Airflow Control Research Articles

Investigation of the effectiveness of top-down natural ventilation of a poultry building in a hot-summer mediterranean climate

In this study, computational fluid dynamics (CFD) was used to examine the efficiency of ventilation and airflow patterns in a multi-level layer hen house. The utilization of windcatchers as a natural ventilation system was the main area of focus. By comparing CFD simulations with experimental data using ANSYS Fluent, the results were validated. The findings showed good agreement in airflow velocity within the windcatchers and throughout the entire building between the CFD calculations and the experimental tests, resulting in uniform airflow distribution and the absence of turbulence in the area where the chickens were kept. This setup provided the layer hens with an acceptable level of comfort by maintaining a consistent and steady temperature profile. The windcatcher-based model demonstrated better temperature uniformity than mechanical window ventilation. The study also emphasized the importance of maintaining appropriate humidity levels throughout the building to ensure the comfort and productivity of layer hens. The advantages of the windcatcher-based system in terms of temperature distribution and airflow control were highlighted by comparison with an alternative ventilation model. These results underscore the importance of using natural ventilation systems, such as windcatchers, to create optimal ventilation conditions and provide layer hens with a comfortable and productive environment (resulting in a temperature reduction from 29°C to 19.85°C with a low and uniform air velocity ranging from 0 m/s to 0.7 m/s at cage level). Practical application An effective and eco-friendly approach to enhance animal health and productivity in poultry farms is to install a natural ventilation system with wind collectors. This setup creates optimal conditions for the animals by improving air quality, regulating temperature, and fine-tuning ventilation. Additionally, it promotes overall sustainability in poultry facilities by lowering energy costs and advocating for environmentally friendly management, aligning agricultural practices with stringent environmental standards.

Enhancing solar façade thermal performance with PCM spheres: A CFD investigation

To improve building energy efficiency and address thermal storage challenges during periods without a heat source, such as cloudy weather or night-time, a range of solutions is required. Innovative technologies and sustainable practices are essential for combating climate change and reducing carbon emissions. This study primarily focuses on Thermal Energy Storage (TES) systems, specifically those using Phase Change Materials (PCMs), to increase energy efficiency for Transpired Solar Collectors used in buildings applications. During the last 30 years Transpired Solar Collectors (TSC) have been extensively investigated. However, a primary concern still exists regarding thermal storage when the heat source is unavailable, such as during periods of cloudy weather or at night. Thus, a Thermal Energy Storage (TES) system coupled with the TSC is a potential solution. In this study we are investigating using numerical simulation the arrangement of encapsulation for TES, integrating phase change materials (PCM) in spherical elements when compared with plate encapsulation elements. The model reproduces a part of a real scale thermal energy storage inserted in a Double Skin TSC. The model consists of a Plexiglas duct in which four different arrangements for the spherical encapsulated PCM were studied. For each of the arrangements the heat transfer between the TES elements and the air passing through the collector was analyzed. The primary finding of the study indicates that the hexagonal arrangement offers better passive airflow control, thus enhancing the heat transfer up to 12.3% compared to the rectangular arrangements

Net Power Enhancement of PEMFC System Based on Dual Loop Multivariable Coordinated Management

A dual loop multivariable coordinated management (DLMCM) is proposed in this paper dealing with the existed nonlinearity and strong coupling between operating parameters such as stack temperature and oxygen excess ratio (OER), to achieve net power enhancement of proton exchange membrane fuel cell (PEMFC) system. The proposed optimization method includes: 1) outer net power optimization loop and 2) inner data-driven multivariable control loop. In solving the outer net power optimization, the experimental data based net power smooth surface model and the security constraints is proposed for maximum net power regulator design. Regarding inner data-driven multivariable control loop, firstly, pseudo partial derivative linearization (PPDL) is proposed for online modeling and estimation of the multi input and multi output (MIMO) system. Then, PPDL based discrete adaptive integral terminal sliding mode control is proposed to achieve maximum net power trajectory tracking. Experimental tests carried out on 5-kW PEMFC system show that the proposed DLMCM has better tracking ability, and internal disturbance rejection compared with sliding mode control (SMC). Moreover, the comparative study with manual guided control, temperature control and air flow control testifies the effectiveness of proposed DLMCM for net power enhancement with a low level of parasitic power consumption ratio.

