Tracer-gas measurements in smooth and artificially roughened ducts

1991 ◽  
Vol 15 (2) ◽  
pp. 101-107 ◽  
Author(s):  
S. B. Riffat
Keyword(s):  
Tracer Gas ◽  
Gas Measurements

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

Application of a miniaturized solid state electrolyte sensor for tracer gas measurements in a two-stage low pressure turbine

2017 ◽  
Vol 82 ◽  
pp. 367-374 ◽  
Author(s):  
Marcel Günter ◽  
Frank Hammer ◽  
Christian Koch ◽  
Klaus Kuhn ◽  
Martin G. Rose ◽  
...  
Keyword(s):  
Solid State ◽  
Low Pressure ◽  
Tracer Gas ◽  
Two Stage ◽  
Solid State Electrolyte ◽  
Low Pressure Turbine ◽  
Gas Measurements

Influence of sampling positions on accuracy of tracer gas measurements in ventilated spaces

2009 ◽  
Vol 104 (2) ◽  
pp. 216-223 ◽  
Author(s):  
S. Van Buggenhout ◽  
A. Van Brecht ◽  
S. Eren Özcan ◽  
E. Vranken ◽  
W. Van Malcot ◽  
...  
Keyword(s):  
Tracer Gas ◽  
Gas Measurements

The Usage of CO2 Tracer Gas Methods for Ventilation Performance Evaluation in Apartment Buildings

2017 ◽  
Author(s):  
Alo Mikola ◽  
Teet-Andrus Kõiv ◽  
Juhan Rehand ◽  
Hendrik Voll
Keyword(s):  
Performance Evaluation ◽  
Natural Ventilation ◽  
Correct Result ◽  
Tracer Gas ◽  
Exhaust Ventilation ◽  
Apartment Buildings ◽  
Gas Measurements ◽  
Ventilation Performance ◽  
Natural Tracer

The purpose of the study is to investigate the potential of the CO2-based tracer gas methods for the ventilation performance evaluation in apartment buildings. To test and elaborate the methods, the ventilation air change rate (ACR) and air change efficiency (ACE) measurements were performed. The methods were tested in laboratory conditions and apartments with natural ventilation, room-based ventilation units, exhaust ventilation and mechanical exhaust ventilation with fresh air radiators. Concentration decay method is applied with both artificially and naturally increasing the concentration of tracer gas. The ACR is also calculated using metabolic constant dosing method with the effective volume. As the traditional tracer gas methods give the correct result only in case of perfect mixed ventilation, then the ACE is also measured. To observe the effectiveness of the air change and the level of air mixing multiple CO2 sensors placed in different positions. The tracer gas measurements were carried out in naturally ventilated apartments to study the influence of the inner doors to the ACE. The daily variation of CO2 level in case the long-term CO2 measurements gives us the possibility to calculate the ACR when inhabitants are sleeping or have left the apartment. Using the CO2 as the natural tracer gas and the concentration decay method together with the metabolic constant dosing strategy, we can calculate the CO2 concentrations according to the long-term CO2 measurements without knowing the exact emission of inhabitants. The studied methods are inexpensive and at the same time sufficiently accurate for airflow measurements. Another reason for the study comes from the ventilation retrofit process in Estonia where the single room ventilation units are used. As these wall-mounted ventilation units are sensitive to in- and outside pressure differences the measurement of ventilation airflow in the traditional way can be inaccurate.

scholarly journals Validation of the sulphur hexafluoride (SF6) tracer gas technique for measurement of methane and carbon dioxide production by cattle

2002 ◽  
Vol 82 (2) ◽  
pp. 125-131 ◽  
Author(s):  
D. A. Boadi ◽  
K. M. Wittenberg ◽  
A. D. Kennedy
Keyword(s):  
Carbon Dioxide ◽  
Block Design ◽  
Carbon Dioxide Production ◽  
Open Circuit ◽  
Tracer Technique ◽  
Sulphur Hexafluoride ◽  
Tracer Gas ◽  
Tracer Techniques ◽  
Gas Measurements ◽  
Maintenance Requirements

