Airflow Patterns Research Articles

Walking-induced particle resuspension in a commercial airliner cabin under different ventilation systems

The potential health risk posed by particle resuspension in the air of an airliner cabin is a concern for passengers. This study employed computational fluid dynamics (CFD) to analyze particle dispersion patterns under different ventilation systems, such as mixing ventilation (MV), underfloor air distribution (UFAD), and aisle displacement ventilation (ADV), within a twin-aisle cabin environment. To ensure the accuracy of the CFD model, the study validated the simulated air velocity distribution against experimental airflow patterns from a small-scale water model reported in existing literature. Additionally, the research included direct measurements of particle resuspension within the breathing zone of a full-scale, twin-aisle cabin mockup, which featured five rows of seats. These measurements were taken in response to the disturbance caused by a volunteer walking over an aviation carpet in the aisle. While the CFD simulation results generally aligned with the experimental data, some discrepancies were noted. Pinpointing the exact causes of these discrepancies proved challenging due to the numerous uncertainties and approximations inherent in the study. Nevertheless, the investigation revealed that the air in the upper region near the moving body was pushed forward, creating a strong airflow that enveloped the body. This dynamic resulted in the formation of a wake that lifted particles from the floor level to the upper cabin area. The study observed that particle concentration within the breathing zone increased in the direction of movement. The airflow patterns produced by the three ventilation systems were different. Despite the cabin's symmetrical design, some particles can still transfer from one side to the other, especially under the MV system. The peak particle concentration in the breathing zone was recorded at 20 s, after which it decreased to negligible levels by 120 s. Among the ventilation systems analyzed, the MV system exhibited the highest peak particle concentration, while the UFAD system showed the lowest peak. However, the UFAD system also presented the possibility of very high particle concentrations at certain seats.

Impact of Intra-Phenotypic Nasal Vestibular Variation on Local Airflow Dynamics.

Many individuals with healthy normal nasal anatomy and function exhibit a prominent notch indentation at the junction of the ala and sidewall, specifically around the anterior-superior region of the unilateral nasal vestibule up to the internal nasal valve. This study evaluates the influence of various sizes of notched indentations at the anterior nasal airway on local airflow pattern. A retrospective study involving 25 healthy individuals, each exhibiting at least one unilateral notched indentation (40 total airways). Each individual's notched indentation was quantified after subject-specific three-dimensional nasal airway reconstruction from radiographic images. Computational fluid dynamics modeling was used to simulate nasal inspiratory airflow in each nasal airway at 15 L/min. Localized airflow distributions passing through the inferior, middle, and superior regions were calculated at 15 cross sections. Notched indentation size ranged 1.75-86.84 mm2 (average = 22.37 mm2). At the anterior airway, notched size significantly correlated with inferior airflow volume (R = 0.32, p = 0.04) but not in the middle (R = 0.21, p = 0.20) or superior (R = 0.06, p = 0.70) regions, whereas middle and superior regional resistance values were significantly correlated with notched size (middle: R = 0.54, p < 0.001; superior: R = 0.41, p = 0.009). Medially, resistance at the middle region significantly correlated with notched size (R = 0.56, p < 0.001). At the posterior airway, airflow distributions through the inferior, middle, and superior regions demonstrated weak correlation with notched size (inferior: R = 0.24, p = 0.14, middle: R = 0.24, p = 0.13; superior:R = 0.03, p = 0.83), whereas resistance was significantly correlated in the middle and inferior regions (middle: R = 0.56, p < 0.001;inferior: R = 0.43, p = 0.006). Anterior nasal airway notched indentation size had significantly stronger influence on localized airflow volume through the anterior-inferior airway than other regions of the nasal passage. N/A Laryngoscope, 2024.

