Journal articles on the topic 'Indoor air and particle flow'
To see the other types of publications on this topic, follow the link: Indoor air and particle flow.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Indoor air and particle flow.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Xu, Jiang Rong, Wen Min Tian, Fang Chen, and Yan Liu. "Inhalable Particles Transportation of the Kitchen in Different Ventilation Methods." Applied Mechanics and Materials 71-78 (July 2011): 2158–62. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.2158.
Full textAbstract:
In order to evaluate the particle exposure level of people indoor, and to improve indoor air quality, research for the particle distribution in residential kitchen is important. In this paper, a residential kitchen is investigated numerically, and the spread and distribution of particles are simulated detailed using the mixture two-phase model. We focused on the particles transportation in different ventilation methods. The four different conditions are designed for simulating the two-phase flow pattern, and the results of particle concentration of different ventilation methods and different particles diameters are obtained. The simulating results are beneficial for increasing the particle removal efficiency and the design of reasonable ventilation methods.
2
Hoque, Shamia, and Firoza Omar. "Coupling Computational Fluid Dynamics Simulations and Statistical Moments for Designing Healthy Indoor Spaces." International Journal of Environmental Research and Public Health 16, no. 5 (March 5, 2019): 800. http://dx.doi.org/10.3390/ijerph16050800.
Full textAbstract:
Cross-contamination between occupants in an indoor space may occur due to transfer of infectious aerosols. Computational fluid dynamics (CFD) provides detailed insight into particle transport in indoor spaces. However, such simulations are site-specific. This study couples CFD with statistical moments and establishes a framework that transitions site-specific results to generating guidelines for designing “healthy” indoor spaces. Eighteen cases were simulated, and three parameters were assessed: inlet/outlet location, air changes per hour, and the presence/absence of desks. Aerosol release due to a simulated “sneeze” in a two-dimensional ventilated space was applied as a test case. Mean, standard deviation, and skewness of the velocity profiles and particle locations gave an overall picture of the spread and movement of the air flow in the domain. A parameter or configuration did not dominate the values, confirming the significance of considering the combined influence of multiple parameters for determining localized air-flow characteristics. Particle clustering occurred more when the inlet was positioned above the outlet. The particle dispersion pattern could be classified into two time zones: “near time”, <60 s, and “far time”, >120 s. Based on dosage, the 18 cases were classified into three groups ranging from worst case scenario to best case scenario.
3
Li, Jing, Shao-Wu Yin, Guang-Si Shi, and Li Wang. "Optimization of Indoor Thermal Comfort Parameters with the Adaptive Network-Based Fuzzy Inference System and Particle Swarm Optimization Algorithm." Mathematical Problems in Engineering 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/3075432.
Full textAbstract:
The goal of this study is to improve thermal comfort and indoor air quality with the adaptive network-based fuzzy inference system (ANFIS) model and improved particle swarm optimization (PSO) algorithm. A method to optimize air conditioning parameters and installation distance is proposed. The methodology is demonstrated through a prototype case, which corresponds to a typical laboratory in colleges and universities. A laboratory model is established, and simulated flow field information is obtained with the CFD software. Subsequently, the ANFIS model is employed instead of the CFD model to predict indoor flow parameters, and the CFD database is utilized to train ANN input-output “metamodels” for the subsequent optimization. With the improved PSO algorithm and the stratified sequence method, the objective functions are optimized. The functions comprise PMV, PPD, and mean age of air. The optimal installation distance is determined with the hemisphere model. Results show that most of the staff obtain a satisfactory degree of thermal comfort and that the proposed method can significantly reduce the cost of building an experimental device. The proposed methodology can be used to determine appropriate air supply parameters and air conditioner installation position for a pleasant and healthy indoor environment.
4
Drąg, Marlena. "Model-Based Fiber Diameter Determination Approach to Fine Particulate Matter Fraction (PM2.5) Removal in HVAC Systems." Applied Sciences 11, no. 3 (January 23, 2021): 1014. http://dx.doi.org/10.3390/app11031014.
Full textAbstract:
Particulate Matter (PM) is a general term to classify air pollutants consisting of airborne particles. The particles vary in composition and size, and the sizes of particles range from 2.5 µm (PM2.5) to 10 µm (PM10). Anthropogenic activity (e.g., industrial processes or fuel/waste combustion) stands as the main emission source of PM. Due to the fact that indoor PM penetrates from the outside to indoor air, Heating, Ventilation, and Air-Conditioning (HVAC) filtration systems may play a significant role in decreasing air pollution indoors. The section of the respiratory tract affected by particulate matter depends on the particle size. The smaller the fraction, the more deeply it can enter into lungs and bronchi, causing a series of health problems. Conventional electret air filters applied in HVAC systems are not able to efficiently remove PM2.5 (e.g., huge gaps between thick fibers and unintentional elimination of electrostatic effects). The electrospinning process allows for the production of fibers of diverse diameters, including ultrathin yarns. The following work presents the axial length scale χχ estimation method for the given conditions and experimental results. According to this approach, it is possible to find out what parameters should be used to produce materials at certain fiber diameters and to capture fine particulate matter fractions (PM2.5). This research refers to poly(acrylonitrile) (PAN) fibers. The most important advantages, limitations, and challenges of the presented methodology are detected and discussed in this work.
5
Wang, Kaiyuan, Suyuan Yu, Yingge Wu, and Wei Peng. "Measurements and analysis of adhesive forces for micron particles on common indoor surfaces." Indoor and Built Environment 29, no. 7 (July 15, 2019): 931–41. http://dx.doi.org/10.1177/1420326x19863830.
Full textAbstract:
Dust particle resuspension from indoor surfaces is an important source of particulate matter in indoor environments. The adhesive force represents the resistance of the particle to resuspension in an air stream and is a key factor in the resuspension process. The present study used an atomic force microscope (AFM) to measure the adhesive forces between three particle samples and four common indoor surfaces including acrylic, marble, epoxy flooring and wood flooring. The effects of different indoor surfaces were investigated using 12 particle–surface combinations. The results show that the average adhesive forces range from 8.2 nN to 448.1 nN for different combinations with the surface roughness being the main factor. The average adhesive force increases with the contact radius and is larger on the wood flooring surface than on the other three surfaces. Then, the resuspension process was simulated using the moment balance method with the measured adhesive forces as the model inputs. The model predictions show that the wood flooring surface has the largest resistance to the air flow entrainment, followed by the epoxy flooring surface, then the marble surface and the least is the acrylic surface.
6
Hashimoto, Akinori, and Toshiki Takahashi. "Simulation Study on Indoor Pollen Removal with Variable Exhaust Angle of an Air Purifier." Key Engineering Materials 643 (May 2015): 199–204. http://dx.doi.org/10.4028/www.scientific.net/kem.643.199.
Full textAbstract:
We calculate pollen grain trajectories in indoor airflow generated by an air purifier to investigate its pollen removal efficiency and effectiveness of the swinging louver at its air outlet. The air purifier has the directional airflow output vent on its top surface, and the elevation angle of the exhaust flow can be changed with time. The turbulent airflow field and particle motion are computed alternately. Since the turbulent calculation requires more computational time than the particle motion simulation, we need to accelerate the computation using graphics processing unit (GPU) to increase simulation research efficiency. As a consequence, the calculation of the indoor turbulent airflow and the particle trajectories on the GPU is 18 times faster than the same simulation on the CPU. It is found that variable exhaust angle enhances pollen removal efficiency by 6.9%. Moreover, it appears that we should swing louver from the upper corner of the ceiling to straight above the air purifier at higher angular velocity than 50 deg/s.
7
HASHIMOTO, Akinori, Toshiki TAKAHASHI, Kensaku MATSUMOTO, and Ken-ichi UZAKI. "Simulation of indoor air flow created by an air purifier and particle tracking calculation for pollen grains." Indoor Environment 15, no. 2 (2012): 147–61. http://dx.doi.org/10.7879/siej.15.147.
