110. Evaluation of the Measurement of Ventilation Rate Using Carbon Dioxide as a Tracer Gas

1999 ◽  
Author(s):  
M.D. Walters ◽  
F-T. Lin ◽  
R.J. Sherwood
Keyword(s):  
Carbon Dioxide ◽  
Ventilation Rate ◽  
Tracer Gas

Comparison of oxygen and carbon dioxide balances in HRAP (high-rate algal ponds)

2003 ◽  
Vol 48 (2) ◽  
pp. 277-281 ◽  
Author(s):  
H. El Ouarghi ◽  
E. Praet ◽  
H. Jupsin ◽  
J.-L. Vasel
Keyword(s):  
Carbon Dioxide ◽  
Diurnal Variations ◽  
High Rate ◽  
Oxygen Balance ◽  
Oxygen Production ◽  
Tracer Gas ◽  
High Rate Algal Ponds ◽  
Hydrodynamic Study ◽  
Oxygen Production Rate ◽  
Photosynthesis And Respiration

We previously suggested a method to characterize the oxygen balance in High-Rate Algal Ponds (HRAPs). The method was based on a hydrodynamic study of the reactor combined with a tracer gas method to measure the oxygen transfer coefficient. From such a method diurnal variations of photosynthesis and respiration can be quantified and the net oxygen production rate determined. In this paper we propose a similar approach to obtain carbon dioxide balances in HRAPs. Then oxygen and carbon dioxide balances can be compared.

Ventilation of Wind-Permeable Clothed Cylinder Subject to Periodic Swinging Motion: Modeling and Experimentation

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
N. Ghaddar ◽  
K. Ghali ◽  
B. Jreije
Keyword(s):  
Cotton Fabric ◽  
Current Model ◽  
Ventilation Rate ◽  
External Pressure ◽  
Motion Modeling ◽  
Tracer Gas ◽  
Wind Speeds ◽  
Air Speed ◽  
Local Thermal Comfort ◽  
Ventilation Rates

Abstract A theoretical and experimental study has been performed to determine the ventilation induced by swinging motion and external wind for a fabric-covered cylinder of finite length representing a limb. The estimated ventilation rates are important in determining local thermal comfort. A model is developed to estimate the external pressure distribution resulting from the relative wind around the swinging clothed cylinder. A mass balance equation of the microclimate air layer is reduced to a pressure equation assuming laminar flow in axial and angular directions and that the air layer is lumped in the radial direction. The ventilation model predicts the total renewal rate during the swinging cycle. A good agreement was found between the predicted ventilation rates at swinging frequencies between 40rpm and 60rpm and measured values from experiments conducted in a controlled environmental chamber (air velocity is less than 0.05m∕s) and in a low speed wind tunnel (for air speed between 2m∕s and 6m∕s) using the tracer gas method to measure the total ventilation rate induced by the swinging motion of a cylinder covered with a cotton fabric for both closed and open aperture cases. A parametric study using the current model is performed on a cotton fabric to study the effect of wind on ventilation rates for a nonmoving clothed limb at wind speeds ranging from 0.5m∕sto8m∕s, the effect of a swinging limb in stagnant air at frequencies up to 80rpm, and the combined effect of wind and swinging motion on the ventilation rate. For a nonmoving limb, ventilation rate increases with external wind. In the absence of wind, the ventilation rate increases with increased swinging frequency.

Experimental Investigation of Ventilation Effectiveness in an Airliner Cabin Mockup

2016 ◽  
Author(s):  
Jignesh A. Patel ◽  
Byron W. Jones ◽  
Mohammad H. Hosni ◽  
Ali Keshavarz
Keyword(s):  
Distribution System ◽  
Ventilation Rate ◽  
Mean Value ◽  
Tracer Gas ◽  
Flight Duration ◽  
Factors Affecting ◽  
Aircraft Cabin ◽  
Local Ventilation ◽  
Effective Ventilation ◽  
Ventilation Effectiveness

Frequent air travel and long flight duration makes the study of airliner cabin environmental quality a topic of utmost importance. Ventilation effectiveness is one of the more crucial factors affecting air quality in any environment. Ventilation effectiveness, along with the overall ventilation rate, is a measure of the ability of the air distribution system to remove internally generated pollutants or contaminants from a given space. Because of the high occupant density in an aircraft cabin, local variations in ventilation are important as a passenger will occupy the same space for the duration of the flight. Poor ventilation in even a small portion of the cabin could impact multiple people for extended time periods. In this study, the local effective ventilation rates and local ventilation effectiveness in an eleven-row, full-scale, Boeing 767 cabin mockup were measured. These measurements were completed at each of the 77 seats in the mockup. Each seat was occupied by a heated mannequin. In order to simulate the thermal load inside the cabin, the mannequins were wrapped with a heating wire to generate approximately 100 W (341 BTU/hour) of heat. Carbon dioxide was used as a tracer gas for the experiments and the tracer gas decay method was employed to calculate the local effective ventilation rate and local ventilation effectiveness. The overall ventilation rate, based on total supply air flow, was approximately 27 air changes per hour. Local ventilation effectiveness ranged from 0.86 to 1.02 with a mean value of 0.94. These ventilation effectiveness values are higher than typically found in other indoor applications and are likely due to the relatively high airspeeds present in the aircraft cabin and the high degree of mixing they provide. The uniformity is also good with no areas of particularly low ventilation effectiveness being identified. No clear patterns with respect to seat location, window versus center versus aisle, were found.

