scholarly journals Leak-Based Method for the Measurement of Air Permeability of Papers

2016 ◽  
Vol 27 (1) ◽  
Author(s):  
Stéphane Colard ◽  
Georges Cholet ◽  
Marlène Testud
Keyword(s):  
Pressure Difference ◽  
Initial Pressure ◽  
Regulatory Compliance ◽  
Air Permeability ◽  
Experimental Investigations ◽  
International Standard ◽  
Alternative Method ◽  
Specific Geometry ◽  
Current Measuring ◽  
Cigarette Paper

SummaryThe air permeability of cigarette paper is currently assessed according to the international standard ISO 2965 by applying a constant pressure difference of 1 kPa between the two faces of a sample and by measuring the corresponding airflow.Lower Ignition Propensity regulations have led tobacco manufacturers to use specific cigarette papers with narrow bands of low air permeability and diffusion capacity to achieve regulatory compliance. The international standard ISO 2965 was revised in 2009 to take into account the specific geometry and characteristics of the bands and to include suitable narrow measuring heads. The consequence was a significant reduction of the measured airflow levels with banded papers and a need for equipment covering specifically low airflow ranges.The well-known pressure-airflow relationship across cigarette paper enables the development of an alternative method to ISO 2965 which does not require direct airflow measurement, and therefore airflow meters which are costly parts of the current measuring devices. The alternative method is based on the measurement of the change of the pressure over time after an initial pressure difference was applied between the two faces of the paper. The consecutive analysis of the pressure difference profile, impacted by the leak across the paper, enables the derivation of the air permeability.The related theoretical aspects were developed for both viscous and inertial airflows, and experimental investigations were conducted with banded and conventional cigarette papers as well as a permeability calibration standard. Results obtained with the proposed method showed good consistency with ISO 2965 measurements and a lower repeatability, demonstrating that a leak-based method could be a simple and reliable alternative.

scholarly journals Experimental and Numerical Study on Hydromechanical Coupled Deformation Behavior of Beishan Granite considering Permeability Evolution

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Z. H. Wang ◽  
W. G. Ren ◽  
Y. L. Tan ◽  
Heinz Konietzky
Keyword(s):  
Pressure Difference ◽  
Numerical Study ◽  
Volumetric Strain ◽  
Initial Pressure ◽  
Numerical Code ◽  
Permeability Evolution ◽  
Beishan Granite ◽  
Pore Pressures ◽  
Damaged Zone ◽  
Hlw Repository

Beishan granite is a potential host rock for a high-level radioactive waste (HLW) repository in China. Understanding the hydromechanical (HM) behavior and permeability evolution of Beishan granite is important for the HLW repository safety. Therefore, the granite of Beishan in Gansu province was studied. HM coupled tests are carried out on Beishan granite under different pore pressures. The results show that the initial pressure difference has little influence on permeability measurement before dilatancy starts. However, after onset of dilatancy, the permeability increases with the increasing initial pressure difference. The initial permeability of Beishan granite is about 10−18 m2 under a confining pressure of 20 MPa. In the initial loading phase, the permeability shows a relatively large reduction. Then, the permeability almost keeps constant until dilatancy starts. From dilatancy point to peak stress, permeability increases linearly with volumetric strain. The proposed permeability evolution rule is implemented into a numerical code to perform HM coupled simulations. The simulation results show that the damaged zone first appears at the model boundary and then extends to the inside, forming high volumetric strain areas. And it provides seepage channels for fluid flow. The macroscopic fracture patterns indicate that pore pressure accelerates rock degradation during HM coupling. The obtained results help to understand the damage mechanisms of granite caused by pore pressures and are of great importance for the safety of a HLW repository.