Experimental Study on Energy Saving through FAN Airflow Control in the Generator Room of a 9200-ton Training Ship

Experimental Study on Energy Saving through FAN Airflow Control in the Generator Room of a 9200-ton Training Ship

Field study on the through-draught characteristics and its influencing factors in subway carriages

The through-draught effect inside a subway significantly impacts the flow field profile, thus causing a potential threat to pollutant dispersion and human health. This study conducted multiple field measurements to systematically analyze the through-draught characteristics during actual train operation. The results show that the total variation of airflow velocity has a high consistency with train operation parameters, which reaches its peak value at the end of the acceleration period (EAP). And the airflow direction reverses as the running speed falls to nearly 0.45 times the maximum of that. For the whole subway train, the air velocity grows continuously in the first four carriages and then drops from the fifth carriage, with a maximum speed of 2.37 ± 0.12 m/s. Moreover, the airflow velocity distribution in a carriage exhibits an approximate “W-shape”, and the profile of the maximum airflow velocity is equivalent to a “parabolic surface”, with a velocity difference of less than 0.45 m/s. Finally, the through-draught effect is comprehensively affected by train acceleration and station spacing which further impact the air inertia forces and internal pressure difference, respectively; the wind speed peak positively correlates with train acceleration and subjects to an inverse exponential function with the station spacing. The research outcome can provide a valid basis for airflow control and air quality improvement in subway carriages operating in the underground tunnel.

Design of mode transition control system for tandem TBCC engine based on direct performance parameters closed-loop control

Abstract This paper conducts a study on closed-loop control of engine performance parameters during mode transition process of TBCC engine based on artificial intelligence method. Firstly, a composite modeling method based on stepwise regression analysis and batch normalization-depth neural network is proposed to establish the on-board model during mode transition to estimate the thrust and inlet airflow in real-time. Secondly, based on the hybrid penalty function-particle swarm optimization algorithm, a mode transition control schedule applicable to the closed-loop control of thrust and inlet airflow is developed. Finally, a data processing method based on similarity conversion is proposed to extend the applicable envelope range of the mode transition control system. The transition time is shortened by 33.3 %, and the fluctuations of thrust and inlet airflow are reduced by 1.33 % and 10.77 %, respectively. When the control system is applied to the off-design mode transition process, a satisfactory mode transition performance is also obtained.

Transforming Adversity Into Opportunity: Assessing User Satisfaction in Hospital Transformation in Lieu of a Pandemic Through the Multi-Corridor Expansion Model for Epidemic Management and Environmental Design Enhancement

The COVID-19 pandemic brought the world to a standstill, demonstrating the critical importance of preparedness and adaptation in the face of pandemics and epidemics. Pandemics and epidemics have been a persistent threat throughout human history, causing significant mortality and morbidity, as well as disrupting economies, societies, and politics. The COVID-19 pandemic, caused by the SARS-CoV-2 virus, had a profound impact on healthcare systems worldwide, leading to hospitals transforming into pandemic centers. This case study, conducted at Riphah International Hospital (RIH) in Islamabad, Pakistan, explores the transformation of an existing facility into a pandemic center, highlighting the challenges faced in managing the pandemic conditions and ensuring the safety of the public and medical teams. The study was based on an observational study and data collection from end users with respect to transformation satisfaction and issues faced. Spatial segregation, logistics, air flow control, managing infection control, etc were major challenges faced and managed. Stress was high for the end users who facilitated in medical teams. The study emphasizes the critical importance of preparedness and adaptation in the face of pandemics/epidemics, including the need for specialized training of medical personnel, dedicated COVID-19 units in hospitals, and a robust and resilient healthcare system that can manage future epidemics.

Experimental Study on Airflow Upwash and Control of Thrust Increase Induced by Ceiling Effect on Microrotor

Abstract This study examines the mechanism of thrust increase due to the ceiling effect in near-ceiling flight, which is one of the concerns for the practical application of micro-air vehicles in indoor environments. We also proposed a novel rotor blade shape with a pressure recovery hole as one of the passive control techniques and investigated its effectiveness in controlling the thrust increase. The obtained results showed a rapid thrust increase, with an outward swirling flow between the rotor blade and ceiling, observed with a rectangular blade with an extremely small distance between the upper surface of the rotor blade and ceiling. The rapid thrust increase was caused by a pressure difference between the rotor blade and the lower surface of the ceiling in addition to the rotor blade rotation, which generated an outward swirling flow between the rotor blade and ceiling. In addition to the force generated by the pressure difference between the upper and lower blade surfaces due to their rotation, the negative pressure area created by the rotor blades generates the airflow upwash. For the thrust-control rotor blade, the ratio of the pressure recovery hole to the rotor blade radius was 0.5, which maintained approximately 90% or more of the thrust without the upper wall of the rectangular blade; moreover, the distance between the ceiling and the rotor blade at which the thrust began to increase rapidly became shorter, flight performance was generally maintained in the absence of the ceiling, and the thrust increase amplitude was suppressed.