scholarly journals Effect of the age and season of fattening period on carbon dioxide emissions from broiler housing

2010 ◽  
Vol 55 (No. 10) ◽  
pp. 436-444 ◽  
Author(s):  
M. Knížatová ◽  
Š. Mihina ◽  
J. Brouček ◽  
I. Karandušovská ◽  
G.J. Sauter ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Indoor Air ◽  
Human Activities ◽  
Carbon Dioxide Emissions ◽  
Major Part ◽  
Ventilation Rate ◽  
Chicken House ◽  
The Mean ◽  
Fattening Period

The quantification of emissions of greenhouse gases from human activities is of prime importance for determining the importance of their effect on the environment. The aim of this study was to test a hypothesis that the interior concentration and emission of carbon dioxide in chicken housing is impacted by the age of animals and season of fattening period. Carbon dioxide (CO<sub>2</sub>) concentrations and emissions were assessed over six fattening periods in total. The major part of CO<sub>2</sub> seemed to have its origin in bird respiration with assumed production of approx. 147 kg of CO2/h. CO<sub>2</sub> emission was most affected by chickens towards the end of the grow-out period (P &lt; 0.001) taking dominance over the process of natural gas burning by heaters. The mean CO<sub>2</sub> emission from the chicken house ranged between 120 and 247 kg/h in the first quarter of periods and between 325 and 459 kg/h in the last ones. The heaters could be theoretically a possible source of approx. 39 kg each hour if they worked continuously. CO<sub>2</sub> emissions were considerably more affected by ventilation rate (P &lt; 0.001) than by CO<sub>2</sub> concentration in the indoor air.

scholarly journals Exposure Assessment in Nail Salons: An Indoor Air Approach

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Cora Roelofs ◽  
Tuan Do
Keyword(s):  
Carbon Dioxide ◽  
Exposure Assessment ◽  
Indoor Air ◽  
Ventilation System ◽  
Ventilation Rate ◽  
Self Report ◽  
Adequate Ventilation ◽  
The Common ◽  
Traditional Approaches ◽  
Nail Salons

Due to the complexity of the nail salon work environment, traditional approaches to exposure assessment in this context tend to mischaracterize potential hazards as nuisances. For this investigation, a workable “indoor air” approach was devised to characterize potential hazards and ventilation in Boston, Massachusetts area nail salons which are primarily owned and staffed by Vietnamese immigrants. A community-university partnership project recruited salons to participate in a short audit which included carbon dioxide measurements and evaluation of other air quality metrics. Twenty-two salons participated. Seventy-three percent of the salons had spot carbon dioxide measurements in excess of 700 ppm, the level corresponding to a ventilation rate recommended for beauty salons. Fourteen salons (64%) did not have a mechanical ventilation system to provide fresh air and/or exhaust contaminated air. The lack of adequate ventilation is of significant concern because of the presence of potentially hazardous chemicals in salon products and the common self-report of symptoms among nail technicians. Community and worker health may be improved through adoption of recommended ventilation guidelines and reduction in the hazard potential of nail products.

scholarly journals Applying the CO2 concentration decay tracer gas method in long-term monitoring campaigns in occupied homes: identifying appropriate unoccupied periods and decay periods

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jessica Few ◽  
Clifford A. Elwell
Keyword(s):  
Indoor Air Pollution ◽  
Weather Conditions ◽  
Co2 Concentration ◽  
Ventilation Rate ◽  
Identification Algorithm ◽  
Tracer Gas ◽  
Content Type ◽  
Rate Analysis ◽  
Specific Implementation ◽  
Ventilation Rates

PurposeVentilation is driven by weather conditions, occupant actions and mechanical ventilation, and so can be highly variable. This paper reports on the development of two analysis algorithms designed to facilitate investigation of ventilation in occupied homes over time.Design/methodology/approachThese algorithms facilitate application of the CO2 concentration decay tracer gas technique. The first algorithm identifies occupied periods. The second identifies periods of decaying CO2 concentration which can be assumed to meet the assumptions required for analysis.FindingsThe algorithms were successfully applied in four occupied dwellings, giving over 100 ventilation measurements during a six-month period for three flats. The specific implementation of the decay identification algorithm had important ramifications for the ventilation rates measured, highlighting the importance of interrogating the way that appropriate periods for analysis are identified.Practical implicationsThe analysis algorithms provide robust, reliable and repeatable identification of CO2 decay periods appropriate for ventilation rate analysis. The algorithms were coded in Python, and these have been made available via GitHub. As well as supporting future CO2 tracer gas experiments, the algorithms could be adapted to different purposes, including the use of other tracer gases or exploring occupant exposure to indoor air pollution.Originality/valueEmpirical investigations of ventilation in occupied dwellings rarely aim to investigate the variability of ventilation. This paper reports on analysis methods which can be used to address this gap in the empirical evidence.

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