Thermal analysis of constant surface area tapered helical Coils: Insights from numerical modelling

Helical coils are integral to numerous engineering and domestic applications, from room heaters and vehicle suspensions to nuclear reactors, owing to their high surface area-to-volume ratio that facilitates efficient heat transfer. This study investigates the natural convection heat transfer characteristics of tapered helical coils under radiative heat loss, focusing on both straight and inverted configurations, within an unconfined air medium. The numerical simulations were validated against experimental results with a maximum deviation of 5 % before proceeding to establish the numerical findings. The analysis considers geometric parameters such as non-dimensional pitch (p*), cone angle (θ), and emissivity (ε), along with Rayleigh number (Ra), to elucidate their impact on average Nusselt number (Nu), mass flow rate of air through the coil core, and heat transfer mechanisms. Results reveal distinct behaviors for straight and inverted coils, with varying Ra and θ influencing heat transfer dynamics and airflow patterns. Notably, inverted coils exhibit enhanced heat transfer characteristics compared to straight coils. For straight coils, Nu initially decreases with increasing θ at lower Ra but rises beyond a critical θ at higher Ra due to independent heat dissipation by the coil turns. When θ changes from 0° to 50° at p* = 6, the change in average Nu is approximately 3 % and 10 % for Ra = 108 and 104 respectively. In contrast, for inverted coils, Nu increases with θ across all Ra, owing to the wider top opening facilitating airflow. Furthermore, empirical correlations are developed to predict Nu based on key parameters, achieving high accuracy with deviations of ± 6 % and ± 4 % for straight and inverted coils, respectively. These correlations provide robust tools for optimizing thermal management in diverse applications. Overall, this study contributes significant insights into tapered coil performance, essential for advancing heat transfer technology and design optimization.

Spray performance simulation and experiment analysis of a greenhouse fixed-pipe twin-fluid cold fogger with different nozzle settings.

High-efficient pesticide application equipment for protected cultivation is scarce. In response, a fixed-pipe twin-fluid clod fogger (FTCF) was proposed as a potential solution. To investigate the optimal nozzle layout and spray performance, a computational fluid dynamics (CFD) model was used to study the airflow distribution and spray deposition of a FTCF with different nozzle settings using the Euler-Lagrange approach. Specifically, two piping configurations, middle-cross-inverted (MCI) and bilateral-malposed-opposite (BMO), were combined with three nozzle spacings (2 m, 3 m, 4 m) resulting in six nozzle settings. Additionally, a greenhouse spray trial was conducted to test the performance of FTCF with the selected nozzle settings and to validate the model. The simulation results revealed that MCI piping configuration exhibited a stronger airflow disturbance compared to BMO configuration, indicating a more significant air-guided effect in the MCI configuration. Combining this finding with the ground droplet distribution analysis of MCI piping configuration, it was observed that MCI-2 m had the lowest coefficient of variation (CV) for ground deposition (20.56%). Consequently, MCI-2 m was determined as the most optimal nozzle setting. Verification results demonstrated a high consistency between experimental and simulated spray deposition results. The FTCF system effectively generated a three-dimensional airflow field throughout the greenhouse environment. Furthermore, jet flow produced by FTCF disrupted the overall airflow pattern within the greenhouse space which facilitated droplet suspension and dispersion. This study provides valuable insights and innovative ideas for enhancing pesticide application technologies in protected cultivations. © 2024 Society of Chemical Industry.

Optimal operations of gaspers for minimizing the exposure risks of airborne disease transmission in an economy-class aircraft cabin

Overhead gaspers with adjustable open ratios and flow directions can alter the airflow pattern in aircraft cabins and consequently influence airborne infectious diseases transmission. To achieve the optimal operations of gaspers for minimizing the passengers’ exposure risks, this study developed a Bayesian optimization method based on computational fluid dynamics (CFD). A seven-row, single-aisle, fully occupied, economy-class aircraft cabin was used for the numerical investigation. Two air distribution systems, i.e., a mixing ventilation system and a personalized displacement ventilation system, were considered. First, the open ratios of all the gaspers were optimized by the CFD-based Bayesian optimization method. The optimal operations of gaspers were determined with only 20 trials calculated by CFD using the Bayesian optimization. With the optimal open ratios of all the gaspers, the number of relatively high-risk passengers (exposure index over 0.95) was effectively reduced by at least 55% and 86% under the mixing ventilation and the personalized displacement ventilation, respectively, when compared with the results with all the gaspers turned off. Next, the optimal open ratios and flow directions of the gaspers near the index passenger were also determined by the proposed method. With the optimized operations of gaspers, the number of relatively high-risk passengers was effectively reduced by at least 50% and 67% under the mixing ventilation and the personalized displacement ventilation, respectively.