Experimental and Analytical Investigation of Ammonia Absorption into Ammonia-Water Solution: Estimated Interface Concentration

2010 ◽  
Vol 297-301 ◽  
pp. 785-789
Author(s):  
Hatem Mustafa
Keyword(s):  
Pressure Difference ◽  
Water Solution ◽  
Water System ◽  
Initial Pressure ◽  
Test Cell ◽  
Major Influence ◽  
Ammonia Vapor ◽  
Ammonia Water ◽  
Interface Concentration ◽  
Ammonia Absorption

Ammonia absorption process of ammonia vapor into ammonia water solution has been investigated experimentally, by inserting superheated ammonia vapor into a test cell containing a stagnant pool of ammonia water solution of several ammonia mass fractions, Ci. Before commencing the experiment, the pressure in the test cell corresponds to the equilibrium vapor of the ammonia-water system at room temperature. When the valve is opened, mechanical equilibrium is established quickly and the ammonia vapor diffuses into ammonia solution [1]. The difference between the initial pressure in the vapor cylinder and the initial pressure in the test cell ΔPi is found to have a major influence not only on the absorption rate but also on the estimated interface concentration. The interface concentration Cint of the cases ΔPi = 50 and 100 kPa exhibits a similar tendency, Cint decreases rapidly compared to other initial pressures ΔPi = 150 and 200 kPa. On the other hand, the interface concentration Cint of the cases ΔPi = 250 and 300 kPa are increasing within about 50 sec, then are hardly changing with time. They behave almost in a similar way as of Cint = 0.27 kg/kg. A correlation which gives the total absorbed mass of ammonia as a function of the initial concentration, the initial pressure difference and time is derived. In addition, the absorbed mass at no pressure difference could be estimated from the absorbed mass at initial pressure difference.

scholarly journals Impact of Viscosity Variation, and Flow Rate on Coefficient of Discharge in Venturimeter Utilizing Taguchi Methodology

2020 ◽  
Vol 9 (4) ◽  
pp. 1838-1840
Keyword(s):  
Pressure Difference ◽  
Flow Measurement ◽  
Head Loss ◽  
Measuring Apparatus ◽  
Cross Sectional ◽  
Measuring Devices ◽  
Specific Geometry ◽  
Viscosity Variation ◽  
Coefficient Of Discharge ◽  
The Impact

Most of the industries are concerned with flow measurement and accurate measurement of fluid is important to obtain specific proportion as per process requirement. Generally Venturimeter (VM) is utilized in enterprises due to notable highlights offered by it. VM works on the principle of pressure difference i.e. Bernoulli’s principle. By varying cross sectional area of flow, it creates pressure difference along its length which is used to calculate theoretical discharge. Head loss in VM is less as compared to other flow measuring apparatus. Because of its specific geometry eddies formation is avoided causing less head loss. The coefficient of discharge (Cd ) is an important parameter always referred in case of flow measuring devices. For VM it varies from 0.95 to 0.99. Tests have been performed in accordance to Taguchi L9 O-A on cast iron pipe to examine the impact of variations of viscosity, and rates of flow on the Cd .

scholarly journals A prospective Study on the Evolution of Airtightness in 41 low energy Dwellings

2020 ◽  
Vol 172 ◽  
pp. 05005
Author(s):  
Stijn Verbeke ◽  
Amaryllis Audenaert
Keyword(s):  
Pressure Difference ◽  
Air Permeability ◽  
Building Envelope ◽  
Low Energy ◽  
Low Energy Buildings ◽  
Construction Type ◽  
Passive Houses ◽  
A Prospective Study ◽  
Pressurisation Test

Airtightness of the building envelope is an important parameter affecting the performance of (low energy) buildings. In case the airtightness is effectively measured, this is typically only done once as part of the commissioning of the construction work. Several factors could affect the evolution of the airtightness of the envelope after the building is constructed. In this work, follow-up airtightness tests have been carried out to investigate the evolution of the performance in the interval of 0.5 up to 12 years compared to the original pressurisation test. The results on 41 low-energy dwellings indicate that the airtightness is indeed not a fixed value over time. Of the 41 buildings, 29 display an increased air permeability resulting in an increase of up to 200% in relative terms or up to 1.36 ACH50 (air changes per hour at 50 Pa pressure difference [h-1]). Conversely, four of the buildings in the dataset show a significant improvement of the airtightness; resulting in a decrease of air leakage of up to -1.19 ACH50. Analysis of the data shows that on average the air permeability at 50 Pa pressure difference increased by 38%, but with great variation depending multiple factors such as initial airtightness value and construction type. This corresponds to an average increase of the specific air permeability of the building envelope of 0.15 m³/(h·m²). Most of the buildings under analysis are low energy buildings or passive houses which were very airtight at time of construction. Despite the observed evolution in air permeability, many buildings under investigation can still be considered sufficiently airtight a few years after initial construction.

