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Tytuł:
Measurements of the dependence of wood’spermeability to air on the temperature of the pyrolysis
Autorzy:
Ronewicz, K.
Heda, Ł.
Kardaś, D.
Powiązania:
https://bibliotekanauki.pl/articles/175320.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
permeability to air
low temperature
wood
Opis:
The paper deals with the wood’s (in this case pine) longitudinal permeability to air and its possible dependence on the temperature of the pyrolysis. The measurement of permeability was indirect and conducted on the original stand constructed solely for this purpose. Before every measurement a special sample preparation procedure was conducted for each sample group. Every group of samples was preheated up to the temperature previously set in the oxygen-less environment. After that, samples were cooled down to the room temperature. The following parameters were measured directly: sample length and diameter, pressure difference, and time. After numerous measurements of the mentioned values, the permeability of wood to air was calculated using the Darcy’s law for a given pyrolysis temperature. The results show a distinct dependence between the wood’s permeability to air and the pyrolysis temperature. The minimum value of the permeability is on the level of 0.56 D for temperature of 50 ◦C and is growing up to the value of 5.8 D (over ten times of the initial value) for the temperature of 350 ◦C.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2015, 128; 131-138
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrodynamics of gas flow through anisotropic porous materials in phenomenological and numerical terms
Autorzy:
Wałowski, G.
Filipczak, G.
Powiązania:
https://bibliotekanauki.pl/articles/240286.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
biochar
coke
CFD
permeability
biowęgiel
koks
filtracja
Opis:
This study discusses results of experiments on hydrodynamic assessment of gas flow through backbone (skeletal) porous materials with an anisotropic structure. The research was conducted upon materials of diversified petrographic characteristics – cokes. The study was conducted for a variety of hydrodynamic conditions, using air. The basis for assessing hydrodynamics of gas flow through porous material was a gas stream that results from the pressure forcing such flow. The results of measurements indicate a clear impact of the type of material on the gas permeability, and additionally – as a result of their anisotropic internal structure – to a significant effect of the flow direction on the value of gas stream. In aspect of scale transfer problem, a method of mapping the flow geometry of skeletal materials has been developed and usefulness of numerical methods has been evaluated to determine pressure drop and velocity distribution of gas flow. The results indicate the compliance of the used calculation method with the result of experiments.
Źródło:
Archives of Thermodynamics; 2018, 39, 3; 149-167
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of the flow of substrate and agricultural biogas through the adhesive skeleton bed in phenomenological and numerical terms
Autorzy:
Wałowski, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/1955031.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pig slurry
agricultural biogas
adhesive bed
permeability
CFD
Opis:
The paper reviews selected methods of agricultural biogas production and characterizes their technical and technological aspects. The conditions of the anaerobic fermentation process in the reactor with adhesive skeleton bed were analyzed. The required technological criteria for the production of biogas from a substrate in the form of pig slurry were indicated. As part of experimental studies, evaluation of the biogas replacement resistance coefficient and the permeability coefficient as a function of the Reynolds number were made. The method of numerical simulation with the use of a tool containing computational fluid dynamics codes was applied. Using the turbulent flow model – the RANS model with the enhanced wall treatment option, a numerical simulation was carried out, allowing for a detailed analysis of hydrodynamic phenomena in the adhesive skeleton bed. The paper presents the experimental and numerical results that allow to understand the fluid flow characteristics for the intensification of agricultural biogas production.
Źródło:
Archives of Thermodynamics; 2021, 42, 3; 243-253
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhanced Microwave Absorption of CNT Composites Mixing with Fe3O4 and Carbonyl Iron
Autorzy:
Park, J. H.
Choi, J.
Lee, K.
Park, J.
Song, J. K.
Jeon, E.
Powiązania:
https://bibliotekanauki.pl/articles/351106.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
magnetic powders
complex permittivity
complex permeability
composite materials
microwave absorption
Opis:
We fabricated two different kinds of composite materials for absorbing microwave in a frequency range of 2 to 18 GHz using coaxial airline and thru-reflect-line (TRL) method. The composite materials having carbon nanotube (CNT) with carbonyl iron (CI) or iron oxide (Fe3 O4 ) were fabricated by mixing each components. Magnetic properties were measured by SQUID equipment. Complex permittivity and complex permeability were also obtained by measuring S-parameters of the toroidal specimen dispersing CI/CNT and Fe3 O4 /CNT into the 50 weight percent (wt%) epoxy resin. The real permittivity was improved by mixing the CNT however, the real permeability was same as pure magnetic powders. The CI/CNT had a maximum value of real permittivity and real permeability, 11 and 1.4 at 10 GHz, respectively. The CNT composites can be adapted to the radar absorbing materials, band width 8-12 GHz.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 3; 1513-1516
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A methodology to estimate permeability in porous and fissured rock specimens at laboratory scale
Autorzy:
Estevez-Ventosa, Xian
Gonzalez-Molano, Nubia Aurora
Blazquez-Pascual, Vanesa
Alverellos, Jose
Alejano, Leandro R.
