Inlet Configuration Research Articles

An Analysis of the Ventilation Efficiency of Various Configurations of Inlet and Outlet Vents in a Residential Building by CFD Simulation

Residential buildings in South Korea have equipped an energy recovery ventilation (ERV) system to improve energy efficiency as well as dilute indoor air pollution. While most studies have focused on the efficiency of energy exchange or the ventilation performance of the ERV itself, the ventilation performance can be improved by the proper location of inlet and outlet vents. For the present study, the ventilation performance of the inlet and outlet vents of the ERV was investigated by using CFD simulation. By varying the locations of inlet and outlet vents, the airflow distributions and the age of air were assessed. In addition, the air exchange effectiveness was analyzed by using the mean age of air quantitatively. As a result, a higher age of air was observed when inlet vents were moved to the center of the plan along the wall and an additional inlet or outlet vent was installed in the kitchen. In addition, the highest air exchange effectiveness was obtained when the inlet vents were located in the center of the plan along the wall. Considering the economic perspective, it is recommended to locate the inlet vents in the center to at least improve the ventilation performance.

CFD Simulation of Dynamic Temperature Variations Induced by Tunnel Ventilation in a Broiler House.

Maintaining the optimal microclimate in broiler houses is crucial for bird productivity, yet enabling efficient temperature control remains a significant challenge. This study developed and validated a computational fluid dynamics (CFD) model to predict temporal changes in indoor air temperature in response to variable ventilation operations in a commercial broiler house. The model accurately simulated air velocity and airflow distribution for different numbers of tunnel fans in operation, with air-velocity errors ranging from -0.22 to 0.32 m s-1. The predicted airflow rates through inlets and cooling pads showed good agreement with measured values with an accuracy of up to 108.1%. Additionally, the CFD model effectively predicted temperature dynamics, accounting for chicken heat production and ventilation effect. The model successfully predicted the longitudinal temperature gradients and their variations during ventilation cycles, validating its reliability through comparison with experimental data. This study also explored different variable inlet configurations to mitigate the temperature gradient. The variable inlet adjustment showed the potential to relieve the high temperatures but may reduce overall ventilation efficiency or intensify temperature gradients, which confirms the importance of optimising ventilation strategies. This CFD model provides a valuable tool for evaluating and improving ventilation systems and contributes to enhanced indoor microclimates and productivity in poultry houses.

DDPM investigation on centrifugal slurry pump with inlet and sideline configuration retrofit

The inlet and sideline configuration modifications are widely investigated to alter regional particle fluid flow conditions, considering pressure, turbulence and erosion, therefore to improve energy saving and compartment longevity of centrifugal slurry pump. This paper aims to analyse pump hydraulic and erosion characteristics with proposed pump sideline and inlet configuration retrofit by the DDPM method. Specifically, the inlet guide vane number () and angle (), and sidelining vane (SDV) curvature are investigated in quantitative manner. Accordingly, by adjusting inlet vane configuration and placement, a trade-off between wall erosion and hydraulic performance is observed. The sidelining vane (SDV) design is suggested to avoid resultant counter-current flow formulation, therefore, to mitigate turbulence induced erosion in impeller and volute. However, the SDV modification effect on pump hydraulic head and efficiency is found marginal. In general, this study offers realistic guideline for performance improvement and device upgrading of centrifugal slurry pumps.

Experimental investigation of the aerodynamics of a UAV inlet with double 90° bends