Full text
8
Pasquarella, Cesira, Carla Balocco, Maria Eugenia Colucci, Elisa Saccani, Samuel Paroni, Lara Albertini, Pietro Vitali, and Roberto Albertini. "The Influence of Surgical Staff Behavior on Air Quality in a Conventionally Ventilated Operating Theatre during a Simulated Arthroplasty: A Case Study at the University Hospital of Parma." International Journal of Environmental Research and Public Health 17, no. 2 (January 10, 2020): 452. http://dx.doi.org/10.3390/ijerph17020452.
Full textAbstract:
Surgical staff behavior in operating theatres is one of the factors associated with indoor air quality and surgical site infection risk. The aim of this study was to apply an approach including microbiological, particle, and microclimate parameters during two simulated surgical hip arthroplasties to evaluate the influence of staff behavior on indoor air quality. During the first hip arthroplasty, the surgical team behaved correctly, but in the second operation, behavioral recommendations were not respected. Microbiological contamination was evaluated by active and passive methods. The air velocity, humidity, temperature, and CO2 concentration were also monitored. The highest levels of microbial and particle contamination, as well as the highest variation in the microclimate parameter, were recorded during the surgical operation where the surgical team behaved “incorrectly”. Turbulent air flow ventilation systems appeared more efficient than in the past and very low air microbial contamination was reached when behavior was correct. Therefore, adherence to behavioral recommendations in operating theatres is essential to not undermine the effectiveness of the heating, ventilation, and air conditioning systems and employed resources.
9
Xu, Yukun, Xin Wang, Chen Huang, Guangyao Du, and Yujie Zhang. "Assessing the interaction of air from a jet diffuser on a thermal plume in a room using two-dimensional particle image velocimetry." Building Services Engineering Research and Technology 40, no. 6 (January 12, 2019): 669–81. http://dx.doi.org/10.1177/0143624418824798.
Full textAbstract:
Traditional design of airflow distributions in large spaces does not consider the interference of thermal plumes on jets. In order to quantitatively describe the indoor environment, it is first necessary to quantify how the airflow gets distributed. In this study, a two-dimensional particle image velocimetry (PIV) system for measuring a wide indoor flow field was established. A total of 24 sub-regions (each with a size of 400 mm × 350 mm) were accurately measured in an unmanned room, and the overall cross-sectional flow field was obtained by splicing. Uncertainty analysis proved the rationality of this experimental method. According to the damage extent of the jet structure introduced by the thermal plume, two groups were divided, i.e. Groups A and B. The distribution of velocity fields, trajectories and velocity attenuation of jet centerlines, and velocity magnitude profiles at nozzle and head levels were compared and analyzed in detail. Through this investigation, detailed information of indoor air flow in large spaces can be effectively characterized, which can be useful to help understand the indoor physics and validate CFD models. Practical application: The key to creating a comfortable and healthy indoor thermal environment is the rational design of the airflow distribution. This paper proposes a method for quantitatively describing the airflow distribution in an enclosed space. The equation of the non-dimensional velocity attenuation of jet centerlines is obtained by using advanced technology (PIV), which provides theoretical basis and useful reference for the design of airflow distribution.
10
Kim, Ji-Hye, Hee-Gang Kim, and Myoung-Souk Yeo. "Ventilation and Filtration Control Strategy Considering PM2.5, IAQ, and System Energy." Atmosphere 11, no. 11 (October 22, 2020): 1140. http://dx.doi.org/10.3390/atmos11111140.
Full textAbstract:
Ventilation or filtration control is widely applied to improve indoor particle matter (PM) concentration. Adjusting the ventilation rates to control indoor PM levels can affect the concentration of other indoor pollutants and energy costs, and increasing the filtration flow rate can lower the indoor PM concentration, but also increase the fan energy consumption. In this study, we developed a ventilation and filtration control strategy to determine the optimal control mode and flow rate of the system to meet indoor PM (especially PM2.5) concentration, ensure adequate indoor air quality (IAQ), and minimize fan energy consumption. First, a dynamic model to estimate the indoor PM2.5 generation rate was developed based on the mass balance model and then verified by experiments. Next, the control limit (CL) curve was developed on the basis of the indoor PM2.5 characteristics depending on ventilation and filtration control during various indoor and outdoor PM2.5 conditions (indoor PM2.5 generation rate and outdoor PM2.5 concentration). In addition, an algorithm was proposed to determine the optimal control mode and flow rate of the system. Condition zone control can keep indoor PM2.5 below or as close to the desired target concentration as possible, maintain IAQ within acceptable ranges, and save about 15~70% of fan energy compared with the conventional rule-based control under the case condition.
11
Lima, Anyele Albuquerque, Izabelly Carollynny Maciel Nunes, José Leandro da Silva Duarte, Lucas Meili, Patricia de Carvalho Nagliate, and Alda Graciele Claudio dos Santos Almeida. "Characteristics of SARS-CoV-2 aerosol dispersion in indoor air: scoping review." Research, Society and Development 10, no. 4 (April 17, 2021): e44310414300. http://dx.doi.org/10.33448/rsd-v10i4.14300.
Full textAbstract:
Background: SARS-CoV-2 is the infectious agent responsible for COVID-19, its transmission occurs through the release of respiratory droplets and aerosols. Aim: Identify the main characteristics of SARS-CoV-2 aerosols dispersion in indoor air. Methods: Scoping Review was conducted using the databases: National Library of Medicines – MEDLINE/Pubmed, Scopus, Web of Science, Virtual Health Library (VHL) and Cochrane Library, the search in gray literature was performed on Google Scholar, OpenGrey and Grey Literature Report, from March to September 2020. The descriptors used were "coronavirus" and "aerosol". Data were selected and screened following the protocol established by the The Joanna Briggs Institute, PRISMA flow diagram and EndNote reference management tool. Findings: Ten papers were selected, which presented characteristics that could influence the SARS-CoV-2 aerosols dispersion, with highlight to: aerosol origin; viral load identified in the air (2.86 copies/liter of air); aerosol particle size with viral load (0.25 μm); dispersion (10.00 m); air stay time (3 h); influence of air temperature and relative humidity. Conclusion: Aerosol particles containing SARS-CoV-2 may have infectious viral charge, presenting a minimum size up to 0.25 μm, being able to reach up to 10 m of distance and survive in the air for a few hours. The variables air temperature and relative humidity did not present consistent evidence to influence the dispersion of SARS-CoV-2 aerosols.
12
Han, Bangwoo, Ji-Su Kang, Hak-Joon Kim, Yong-Jin Kim, and Hyosig Won. "Analysis on Particle Cleaning Capacity of Indoor Air Cleaners for Different Flow Rates Considering Energy Consumption." Journal of Korean Association for Particle and Aerosol Research 9, no. 3 (September 30, 2013): 139–47. http://dx.doi.org/10.11629/jpaar.2013.9.3.139.
Full text
13
Geiling, Thomas, Lothar Dressler, Tilo Welker, and Martin Hoffmann. "Fine Dust Measurement with Electrical Fields – Concept of a Hybrid Particle Detector." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2013, CICMT (September 1, 2013): 000131–36. http://dx.doi.org/10.4071/cicmt-2013-wp15.
Full textAbstract:
Fine dust measurements are only conducted at few locations in our daily environment, although it is getting clearer that fine dust poses a high risk on human health. A reason for this deficit is the lack of suitable measurement systems, especially for indoor environments. Of special interest are particles with critical dimension smaller than 10 μm. They constitute the highest risk to human health as they are not filtered out by the respiratory system. By miniaturizing particle detector concepts point-of-care applications are rendered possible and production costs can be greatly reduced with microsystem fabrication technologies. The pursued detector principle is based on the interaction of single particles with electric fields. The field is created within a micro-aperture machined in a silicon substrate. Two electrodes are deposited near the aperture and form a capacitive setup. An air flow drives particles through this aperture one by one. Passing particles distort the electric field, and their presence is detected by an impedance measurement. The changes induced by a single particle are tiny and require precise measurement circuits. Our contribution presents the design of a hybrid particle detector: The sensing element consists of an array of these micro apertures with lead-outs to a measurement circuit. This element is mounted on a LTCC module, which provides all necessary electrical and fluidic functions to operate the particle detector within a larger sensor platform. Sensitive parts of the measurement circuit are mounted on the LTCC module and positioned closely to the sensing elements. Microfluidic channels guide the air flow from the sensor platform to the micro-aperture and back. Therefore, the hybrid module is both: a ceramic interconnect and a ceramic microsystem.
