discharging process and maximizing the useful hot water delivered from the tank or enhancing the thermal efficiency of the heating device during the heating process. In this study, the inlet structure and the obstacle plate were designed and modified based on two main factors, the reduction of inlet water velocity and the stipulation of the water recirculation area, to develop temperature stratification through the computational fluid dynamics method. The simulation model’s accuracy was validated against the experimental results. The results showed that using the equalizer as an inlet pipe’s auxiliary device was the best approach for decreasing the inlet water velocity, which resulted in enhancing temperature stratification. The discharging efficiency improved from 77.3% for the original tank model to 86.1% for the tank with equalizer IV model, which meant an additional 45 L of useful hot water was gained from the good temperature stratification storage tank. The installation of the obstacle plate for controlling the turbulence zone could not improve temperature stratification significantly, which resulted in an increase in discharging efficiency by only 4% more than the original tank model.

Research on Valveless Piezoelectric Micropump Based on COMSOL and 3D Printing Technology

In order to make the output flow of the valveless micropump larger and obtain continuous pumping capacity, a valveless piezoelectric micropump with a combination of V-shaped structure inlet and Y-shaped structure outlet is designed, which saves the design and installation of microvalve and makes the structure relatively simple and easy to process. In this paper, first, the operating principle of the valveless piezoelectric micro pump is analyzed; secondly, COMSOL simulation software was used to perform modal analysis on the drive and the appropriate vibration mode was obtained. The displacement trend of the piezoelectric vibrator was simulated and tested at the frequency of 40 Hz and different voltages; finally, 3D printing technology was used to produce an experimental prototype of the micro-pump, and t the specific size of the micro pump is 20 mm×20 mm×6 mm. The test results show that, driven by AC voltage, the discharge liquid of the valveless piezoelectric micropump can reach 658.8μl/min.

Research on flexible skin technique for adaptive bump inlet structure

PurposeAdaptive bump inlet can adaptively change the shape of inlet bump surface according to the flight speed of aircraft, ensuring that the inlet has good inlet-engine match performance in a wide speed range. This paper aims to use a composite flexible skin reinforced by shape memory alloy (SMA) fiber as the deformable structure at bump surface to realize the adjustable bump surface of adaptive bump inlet.Design/methodology/approachAccording to the deformation and load-bearing requirements of adaptive bump, SMA is applied to the design of adaptive bump inlet due to its characteristic of super-elasticity. A kind of SMA fiber is studied. A composite flexible skin reinforced by SMA is proposed, and its mechanical properties are analyzed. On this basis, an adaptive bump inlet is designed in which the composite flexible skin reinforced by SMA is used as bump surface, and the shape of the bump surface is adjusted by way of pressuring. The design scheme and specific parameters of the adaptive bump are given.FindingsAn adaptive bump surface that meets the design requirements of the inlet is designed, which can effectively adjust the inlet throat area with a throat area change rate of 20%.Originality/valueAn adaptive bump inlet with composite flexible skin as a deformable structure at bump surface is designed, and SMA is applied as the reinforcing fiber.

Influence of different type of inlet pipe on the separation characteristic of double-field coupling demulsification and dewatering device

ABSTRACT Achieve high-efficiency dewatering and purification of emulsion is not always feasible using conventional single method. A centrifugal separator embedded in electric field can achieve efficient demulsification and dewatering, and reasonably designing the inlet structure is important to improve the separation performance of the device coupled with electric and centrifugal fields. In this paper, the separation performance of a coupling device with four inlet structures was numerically investigated. Coupled (CFD)-population balance model (PBM) was applied to establish a multiphase flow model considering the coalescence and breakage of droplets. The Reynolds stress model was used to predict turbulent flow. The effects of adjusting the inlet type on flow field and separation efficiency were analyzed, and the structure was optimized. Experimental results are in good agreement with the numerical results. Variations in the inlet structures significantly influenced the oil and water separation process. Compared with three other coupling devices, the involute-type inlet coupling device has smaller pressure drop and lower energy loss; larger tangential velocity as well as larger centrifugal force on droplets to increase droplet size, weak turbulence intensity, and stable flow field for promoting oil–water separation. The involute inlet is more conducive to improve the separation efficiency of the coupling device by about 96.57%.

Performance Research and Optimization of Sound Insulation Hood of Air Compressor Unit

The noise control of a compressor has always been a hot spot in the field of industrial application. In this paper, the air inlet structure of the sound insulation hood of an air compressor unit was studied and improved. Acoustic finite element numerical simulation analysis of the sound insulation hood model was carried out using the acoustic software LMS Virtual Lab Acoustics. The simulation results were compared with the experimental data to verify the correctness of the model, and the theoretical results showed a good agreement with the experiment data. The sound insulation performance of the sound insulation hood under different structures was also investigated in this paper. The results show that the main source of unit noise leakage is outward radiation through the air inlet. In addition, the noise at the air inlet of the unit and the overall noise were significantly reduced compared with the traditional sound insulation hood upon installing 120° and 90° diaphragm structures on the inner wall of the air inlet. The optimization results show that the noise reduction effect of the sound insulation hood with a 90° diaphragm structure was better than that with a 120° diaphragm structure.