Unmanned aerial vehicle (UAV) inlets commonly have a compact S-shaped inlet structure for the sake of stealth. Most of the current studies on subsonic inlets have focused on S-shaped configurations with relatively gentle transitions of the flow channel. In this study, the aerodynamic performance and swirl flow characteristics of a UAV inlet, which has double 90° bends in the duct and is integrated with an aircraft fuselage and a volute, are studied both experimentally and numerically. The influences of angle of attack, sideslip angle, AIP (Aerodynamic Interface Plane) Mach number, and freestream airspeed are analyzed. A measure of adding two deflectors in front of the first bend and a baffle at the bottom of the volute is proposed to improve the total pressure distortion and swirl distortion characteristics of the inlet. Finally, a practice of shape optimization is performed to further improve the aerodynamic performance and swirl flow characteristics on the basis of the baseline configuration. The results indicate that the maximum and minimum total pressure recovery coefficients of the baseline inlet configuration are 0.982 and 0.969, respectively, as well as the maximum total pressure distortion index of –0.0814 and the maximum swirl distortion index of 32.1 % under normal operating conditions. Through a total of 8 iterations of optimization, the total pressure recovery coefficient is eventually improved by 0.21 % of that of the baseline configuration, as well as the total pressure distortion index, swirl distortion index and maximum swirl angle reduced by 43.6 %, 4.6 % and 11.1 %, respectively.

Impact of Changing Inlet Modes in Ski Face Masks on Adolescent Skiing: A Finite Element Analysis Based on Head Models

Due to the material properties of current ski face masks for adolescents, moisture in exhaled air can become trapped within the material fibers and freeze, leading to potential issues such as breathing difficulties and increased risk of facial frostbite after prolonged skiing. This paper proposes a research approach combining computational fluid dynamics (CFD) and ergonomics to address these issues and enhance the comfort of adolescent skiers. We developed head and face mask models based on the head dimensions of 15–17-year-old males. For enclosed cavities, ensuring the smooth expulsion of exhaled air to prevent re-inhalation is the primary challenge. Through fluid simulation of airflow characteristics within the cavity, we evaluated three different inlet configurations. The results indicate that the location of the air inlets significantly affects the airflow characteristics within the cavity. The side inlet design (type II) showed an average face temperature of 35.35 °C, a 38.5% reduction in average CO2 concentration within the cavity, and a smaller vortex area compared to the other two inlet configurations. Although the difference in airflow velocity within the cavity among the three configurations was minimal, the average exit velocity differed by up to 0.11 m/s. Thus, we conclude that the side inlet configuration offers minimal obstruction to airflow circulation and better thermal insulation when used in the design of fully enclosed helmets. This enhances the safety and comfort of adolescent wearers during physical activities in cold environments. Through this study, we aim to further promote the development of skiing education, enhance the overall quality of adolescents’ skiing, and thus provide them with more opportunities for the future.

Thermal Energy Storage With Horizontal Thermocline Tank for Sludge Drying Application

Solar thermal technologies can be an attractive option for the decarbonization of process heat applications; in particular, thermal energy storage is a high value proposition for continuous processes that may operate at a range of thermal conditions. A thermal-fluid model is developed to investigate the buoyant flow in a horizontal thermocline storage tank for a sludge-drying application. The process conditions and tank geometry considered are unique compared to the domestic water heating application typically considered in the literature and well suited for parabolic trough collectors. It was found that good separation of hot and cold fluids can be achieved with the long horizontal tank geometry depending on the inlet configuration. Uniform flow distribution along the length of the tank is required to establish a thermocline. Assuming desirable inlet conditions can be achieved, the tank outlet temperature predicted by the thermal-fluid model shows good agreement with the system-level performance model.

Optimization of passive micromixers: effects of pillar configuration and gaps on mixing efficiency