14
Sahu, A. K., T. N. Verma, and S. L. Sinha. "Numerical Simulation of Air Flow in Multiple Beds Intensive Care Unit of Hospital." International Journal of Automotive and Mechanical Engineering 16, no. 2 (July 5, 2019): 6796–807. http://dx.doi.org/10.15282/ijame.16.2.2019.24.0511.
Full textAbstract:
Indoor air quality ventilation diminishes airborne respiratory and other transmission in hospitals. Airflow in associate medical care Unit (ICU) may be provided through natural mean and additionally by the assistance of mechanical ventilation. Natural ventilation might not be enough to satisfy the requirement of ventilation for associate degree ICU. In the present study, numerical simulation of the airflow pattern and contaminant movement using Computational Fluid Dynamics (CFD) has been carried out for multiple bed hospital ICU with different inlet angles to examine path of contaminant transfer in the hospital. The measurement of air velocity is used as an input and standard k-ɛ turbulence model used in simulation work. Grid Independence Test (GIT) of hospital ICU has been carried out using high-quality tetrahedral unstructured mesh. In order to predict CFD simulations accurately, flow pattern has been validated using model of ICU with four bed and patient occupied with light source. Results shows that increasing rate of air flow change decreases the mean age of air. Importance of outlet position is high for transfer of contaminant particle from ICU.
15
Ahn, Hosang, Jae Sik Kang, Gyeong-Seok Choi, and Hyun-Jung Choi. "Optical Sensing Approach to the Recognition of Different Types of Particulate Matters for Sustainable Indoor Environment Management." Sustainability 12, no. 24 (December 17, 2020): 10568. http://dx.doi.org/10.3390/su122410568.
Full textAbstract:
The indoor environment is a crucial part of the built environment where our daily time is mostly spent. It is governed not only by indoor activities, but also affected by interconnected activities such as door opening, walking and routine tasks throughout the inside and outside of buildings and houses. Pollutant control is one of the major concerns for maintaining a sustainable indoor environment, and finding the source of pollutants is a relatively hard part of that task. Pollutants are emitted from various sources, transformed by sunlight, react with vapor in ozone and are transported into cities and from country to country. Due to these reasons, there has been high demand to monitor the transportation of particulate matters and improve air quality. The monitoring of pollutants and identification of their type and concentration enables us to track and control their generation and consequently discover reliable suitable mitigation measures to control air quality at regulated levels by contaminant source removal. However, the monitoring of pollutants, especially particulate matter generation and its transportation, is still not fully operated in atmospheric air due to its open nature and meteorological factors. Even though indoor air is relatively easier to monitor and control than outdoor air in the aspect of specific volume and contaminant source, meteorological parameters still need to be considered because indoor air is not fully separated from outdoor air flow and contaminants’ transportation. In this study, an optical approach using a spectral sensor was attempted to reveal the feasibility of wavelength and chromaticity values of reflected light from specific particles. From the analysis of reflected light of various particulate matters according to different liquid additives, parameter studies were performed to investigate which experimental conditions can contribute to the enhanced selective sensing of particulate matter. Five different particulate matters such as household dust, soil, talc powder, gypsum powder and yellow pine tree pollen were utilized. White samples were selectively identified by the peak at 720 nm for talc and 433 nm and 690 nm in wavelength for gypsum under chemical additives. Other grey household dust and yellowish soil and pine tree pollen revealed a distinct chromaticity x, y coordinates shift in vector within the maximum range from (0.22, 0.19) to (0.55, 0.48). Applicable approaches to assist current particle matter sensors and improve the selective sensing were suggested.
16
Olstrup, Henrik, Annika Hagenbjörk, and Hans Orru. "Ventilation Systems and Their Impact on Nanoparticle Concentrations in Office Buildings." Applied Sciences 11, no. 19 (September 25, 2021): 8930. http://dx.doi.org/10.3390/app11198930.
Full textAbstract:
Nanoparticles (NPs) can infiltrate indoor environments and have a large impact on human health when inhaled. Thus, indoor air quality is highly dependent on the outdoor air and on the filters used in the ventilation systems. In the NanoOffice study, the concentrations and the size distribution of NPs were measured with a five-minute time resolution in twelve office buildings in Umeå. Measurements were taken with an SMPS 3938 during a one-week period in the heating and nonheating seasons. Large differences in ventilation between buildings appeared, despite the fact that similar MVHR ventilation systems were used, and most of them were equipped with F7 filters. The NP concentrations and the simultaneous ventilation flows were measured in buildings with a variable and a more constant ventilation flow. In some cases, an increase in NP concentration could be seen after ventilation turn-on or after an increase in the ventilation flow. There was also one case where the NP concentrations increased in connection with the ventilation being switched off or reducing its flow. However, variable NP concentrations were also shown in buildings with a fairly constant ventilation flow, which was prominent for the two buildings located closest to busy streets. The correlation coefficients between the ventilation flow and particles in different size classes were in general smallest for particles in the smallest size classes, indicating higher filtration efficiency.
17
Topisirovic, G., D. V. Petrovic, and R. Maletic. "Spatial distributions of airborne dust in a cows barn exposed to influence of different ventilation rates." Biotehnologija u stocarstvu 29, no. 2 (2013): 373–83. http://dx.doi.org/10.2298/bah1302373t.
Full textAbstract:
Information on the concentration of dust particles is an important microclimate parameter that characterizes the local environmental quality of each livestock building. Increased concentration of dust particles primarily affects the indoor air quality and, consequently, the animal and workers health. Among many others, ventilation rate is a vital parameter that controls the spatial distribution of airborne dust particles in livestock buildings. This was the main motive for authors of this paper to research the influence of rotation rate of under-roof axial fans (i.e. the air flow rate) on airborne dust particles distribution crossover the barn specified for tied cows breeding. During a series of performed experiments, six different air flow rates have been maintained in the range between 0 m3?h-1 and 48000 m3?h-1. Flow rate has been controlled by special electronic control unit, which provided six different rotation rates of two under-roof fans, including the neutral regime (natural ventilation only). Measurements have been performed at four typical height levels (0,5 m; 1,0 m; 1,5 m and 2,0 m), cross-over the three lateral and four longitudinal characteristic building sections. Consequently, 48 measuring points were appropriately selected, in order to cover the indoor space in adequate way. Comparative analysis of air flow velocities and dust concentrations showed that this fan setup may give satisfactory results under adequate operational regime. Certain working regimes were recommended for use, and the third rotation rate step, generating the airflow of 37300 m3?h-1 or indoor air exchange level of approximately 25 h-1, has been found as the most suitable. Projekat Ministarstva nauke Republike Srbije, br. TR31086: Optimization of technological procedures and zoo-technical resources on farmsin purpose of milk production sustainability improvement, br. TR 31051: Improvement of biotechnological procedures as a function of rational utilizationof energy, agricultural products productivity and quality increase, br. III46009: Improvement and development new technological procedures in production ofanimal products, to achieve high quality and safe competitive products inmarket i br. OI 174011: Dynamical stability and instability of mechanical systems exposed to stochasticdisturbances
18
Luo, Na, Wenguo Weng, Xiaoyu Xu, and Ming Fu. "Human-walking-induced wake flow – PIV experiments and CFD simulations." Indoor and Built Environment 27, no. 8 (March 28, 2017): 1069–84. http://dx.doi.org/10.1177/1420326x17701279.