Methane (CH4) and carbon dioxide (CO2) production from six crossbred yearling beef heifers (400 ± 13.0 kg) were measured, using the sulphur hexafluoride (SF6) tracer gas technique (Tracer) and open-circuit hood calorimetry (Cal) to validate the former in estimating rumen CH4 and CO2 production in the field. Animals were individually fed a diet consisting of 50% barley concentrate and 50% alfalfa cubes at 1.3 &times ;maintenance requirements daily. Hifers were divided into two groups for individual animal 24- h gas measurements by each method. Each group of heifers was rotated between the Cal and Tracer techniques for 6 consecutive days in an incomplete block design. Methane production ranged from 108 to 145 L d-1 (mean 130 ± 4.0 L d-1) using the Cal technique, and 90 to 167 L d-1 (mean 137 ± 4.0 L d-1) using the Tracer technique. The mean CH4 production (L d-1) was not different (P = 0.24) between the two methods. Carbon dioxide production with the Tracer technique was 20% higher than CO2 production with the Cal technique (P < 0.01). The range of CO2 production was 1574 to 2049 L d-1 (mean 1892 ± 74.0 L d-1) by Cal, and 1541 to 3330 L d-1 (mean 2353 ± 74.0 L d-1) by Tracer. Day-to-day variation in CH4 production was not different within each method (P > 0.05); however, animal-to-animal variation (11.7%) was significant for the Tracer technique (P = 0.04), but not for the Cal technique (P = 0.53). Comparison of the equality of variance between the two methods showed that there were no differences in variations (P > 0.05) between Cal and Tracer for CH4 production. On the other hand, variations in CO2 production were not equal (P > 0.05) between methods. Day-to-day variation in CO2 production was significant using Cal, but not Tracer (P > 0.05). Animal-to-animal variation in CO2 production was 1.6 and 11.8% by Cal and Tracer techniques, respectively. It can be concluded that the SF6 tracer technique accurately estimated rumen CH4 production, but CO2 production was 20% higher. The study suggests that for CH4 measurements using the SF6 tracer technique, more animal numbers are needed than for Cal to reduce animal-to-animal variation. Key words: Methane, carbon dioxide, SF6 tracer technique, validation, cattle

CRDS-based dissolved N₂O & CH₄ measurement system

2020 ◽  
Author(s):  
Il-Nam Kim ◽  
Seong-Su Kim ◽  
Ki-Tae Park ◽  
Jae-Hyun Lim
Keyword(s):  
High Performance ◽  
Continuous Measurement ◽  
Trace Gases ◽  
Optical Signal ◽  
Tracer Gas ◽  
Gas Concentration ◽  
Rate Of Decay ◽  
Gas Measurements ◽  
Seawater Samples ◽  
Analytical Equipment

&lt;p&gt;&amp;#160;Gas chromatography (GC) is the most commonly used analytical equipment for tracer gas measurements. However, high performance equipment such as cavity ring-down spectrometer (CRDS) has been developed and currently become commercially available (G2308, PICARRO). CRDS is optical spectrometer to measure tracer gas, and its principal is that determines the gas concentration through the rate of decay of the optical signal. The great advantage of using CRDS is that not required too many material, time, and easy to handle than GC system. In general, CRDS is used for continuous measurement, which requires a large amount of gas for quantification. So, we have modified CRDS system to measure small amount of N&lt;sub&gt;2&lt;/sub&gt;O/CH&lt;sub&gt;4&lt;/sub&gt; gases which is extracted from seawater samples using headspace method, and in turn have tested in various marine environments from coastal regions to open oceans. As a result, we have obtained highly accurate concentrations of dissolved N&lt;sub&gt;2&lt;/sub&gt;O &amp; CH&lt;sub&gt;4&lt;/sub&gt; gases, suggesting that the system would be useful to study dynamics of climate-relevant trace gases.&lt;/p&gt;

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