scholarly journals Using to Determine Inhaled Contaminant Volumes and Blower Effectiveness in Several Types of Respirators

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Arthur T. Johnson ◽  
Frank C. Koh ◽  
William H. Scott ◽  
Timothy E. Rehak
Keyword(s):  
Tidal Volume ◽  
Concentration Ratio ◽  
Ambient Air ◽  
Exhaled Breath ◽  
Tracer Gas ◽  
Protection Factor ◽  
Flow Rates ◽  
Different Types ◽  
Head Form ◽  
Experiment Point

This experiment was conducted to determine how much contaminant could be expected to be inhaled when overbreathing several different types of respirators. These included several tight-fitting and loose-fitting powered air-purifying respirators (PAPRs) and one air-purifying respirator (APR). CO2was used as a tracer gas in the ambient air, and several loose-and tight-fitting respirators were tested on the head form of a breathing machine. CO2concentration in the exhaled breath was monitored as well as CO2concentration in the ambient air. This concentration ratio was able to give a measurement of protection factor, not for the respirator necessarily, but for the wearer. Flow rates in the filter/blower inlet and breathing machine outlet were also monitored, so blower effectiveness (defined as the blower contribution to inhaled air) could also be determined. Wearer protection factors were found to range from 1.1 for the Racal AirMate loose-fitting PAPR to infinity for the 3M Hood, 3M Breath-Easy PAPR, and SE 400 breath-responsive PAPR. Inhaled contaminant volumes depended on tidal volume but ranged from 2.02 L to 0 L for the same respirators, respectively. Blower effectiveness was about 1.0 for tight-fitting APRs, 0.18 for the Racal, and greater than 1.0 for two of the loose-fitting PAPRs. With blower effectiveness greater than 1.0, some blower flow during the exhalation phase contributes to the subsequent inhalation. Results from this experiment point to different ways to measure respirator efficacy.

scholarly journals Breathing resistance in heat and moisture exchanging devices

2020 ◽  
pp. 175433712098066
Author(s):  
Mats Ainegren ◽  
Helen Hanstock ◽  
Nikolai Stenfors
Keyword(s):  
Energy Cost ◽  
Ambient Air ◽  
Flow Rates ◽  
Breathing Resistance ◽  
Different Types ◽  
The Face ◽  
The Difference ◽  
Heat And Moisture ◽  
Gas Fractions ◽  
Expiratory Air

The purpose of this study was to investigate the resistance to breathing (RES) in heat and moisture exchanging devices (HME) intended for use during physical activity in the cold. RES was investigated for seventeen HMEs, including different types of filters. In addition, the influence of headwind on RES was tested using four representative HMEs. HMEs were mounted to the face of an artificial head manufactured from ABS plastic. The HMEs were connected to a mechanical lung simulator, which delivered standardised inspiratory and expiratory air flow rates ([Formula: see text], L/s). The delta pressure (Δ p, Pa) between ambient air and the air inside the HME was measured, whereupon RES was calculated. The results showed significant ( p < 0.05) differences in RES between HMEs from different manufacturers, while the difference was smaller, and in some cases not significant ( p > 0.05), between different models/filters within the same brand. The results also showed that RES was highly influenced by different ventilations and headwind conditions. RES increased with increased [Formula: see text] and, when a headwind was introduced, RES decreased during inspiration and increased during expiration. Calculations showed that the oxygen and energy cost for breathing through an HME was very small for most of the tested models. The effect of HME dead space on pulmonary gas fractions depends on the tidal volume. At large tidal volumes and ventilations, the effect of HMEs on pulmonary gas fractions becomes relatively small.

scholarly journals The Impact of Short-Term Exposure to Air Pollution on the Exhaled Breath of Healthy Adults

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2518
Author(s):  
Ariana Lammers ◽  
Anne H. Neerincx ◽  
Susanne J. H. Vijverberg ◽  
Cristina Longo ◽  
Nicole A. H. Janssen ◽  
...  
Keyword(s):  
Air Pollution ◽  
Ambient Air ◽  
Healthy Adults ◽  
Partial Least Square ◽  
Exhaled Breath ◽  
Short Term ◽  
Post Exposure ◽  
Short Term Exposure ◽  
Validation Set ◽  
The Impact