Full textAbstract:
Quantitative measurement of indoor air distribution or local air velocity around a moving occupant is necessary to study the contaminant transport and energy efficiency in a building. This study measured the longitudinal and cross-sectional air flow distributions at different moving speeds. Experiments were conducted in a small-scale chamber with a moving cylinder, which served as a surrogate of a scaled-down human body. The flow field was measured by the particle image velocimetry technique. The measurements revealed an upward air vortex and a strong downward airflow behind the moving body along the vertical centreline. A vertical mixing and recirculation could be predicted, and such air movements would likely carry the contaminants on and near the floor upwards along the moving path. Symmetric downward and expansive vortices were also observed in the wake flow during the movement, from the top corners of the moving object to the floor. The disturbance range of the moving body was related to the moving speed, especially in consideration of the initial position of the vortex. The experimental results were used to validate a computational fluid dynamic model, which captured these fundamental flow features reasonably well. The large eddy simulation model yielded a higher accuracy than the Reynolds Average Navier-Stokes model in predicting the unsteady instantaneous flow in the entire domain.
19
Do, Sangwon, Myeongjae Lee, and Jong-Seon Kim. "The Effect of a Flow Field on Chemical Detection Performance of Quadrotor Drone." Sensors 20, no. 11 (June 8, 2020): 3262. http://dx.doi.org/10.3390/s20113262.
Full textAbstract:
The determination of a suitable sensor location on quadrotor drones is a very important issue for chemical reconnaissance platforms because the magnitude and direction of air velocity is different for each location. In this study, we investigated a customized chemical reconnaissance system consisting of a quadrotor drone and a chip-sized chemical sensor for detecting dimethyl-methylphosphonate (DMMP; a Sarin simulant) and investigated the chemical detection properties with respect to the sensor position through indoor experiments and particle image velocimetry (PIV) analysis of the system. The PIV results revealed an area free of vortex–vortex interaction between the drone rotors, where there was distinctly stable and uniform chemical detection of DMMP. The proposed chemical reconnaissance system was found to be realistic for practical application.
20
Craven, Brent A., and Gary S. Settles. "A Computational and Experimental Investigation of the Human Thermal Plume." Journal of Fluids Engineering 128, no. 6 (March 19, 2006): 1251–58. http://dx.doi.org/10.1115/1.2353274.
Full textAbstract:
The behavior of the buoyant plume of air shed by a human being in an indoor environment is important to room ventilation requirements, airborne disease spread, air pollution control, indoor air quality, and the thermal comfort of building occupants. It also becomes a critical factor in special environments like surgery rooms and clean-rooms. Of the previous human thermal plume studies, few have used actual human volunteers, made quantitative plume velocity measurements, or considered thermal stratification of the environment. Here, a study of the human thermal plume in a standard room environment, including moderate thermal stratification, is presented. We characterize the velocity field around a human volunteer in a temperature-stratified room using particle image velocimetry (PIV). These results are then compared to those obtained from a steady three-dimensional computational fluid dynamics (CFD) solution of the Reynolds-averaged Navier-Stokes equations (RANS) using the RNG k‐ε two-equation turbulence model. Although the CFD simulation employs a highly simplified model of the human form, it nonetheless compares quite well with the PIV data in terms of the plume centerline velocity distribution, velocity profiles, and flow rates. The effect of thermal room stratification on the human plume is examined by comparing the stratified results with those of an additional CFD plume simulation in a uniform-temperature room. The resulting centerline velocity distribution and plume flow rates are presented. The reduction in plume buoyancy produced by room temperature stratification has a significant effect on plume behavior.
21
Sakharov, Alexander S., and Konstantin Zhukov. "Study of an Air Curtain in the Context of Individual Protection from Exposure to Coronavirus (SARS-CoV-2) Contained in Cough-Generated Fluid Particles." Physics 2, no. 3 (July 6, 2020): 340–51. http://dx.doi.org/10.3390/physics2030018.
Full textAbstract:
The ongoing respiratory COVID-19 pandemic has heavily impacted the social and private lives of the majority of the global population. This infection is primarily transmitted via virus-laden fluid particles (i.e., droplets and aerosols) that are formed in the respiratory tract of infected individuals and expelled from the mouth in the course of breathing, talking, coughing, and sneezing. To mitigate the risk of virus transmission, in many places of the world, the public has been asked or even obliged to use face covers. It is plausible that in the years ahead we will see the use of face masks, face shields and respirators become a normal practice in our life. However, wearing face covers is uncomfortable in some situations, like, for example, in summer heat, while staying on beaches or at hotel swimming pools, doing exercises in gyms, etc. Also, most types of face cover become contaminated with time and need to be periodically replaced or disinfected. These nuisances are caused by the fact that face covers are based on material barriers, which prevent inward and outward propagation of aerosol and droplets containing the pathogen. Here, we study a non-material based protection barrier created by a flow of well directed down stream of air across the front of the open face. The protection is driven by dragging virus-laden particles inside the width of the air flow and hence, as a consequence, displacing them away from their primary trajectories. Applying well established gas-particle flow formalism, we analyzed the dynamics of aerosols and droplets at different regimes of the flow laying over the bodies of the fluid particles. The analysis allowed us to establish the rates of velocity gain of the fluid particles of dimensions relevant for the pathogen transmissions, while they are crossing the width of the air barrier. On the basis of this analysis, we provide a comprehensive study of the protection effectiveness of the air barrier for a susceptible individual located indoor, in an infected environment. Our study shows that such, potentially portable, air curtains can effectively provide both inward and outward protection and serve as an effective personal protective equipment (PPE) mitigating human to human transmission of virus infection like COVID-19.
22
Li, Chunying, Haida Tang, Junyi Tan, Cuimin Li, Yinan Yang, and Fanbo Zeng. "Numerical simulation on year-round performance of water-flow window with different shading control modes." Building Services Engineering Research and Technology 42, no. 2 (November 3, 2020): 157–74. http://dx.doi.org/10.1177/0143624420970397.
Full textAbstract:
Water-flow window combines the functions of transparent building envelop, solar collector, as well as sun shading. Coloured particles are added to the flowing water within window cavity in order to provide extra shading, prevent indoor glare and enhance solar collection. The energy consumption of both air-conditioning system and water heating device can be further reduced. The aim of present investigation is to predict and analyze the year-round energy performance of a well-insulated water-flow window with different shading control modes. Accordingly, physical model of water-flow window is built up. FORTRAN program is developed and utilized in the numerical simulation. Results show that water-flow window can achieve exceptional sun blocking and cooling load reduction without occupying extra space. The year-round solar energy collection efficiency is within the range of 17.95∼21.06%. At the same time, indoor heat gain through the window can be reduced by around 50% compared with common double-layer window. The water-flow window under discussion has great application potential in buildings with constant hot water demand and high-density air-conditioning cooling load. In practice, the shading control mode should be carefully decided, and factors including climate region, hot water demand, window size and occupants' preference on indoor light environment should be taken into consideration. Numerical simulation proves to be an efficient method in predicting the energy performance of similar innovative-designed windows and a good assist in decision-making of real projects.
23
Wang, Yuan Yuan, Gang Cheng Wang, and Yu Cao. "Process of Micro-Simulation of Infilitration Clogging for Highland Reservoir Dam Foundation." Advanced Materials Research 490-495 (March 2012): 2386–90. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.2386.
Full textAbstract:
Using of numerical models of particle flow are based on discrete element theory, combining with the indoor infiltration clogging tests in the region of south mountain in Tibet, the whole development process of the infiltration clogging of loose foundation is simulated. The loss volume, fluid velocity，osmotic coefficient, porosity and moving track of particle samples are recorded and traced in the analytical model, which reveals the water-soil interaction throughout the whole process of the infiltration clogging. The results show that clogging often occurs in the upper soil. Particle trajectory is random reveals the certain randomness of formation of pores. Results of simulation are consistent with the indoor test, to some extent, which validate the feasibility of numerical method in infiltration clogging research. These results provide certain useful data for the further study of infiltration clogging, and also provide a new way for interpretation and analysis of penetration clogging phenomenon in micro-scale .