INFLUENCE OF THE WIDTH OF TOBACCO FIBER AND THE PROPERTIES OF CIGARETTE PAPER ON THE CHEMICAL COMPOSITION OF THE SMOKE OF TOBACCO PRODUCTS FROM THIN-CUT TOBACCO

2021 ◽  
Author(s):  
Е.Ю. СМИРНОВА ◽  
Е.В. ГНУЧИХ ◽  
А.Ю. ЛУШНИКОВА
Keyword(s):  
Chemical Composition ◽  
Raw Materials ◽  
Air Permeability ◽  
Clear Correlation ◽  
Physical Parameters ◽  
Technological Properties ◽  
Tobacco Products ◽  
Cigarette Paper ◽  
Cut Tobacco ◽  
Different Diameters

Рассмотрены технологические свойства табачного сырья скелетного типа сорта Юбилейный с шириной табачного волокна 0,5 и 0,8 мм и табачной мешки американского типа с шириной волокна 0,6 и 0,9 мм, использованных для изготовления изделий из табака курительного тонкорезаного. Выявлено, что у табака сорта Юбилейный с шириной волокна 0,8 мм наибольший условный расход на изготовление 1000 шт. изделий. Проведен анализ состава и воздухопроницаемости сигаретной бумаги для изготовления курительных изделий разных диаметров. Исследовано влияние физических параметров изделий из табака курительного тонкорезаного (диаметр, ширина табачного волокна, воздухопроницаемость сигаретной бумаги) на химический состав дыма (никотин, смола, монооксид углерода). Установлено, что увеличение ширины табачного волокна привело к значительному повышению содержания никотина и смолы в дыме изделий с табаком сорта Юбилейный; в дыме курительных изделий с американской мешкой столь четкой корреляции не наблюдалось. При использовании бумаги на основе конопли с меньшей, чем в бумаге с рисовой основой, воздухопроницаемостью в дыме курительных изделий возрастала концентрация как никотина, так и смолы, содержание которой в дыме образцов изделий с табаком сорта Юбилейный при ширине волокна 0,5 мм повышалось на 4–23%, при ширине волокна 0,8 мм – на 6–13%; с американской мешкой при ширине волокна 0,6 мм возрастало на 7–11%, при ширине волокна 0,9 мм – на 2–4%. Результаты исследований помогут выработать рекомендации для производителей и потребителей этого вида продукции. The paper considers the technological properties of skeletal-type tobacco raw materials of the Yubileynyy variety with a fiber width of 0,5 and 0,8 mm and American-type tobacco bags with a fiber width of 0,6 and 0,9 mm, used for the manufacture of products from thin-cut smoking tobacco. It was revealed that tobacco of the Yubileynyy variety with a fiber width of 0,8 mm has the highest conventional consumption for the manufacture of 1000 pieces products. The analysis of the composition and air permeability of cigarette paper for the manufacture of smoking products of different diameters was carried out. The influence of the physical parameters of tobacco products made of thin-cut tobacco (diameter, width of tobacco fiber, breathability of cigarette paper) on the chemical composition of smoke (nicotine, tar, carbon monoxide) is investigated. It was found that an increase in the width of tobacco fiber led to a significant increase in the content of nicotine and tar in the smoke of tobacco products of the Yubileynyy variety; such a clear correlation was not observed in the smoke of smoking products with an American-type. When using hemp-based paper with less air permeability than in rice-based paper, the concentration of nicotine and tar in the smoke of smoking products increased. The tar content in the smoke of samples of tobacco products of the Yubileynyy variety with a fiber width of 0,5 mm increased by 4–23%, with a fiber width of 0,8 mm – by 6–13%; with an American-type with a fiber width of 0,6 mm increased by 7–11%, with a fiber width of 0,9 mm – by 2–4%. The research results will help to develop recommendations for manufacturers and consumers of this type of products.