Environmental factors, such as air pollution, can affect the composition of exhaled breath, and should be well understood before biomarkers in exhaled breath can be used in clinical practice. Our objective was to investigate whether short-term exposures to air pollution can be detected in the exhaled breath profile of healthy adults. In this study, 20 healthy young adults were exposed 2–4 times to the ambient air near a major airport and two highways. Before and after each 5 h exposure, exhaled breath was analyzed using an electronic nose (eNose) consisting of seven different cross-reactive metal-oxide sensors. The discrimination between pre and post-exposure was investigated with multilevel partial least square discriminant analysis (PLSDA), followed by linear discriminant and receiver operating characteristic (ROC) analysis, for all data (71 visits), and for a training (51 visits) and validation set (20 visits). Using all eNose measurements and the training set, discrimination between pre and post-exposure resulted in an area under the ROC curve of 0.83 (95% CI = 0.76–0.89) and 0.84 (95% CI = 0.75–0.92), whereas it decreased to 0.66 (95% CI = 0.48–0.84) in the validation set. Short-term exposure to high levels of air pollution potentially influences the exhaled breath profiles of healthy adults, however, the effects may be minimal for regular daily exposures.

Flat-Plate Solar Collector in Transient Operation: Modeling and Measurements

2014 ◽  
Vol 7 (1) ◽  
Author(s):  
Ahmad M. Saleh ◽  
Donald W. Mueller ◽  
Hosni I. Abu-Mulaweh
Keyword(s):  
Differential Equations ◽  
Flat Plate ◽  
Solar Collector ◽  
Storage Tank ◽  
Ambient Air ◽  
Fluid Temperature ◽  
Ambient Conditions ◽  
Flow Rates ◽  
Collector System ◽  
Nodal Model

This paper describes a mathematical model for simulating the transient processes which occur in liquid flat-plate solar collectors. A discrete nodal model that represents the flat-plate solar collector's layers and the storage tank is employed. The model is based on solving a system of coupled differential equations which describe the energy conservation for the glass cover, air gap, absorber, fluid, insulation, and the storage tank. Inputs to the model include the time-varying liquid flow rate, incident solar radiation, and the ambient air temperature, as well as the volume of liquid in the storage tank and initial temperature of the system. The system of differential equations is solved iteratively using an implicit, finite-difference formulation executed with Matlab software. In order to verify the proposed method, an experiment was designed and conducted on different days with variable ambient conditions and flow rates. The comparison between the computed and measured results of the transient fluid temperature at the collector outlet shows good agreement. The proposed method is extremely general and flexible accounting for variable ambient conditions and flow rates and allowing for a geometrical and thermophysical description of all major components of the solar collector system, including the storage tank. The validated, general model is suitable to investigate the effectiveness of various components without the necessity of carrying out experimental work, and the flexible computational scheme is useful for transient simulations of energy systems.

the emission; this is the entrance of the airborne pollutants into the open atmosphere. The local position of this entrance is the emission source, - the transmission, including all phenomena of transport, dispersion and dilution in the open atmosphere, - the immission; this is the entrance of the pollutant into an acceptor. As we are regarding odoriferous pollutants, the immisson is their entrance into a human nose. About air pollution from industrial emission sources, i.g. S02 from power plants, a wide knowledge is available, including sophisticated methods of emission measurement, atmospheric diffusion calculation and measurement of immission concentration in the ambient air. In most countries we have complete national legal regulations, concerning limitation of air contaminent emissions, calculation of stack height and at least evaluation and determination of maximum inmission values. Within this situation the question arises, whether these wellproved methods and devices are suitable for agricultural odour emissions from agricultural sources too. It is well known that all calculations and values, established in air pollution control, are based on large sets of data, obtained by a multitude of experiments and observations. The attempt to apply these established dispersion models to agricultural emission sources, leads to unreasonable results. A comparison in table 1 shows that the large scale values of industrial air pollutions, on which the established dispersion models are based, are too different from those in agriculture. In order to modify the existing dispersion models or to design other types of models, we need the corresponding sets of observations and of experimental data, adequate to the typical agricultural conditions. There are already a lot of investigations to measure odour at the source and in the ambient air. But we all know about the reliability of those measurements and about the difficulties to quantify these results adequate to a computer model calculating the relation between emission and immision depending on various influences and parameters. So we decided to supplement the odour measurements by tracer gas measurements easy to realise with high accuracy. The aim is to get the necessary sets of experimental data for the modification of existing dispersion models for agricultural conditions. 2. INSTRUMENTAL 2.1 EMISSION the published guideline VDI 3881 /2-4/ describes, how to measure odour emissions for application in dispersion models. Results obtained by this method have to be completed with physical data like flow rates etc. As olfactometric odour threshold determination is rather expensive, it is supplemented with tracer gas emissions, easy to quantify. In the mobile tracer gas emission source, fig. 2, up to 50 kg propane per hour are diluted with up to 1 000 m3 air per hour. This blend is blown into the open atmosphere. The dilution device, including the fan, can be seperated from the trailer and mounted at any place, e.g. on top of a roof to simulate the exaust of a pig house or in the middle of a field to simulate undisturbed air flow. 2.2 TRANSMISSION For safety reasons, propane concentration at the source is always below the lower ignition concentration of 2,1 %. As the specific gravity of this emitted propane-air-blend is very close to that of pure air (difference less than 0,2%) and as flow parameters can be chosen in a wide range, we assume