24
Özer, Özgün, and Dilek Kumlutaş. "Experimental investigation on cross flow fan’s casing parameters inside of a split air conditioner indoor unit by Stereo Particle Image Velocimetry." Applied Thermal Engineering 124 (September 2017): 1233–46. http://dx.doi.org/10.1016/j.applthermaleng.2017.06.053.
Full text
25
Mbazima, Setlamorago Jackson, Masilu Daniel Masekameni, and Gill Nelson. "Physicochemical Properties of Indoor and Outdoor Particulate Matter 2.5 in Selected Residential Areas near a Ferromanganese Smelter." International Journal of Environmental Research and Public Health 18, no. 17 (August 24, 2021): 8900. http://dx.doi.org/10.3390/ijerph18178900.
Full textAbstract:
Particulate matter (PM) of different sizes and elemental composition is a leading contributor to indoor and outdoor air pollution in residential areas. We sought to investigate similarities between indoor and outdoor PM2.5 in three residential areas near a ferromanganese smelter in Meyerton to apportion the emission source(s). Indoor and outdoor PM2.5 samples were collected concurrently, using GilAir300 plus samplers, at a flow rate of 2.75 L/min. PM2.5 was collected on polycarbonate membrane filters housed in 37 mm cassettes coupled with PM2.5 cyclones. Scanning electron microscopy coupled with energy-dispersive spectroscopy was used to study the morphology, and inductively coupled plasma-mass spectroscopy was used to analyse the elemental composition of the PM2.5. Mean indoor and outdoor PM2.5 mass concentrations were 10.99 and 24.95 µg/m3, respectively. Mean outdoor mass concentration was 2.27-fold higher than the indoor concentration. Indoor samples consisted of irregular and agglomerated particles, ranging from 0.09 to 1.06 µm, whereas outdoor samples consisted of irregular and spherical particles, ranging from 0.10 to 0.70 µm. Indoor and outdoor PM2.5 were dominated by manganese, silicon, and iron, however, outdoor PM2.5 had the highest concentration of all elements. The ferromanganese smelter was identified as the potential main contributing source of PM2.5 of different physicochemical properties.
26
Wang, Huan, Guijin Wang, and Xianting Li. "Implementation of demand-oriented ventilation with adjustable fan network." Indoor and Built Environment 29, no. 4 (January 7, 2020): 621–35. http://dx.doi.org/10.1177/1420326x19897114.
Full textAbstract:
Airflow patterns are essential for heating, ventilation and air conditioning (HVAC) systems. Traditional HVAC systems are predesigned and operated using a fixed airflow pattern. However, the indoor occupancy and heat source always vary and therefore, the fixed flow pattern cannot efficiently maintain the required indoor environment conditions. In this study, a novel Adjustable Fan Network (AFN) for improving airflow pattern manoeuvrability is proposed. It integrates multiple small and adjustable axial fans into an AFN, enabling it to change the airflow pattern based on the actual demand with only one set of equipment. Further, the outflow characteristics of two types of axial fans were measured using a quad-view colour sequence particle streak velocimetry (CSPSV) in a test chamber. The ventilation system was then designed based on typical scenarios. Finally, the performance of the AFN was evaluated under different scenarios using a quad-view CSPSV. Based on the results, it was evident that the AFN can provide a better direct supply of air to the occupied zone under different scenarios. With the growing demand for personal thermal comfort and energy-saving in HVAC systems, the novel AFN system has a great potential to be a highly controllable terminal for demand-oriented ventilation.
27
Wang, Jian, Li Sha Chai, and Hao Wu. "Numerical Simulation on the Sinking Process of Open Caisson with Particle Flow Code (PFC)." Advanced Materials Research 838-841 (November 2013): 831–34. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.831.
Full textAbstract:
Sidewall pressure is important to open caisson design. However, FEM simulation for the sinking process of open caisson is quite difficult due to extremely large deformation including soil flow and solid boundary movement. In order to overcome this problem, Particle Flow Code (PFC), which is based upon discrete element method (DEM), was applied to simulate the whole sinking process of an open caisson using proposed load servo mechanism, and the variations of the sidewall pressure with sinking depth and elevation were investigated. The outcomes agree well with the in-situ observation data and the indoor experiment data, which verifies the feasibility of modeling the sinking process of open caissons using PFC and further studying their soil-structure interaction mechanisms from the microscopic prospect.
28
Caldart, C., J. Souza, M. Z. Pellegrin, Glaucea Warmeling Duarte, M. R. Rocha, E. Angioletto, A. A. Pasa, and M. A. Fiori. "Influence of High Energy Milling on the Airflow Sensorproperty of the NBCa Ceramic." Materials Science Forum 727-728 (August 2012): 499–504. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.499.
Full textAbstract:
Some materials have been applied in many surrounding conditions as sensors, electronic devices and other applications. Inexpensive and reliable temperature and flow measurement are important in many applications including, for example, environmental monitoring and control, indoor air conditioning, weather forecasting, automotive and aerospace systems. Special ceramics are an example of such materials. Neodymium-Barium-Copper is a special ceramic that has high electrical conductivity and airflow sensor characteristics. This property is influenced by high energy milling of the powder, when it is not sintered. To evaluate the influence of this type of milling it was carried out an analysis of particle size as a function of milling time. SEM images and granulometric analysis showed significant reduction of particle size with the increase of milling time. For longer times of milling the mixture of precursor powders is favored, resulting in better homogeneity of the ceramic. This is reflected in the properties of airflow sensor.
29
Fonseca, Ana Sofia, Anna-Kaisa Viitanen, Tomi Kanerva, Arto Säämänen, Olivier Aguerre-Chariol, Sebastien Fable, Adrien Dermigny, et al. "Occupational Exposure and Environmental Release: The Case Study of Pouring TiO2 and Filler Materials for Paint Production." International Journal of Environmental Research and Public Health 18, no. 2 (January 7, 2021): 418. http://dx.doi.org/10.3390/ijerph18020418.
Full textAbstract:
Pulmonary exposure to micro- and nanoscaled particles has been widely linked to adverse health effects and high concentrations of respirable particles are expected to occur within and around many industrial settings. In this study, a field-measurement campaign was performed at an industrial manufacturer, during the production of paints. Spatial and personal measurements were conducted and results were used to estimate the mass flows in the facility and the airborne particle release to the outdoor environment. Airborne particle number concentration (1 × 103–1.0 × 104 cm−3), respirable mass (0.06–0.6 mg m−3), and PM10 (0.3–6.5 mg m−3) were measured during pouring activities. In overall; emissions from pouring activities were found to be dominated by coarser particles >300 nm. Even though the raw materials were not identified as nanomaterials by the manufacturers, handling of TiO2 and clays resulted in release of nanometric particles to both workplace air and outdoor environment, which was confirmed by TEM analysis of indoor and stack emission samples. During the measurement period, none of the existing exposure limits in force were exceeded. Particle release to the outdoor environment varied from 6 to 20 g ton−1 at concentrations between 0.6 and 9.7 mg m−3 of total suspended dust depending on the powder. The estimated release of TiO2 to outdoors was 0.9 kg per year. Particle release to the environment is not expected to cause any major impact due to atmospheric dilution
30
Fonseca, Ana Sofia, Anna-Kaisa Viitanen, Tomi Kanerva, Arto Säämänen, Olivier Aguerre-Chariol, Sebastien Fable, Adrien Dermigny, et al. "Occupational Exposure and Environmental Release: The Case Study of Pouring TiO2 and Filler Materials for Paint Production." International Journal of Environmental Research and Public Health 18, no. 2 (January 7, 2021): 418. http://dx.doi.org/10.3390/ijerph18020418.