scholarly journals The Pore Size Distribution of Naturally Porous Cigarette Paper and its Relation to Permeability and Diffusion Capacity

2015 ◽  
Vol 26 (7) ◽  
Author(s):  
Bernhard Eitzinger ◽  
Maria Gleinser ◽  
Stefan Bachmann
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Filler Content ◽  
Air Permeability ◽  
Size Distributions ◽  
Diffusion Capacity ◽  
Pore Size Distributions ◽  
Cigarette Paper ◽  
And Diffusion

SummaryThe pore size distribution of cigarette paper determines its air permeability and diffusion capacity and thereby has a significant influence on the gas exchange of a cigarette through the cigarette paper during smoking and during smouldering. For the design of cigarettes and in particular of cigarette papers it is important to understand how the pore size distribution of the cigarette paper is affected by the paper composition and paper properties and how it influences air permeability and diffusion capacity.It was the aim of this study to investigate how the composition of the cigarette paper such as filler content, fibre type and burn additive content qualitatively influenced the pore size distribution and how the pore size distribution and, in particular, which pore size range is correlated with air permeability and diffusion capacity, respectively. To this end eight naturally porous cigarette papers were selected which differed in air permeability, diffusion capacity, fibre type, filler content and burn additive content. The pore size distributions of these papers were measured by mercury porosimetry before and after the papers had been heated to 230 °C for 30 min. The pore size distributions were investigated for qualitative differences when air permeability, fibre type and filler content of the cigarette paper are modified. Furthermore by appropriate weighting of the pore size distributions optimal correlations between a weighted pore volume and air permeability or diffusion capacity were determined. The results show a good correlation with correlation coefficients greater than 0.9 for air permeability as well as for diffusion capacity. The results indicate that large pores are better correlated with changes in air permeability, while small pores are more strongly correlated with changes in diffusion capacity and support previous theoretical results obtained from flow and diffusion models. They also demonstrate the tight relationship between pore size distribution, air permeability and diffusion capacity, which makes the pore size distribution a tool to further optimize cigarette papers, for example, with respect to carbon monoxide yields in the smoke of a cigarette. [Beitr. Tabakforsch. Int 26 (2015) 312-319]

scholarly journals The Basic Results on Reinitiation Processes in Diffracting Multifront Detonations. Part I.

2016 ◽  
Vol 5 (4) ◽  
pp. 279 ◽  
Author(s):  
A.A. Vasil'ev ◽  
A.V. Trotsyuk ◽  
P.A. Fomin ◽  
V.A. Vasiliev ◽  
V.N. Rychkov ◽  
...  
Keyword(s):  
Initial Pressure ◽  
Gaseous Detonation ◽  
Inert Gases ◽  
Experimental Investigations ◽  
Practical Application ◽  
Physical Processes ◽  
Transverse Waves ◽  
Wide Range ◽  
Multifront Detonation ◽  
Concave Boundary

The basic results of experimental investigations on reinitiation processes in diffracting multifront detonation wave (DW) are discussed in connection with problem of practical application of new ecological technology for worn-out tire destruction, where the cooled worn-out tire destroys with the help of gaseous detonation. The experimental results for various fuel-oxygen and fuel-air mixtures are presented at wide range of mixture compositions, initial pressure and temperature, geometrical sizes of experimental equipment, symmetry types, dilution of inert gases, etc. Classical and nontraditional schema of DW-diffraction are investigated, such as multipointed initiation, DW-excitation by circular charge, initiation space-oriented longitudinal charges, initiation by circular charge, diffraction on concave boundary, diffraction on contact surface of different mixtures, flame diffraction, etc. The main characteristic parameters are identified for each diffraction schema. The physical processes taking place directly in the DW-front plays the governing role in reinitiation. The most important among these processes are collisions of transverse waves, which stick out as microscopic initiators. The optimization problem of DW-initiation from spatial and temporary distribution of energy is discussed carefully. This data can be used at hazard estimation also.