Powiązania:
https://bibliotekanauki.pl/articles/1853852.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
przepuszczalność
skała
test laboratoryjny
permeability
artificially jointed rock
lab tests
Opis:
The correct management of underground works, petroleum and gas reservoirs and geothermal appli-cations relies on the hydromechanical behaviour of rock masses. We describe a laboratory approach to measuring permeability for different types of rock specimens. A laboratory system was designed and set up using rock mechanics equipment (a servo-controlled hydraulic press, a Hoek cell, a pump for injecting water and a scale for measuring the volume of water flow). To verify the validity of the permeability measurements, tests were carried out on a reference porous rock (Corvio sandstone), with results showing good agreement with those published in the literature. Tests were subsequently carried out on artificially fissured granite specimens with different joint patterns, submitted to various confinement stresses up to 20 MPa. Results showed good agreement with traditional Klinkenberg test results. Other tests done with artificially fissured specimens are described for demonstrative purposes.
Źródło:
Archives of Mining Sciences; 2020, 65, 4; 821-833
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Some Moulding Properties of a Nigerian Clay-Bonded Sand
Autorzy:
Oke, A. O.
Omidiji, B. V.
Powiązania:
https://bibliotekanauki.pl/articles/380482.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
flowability
moulding
permeability
refractoriness
river sand
płynność
odlewanie
przepuszczalność
piasek rzeczny
Opis:
Moulding properties of Isasa River Sand bonded with Ipetumodu clay (Ife-North Local Government Area, Osun State, Nigeria) were investigated. American Foundry men Society (AFS) standard cylindrical specimens 50mm diameter and 50mm in height were prepared from various sand and clay ratios (between 18% and 32%) with 15% water content. The stress-strain curves were generated from a universal strength testing machine. A flow factor was calculated from the inclination of the falling slope beyond the maximum compressive strength. The result shows that the flowability of the samples increases from 18% to 26% clay content, its maximum value was attained at 26% and then it decreases from 30% to 32% clay content. The green compressive strength, dry compressive strength and air permeability values obtained from the mould samples were in accordance with standard values used in foundry practice. The x-ray diffraction test shows that the sand contains silicon oxide (SiO2), Aluminium oxide (Al2O3), and Aluminium silicate (Al6Si2O13). The mould samples were heated to a temperature of 1200 oC to determine the sintering temperature; fussion did not take place at this temperature. The results showed that the sand and clay mixture can be used to cast ferrous and non-ferrous alloys.
Źródło:
Archives of Foundry Engineering; 2016, 16, 3; 71-76
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relative profiling of L-tryptophan derivatives from selected edible mushrooms as psychoactive nutraceuticals to inhibit P-glycoprotein: a paradigm to contest blood-brain barrier
Autorzy:
Margret, A.A.
Mareeswari, R.
Kumar, K.A.
Jerley, A.A.
Powiązania:
https://bibliotekanauki.pl/articles/2096367.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
depression
blood-brain barrier
mushrooms
L-tryptophan
psychoactive nutraceuticals
permeability
glycoprotein
Opis:
Depression is a mental illness and is considered to be a global threat. It is designated as burden of disease. There is therefore an intense need to improve the therapeutic response of antidepressants. India beholds a wide fraction (Agaricus bisporus and Pleurotus ostreatus ) as a vital source of non-hallucinogenic indole compounds. The amino acids L-tryptophan and 5-hydroxytryptophan (5-HTP) are precursors of serotonin. 5-HTP is a potential antidepressant that can cross the blood-brain barrier (BBB) at a high rate and is converted into serotonin more efficiently. Drug delivery across this blockade remains a challenge due to the stimulation of efflux pump receptors called permeability glycoprotein (P-gp). This work reports a comparative phytochemical assay and profiling of nonhallucinogenic tryptophan metabolites using HPLC from two organic extracts of edible mushrooms. The efficacy of the eluted compounds was authenticated as P-gp inhibitors with in vitro and in silico studies. The following four derivatives were obtained from the methanol and ethanol extracts of the mushrooms: 5-hydroxy-L-tryptophan (5HTR), 5-hydroxy tryptamine (5-HT), L-tryptophan (L-Trp), and tryptamine (TA). In vitro and molecular docking studies targeting P-gp (minimum energy: -64.38 and -83.93 kcal/mol, respectively) substantiated the ability of mushroom-derived metabolites to facilitate drug delivery in the brain. This study verified that mushrooms containing non-hallucinogenic metabolites can act as psychoactive nutraceuticals that are significant for enhancing mental health. The high therapeutic efficacy, these mushrooms can serve as ideal neurological drug leads to fortify treatment for mental illness.