1986 ◽  
pp. 114-114
Keyword(s):  
Experimental Data ◽  
Air Pollution ◽  
Ambient Air ◽  
Emission Source ◽  
Emission Sources ◽  
Dispersion Models ◽  
Tracer Gas ◽  
Open Atmosphere ◽  
Gas Measurements ◽  
Odour Emissions

Ventilation inhomogeneity during controlled ventilation. Which index should be used?

1988 ◽  
Vol 65 (5) ◽  
pp. 2030-2039 ◽  
Author(s):  
A. Larsson ◽  
C. Jonmarker ◽  
O. Werner
Keyword(s):  
Tidal Volume ◽  
Dead Space ◽  
Mean Value ◽  
Mixing Ratio ◽  
Tracer Gas ◽  
Ventilation Inhomogeneity ◽  
Pulmonary Clearance ◽  
Significant Difference ◽  
Uneven Ventilation ◽  
Spontaneously Breathing

Six indexes for diagnosing uneven ventilation by tracer gas washout were studied. The indexes were lung clearance index, mixing ratio, Becklake index, multiple-breath alveolar mixing inefficiency, moment ratio, and pulmonary clearance delay, all of which increase with impaired pulmonary gas mixing. In model lung tests, indexes that compared the actual washout curve with a calculated ideal curve (mixing ratio, multiple-breath alveolar mixing inefficiency, and pulmonary clearance delay) were unaffected by changes in tidal volume and series dead space, whereas the others varied markedly. In both spontaneously breathing and mechanically ventilated patients all indexes showed a significant difference between smokers and nonsmokers (P less than 0.002), but the indexes were somewhat different in their assessment of different ventilatory patterns. However, the mean value for all indexes, with the exception of mixing ratio, was smallest with a fast insufflation followed by an end-inspiratory pause. Any of the indexes may be useful if its limitations are recognized, but mixing ratio, multiple-breath alveolar mixing inefficiency, and pulmonary clearance delay seem preferable, because they are not affected by changes in tidal volume and dead space fraction.

scholarly journals Target Analysis of Volatile Organic Compounds in Exhaled Breath for Lung Cancer Discrimination from Other Pulmonary Diseases and Healthy Persons

Metabolites ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 317
Author(s):  
Michalis Koureas ◽  
Paraskevi Kirgou ◽  
Grigoris Amoutzias ◽  
Christos Hadjichristodoulou ◽  
Konstantinos Gourgoulianis ◽  
...  
Keyword(s):  
Machine Learning ◽  
Computed Tomography ◽  
Lung Cancer ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Ambient Air ◽  
Breath Analysis ◽  
Exhaled Breath ◽  
Healthy Controls ◽  
Volatile Organic