Optimal location design for multiple Far-UVC lamps to enhance indoor bioaerosol disinfection by CFD-based Bayesian optimization

In occupied indoor environments, 222 nm far-UVC is a secure and effective approach for controlling the spread of infectious bioaerosols. To enhance the disinfection effectiveness, it is crucial to carefully design the placement of far-UVC lamps, by considering the impact of airflow pattern, bioaerosol distribution, and irradiance exposure. Using CFD alone for designing the locations of multiple lamps presents challenges due to the high computational cost resulting from the high number of potential combinations. Therefore, this study combined CFD with the Bayesian optimization method to improve the computational efficiency, enabling customized design for complex scenarios. The proposed method was first validated with experimental data and the results from the grid search method. Next, the validated method was applied to design the placement of multiple far-UVC lamps in a railway compartment. In the studied railway compartment, just 1 h of optimization led to 1.05-fold–2.87-fold improvement in bioaerosol disinfection efficiency compared to random selection and uniform distribution. This optimization method for customized location design can maximize the utilization of far-UVC lamps, reducing equipment investment and energy consumption while ensuring effective disinfection.

Micro-environment strategy for efficient cooling in telecommunication base stations

The cooling systems of telecommunication base stations (TBSs) primarily rely on room-level air conditioners. However, these systems often lead to problems such as messy airflow, hot spots, and excessive energy consumption. With the rapid development of 5G technology, the integration and power density of communication equipment continue to increase, exacerbating these problems. To address these issues, a micro-environment strategy has been developed. This strategy combines cabinet-level airflow components with unique multi-adjustable-vent air conditioners(MAVACs), which are suitable for the co-deployment of various high power density communication equipment with different airflow patterns in TBSs. An experimental study was conducted to evaluate the cooling performance of the proposed MAVAC, and CFD simulation was carried out to investigate the temperature distribution and airflow patterns using a typical TBS in China that has implemented the micro-environment strategy. The results demonstrate that the micro-environment strategy effectively separates the cold air and hot air, preventing the occurrence of hot spots. The maximum return air temperature of MAVACs was found to be 38.6℃. Additionally, the energy efficiency ratio of the MAVAC system increases by approximately 20 % when the return air temperature is raised from 35℃ to 40℃. This study is expected to contribute to energy savings in TBSs and the successful construction of 5G networks.

The promotion effect of human activity intensity on displacement ventilation efficiency by the enhancement indoor thermal stratification

In a displacement ventilation system, the human body heat source plays a significant role and should not be overlooked. The intensity of human activity is a crucial factor in determining the amount of heat generated by the human body. In this work, the impact of thermal plumes generated by different levels of human activity intensity on the temperature stratification and ventilation efficiency in displacement ventilation system have been explored with experimental and numerical methods. The airflow patterns in the displacement air supply system under various levels of human activity intensity were simulated. The results show that under the same air supply speed, as the human activity intensity increasing from 125 W to 402 W, the phenomenon of temperature stratification becomes more pronounced. With the promotion of thermal plumes, the air flow velocity on the human body surface increases, leading to an enhancement in ventilation efficiency. Therefore, to elimination of the indoor thermal load, the air supply speed can be reasonably reduced according to the human activity intensity in the room, further enhancing the energy-saving effect of displacement ventilation.