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2021, 102, 1; 55-64
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrodynamic and kinetic study of an elution of a high viscosity liquid from the sand bed using eluent of low viscosity
Autorzy:
Sęk, J.
Błaszczyk, M.
Bartos, M.
Powiązania:
https://bibliotekanauki.pl/articles/185535.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
granulacja
wymywanie
przepuszczalność
kinetyka
porous beds
granular bed
elution
permeability
kinetics
Opis:
The study was aimed to determine the hydrodynamic of water seepage through a porous bed saturated with different amounts of high viscosity liquids. An attempt was made to describe the process of seepage through beds saturated with oils using the theory of outflow of a liquid from the tank. It was assumed that the discharge coefficient will represent changes of flow resistance during the process. It was found that the dependence of this factor on time is linear. In the second part of this work kinetics of the seepage process was investigated. Dependence of oil concentrations, eluted from the deposit with the flowing water, on time has been evaluated. Thanks to these studies it was possible to determine the effectiveness of an elution of high viscosity liquids from porous beds using water as the washing out liquid.
Źródło:
Chemical and Process Engineering; 2012, 33, 1; 31-41
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation on the Effect of Granulometric Features on the Permeability of No-Bake Resin Bonded Sand Cores
Autorzy:
Hudák, H.
Gyarmati, G.
Varga, L.
Powiązania:
https://bibliotekanauki.pl/articles/1837703.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
foundry sand
granulometric features
grain size
grain morphology
grain shape
permeability
Opis:
Foundry sand is the main element of sand mixtures from which molds or sand cores are made. Due to the continuous development of core making technologies, the selection of the right type of base sand becomes more and more important. The major features of foundry sand are determined by the following factors: chemical and mineralogical composition, sand grain size, grain size distribution, sand grain shape, and surface quality. The main goal of our research was to develop a qualification method that can be used to predict the characteristics of sand cores made from different sand types. Samples made from different types of foundry sand were used during the research whose properties were examined with a new qualification system, and then its connection with the gas permeability of sand cores was analyzed. Based on the research results, a strong correlation could be established between the suggested quality indicators: CQi (Core Quality Index), CG (Coefficient of Granulometry), and permeability.
Źródło:
Archives of Foundry Engineering; 2021, 21, 2; 99-105
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exact solution of flow in a composite porous channel
Autorzy:
Singh, Sanjeeva Kumar
Verma, Vineet Kumar
Powiązania:
https://bibliotekanauki.pl/articles/140317.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
composite cylindrical channel
porous medium
permeability variation
Brinkman equation
modified Bessel function
Opis:
This article concerns fully developed laminar flow of a viscous incompressible fluid in a long composite cylindrical channel. Channel consist of three regions. Outer and inner regions are of uniform permeability and mid region is a clear region. Brinkman equation is used as a governing equation of motion in the porous region and Stokes equation is used for the clear fluid region. Analytical expressions for velocity profiles, rate of volume flow and shear stress on the boundaries surface are obtained and exhibited graphically. Effect of permeability variation parameter on the flow characteristics has been discussed.
Źródło:
Archive of Mechanical Engineering; 2020, LXVII, 1; 97-110
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Assessment of the Permeability of Selected Protective Coatings Used for Sand Moulds and Cores
Autorzy:
Jamrozowicz, Ł.
Siatko, A.