Semilog Analysis of the Pulse-Decay Technique of Permeability Measurement

1984 ◽  
Vol 24 (06) ◽  
pp. 639-642 ◽  
Author(s):  
Techien Chen ◽  
P.W. Stagg
Keyword(s):  
Experimental Data ◽  
Pressure Difference ◽  
Constant Pressure ◽  
Error Function ◽  
Initial Pressure ◽  
Core Sample ◽  
Alternative Solution ◽  
Dimensionless Time ◽  
Permeability Measurement ◽  
The Core

Semilog Analysis of the Pulse-Decay Technique Pulse-Decay Technique of Permeability Measurement Abstract An alternative solution to the system of equations describing the pulse-decay technique of permeability measurement has been obtained. It is a solution in which the sample PV is not neglected. The experimental data are analyzed by using the slope of a semilog plot to evaluate permeability. permeability. Introduction The pulse-decay technique of permeability measurement has been used by workers interested in radioactive waste storage and low-permeability gas reservoirs. The basic idea of this method is to allow the pressure in two vessels, initially maintained at different pressures, equilibrate by flowing through a core sample. The permeability of the sample then can be determined from permeability of the sample then can be determined from the pressure-decay record. Brace et al. assumed that the compressibility of the rock matrix is negligible compared with that of the pore fluid and that the PV is negligible compared with the downstream volume. Subsequent attempts have been made to eliminate one or both of these assumptions by numerical 12.4 or analytical solutions. Of these solutions, the error-function solution of Bourbie and Walls is particularly well suited to experimental-data reduction. However the applicable range of their solution is limited to dimensionless time, tD, of less than unity and a ratio of PV to downstream volume, y, of less than 0.6. This paper presents an alternative solution that is not restricted paper presents an alternative solution that is not restricted by to or y. It reduces to an exponential-decay solution similar to Brace et al.'s solution when to is greater than 0. 3. Experimental Setup A schematic of the setup is shown in Fig. 1. A cylindrical core sample is mounted inside the coreholder and hydrostatic pressure is applied to the circumference and ends of the sample. With Valves 1 and 2 open, nitrogen is pumped into Vessel 1 to a pressure of p 0. When the pressure in the system has reached equilibrium, Valves pressure in the system has reached equilibrium, Valves 1 and 2 are closed and the pressure in Vessel 1 is raised slightly to pi. A few minutes are allowed for the temperature and pressure in Vessel 1 to equilibrate. The test begins at time t=O with the opening of Valve 1. The differential pressure transducer measures the pressure drop as the gas in the large Vessel 1 flows through the core into the small Vessel 2. The test continues until the pressure difference is 50 to 80% of the initial pressure pressure difference is 50 to 80% of the initial pressure difference. Theory The diffusion equation for flow across the core is .....................................(1) where p1-p(x, t) PD (xD, tD = ., ............(2) PD (xD, tD = ., ............(2) p1-p02 Xd=x/L,..............................(3) .....................................(4) p1 is the constant pressure of the upstream vessel, p02 p1 is the constant pressure of the upstream vessel, p02 is the initial pressure of Vessel 2, L is the length of the core, and the rest of the symbols are as defined in the nomenclature. The initial and boundary conditions are PD (xD,0)=1,.........................(5) PD (xD,0)=1,.........................(5) Pd (0, tD)=0,.........................(6) Pd (0, tD)=0,.........................(6) and .....................................(7) where .....................................(8) A is the cross-sectional area of the core sample, and V2, is the volume of Vessel 2. Therefore, is the ratio of the PV to the volume of Vessel 2. SPEJ P. 639

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