Use of innovative sample dryer for effective sample drying in forensic investigations: An experimental study

Back groundThe sample collection and preservation before transportation to a Forensic Science Laboratory in a medicolegal case in India is a crucial step in establishing a link between accused, victim, crime scene and the weapon. This paper discusses pioneering advancement in health technology—a state-of-the-art sample dryer developed to preserve biological samples during Forensic investigations. This unique design has been officially registered with the design office in India as a copy right. Aims and ObjectivesThe primary goal of the sample dryer is to augment the preservation of biological evidence by removing moisture content through air drying before packaging, sealing and its transportation to a Forensic Science Laboratory. Material and MethodsThe process of air drying of biological samples by variety of experiments conducted in sample’s dryer designed for the purpose which employs a range of air movement techniques including horizontal, vertical, and circular laminar flows to swiftly extract moisture from the samples. The drying duration for each experimental sample was documented upon manual confirmation of complete drying. ResultsThe results were extraordinary, showcasing that the sample’s dryer reduced the drying time drastically by up to 27 times lesser in comparison to conventional methods for identical samples. The diverse airflow patterns generated by the sample dryer unequivocally demonstrated it’s utility in achieving superior sample preservation through efficient air drying. ConclusionGiven the exceptional outcomes observed in the experimental phase, the authors strongly advocate for the widespread adoption of this innovative sample’s dryer equipment to ensure effective air drying of biological samples and their efficient sample preservation to enable successful forensic analysis as expected.

Using mobile air cleaners in school classrooms for aerosol removal: Which, where and how

Mobile air cleaners (MACs) have been proposed as a supplementary solution to combat the spread of respiratory aerosols in school classrooms. To determine which, where and how to use MACs, seven small- and medium-sized MACs were selected and assessed for different settings and configurations by 1) a decay test for determining the clean air delivery rate (CADR), and 2) a perception test with a panel of subjects, together with physical measurements, of noise and air movement. The findings show that to achieve the desired CADR (appr. 1000 m3/h for 30 students per classroom), the key factors are the induced airflow pattern and the location of the MACs. MACs with an upward air supply toward the occupied zone showed much higher CADR (max. 775–1332 m3/h) than those with a horizontal air supply (max. 219–333 m3/h). Moreover, using multiple devices simultaneously was crucial when the room size was increased, and combining mechanical ventilation could improve aerosol removal. Achieving a sufficient CADR would always lead to a noise level above the limit of 35 dB(A), yet sometimes the rating of the panel was more than 50% acceptable. The air velocities mostly fulfilled the requirement (&lt;0.2 m/s), which aligned with the positive panel assessment. Hence, the evaluation by a panel of subjects can help to optimize the use of MACs in a classroom.

Assessment of airborne viral transmission risks in a large-scale building using onsite measurements and CFD method

Screening patients for potential respiratory infections through nucleic acid sampling was a critical non-pharmacologic intervention during a respiratory infectious disease pandemic. Evaluating the cross-infection risk of crowded activities conducted indoors is necessary. We conducted a field study of this event in a large-scale stadium and measured the variation in CO2 concentrations. We conducted simulations on the stadium's flow field, CO2 and N2O concentration distribution using the CFD method, which was validated by the on-site measured data. We simulated the diffusion of virus aerosols exhaled by the sampled individuals under an all-fresh and primary return air system, respectively. It was found that space morphology and airflow pattern are the main factors influencing the concentration distribution of human exhaled contaminants. Primary return air systems can reduce the infection risk for sampled individuals by the filtration system and improve the airflow pattern. With the ratio of fresh air to return air of 1.2, the primary return air systems with 70 %, 85 %, and 95 % filtration levels can reduce the infection risk by an average of 54.5 %, 58.3 %, and 62.1 %, respectively, compared to all-fresh air system. It is necessary to optimize the processes and queue setups for nucleic acid sampling activities in the room based on the room airflow characteristics and the return air system using an efficient filtration system.

Flow-Field Inference for Turbulent Exhale Flow Measurement.