Chemical bioreactions play a significant role in many of the microfluidic devices, and their applications in biomedical science have seen substantial growth. Given that effective mixing is vital for initiating biochemical reactions in many applications, micromixers have become increasingly prevalent for high-throughput assays. In this research, a numerical study using the finite element method was conducted to examine the fluid flow and mass transfer characteristics in novel micromixers featuring an array of pillars. The study utilized two-dimensional geometries. The impact of pillar configuration on mixing performance was evaluated using concentration distribution and mixing index as key metrics. The study explores the effects of pillar array design on mixing performance and pressure drop, drawing from principles such as contraction–expansion and split-recombine. Two configurations of pillar arrays, slanted and arrowhead, are introduced, each undergoing investigation regarding parameters such as pillar diameter, gap size between pillar groups, distance between pillars, and vertical shift in pillar groups. Subsequently, optimal micromixers are identified, exhibiting mixing efficiency exceeding 99.7% at moderate Reynolds number (Re = 1), a level typically challenging for micromixers to attain high mixing efficiency. Notably, the pressure drop remains low at 1102 Pa. Furthermore, the variations in mixing index over time and across different positions along the channel are examined. Both configurations demonstrate short mixing lengths and times. At a distance of 4300 μm from the inlet, the slanted and arrowhead configurations yielded mixing indices of 97.2% and 98.9%, respectively. The micromixers could provide a mixing index of 99.5% at the channel’s end within 8 s. Additionally, both configurations exceeded 90% mixing indices by the 3 s. The combination of rapid mixing, low pressure drop, and short mixing length positions the novel micromixers as highly promising for microfluidic applications.

Improving the cooling effect of proton exchange membrane fuel cells by using biomimetic capillary cooling channels based on topology optimization method

Proton exchange membrane hydrogen fuel cells (PEMFCs) are promising energy conversion devices, capable of directly converting chemical energy into electrical energy. However, the ideal operating temperature range for PEMFCs is narrow, and the intense exothermic reactions can easily lead to internal temperatures exceeding optimal levels. Thus, carefully designed cooling channels are crucial to maintain proper operating temperatures. Drawing inspiration from the heat dissipation characteristics of human capillaries on the skin, this study develops three biomimetic capillary cooling channels using a two-objective topology optimization approach. The heat transfer performance of these biomimetic cooling channels is compared against traditional parallel channels (TPC). Additionally, two new flow channel designs with varying inlet and outlet configurations are analyzed. The study examines the impact of different weight factors on the biomimetic cooling channels and uses Pareto frontiers to compare the results from varying weight factors. Findings indicate that topology-optimized biomimetic cooling channels can significantly enhance overall performance. Using a PEC = 1 for TPC as a benchmark, the biomimetic channels achieve average PECs of 1.72, 3.03, and 3.77, indicating superior performance over TPC. Furthermore, the ratio of weight factors also plays a role in the formation of cooling channels. The model with a weight factor ratio of w1:w2 = 0.6:0.4 for double inlets and double outlets arranged in opposite directions shows improved performance. Lastly, this study outlines a design guideline for PEMFC cooling channels based on biomimetic capillary structures and the appropriate ratio of the double objective functions to enhance heat dissipation performance.

Investigation of the relationship between combustion efficiency and total pressure gain for RDE

Total pressure gain is an important parameter in RDC engineering applications. Many factors affect the total pressure gain, such as the area ratio of the outlet to the inlet (A8/A3.1) and type of fuel. In this study, convergent–divergent slot and Tesla valve inlet configurations were adopted. Three convergent nozzles were used, and the ratios of the outlet area to the combustor cross-sectional area (A8/A3.2) were 0.65, 0.5, and 0.25, respectively. The experiments were conducted at mass flow rate of 1.5 kg/s, 1.3 kg/s, and 1.0 kg/s. The combustion efficiency and total pressure gain were calculated using the temperature increase and Mach-corrected static pressure (MCSP). When A8/A3.2 is 0.25, most of the propagation modes are longitudinal pulsed detonations (LPD). The combustion efficiency increased with the equivalence ratio within the range of the detonation boundary. A model was developed to describe the relationship between combustion efficiency and total pressure gain. Once the configuration of the RDC is fixed, a proportional relationship exists between the combustion efficiency and total pressure gain. Improving combustion efficiency enhances the total pressure gain.