The aim of the present study was to investigate the ability of breath analysis to distinguish lung cancer (LC) patients from patients with other respiratory diseases and healthy people. The population sample consisted of 51 patients with confirmed LC, 38 patients with pathological computed tomography (CT) findings not diagnosed with LC, and 53 healthy controls. The concentrations of 19 volatile organic compounds (VOCs) were quantified in the exhaled breath of study participants by solid phase microextraction (SPME) of the VOCs and subsequent gas chromatography-mass spectrometry (GC-MS) analysis. Kruskal–Wallis and Mann–Whitney tests were used to identify significant differences between subgroups. Machine learning methods were used to determine the discriminant power of the method. Several compounds were found to differ significantly between LC patients and healthy controls. Strong associations were identified for 2-propanol, 1-propanol, toluene, ethylbenzene, and styrene (p-values < 0.001–0.006). These associations remained significant when ambient air concentrations were subtracted from breath concentrations. VOC levels were found to be affected by ambient air concentrations and a few by smoking status. The random forest machine learning algorithm achieved a correct classification of patients of 88.5% (area under the curve—AUC 0.94). However, none of the methods used achieved adequate discrimination between LC patients and patients with abnormal computed tomography (CT) findings. Biomarker sets, consisting mainly of the exogenous monoaromatic compounds and 1- and 2- propanol, adequately discriminated LC patients from healthy controls. The breath concentrations of these compounds may reflect the alterations in patient’s physiological and biochemical status and perhaps can be used as probes for the investigation of these statuses or normalization of patient-related factors in breath analysis.

scholarly journals Theoretical Investigation of the Temperature Limits of an Actively Cooled High Concentration Photovoltaic System

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1902 ◽  
Author(s):  
Asmaa Ahmed ◽  
Katie Shanks ◽  
Senthilarasu Sundaram ◽  
Tapas Kumar Mallick
Keyword(s):  
Solar Cell ◽  
Concentration Ratio ◽  
Photovoltaic System ◽  
Thermal System ◽  
Outlet Temperature ◽  
Water Mixture ◽  
High Concentration ◽  
Cell Temperature ◽  
Photovoltaic Thermal System ◽  
Different Types

Concentrator photovoltaics have several advantages over flat plate systems. However, the increase in solar concentration usually leads to an increase in the solar cell temperature, which decreases the performance of the system. Therefore, in this paper, we investigate the performance and temperature limits of a high concentration photovoltaic Thermal system (HCPVT) based on a 1 cm2 multi-junction solar cell subjected to a concentration ratio from 500× to 2000× by using three different types of cooling fluids (water, ethylene glycol and water mixture (60:40), and syltherm oil 800). The results show that, for this configuration, the maximum volumetric temperature of the solar cell did not exceed the manufacturer’s recommended limit for the tested fluids. At 2000× the lowest solar cell temperature obtained by using water was 93.5 °C, while it reached as high as 109 °C by using syltherm oil 800, which is almost equal to the maximum operating limit provided by the manufacturer (110 °C). Overall, the best performance in terms of temperature distribution, thermal, and electrical efficiency was achieved by using water, while the highest outlet temperature was obtained by using syltherm oil 800.

scholarly journals Contrail study with ground-based cameras

2013 ◽  
Vol 6 (4) ◽  
pp. 7425-7472
Author(s):  
U. Schumann ◽  
R. Hempel ◽  
H. Flentje ◽  
M. Garhammer ◽  
K. Graf ◽  
...  
Keyword(s):  
Weather Prediction ◽  
Ambient Air ◽  
Lagrangian Model ◽  
Wake Vortex ◽  
The Moon ◽  
Movement Data ◽  
Different Types ◽  
Nwp Model ◽  
Better Than

Abstract. Photogrammetric methods and analysis results for contrails observed with wide-angle cameras are described. Four cameras of two different types (view angle < 90° or whole-sky imager) at the ground at various positions are used to track contrails and to derive their altitude, width, and horizontal speed. Camera models for both types are described to derive the observation angles for given image coordinates and their inverse. The models are calibrated with sightings of the Sun, the Moon and a few bright stars. The methods are applied and tested in a case study. Four persistent contrails crossing each other together with a short-lived one are observed with the cameras. Vertical and horizontal positions of the contrails are determined from the camera images to an accuracy of better than 200 m and horizontal speed to 0.2 m s−1. With this information, the aircraft causing the contrails are identified by comparison to traffic waypoint data. The observations are compared with synthetic camera pictures of contrails simulated with the contrail prediction model CoCiP, a Lagrangian model using air traffic movement data and numerical weather prediction (NWP) data as input. The results provide tests for the NWP and contrail models. The cameras show spreading and thickening contrails suggesting ice-supersaturation in the ambient air. The ice-supersaturated layer is found thicker and more humid in this case than predicted by the NWP model used. The simulated and observed contrail positions agree up to differences caused by uncertain wind data. The contrail widths, which depend on wake vortex spreading, ambient shear and turbulence, were partly wider than simulated.

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