Vision-based pulmonary diagnostics present a unique approach for tracking and measuring natural breathing behaviors through remote imaging. While many existing methods correlate chest and diaphragm movements to respiratory behavior, we look at how the direct visualization of thermal CO2 exhale flow patterns can be tracked to directly measure expiratory flow. In this work, we present a novel method for isolating and extracting turbulent exhale flow signals from thermal image sequences through flow-field prediction and optical flow measurement. The objective of this work is to introduce a respiratory diagnostic tool that can be used to capture and quantify natural breathing, to identify and measure respiratory metrics such as breathing rate, flow, and volume. One of the primary contributions of this work is a method for capturing and measuring natural exhale behaviors that describe individualized pulmonary traits. By monitoring subtle individualized respiratory traits, we can perform secondary analysis to identify unique personalized signatures and abnormalities to gain insight into pulmonary function. In our study, we perform data acquisition within a clinical setting to train an inference model (FieldNet) that predicts flow-fields to quantify observed exhale behaviors over time. Expiratory flow measurements capturing individualized flow signatures from our initial cohort demonstrate how the proposed flow field model can be used to isolate and analyze turbulent exhale behaviors and measure anomalous behavior. Our results illustrate that detailed spatial flow analysis can contribute to unique signatures for identifying patient specific natural breathing behaviors and abnormality detection. This provides the first-step towards a non-contact respiratory technology that directly captures effort-independent behaviors based on the direct measurement of imaged CO2 exhaled airflow patterns.

Mucus, airway and plume temperature effects on pMDI-drug delivery in a mouth-throat airway: Experimental and numerical studies

Effective pulmonary drug delivery through pressurized-metered dose inhalers (pMDIs) depends on accurately targeting pharmaceutical aerosols to specific lung areas. Achieving this necessitates a comprehensive understanding of airflow dynamics in the airway and particle transport mechanisms.In this study, a replica of the realistic geometry of the VCU medium-sized mouth-throat (MT) airway was fabricated by rapid prototyping (3D printing) to connect to a next-generation impactor (NGI) setup. The drug concentration deposited in the replica was measured at a constant flow rate of 30 L/min and room temperature using a high-performance liquid chromatography (HPLC) assay. This measurement validated our computational fluid dynamics (CFD) model for simulating particle transport under the same conditions. Large eddy simulation (LES) and discrete phase model (DPM) were employed to model the MT's airflow and particle transport. Using our CFD modeling, we focused on the effects of the temperature distribution of aerosol injection (plume), the influence of inlet air temperature, and the presence of the mucus layer on particle transport and deposition.Our findings revealed that decreasing the plume temperature from 10 °C to −54 °C reduced deposition by approximately 15%, although increasing the average deposited particle sizes within the MT by about 34.5%. The airflow pattern, affected by different plume temperatures, was the prevalent parameter in particle MT deposition. In contrast, the effect of different air inlet temperatures on deposition was negligible. Additionally, incorporating mucus layer features in CFD modelling could further modify the inhaler's efficiency by up to 11%, depending on the specific conditions like diverse plume temperature (−54 °C–10 °C) and airflow temperature conditions (−15 °C–45 °C).

Improving energy consumption for dynamic intake and exhaust FAÇADES: A new setup design: Part B

Dynamic insulation technology adjusts thermal resistance to reduce building energy consumption in response to climate changes. Sustainable building practices prioritize optimizing the building envelope to enhance energy efficiency and regulate the interaction between indoor and outdoor environments. The previous part of this study (Part A) provided an overview of dynamic insulation technology and its potential effectiveness in Iraqi structures with intermittent heating and cooling. The successful implementation of dynamic thermal insulation necessitates careful planning and design solutions that balance performance and efficiency. This paper (Part B) three wall models (static, dynamic, modified dynamic) to evaluate their thermal performance during the heating season. The results demonstrate that the intake facade achieves a preheating efficiency of 77% for the dynamic wall and 81.8% for the modified dynamic wall at the maximum permissible fresh air limit. This improvement in efficiency enhances the quality and conditions of fresh air intake. Additionally, the modified dynamic wall exhibits a notable 50% reduction in pressure loss compared to the dynamic wall, resulting in lower intake or exhaust fan power and thus energy consumption. The results of this paper will guide the presentation of cooling season results and the experimental aspect of future work, offering valuable insights for further exploration. Practical applications This study aims to enhance the efficiency of dynamic facades by investigating the physical phenomena within wall layers. The paper delves into the determination of optimal airflow patterns within facades, the assessment of airflow path modifications, and the evaluation of energy efficiency achieved by implementing dynamic insulation at the intake and exhaust facades during the heating season. The findings contribute to streamlining design complexities and expanding design options for specific climates, thereby ensuring the pragmatic implementation of this technology.