A facile heat-treatment solid phase microextraction method for SERS detection of isocarbophos in tea using a hand-held Raman spectrometer.

A facile sensor system based on heat-treatment solid phase microextraction and Surface-Enhanced Raman Scattering (HT-SPME-SERS) was established for in-situ detection of isocarbophos in complex tea matrix. Starting from the action optimization of temperature control unit and air flow control unit, pesticide molecules volatilizing from solution are efficiently captured by substrate and generate real-time SERS signals by a hand-held Raman spectrometer, and the sensor system based on HT-SPME-SERS was finally established. A novel SERS substrate of Cu@rGO@Ag was developed as HT-SPME-SERS material, where reduced graphene oxide (rGO) enriched pesticide molecules by π-π stacking. A superior detection sensitivity brought by the ultra-high enhancement effect of Cu@rGO@Ag substrate was obtained. A good linear relationship between Raman intensity and isocarbophos concentration was obtained and the limit of detection (LOD) was as low as 0.00451ppm. The detection results obtained from the sensor system have been verified by gas chromatography-mass spectrometer (GC-MS), showing its great application potential for the safety of agricultural products.

Activation of CD8+ T Cells in Chronic Obstructive Pulmonary Disease Lung.

Rationale: Despite the importance of inflammation in chronic obstructive pulmonary disease (COPD), the immune cell landscape in the lung tissue of patients with mild-moderate disease has not been well characterized at the single-cell and molecular level. Objectives: To define the immune cell landscape in lung tissue from patients with mild-moderate COPD at single-cell resolution. Methods: We performed single-cell transcriptomic, proteomic, and T-cell receptor repertoire analyses on lung tissue from patients with mild-moderate COPD (n = 5, Global Initiative for Chronic Obstructive Lung Disease I or II), emphysema without airflow obstruction (n = 5), end-stage COPD (n = 2), control (n = 6), or donors (n = 4). We validated in an independent patient cohort (N = 929) and integrated with the Hhip+/- murine model of COPD. Measurements and Main Results: Mild-moderate COPD lungs have increased abundance of two CD8+ T cell subpopulations: cytotoxic KLRG1+TIGIT+CX3CR1+ TEMRA (T effector memory CD45RA+) cells, and DNAM-1+CCR5+ T resident memory (TRM) cells. These CD8+ T cells interact with myeloid and alveolar type II cells via IFNG and have hyperexpanded T-cell receptor clonotypes. In an independent cohort, the CD8+KLRG1+ TEMRA cells are increased in mild-moderate COPD lung compared with control or end-stage COPD lung. Human CD8+KLRG1+ TEMRA cells are similar to CD8+ T cells driving inflammation in an aging-related murine model of COPD. Conclusions: CD8+ TEMRA cells are increased in mild-moderate COPD lung and may contribute to inflammation that precedes severe disease. Further study of these CD8+ T cells may have therapeutic implications for preventing severe COPD.

Better CO2 utilization under comprehensive control of airflow and electromagnetic field

The gliding arc plasma is an effective way to convert CO2 into value-added products. In this paper, the promotion of CO2 conversion by the airflow field control and electromagnetic field control of gliding arc is studied. Firstly, the self-electromagnetic field control of gliding arc is studied through the change of current level or electrode spacing. When increasing the current level or electrode spacing, a better conversion effect can be achieved under high flow rate. In addition, through the introduction of external magnetic field, the processing capacity of gliding arc is further improved under the effect of Lorentz force. Based on the multi-dimensional analysis of airflow field control and magnetic field control, it was found that only under the airflow field control plasma reactor, the conversion effect under 3.3 mm electrode spacing and 5 L min−1 flow rate reached the best, and the corresponding conversion rate and energy efficiency were 13.04% and 26.90%, respectively.