Full textAbstract:
Pulmonary exposure to micro- and nanoscaled particles has been widely linked to adverse health effects and high concentrations of respirable particles are expected to occur within and around many industrial settings. In this study, a field-measurement campaign was performed at an industrial manufacturer, during the production of paints. Spatial and personal measurements were conducted and results were used to estimate the mass flows in the facility and the airborne particle release to the outdoor environment. Airborne particle number concentration (1 × 103–1.0 × 104 cm−3), respirable mass (0.06–0.6 mg m−3), and PM10 (0.3–6.5 mg m−3) were measured during pouring activities. In overall; emissions from pouring activities were found to be dominated by coarser particles >300 nm. Even though the raw materials were not identified as nanomaterials by the manufacturers, handling of TiO2 and clays resulted in release of nanometric particles to both workplace air and outdoor environment, which was confirmed by TEM analysis of indoor and stack emission samples. During the measurement period, none of the existing exposure limits in force were exceeded. Particle release to the outdoor environment varied from 6 to 20 g ton−1 at concentrations between 0.6 and 9.7 mg m−3 of total suspended dust depending on the powder. The estimated release of TiO2 to outdoors was 0.9 kg per year. Particle release to the environment is not expected to cause any major impact due to atmospheric dilution
31
Zheng, Li Ning, Qiang Xie, Wen Zhao, Meng Fei Qu, and Chun Hua Li. "Microscopic Mechanics of Debris Accumulation Body with Expansive Fine Grain and PFC Numerical Simulation." Advanced Materials Research 243-249 (May 2011): 4188–94. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.4188.
Full textAbstract:
To study the influence mechanism of the excavation stability of the debris accumulation body by the expansive fine grain, it has used by Particle Flow Code, based on indoor test, the fine-grain expansive effect has divided into fine-grain intensity attenuation and volume expansion, and it has linear decreased down from the surface on the accumulation body. Based on the contrastive analysis between simulated result and traditional finite element, the Particle Flow Code is more accurate and true. The analysis result has suggested that when consider the expansive action, the damage model is changed into surface sliding from part slump, and the X-direction stress added 20kPa in the interior of the accumulation body, and the whole sliding force added 30% more or less. At present, the field excavation situation is consistent with the calculation result.
32
Borowski, Marek, Michał Karch, Rafał Łuczak, Piotr Życzkowski, and Marek Jaszczur. "Numerical and experimental analysis of the velocity field of air flowing through swirl diffusers." E3S Web of Conferences 128 (2019): 05003. http://dx.doi.org/10.1051/e3sconf/201912805003.
Full textAbstract:
The air swirl diffusers are popular for the ceiling level air supply system and have been widely used for Indoor Air Quality. They are nowadays one of the most popular diffusers commonly used in airconditioning systems [1, 2]. The swirl diffusers are intended to use in low- and medium-pressure ventilation systems. They allow for obtaining the swirl airflow and are especially recommended to use in spaces with the height from 3m up to 12m, where heating and cooling is performed by the ventilation system and where the exact setting of supply air velocity is important [3-6]. In the case of swirl diffusers,fluid flow is usually significantly influenced by the characteristics of different diffuser designs. In the ventilation system design phase, a typically focus on ventilation effectiveness and takes into account a large number of parameter. However, the discrepancy between design and practice are often experienced mainly because operating conditions don’t correspond to the designing conditions [7-9]. Inthis work, the airflow of swirl diffuser has been studied using Particle Image Velocimetry (PIV) method to analyse the mean airflow and geometry influence on the results. The paper presents a comparison of the results of velocity field measurements using the PIV method and the results obtained by means ofnumerical analysis CFD. Based on the analysis the velocity flow field was evaluated and the range of effective operation of the diffuser have been determined [10].
33
Wang, Huan, Maohui Luo, Guijin Wang, and Xianting Li. "Airflow pattern induced by ceiling fan under different rotation speeds and blowing directions." Indoor and Built Environment 29, no. 10 (November 25, 2019): 1425–40. http://dx.doi.org/10.1177/1420326x19890054.
Full textAbstract:
Ceiling fans have been widely used as effective cooling and air mixing method for building environment conditioning. Understanding its airflow characteristics can be helpful to utilize ceiling fan or integrate it with background air conditioning system. However, the airflow induced by ceiling fan has different flow patterns under different rotating speeds and blowing directions. To date, it is still challenging to capture those complicated airflow fields in room scale. In this study, the airflow pattern induced by a ceiling fan was measured with a new technology, quad-view colour sequence particle streak velocimetry. A series of isothermal experiments were conducted under five rotation speed levels with downward and upward blowing directions in a room-size (4 m × 2.5 m × 3 m) chamber. Based on comprehensive three-dimensional three-component vector measurement results, the average velocity, turbulence intensity and vorticity on the middle section were calculated and used to analyse airflow patterns induced by ceiling fan. The results show that the blowing direction of the fan determines the indoor airflow pattern. When blowing downward, the flow will cause high diversion between jet core under the fan blades and surrounding region. While for upward blowing, the air speed in lower part of the room is much lower but pretty uniform. The detailed measured airflow fields can serve as reference for ceiling fan design and operation.
34
Alimohammadi, Hossein, Kristina Vassiljeva, Eduard Petlenkov, Martin Thalfeldt, Alo Mikola, Tuule Mall Kull, and Ahmet Köse. "Gray Box Time Variant Clogging behaviour and Pressure Drop Prediction of the Air Filter in the HVAC System." E3S Web of Conferences 246 (2021): 10002. http://dx.doi.org/10.1051/e3sconf/202124610002.
Full textAbstract:
Identification and prediction of clogging behavior in heating, ventilation, and air conditioning (HVAC) filters is crucial to avoid issues such as system overheating, energy waste, lower indoor air quality, etc. Researchers are focusing more on the particle loading characteristics of a filter medium in a laboratory environment under steady-state conditions, fixed particle concentrations, area of porosity, dust feed and volumetric flow rate. However, recent research still shows uncertainties in modeling as well as the implementation problems of constructing the HVAC laboratory test bench and equipment. In addition, subjects such as non-uniform particle deposition depreciation of the condition and various type of mechanical filters such as fibrous, fabric, granular, and membrane filter or electrostatic filters which typically used in HVAC systems perform under some assumptions and still need more research. The studies become even more difficult acquiring a large number of time-varying and noisy signals. Another approach among studies is data-driven knowing that Building Automation System (BAS) is not equipped with appropriate sensor measuring the clogging, it is needed to drive the clogging mathematical model from the pressure drop signal. This paper bridges the gap between particle-size study and black box modeling of HVAC filter which has not received much attention from authors. The proposed method assumes that the pressure drop is the result of two time-varying functions; f(t), which represents the dynamics of clogging and, g(t), which refers to dynamics of remained terms. The exponential and polynomial of second order functions are proposed to express the clogging behavior. The software package based on Particle Swarm Optimization Artificial Bee Colony (PSOABC) algorithm, is developed and implemented to estimate the coefficients of the clogging functions based on smallest RMSE, high coefficient of correlation and acceptable tracking. Five Air Handling Unit (AHUs) are selected for practical verification of the model and the results show that the applied method can successfully predict clogging and pressure drop behaviour of HVAC filters.
35
Orlando, Roberta, Merve Polat, Alireza Afshari, Matthew S. Johnson, and Peter Fojan. "Electrospun Nanofibre Air Filters for Particles and Gaseous Pollutants." Sustainability 13, no. 12 (June 8, 2021): 6553. http://dx.doi.org/10.3390/su13126553.
Full textAbstract:
Nanofibre filters may offer new properties not available in commercial fibre filters. These include a higher surface area and the ability to include novel materials within the fibres. In addition the small size allows potential gains in performance due to the slip-flow phenomenon in which normal gas viscosity does not apply to objects smaller than the mean free path of the gas. We tested the properties of novel electrospun fibre filters generated from polyvinyl alcohol solutions, optionally embedded with nano-grains of photocatalytic TiO2 and activated charcoal. The tested materials exhibited pressure drops in the range of 195 Pa to 2693 Pa for a face velocity of 5.3 cm/s and a removal efficiency greater than 97% for 12–480 nm particles. Basis weights for the filters ranged from 16.6 to 67.6 g/m2 and specific surface areas ranged from 1.4 to 17.4 m2/g. Reactivity towards volatile organic compounds (VOCs) was achieved by irradiating the photocatalytic filters with ultraviolet light. It is necessary to solve the problems connected to the absorbance of VOCs and further reduce the resistance to airflow in order for these filters to achieve widespread use. The incorporation of reactive air filtration into building ventilation systems will contribute to improved indoor air quality.