Investigation of a DNA tagged aerosol tracer method for In Situ evaluation of germicidal UV air cleaner effectiveness

Transmission of respiratory pathogens occurs primarily in indoor settings, interventions to reduce the risk of their transmission include increases in outdoor air introduction, filtration, and ultraviolet germicidal irradiation (UVGI). However, validating these interventions is challenging, particularly in actual applications. This study introduces an aerosol tracer system utilizing DNA as tracer molecule, aimed at quantitative characterization of the performance of indoor air cleaning systems. Two DNA tracers, designed one to be relatively UV-resistant and another relatively UV-sensitive, were employed to assess air quality changes related to filtration and ventilation and the contributions of UVGI fixtures in various built environments. We conducted controlled UV exposure experiments of DNA-tagged tracers on foil coupons, aerosolization studies in a test chamber, and in a commercial building conference room. The DNA tracer results provided insights at the point of sampling into the effects of complex airflow dynamics. Additionally, a way to scale the DNA tracer results to MS2 bacteriophage is proposed. Four distinct UV devices challenged with MS2 in a chamber test produced equivalent clean airflow rates of 13–147 CFM. Scaled equivalent clean airflow rates in a commercial building setting using the UV-sensitive tracer varied from 47 percent less to 101 percent more than the chamber results, possibly due to differences in airflow patterns, equipment configuration, and other factors. Our findings provide quantitative understanding of the interaction between UV-sensitive aerosols and the built environment, with implications for environmental monitoring, measuring UVGI fixture impact in field settings, and addressing current technologies limitations for assessing UVGI disinfection efficacy.

Compact Spinning with Different Fibre Types: An Experimental Investigation on Yarn Properties in the Condensing Zone with 3D-Printed Guiding Device

Abstract The lattice apron-based compact spinning system is a form of pneumatic compact spinning that employs airflow to condense fibres into a bundle, enhancing the yarn’s attributes. To explore the airflow dynamics in pneumatic compact spinning, researchers primarily employ traditional theoretical approaches, experimental measurement techniques, and computational fluid dynamics (CFD) methods. In our previous research, we utilized CFD to observe the airflow patterns in pneumatic compact spinning. In this study, we implemented experimental measurement techniques to assess the impact of a 3D-printed guiding device (B-type) on yarn properties. We tested different fibre types in the condensing zone of the compact spinning system with a lattice apron. We used three types of roving to spin the yarn: pure cotton, cotton/polyester (80/20), and polyester/viscose (65/35). The findings revealed that yarns spun using the guiding device exhibited superior strength, hairiness, and evenness compared to those spun without the device.

The Effect of Perforated Plate Geometry on Thermofluid Characteristics of Briquette Drying Oven: A 3D Computational Fluid Dynamics (CFD) Study

The process of drying briquettes in an oven is very costly due to the amount of fuel, labor, and drying time required. Furthermore, inadequate air circulation also results in an uneven and ineffective drying process for briquettes. The performance of the briquette drying oven can be improved by changing the geometry of the perforated plate in the oven to optimize the air distribution. This research process was conducted through Computational Fluid Dynamics (CFD) simulations using Ansys Fluid Flow (Fluent) software by testing three different perforated plate geometries in the oven to determine their effect on the air distribution that occurred in the oven. The research findings indicate that the temperature, velocity, pressure, and airflow pattern of the air are all considerably impacted by the incorporation of perforated plates into the first, second, and third geometries of the oven. When compared to the original geometry, the average air temperature in ovens using the first, second, and third geometries increased by 6.86%, 7.38%, and 9.15%, respectively. Average air velocity increased by 226.04%, 235.77%, and 431.60% in ovens with the first, second, and third geometries. However, the air pressure in ovens with the first, second, and third geometries decreased by 11.05%, 8.62%, and 10.66%. The use of perforated plates on the right, back, and left sides in an oven with the third geometry is the best geometry produced in this research. This happens because this oven produces the most even airflow pattern in the oven compared to other geometries. In addition, the oven with the third geometry has the highest average temperature and average air velocity, with a lower average air pressure compared to the other geometries. Consequently, drying is more effective and takes less time.