The Effect of Wire Mesh on Premix Combustion with Butane Fuel in Bunsen Burners

Combustion is an important process in a variety of industrial, laboratory and household applications, and the use of devices that control the characteristics of the fire is essential. Bunsen burner is one of the common laboratory equipment used to produce flames in experiments and heating processes. Wire mesh is placed above the Bunsen burner to control air flow and has a crucial role in premix combustion by affecting efficiency, stability and heat distribution. In this study, an experimental investigation will be carried out on Bunsen burners using wire mesh 30, 40, and 50. Furthermore, parameters such as flame stability, flame height, and combustion speed will be measured. The results of this study indicate that the looser the wire mesh density, the burning speed tends to decrease. When using wire mesh 30, the value of the combustion velocity reaches 3.09 cm/s. Meanwhile, when using wire mesh 50, the value of the combustion velocity increased to 3.24 cm/s. This indicates that the wire mesh is getting tighter, air and fuel flow can move faster, thus increasing the combustion velocity. In addition, the density of wire mesh also affects the high flame produced. By using wire mesh 30, the flame height reached 29.69 mm, while using wire mesh 50, the flame height reached 21.56 mm. This shows that the higher the wire mesh density, the flame tends to be more stable and has a smaller height.

Performance evaluation of a novel relay parallel push-pull ventilation system for long-distance pollution control

The push-pull ventilation system, which uses air supply jets to enhance the transport of airflow, is an effective local ventilation method to control pollutants generated in industrial buildings. However, factors such as the increased scale of industrial plants and the restricted location of exhaust hoods have highlighted the need for long-distance pollutant control. In this paper, a novel relay parallel push-pull ventilation (RPPV) system was proposed to enhance the performance of long-distance local ventilation. Through experiments and numerical simulations, this system was evaluated and compared to the traditional parallel push-pull ventilation (PPV) system. Key performance metrics included the performance coefficient, airflow diffusion height, and energy-saving capability. The results indicated that the RPPV system is a very effective mode of long-distance transport. Firstly, the RPPV system exhibited superior airflow control over extended distances, enhancing airflow control by 30.5%. Importantly, it also managed to at least double the critical velocity, demonstrating the potential for longer control distances. Secondly, the RPPV system could achieve targeted airflow delivery, significantly reducing the diffusion height of supply airflows by up to 57%. Finally, the RPPV system consistently achieved the same airflow control as the PPV system, but with a smaller pull airflow rate, saving up to 40% of the pull airflow rate. These results present a promising solution to the problem of pollutant capture and airflow transport over long distances.

Development of an airfoil-based passive volumetric air sampling and flow control system for fixed-wing UAS

This study aims to develop a concept of a passive volumetric flow control system for gas sampling applications onboard fixed-wing UAS based on the pressure field around airfoils. The passive flow control system utilizes the aerodynamics of a UAS to create a vacuum pump effect that ensures constant gas sampling, which can be used to facilitate airborne aerosol and gas measurements. The pump effect is achieved by short-circuiting the pressure field’s minima and maxima points around an airfoil through pipes and 3D printed structures that could function both as a pump system and a gas measurement chamber. The design of this structurally integrated functionality brings many advantages for scientific applications, especially onboard small research UAS, which would dispense entirely with complex active pump systems, thus reducing weight and ensuring gas sampling at a constant volumetric flow rate independent of altitude and atmospheric variance. In favor of developing further applications, this paper outlines the development steps of the passive pump concept starting from the theory and numerical modeling of the effect to the implementation on board a fixed-wing UAS. Finally, possible improvements based on numerical models and flight measurements are discussed.

Self-Powered Airflow Sensor Based on Energy Harvesting of Ventilation Air in Buildings

Heating, ventilation, and air conditioning (HVAC) systems account for one-third of the total energy consumption in office buildings. The use of airflow measurements to control the operation of HVAC systems can reduce energy consumption; thus, a sensor capable of monitoring airflow in a duct system is critical. Triboelectric nanogenerators (TENGs) can be utilized as self-powered sensors in airflow-driven TENGs (ATENGs) as self-powered sensors. By employing ferroelectric materials and surface modifications, the surface charges of TENGs can be increased. In this study, fibrous-mat TENGs were prepared using ferroelectric materials consisting of poly (vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) and polyamide 11 (nylon-11). And these materials were subsequently investigated. Poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) was added to PVDF-TrFE to enhance the ferroelectric crystalline phase. X-ray diffraction analysis revealed that this incorporation affects the β phase. In addition, the surface of nylon-11 was modified using the electrospray technique for post-treatment, thereby improving the interfacial adhesion between the fibers. These materials were then utilized in fibrous-mat ATENGs (FM-ATENGs) to demonstrate their practical application. The FM-ATENGs can be effectively used in an Arduino airflow-check sensor, showcasing their potential for application in HVAC systems, to enhance airflow control and energy efficiency.Graphical

Thermal management in high-frequency, high-power density, solar PV integrated GaN converter system