Investigating Non-Newtonian Fluid Behavior in Hydrocyclones Via Computational Fluid Dynamics

Expert researchers examine complex patterns of pressure, viscosity, and velocity in a CFD study of viscoelastic food inside hydrocyclones to obtain a detailed grasp of particle behavior and fluid dynamics. Velocity profiles show how fluids and particles flow through the hydrocyclone in complex ways, while pressure distributions show where high and low pressure is found, regions that are critical for maximizing separation efficiency. Furthermore, the analysis of viscosity fluctuations clarifies the intricate relationship between fluid rheology and flow dynamics, providing information on how food's viscoelastic characteristics affect particle trajectories and separation efficiency. Utilizing this comprehensive examination, scientists hope to optimize the design and functioning parameters of the hydrocyclones, which will in turn improve the efficacy and efficiency of particle separation procedures in viscoelastic food solutions. This will ultimately lead to improvements in food processing technology and product quality. Researchers look into the impact of geometric elements on flow patterns and separation efficiency in addition to these characteristics, such as hydrocyclone size and inlet configurations. Additionally, they investigate how different operating parameters, such rotational speed and flow rate, affect how well the hydrocyclone handles viscoelastic food items. Through the integration of these complex analyses, researchers hope to create all encompassing models that can precisely forecast and optimize the behavior of viscoelastic food flows inside hydrocyclones, opening the door to improved process control and food sector product quality.

Simulation design and optimization of reactors for carbon dioxide mineralization

To achieve a synergistic solution for both sustainable waste management and permanent CO2 sequestration, CO2 mineralization via fly ash particles is an option. Based on computational fluid dynamics, two specialized reactors for fly ash mineralization were designed. The reactor designs were strategically tailored to optimize the interactions between fly ash particles and flue gas within the reactor chamber while concurrently facilitating efficient post-reaction-phase separation. The impinging-type inlet configuration dramatically enhanced the interfacial interaction between the fly ash particles and the gaseous mixture, predominantly composed of CO2 and steam. This design modality lengthens the particle residency and reaction times, substantially augmenting the mineralization efficiency. A rigorous investigation of three operational parameters, that is, flue gas velocity, carrier gas velocity, and particle velocity, revealed their influential roles in gas-particle contact kinetics. Through a computational investigation, it can be ascertained that the optimal velocity regime for the flue gas was between 20 and 25 m⋅s−1. Concurrently, the carrier gas velocity should be confined to the range of 9–15 m⋅s−1. Operating within these finely tuned parameters engenders a marked enhancement in reactor performance, thereby providing a robust theoretical basis for operational efficacy. Overall, a judicious reactor design was integrated with data-driven parameter optimization.

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.

Numerical modelling of flow field at shaft spillways with the marguerite-shaped inlets

By decreasing the entrained air flow discharge and improving the hydraulic characteristics of vertical shaft spillways, Marguerite-shaped inlets (MSIs) can mitigate the effects of swirling flow surrounding their inlet. The hydraulic and hydrodynamic characteristics of flow around MSIs under orifice flow regime were numerically investigated, applying different geometrical parameters. This inlet configuration can decrease the strength of swirling flow and increase the flow discharge through the shaft. The finite-volume method and the re-normalisation group k–ε turbulence model were employed to solve the governing equations of motion in a cylindrical coordinate system and a two-phase air–water flow on the water free-surface. Increasing the height and length of the blades of the MSIs was found to increase the area of the barriers against swirling flow, weaken the swirling flow strength, engender a more uniform flow and lower the water free-surface level. Extremely long or high blades, however, resulted in an intense collision of the flow with the spillway and increased the water free-surface level and the swirling flow strength at the MSI.

Fluidized bed hydrodynamics under variable air inlet configurations to enhance gasification reactor efficiency: Computational study

This study employs diverse strategies to enhance motion dynamics within the reactor, with a specific focus on the critical geometric parameter of air nozzle configuration. Methodical analysis of various air nozzle angles, 0°, 45o, and 90° relative to the horizontal bottom line is undertaken to discern their influence on these key parameters throughout multiple stages during the recorded flow duration. A CFD model of the physical model is constructed and solved using ANSYS software. Parameters scrutinized include the longitudinal and lateral distribution of particle volume fraction, alongside radial and axial velocities of particles. The results emphasize the significant impact of air-feeding orientation on both radial and axial particle velocities. Notably, 45° air nozzle angle is the best orientation for the fluidized bed reactor displaying maximal values in particle volume fraction fluctuations and bed height. Furthermore, peak values for radial and axial velocity persist consistently throughout the entire flow duration.