36
Pérez, Agustín Leiva, Ely F. Sacón Vera, Rodolfo Najarro Quintero, Azucena Elizabeth Bernal, David W. Moreira Vega, and Joffre A. Andrade Candell. "Purificación Del Aire Ambiente Interior En La Fábrica De Productos Lácteos “Quesos Latacunga” , Cotopaxi, Ecuador." European Scientific Journal, ESJ 13, no. 15 (May 31, 2017): 47. http://dx.doi.org/10.19044/esj.2017.v13n15p47.
Full textAbstract:
The purification of the internal ambient air of the "Latacunga Cheese" factory was studied by the application of ozone. It is an energetic oxidizing agent which is able to kill the microorganisms present in the medium where it is found. It is applied in its appropriate doses with the aim of purifying the air environment of the workshop. The concentrations of fungi and bacteria found before the application of ozone were higher than that allowed by the Spanish legislation "UNE 100012 Hygiene of systems". Among the fungi identified were Aspergillus sp., Penicilium sp., Scopulariopsis sp., Fusarium sp., and Cladosporium sp. The major bacteria identified were Staphylococcus sp., Streptococcus sp., Bacillus sp., Streptomyces sp., and Enterobacter agglomerans. The main material used for the treatment of indoor air with ozone was a SEFILTRA purifier. This purifier, however, generates an ozonated air flow rate of 2 dm3 / min with an ozone concentration in air of 9.5 g / m3. This means it has an ozone charge of about 1.14 g / hr. A High Efficiency Particle Arresting (99.995%) filter was used to measure microbial air content before and after treatment. After an hour of application of ozone, the reduction of fungi was sufficient to ensure that its presence was complied with the maximum limit established in the legislation in question. However, this does not happen with bacteria which needs about 25 minutes more to conclude which is the same as for fungi.
37
Karadeniz, Ziya Haktan, Dilek Kumlutaş, and Özgün Özer. "Experimental visualization of the flow characteristics of the outflow of a split air conditioner indoor unit by meshed infrared thermography and stereo particle image velocimetry." Experimental Thermal and Fluid Science 44 (January 2013): 334–44. http://dx.doi.org/10.1016/j.expthermflusci.2012.07.005.
Full text
38
Di, Yiwen, Jinhan Mo, Yinping Zhang, and Jiewen Deng. "Ozone deposition velocities on cotton clothing surface determined by the field and laboratory emission cell." Indoor and Built Environment 26, no. 5 (January 28, 2016): 631–41. http://dx.doi.org/10.1177/1420326x16628315.
Full textAbstract:
Interfacial ozone-initiated chemistry can greatly influence human exposure to reactants and products in the indoor environment. As the nearest reaction interface to human body, clothing assumes an important role in the generation of ultrafine particles and volatile organic compounds when reacting with indoor ozone. However, little is known about the kinetics of ozone-clothing reactions. This investigation developed a convenient method to examine the reaction kinetic parameters of ozone-clothing reactions by using a field and laboratory emission cell. Deposition velocity can be determined in a short period by this method. The study found that the deposition velocity and reaction rate constant for ozone-cotton vest reactions were not significantly affected by the ozone concentration, air flow velocity and long soiling duration (>6 h) of the vest. However, whether or not the vest had been soiled with skin oil is key to the magnitude of the deposition velocity and reaction rate constant. The ozone deposition velocities on soiled cotton vest surface are approximately constant under typical indoor conditions. The deposition velocity and reaction rate constant of ozone-initiated reactions with soiled cotton vest are 0.79 ± 0.17 and 2.43 ± 0.71 cm/s, respectively, at room temperature.
39
Schuster, Romain, Dominique Heitz, Philippe Georgeault, and Etienne Mémin. "On-site airflow measurement of a laboratory fume hood using customized large-scale image-based velocimetry." Indoor and Built Environment 29, no. 6 (July 29, 2019): 810–19. http://dx.doi.org/10.1177/1420326x19865928.
Full textAbstract:
This study demonstrates the feasibility of conducting on-site large-scale image-based measurements for indoor airflows characterisation. To illustrate the potential of our method, we chose to study the suction flow generated by a laboratory fume hood in operating conditions. As a matter of fact, laboratory fume hoods are frequently subject to routine checks during which air speed measurements by hot-wire anemometry are performed. However, classical point-to-point hot-wire anemometry may be not sufficient to detect and locate potential leakages. To improve these controls, we developed and tested a new method based on particle image velocimetry principles, which is non-intrusive and authorizes a good spatio-temporal analysis. To face large-scale and on-site issues, we had to make some adaptations. For this reason, we used tracers like bubbles or smoke which have good scattering properties. We also developed our own low-cost light system. To compute velocities from image sequences, we developed an optical flow algorithm based on a large-scale flow model instead of using traditional correlation. The tested method gave good results with a good agreement with sparse hot-wire anemometry measurements but with a wider spatial distribution. In addition, the method provided turbulence intensity estimation and a good monitoring of dynamic flow features, which is important for the detection of leakages.
40
Yang, Young Kwon, Min Young Kim, Yong Woo Song, Sung Ho Choi, and Jin Chul Park. "Windcatcher Louvers to Improve Ventilation Efficiency." Energies 13, no. 17 (August 28, 2020): 4459. http://dx.doi.org/10.3390/en13174459.
Full textAbstract:
Windcatcher louvers are designed to capture air flowing outside a building in order to increase its natural ventilation. There are no studies that have designed the shape of the louver to increase the natural ventilation efficiency of the building. This study aimed to conduct a computational fluid dynamics simulation and mock-up test of a Clark Y airfoil-type windcatcher louver designed to increase the natural ventilation in a building. The following test results were obtained. The optimal angle of attack of the airfoil was calculated via a numerical analysis, which demonstrated that the wind speed was at its highest when the angle of attack was 8°; further, flow separation occurred at angles exceeding 8°, at which point the wind speed began to decrease. The results of the mock-up test demonstrated that the time required to reduce the concentration of fine particles in the indoor air was 120 s shorter when the windcatcher was installed than when it was not, which indicating that the time to reduce particles represents a 37.5%reduction. These results can be seen as reducing the energy consumption of ventilation in the building because the natural ventilation efficiency is increased.
41
Chen, Chun, Bin Zhao, and Xudong Yang. "Impact of two-way air flow due to temperature difference on preventing the entry of outdoor particles using indoor positive pressure control method." Journal of Hazardous Materials 186, no. 2-3 (February 2011): 1290–99. http://dx.doi.org/10.1016/j.jhazmat.2010.12.003.
Full text
42
Ribalta, Carla, Ana López-Lilao, Ana Sofia Fonseca, Alexander Christian Østerskov Jensen, Keld Alstrup Jensen, Eliseo Monfort, and Mar Viana. "Evaluation of One- and Two-Box Models as Particle Exposure Prediction Tools at Industrial Scale." Toxics 9, no. 9 (August 29, 2021): 201. http://dx.doi.org/10.3390/toxics9090201.