Optimizing airflow in spiral blast freezers

Spiral blast freezing is a common unit operation used in food processing facilities for rapidly freezing a variety of foodstuffs. The purpose of a blast freezer is to generate high velocity, low temperature air flow over food products being conveyed within refrigerated enclosures to accomplish the freezing process. However, air flow patterns observed within field operating blast freezers are often suboptimal, resulting in diminished system performance. This paper applies a Monte Carlo simulation technique to a food product freezing simulation in order to identify velocity profiles that optimize the freezing process. A one-dimensional food product model is used to evaluate the interplay between the time variation in the magnitude of the air velocity over food products conveyed through the freezing system and the resulting dwell time needed to achieve a target product core temperature at the blast freezer exit. Temporal heat transfer coefficients derived from field measurements made in a newly installed spiral blast freezer serve as a basis to calibrate the one-dimensional product model.The results of the Monte Carlo analysis show freezing system performance is improved when high and stable air velocities over the product are achieved early in the freezing process dwell time. Air flow patterns within a freezing system that result in high air velocity later in the freezing process dwell time are suboptimal. Field-measured data on a newly installed spiral blast freezer showed this suboptimal air flow pattern and the use of baffling within the spiral enables improved airflow leading to an estimated 10 % increase in production throughput.

Enhancing smoke management in underground parking areas using jet fan systems with a focus on dead-end areas

This study delves into the utilization of jet fans in underground parking structures for smoke management during fires, with a specific focus on enhancing smoke control near critical areas adjacent to dead-end sections through innovative jet fan designs. Through the analysis of airflow patterns and computational fluid dynamic simulations, the research aims to effectively contain smoke and prevent its dispersion to unaffected zones. Findings underscore the significance of parking layout designs in ventilation strategies and soot dispersion rates. Altering the downward orientation of the jet fan outlet results in a notable portion of smoke being confined within the parking facility. Additionally, widening the jet fan outlet, as proposed in the design, can enhance smoke evacuation in all directions. Two hazard detection scenarios were executed within the parking structure following the British standard (BS), with one scenario simulated as a fire ignition source. The chosen scenario considers all escape routes and evacuation procedures within the underground parking area based on architectural specifications. By employing OpenFOAM software with the buoyantBoussinesqPimpleFOAM solver, the study assesses the efficacy of this approach, achieving a reduction in airflow irregularities of over 30%. It also provides valuable insights for designers to refine their comprehension of jet fan design, recommending tailored designs for specific zones. This research offers practical guidance for designers to optimize jet fan configurations for effective smoke control in underground parking facilities.

Strategic ventilation design for reducing airborne infection transmission in a two-story building: A numerical approach

This study employs Computational Fluid Dynamics (CFD) to assess the impact of various ventilation configurations on respiratory droplet dispersion in a two-story restaurant building, aiming to reduce airborne infection transmission. A total of 24 scenarios, involving three ventilation configurations and eight individuals as potential droplet sources, are studied. The configurations—Case A, Case B, and Case C—are analyzed for their effectiveness in controlling droplet dispersion and improving air exchange effectiveness (AEE). Case B, with an outlet near occupants and an inlet above the zone separation, proved most effective in minimizing the droplet transmission between floors, reducing suspended airborne droplets on each floor, and preventing surface contamination, thereby enhancing indoor air quality. Despite the positioning inlet and outlet vents near crowded areas, Case A falls short in effectively removing droplets due to the intricate airflow patterns caused by air diffusers. Case C showed larger AEE but was less effective in droplet dispersion control, indicating a crucial balance between optimizing air circulation and limiting pathogen dispersion is needed. The findings underscore the importance of strategic ventilation design in mitigating airborne infection transmission in multi-level buildings. An optimal configuration, as demonstrated by Case B, combines efficient air distribution with strategic placement of ventilation components to create barriers against interzonal droplet transmission. This study highlights the potential of targeted ventilation strategies to significantly reduce the risk of airborne infection in enclosed, populated spaces.