Decoupling inert and reactive gas supply to optimize ion beam sputter deposition apparatus for a more efficient material deposition

For all technologies, the energy-payback time (EPBT) serves as a critical metric. As an example, we study ion beam sputter deposition (IBSD), a sputter deposition approach where plasma, target, and substrate are decoupled. We compare three different configurations for reactive gas injection in order to demonstrate how the corresponding thin-film deposition processes can be improved, i.e., via the ion source, close to the target, or close to the substrate. The latter two decouple the introduction of inert and reactive gases, thus enabling substantial additional control in the deposition process. We investigate nickel oxide (NiOx) thin films as a versatile model system which is of interest for a wide range of applications. In the growth process, we vary growth times between 5 and 205 min and examine O2/Ar flow ratios between 0.13 and 5.82 for the different gas inlet configurations. Based on detailed structural and compositional analyses of the deposited thin films, we show that the deposition mode significantly influences crystal quality, growth rate, and surface roughness. Notably, the configuration where the reactive gas is injected close to the Ni target leads to significant improvement of the crystalline quality of the deposited NiOx layers for thicknesses of 30–200 nm. Furthermore, reactive gas injection close to the substrate yields films of comparable quality for thicknesses of 800 nm and above, but at almost twice the growth rate. These findings present a promising avenue for optimizing EPBT of IBSD by yielding better films in shorter process times and at less energy consumption. Yet, for low O2/Ar ratios the formation of a secondary phase of NiAl2O4 spinel is observed.

Opening configurations and natural cross ventilation performance in a double-loaded multi-level apartment building: A CFD analysis

This study investigates the impact of varied opening configurations on natural cross ventilation of a double-loaded multi-level apartment. Using computational fluid dynamics (CFD) simulations, twenty-five building models with combinations of top-top (TT), top-bottom (TB), center-center (CC), bottom-bottom (BB), and bottom-top (BT) opening configurations were analyzed in both windward and leeward building blocks. In the windward block, the BB configuration yielded the highest dimensionless flow rate (DFR) for levels 1–3, and BT was highest for levels 5 and 6. Air Exchange Efficiency (AEE) was optimal at 45–55% for TB configurations on levels 1–3, and for CC and BT on levels 4–6. Factor optimization (α) was introduced to balance DFR and AEE, favoring TB configurations for level 1–3 and BT configurations for levels 4–6. Additionally, the leeward block's ventilation was slightly influenced (±3.5%) by the windward block's configurations. Notably, the TT configuration achieved the highest α score at level 1 and TB at level 2, even with the lowest DFR. Conversely, the CC configuration, while having the lowest AEE for the first two levels, yielded the highest DFR values. Bottom inlet configurations recorded the lowest α scores for levels 3–6. The research suggests that the TT and CC configurations are the most effective for ventilation in the leeward block. The results indicate that building design can be optimized for ventilation performance at each level without significant impact to adjacent structures. This informs improved ventilation strategies in high-rise buildings, emphasizing design adaptability to enhance indoor air quality.