The High-Frequency and High-Power Density (HPD) converters are the choices of the module integrated Solar Photo Voltaic (SPV) for standalone and interconnected renewables. The operation of the Module Integrated Converters (MIC) in these conditions facilitates better electrical characteristics but care is to be taken in designing the thermal management as the conditions are harsh and vary from that of the non-integrated. The unique design starts from the circuit operations, device packaging, component placement, thermal options with a selection of elements, and finally the airflow control methods. A 300 W, Poly-phase Synchronous Boost Converter with Gallium Nitride devices, operating at 500 kHz is designed for the module integrated conditions in a fixed standalone operation. The EPC-GaN device is used, enabling an effective dual dissipative thermal management, compared to conventional methods. A single heat-sink design for the six devices of the converter in common for effective dissipation through the case is presented. Further, methods for improved dissipations through PCB were explained. An adaptive digital controlled method of airflow control to maintain the acquired-ambient, for the endured operations of the MIC, is discussed. Finally, a stable, high-power density, MIC with 64.3 W/in3, is designed and demonstrated for a standalone street lighting application.

Experimental study on forced ventilation and dust -control in a heading face based on response surface method

Aiming at the problems of unreasonable air flow distribution and serious dust pollution in roadway under forced ventilation of coal mine in a heading face, this study conducted experimental research based on response surface method, and effectively reduced dust concentration by changing air flow distribution in roadway. Firstly, a single factor experiment was conducted to explore the impacts of air outlet wind speed (Va), distance from air outlet to heading face (LS), and driving height (Hd) on the dust concentration at the position of the driver (Y1) and the height of the pedestrian breathing belt (Y2). Subsequently, a comprehensive air flow control response surface test was designed based on the Box-Behnken principle to optimize the dust field, with Y1 and Y2 as the response index. Finally, the sequence of the impact of each variables on the dust concentration and the optimal air flow scheme were determined through the response surface method. The test results showed that the order of significance of Y1 was Hd > Va > LS, and the order of significance of Y2 was LS > Va > Hd. The maximum error between the test value and the predicted value in the optimization model is only 4.01%, the dust concentration at the driver's position and the pedestrian's breathing belt height decreased by 57.7% and 53.8%, respectively, and the dust-control effect was obvious.

Effect of multi parameter synergy on the upgrading characteristics of wide size moist coal

ABSTRACT Through composite dry separation, effective precipitation and impurity removal can be achieved, improving the quality of raw coal. This paper mainly systematically analyzes the synergistic control mechanisms of airflow velocity, airflow transition layer height and control angle on the upgrading characteristics of moist coal. The results show that Zone I is a high airflow area, and when v = 2.12 m/s, it can effectively destroy the original static stable structure of low-density particles, increase the degree of freedom of particle accumulation volume, and achieve effective precipitation of particles. Zone II is a medium air volume area, and when v = 1.78 m/s, the high-density particle group in this area has the weakest obstruction effect on airflow, which can achieve efficient particle precipitation. Zone III is a low airflow area, where the dispersion of high-density particle groups increases at v = 1.36 m/s. The airflow can effectively act on the particles through the bed layer, reducing their surface water. When the height (H) of the gas transition layer is 49-52 mm and the regulatory perspective is 20–25, the distribution uniformity of the gas flow in the bed is the best. After separation and upgrading, the moist coal concentrate yield is 78.3%, ash content is 10.05%, as well as the possible deviation E value is 0.1 g/cm3.

Control of airflow induced vibrations on a cantilever beam by actuating on the exposure of its machined surface notch pattern

Control of airflow induced vibrations on a cantilever beam by actuating on the exposure of its machined surface notch pattern

Model and simulator of inlet air flow in grinding installation with electromagnetic mill

Comminution of raw materials consumes great shares of energy and operating costs of production and processing plants. Savings may be achieved, e.g., by developing new grinding equipment, such as the electromagnetic mill with its dedicated grinding installation; and by applying efficient control algorithms to these elements. Good quality control relies on mathematical models, and testing of versatile control algorithms is much simplified if a plant simulation environment is available. Thus, in this research, measurements were collected at the grinding installation with electromagnetic mill. Then, a model was developed that characterised the flow of transport air in the inlet part of the installation. The model was also implemented in software to provide the pneumatic system simulator. Verification and validation tests were conducted. They confirmed the correct behaviour of the simulator and good compliance with the experimental data, for both steady-states and transients. The model is then suitable for design and parametrization of air flow control algorithms and for their testing in simulation.