Full textAbstract:
One- and two-box models have been pointed out as useful tools for modelling indoor particle exposure. However, model performance still needs further testing if they are to be implemented as trustworthy tools for exposure assessment. The objective of this work is to evaluate the performance, applicability and reproducibility of one- and two-box models on real-world industrial scenarios. A study on filling of seven materials in three filling lines with different levels of energy and mitigation strategies was used. Inhalable and respirable mass concentrations were calculated with one- and two-box models. The continuous drop and rotating drum methods were used for emission rate calculation, and ranges from a one-at-a-time methodology were applied for local exhaust ventilation efficiency and inter-zonal air flows. When using both dustiness methods, large differences were observed for modelled inhalable concentrations but not for respirable, which showed the importance to study the linkage between dustiness and processes. Higher model accuracy (ratio modelled vs. measured concentrations 0.5–5) was obtained for the two- (87%) than the one-box model (53%). Large effects on modelled concentrations were seen when local exhausts ventilation and inter-zonal variations where parametrized in the models. However, a certain degree of variation (10–20%) seems acceptable, as similar conclusions are reached.
43
Seng, Ng Chee, Abdul Mutalib Leman, and Azmahani Sadikin. "Experimental and Simulation Validation Methods of Local Exhaust Ventilation (LEV) in Training Facilities Building." Applied Mechanics and Materials 315 (April 2013): 997–1001. http://dx.doi.org/10.4028/www.scientific.net/amm.315.997.
Full textAbstract:
LEV is a ventilation system that collects and sucks out particles such as dusts, mists, gases, vapors or fumes out of work station, so that they can’t be breathed in by occupants. There is a lot of LEV allocated and installed in order to help protecting occupants’ health but it doesn’t work properly. To overcome this issue, computational fluid dynamics (CFD) will be implemented. Past studies CFD techniques represent a very significant improvement of air ventilation systems. However, CFD is just a tool in prediction model, which can lead to inaccuracy of predicting airflow due to problems with pre-processing, solver and post-processing with parameter from actual experimental results. As of yet, it is not possible to 100% accurately simulate airflow around a body. These codes are simply models which are close to that of a real flow, but not an exact match. All of these require validation to help minimizing percentage error in CFD methodology. Several strategies are needed to boost effectiveness of LEV in terms of predicting airflow in a geometry model. The outcome of this research can be used as a benchmark or guideline for industries to help improving indoor air quality (IAQ).
44
Verma, Tikendra Nath, and Shobha Lata Sinha. "Contaminant Control in Intensive Care Unit of Hospital." Applied Mechanics and Materials 592-594 (July 2014): 2486–90. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.2486.
Full textAbstract:
The complex hospital environment requires special attention to ensure healthy indoor air quality (IAQ). It is necessary to protect to patient and healthcare workers against hospital acquired infections and occupational diseases. In a hospital environment, there is a trend of high concentrations of harmful micro-organisms. From an infection control perspective, the primary objective of hospital design is to place the patient at no risk of infection during hospitalization. Many people consider that hospitals are generally clean and free from pathogens which are actually not true. Hospitals are having very complex environment that require effective ventilation for comfort of patients & control from infections. Intensive care represents the highest level of continuing patient care and treatment. Therefore a turbulent airflow study has been performed in Intensive Care Unit (ICU) of hospital. The present investigation stresses preventing airborne infections, protecting the doctor and other patient in ICU, using Computational Fluid Dynamics (CFD) software FLUENT. In which, Navier Stokes and energy equations in three-dimensional co-ordinates have been solved by control volume method. The SIMPLE algorithms are used to solve these equations. Steady state, k-ε turbulence model and incompressible flow of a constant property fluid have been considered. The tracking of massless contaminated particle (infection) has also been carried out by simulation. It is observed that stagnant zone of the room is not healthy for the patients as well as doctor. Therefore suitable ventilation arrangement must be provided for healthy environment in the hospital.
45
Mishra, Rosaline, B. K. Sapra, and Y. S. Mayya. "Emerging Trends in 222Rn and 220Rn Decay Products Detection." Solid State Phenomena 238 (August 2015): 134–39. http://dx.doi.org/10.4028/www.scientific.net/ssp.238.134.
Full textAbstract:
The importance of measuring the decay products of 222Rn (radon) and 220Rn (Thoron) is being realized by researchers as these are the major inhalation dose givers to the general population. Basically the decay products are radioisotopes of Polonium, Bismuth and Lead, which are solid particles. Upon inhalation, these particles deposit in different parts of the respiratory tract, undergo radioactive decay and irradiate the nearby tissues. So, the study of the behavior of the decay products in indoor air is important for assessing the natural background radiation exposures received by general populations through the inhalation route. Although the inhalation doses are predominantly due to decay products yet it had been the usual practice to measure the gas concentration rather than the decay products because of the complexities involved in their detection. The most common method is to derive the progeny concentration from the measured gas concentration using an assumed equilibrium factor. While this is fairly justified for radon in view of the short-lived nature of the progeny as compared to the gas, this approach is beset with serious limitations in thoron-rich environments. However, the development of passive detection system for the decay products known as deposition-based Direct Radon and Thoron Progeny Sensors, has provided a solution to the long standing problem of measuring the time integrated decay product activity concentration. These deposition sensors are calibrated against active measurement techniques, and provide an easy to use method for passive and simultaneous time integrated decay product measurement. In addition, for multi-parametric study, the different modes of these passive sensors, like flow-mode and wire-mesh capped mode, are also used. These are further discussed in the manuscript.
46
Chung, K. C., and C. Y. Lee. "Using Particle Trajectories to Evaluate Indoor Air Quality." Indoor Environment 4, no. 3-4 (May 1995): 170–76. http://dx.doi.org/10.1177/1420326x9500400307.
Full text
47
Chung, K. C., and C. Y. Lee. "Using Particle Trajectories to Evaluate Indoor Air Quality." Indoor and Built Environment 4, no. 3-4 (1995): 170–76. http://dx.doi.org/10.1159/000463630.
Full text
48
Owen, M. K., D. S. Ensor, and L. E. Sparks. "Airborne particle sizes and sources found in indoor air." Atmospheric Environment. Part A. General Topics 26, no. 12 (August 1992): 2149–62. http://dx.doi.org/10.1016/0960-1686(92)90403-8.
Full text
49
Górny, Rafał L., Tiina Reponen, Klaus Willeke, Detlef Schmechel, Enric Robine, Marjorie Boissier, and Sergey A. Grinshpun. "Fungal Fragments as Indoor Air Biocontaminants." Applied and Environmental Microbiology 68, no. 7 (July 2002): 3522–31. http://dx.doi.org/10.1128/aem.68.7.3522-3531.2002.
Full textAbstract:
ABSTRACT The aerosolization process of fungal propagules of three species (Aspergillus versicolor, Penicillium melinii, and Cladosporium cladosporioides) was studied by using a newly designed and constructed aerosolization chamber. We discovered that fungal fragments are aerosolized simultaneously with spores from contaminated agar and ceiling tile surfaces. Concentration measurements with an optical particle counter showed that the fragments are released in higher numbers (up to 320 times) than the spores. The release of fungal propagules varied depending on the fungal species, the air velocity above the contaminated surface, and the texture and vibration of the contaminated material. In contrast to spores, the release of fragments from smooth surfaces was not affected by air velocity, indicating a different release mechanism. Correlation analysis showed that the number of released fragments cannot be predicted on the basis of the number of spores. Enzyme-linked immunosorbent assays with monoclonal antibodies produced against Aspergillus and Penicillium fungal species showed that fragments and spores share common antigens, which not only confirmed the fungal origin of the fragments but also established their potential biological relevance. The considerable immunological reactivity, the high number, and the small particle size of the fungal fragments may contribute to human health effects that have been detected in buildings with mold problems but had no scientific explanation until now. This study suggests that future fungal spore investigations in buildings with mold problems should include the quantitation of fungal fragments.
50
Wang, Yue Ren, Cong Xue, and Jing Zhang. "Kitchen and Toilet of the Residence Exhaust Flow Field Analysis." Advanced Materials Research 354-355 (October 2011): 726–31. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.726.
Full textAbstract:
Adopting the k-ε standard model, the CFD simulation software to simulate the indoor kitchen and toilet different row of indoor air volume air distribution in natural ventilated circumstance, by comparison results show that different row of indoor air volume changes in the rate of secondary pollution rate, and then to provide the change rule of indoor air quality protection reference basis.