Indoor Thermal Comfort Sector: A Review of Detection and Control Methods for Thermal Environment in Livestock Buildings

The thermal environment is crucial for livestock production. Accurately detecting thermal environmental conditions enables the implementation of appropriate methods to control the thermal environment in livestock buildings. This study reviewed a comprehensive survey of detection and control methods for thermal environments in livestock buildings. The results demonstrated that temperature, humidity, velocity, and radiation are major elements affecting the thermal comfort of animals. For single thermal environmental parameters, the commonly employed detection methods include field experiments, scale models in wind tunnels, computational fluid dynamics (CFD) simulation, and machine learning. Given that thermal comfort for livestock is influenced by multiple environmental parameters, the Effective Temperature (ET) index, which considers varying proportions of different environmental parameters on the thermal comfort of livestock, is a feasible detection method. Environmental control methods include inlet and outlet configuration, water-cooled floors, installation of a deflector and perforated air ducting (PAD) system, sprinkling, etc. Reasonable inlet configuration increased airflow uniformity by more than 10% and decreased ET by more than 9 °C. Proper outlet configuration improved airflow uniformity by 25%. Sprinkling decreased the temperature by 1.1 °C. This study aims to build a comprehensive dataset for the identification of detection and control methods in research of the thermal environment of livestock buildings.

Modeling Environmental Conditions in Poultry Production: Computational Fluid Dynamics Approach

In recent years, computational fluid dynamics (CFD) has become increasingly important and has proven to be an effective method for assessing environmental conditions in poultry houses. CFD offers simplicity, efficiency, and rapidity in assessing and optimizing poultry house environments, thereby fueling greater interest in its application. This article aims to facilitate researchers in their search for relevant CFD studies in poultry housing environmental conditions by providing an in-depth review of the latest advancements in this field. It has been found that CFD has been widely employed to study and analyze various aspects of poultry house ventilation and air quality under the following five main headings: inlet and fan configuration, ventilation system design, air temperature–humidity distribution, airflow distribution, and particle matter and gas emission. The most commonly used turbulence models in poultry buildings are the standard k-ε, renormalization group (RNG) k-ε, and realizable k-ε models. Additionally, this article presents key solutions with a summary and visualization of fundamental approaches employed in addressing path planning problems within the CFD process. Furthermore, potential challenges, such as data acquisition, validation, computational resource requirements, meshing, and the selection of a proper turbulence model, are discussed, and avenues for future research (the integration of machine learning, building information modeling, and feedback control systems with CFD) are explored.

Effects of flow direction and thermal short-circuiting on the performance of coaxial ground heat exchangers

The effects of flow direction and thermal short-circuiting on the performance of coaxial ground heat exchangers are studied by finite-element simulations, performed through COMSOL Multiphysics 3.4 (©Comsol, Inc.). The real 2-D axisymmetric unsteady heat conduction and convection problem is considered. The distribution of the fluid bulk temperature in the inner circular tube is determined by means of the “weak boundary form” boundary condition available in COMSOL Multiphysics; the laminar convective heat transfer in the outer annular passage is simulated directly. Two Coaxial Ground Heat Exchangers (CGHEs) with the same length but different cross sections are examined; moreover, two values of the ground thermal conductivity, as well as two materials for the inner tube wall are considered. The results point out that the annulus-in flow direction (fluid inlet in the outer annular passage) is more efficient than the center-in flow direction (fluid inlet in the inner circular tube) and that the effect of short circuiting is not very important, if the annulus-in flow direction is employed. Indeed, with this inlet configuration the energy loss for thermal short-circuiting is less than 1% for time intervals longer than 1 hour.

Numerical investigation of hydrocyclone inlet configurations for improving separation performance

Optimizing hydrocyclone inlet design is regarded as an effective strategy to mitigate the adverse effect of particle misplacement and improves separation efficiency. This work proposes innovative hydrocyclone designs based on spiral inlet with a specific spiral angle and tangential inlet with a specific curvature radius. The new designs are evaluated and compared with a standard design using a validated two–fluid model. The separation performance, flow characteristics and volume fraction distribution are considered in the evaluation. An optimum spiral inlet design is identified, with an inlet spiral angle of 90° under the current conditions. This inlet design evidently improves the tangential velocity, strengthens the stability of the air core and reduces short-circuit flows. Additionally, the new inlets help improve the volume fraction of coarse particles in the region near the spigot, mitigating the misplacement of coarse and fine particles. This study offers a new perspective for improving hydrocyclone flows and performance.