Powiązania:
https://bibliotekanauki.pl/articles/381009.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
permeability
protective coatings
coating viscosity
core
mold
przepuszczalność
powłoki ochronne
lepkość powłoki
rdzeń
forma
Opis:
The article presents the results of permeability measurements of a zirconium alcohol coating applied on moulds and cores. The introduction extensively discusses the reasons for the application of protective coatings, as well as their advantages and disadvantages. Also, the problems related to the application of protective coatings are presented i.e. limited permeability and thus the possibility of the presence of gas-originated defects in the casts. Next, the paper discusses the methods of measuring the permeability of protective coating proposed by Falęcki and Pacyniak. The study also presents an indirect permeability measurement method. For the investigations, zirconium alcohol coatings with the three conventional viscosities 10, 20 and 30s were used. The viscosity was determined by means of the Ford cup with the clearance of 4mm. The coatings were applied onto profiles of Φ 50x50 mm, made of moulding sand consisting of a sand matrix with the mean grain size of dL = 0,11, 17, 24, 31 and 34 mm and phenol-formaldehyde resin. The effect of the matrix grain size on the permeability of the sand with and without a coating was determined.
Źródło:
Archives of Foundry Engineering; 2020, 20, 1; 17-22
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and soft magnetic properties of Fe61Co10Y8Me1B20 (where Me = W, Zr or Nb) amorphous alloys
Struktura i własności magnetyczne stopów amorficznych Fe61Co10Y8Me1B20 (M = W, Zr, Nb)
Autorzy:
Pietrusiewicz, P.
Nabiałek, M.
Szota, M.
Perduta, K.
Powiązania:
https://bibliotekanauki.pl/articles/354639.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
właściwości magnetyczne
stopy amorficzne
przenikalność magnetyczna
magnetic properties
core losses
amorphous alloys
magnetic permeability
Opis:
The microstructure and the soft magnetic properties of the multi-component Fe61Co10Y8Me1B20 amorphous alloys (where Me = W, Zr or Nb) have been investigated; the samples were in the form of ribbons of 3 mm width and 30 µm thickness. The samples were produced using a single-roller melt-spinning method. The alloy composition was investigated using an X-ray diffractometer. The amorphous nature of the entire volume of all the as-quenched samples was confirmed. From the magnetic measurements performed using the ‘LakeShore’ vibrating sample magnetometer, magnetic parameters such as: coercivity, saturation of the magnetization for the as-quenched samples were derived. All of the investigated alloys displayed good soft magnetic properties, making them perfect materials for magnetic cores. The core losses for different values of magnetic field and operating frequency were also measured. It was shown that the investigated alloys featured lower core losses than commercially-used classical FeSi steel.
W pracy przedstawiono wyniki badań mikrostruktury i właściwości magnetycznych wieloskładnikowych stopów amorficznych o składach Fe61Co10Y8Me1B20 (Me = W, Zr, Nb) w postaci taśm o szerokości 3 mm i grubości około 30 µm. Badane materiały otrzymano metodą szybkiego chłodzenia ciekłego stopu na wirującym walcu miedzianym. Za pomocą dyfraktometru rentgenowskiego zbadano strukturę wytworzonych materiałów. Z badań tych wynika, że otrzymane w stanie po zestaleniu próbki były w pełni amorficzne. Na podstawie przeprowadzonych pomiarów wykonanych przy użyciu magnetometru wibracyjnego określono wartość: pola koercji, magnetyzacji nasycenia. Straty energii na przemagnesowanie oraz maksymalną przenikalność magnetyczną wyznaczono przy zastosowaniu aparatury, w której wykorzystuje się metodę transformatorową. Pomiar wykonano w zmiennym polu magnetycznym i przy różnych częstotliwościach. Badania te wykazały, że wytworzone szkła metaliczne w stanie po zestaleniu cechują się znacznie mniejszymi stratami na przemagnesowanie niż klasyczne blachy transformatorowe FeSi.
Źródło:
Archives of Metallurgy and Materials; 2012, 57, 1; 265-270
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wedge functions applied to 2D magnetostatic problems
Autorzy:
Huijer, E.
Karaki, S.H.
Powiązania:
https://bibliotekanauki.pl/articles/140344.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
klin
przenikalność magnetyczna
metoda całkowo-brzegowa
finite permeability
wedge functions
segment functions
boundary integral method
Opis:
In this paper the application of so called wedge functions is presented to solve two-dimensional simple geometries of magnetostatic and electrostatic problems, e.g. rectangles of varying aspect ratio and with different values of the magnetic permeability μ. Such problems require the use of surface charge density, or segment source, functions of the form ρs = σa-1, where the power parameters, a, have special fractional values. A methodology is presented to determine these special values of a and use them in segment sources on simple geometries, i.e. rectangles of varying aspect ratio, and with different values of the magnetic permeability μ. Wedge solutions are obtained by coupling the strength coefficients of source segments of the same power around an edge. These surface source functions have been used in the analysis of conducting and infinite permeability structures. Here we apply such functions in a boundary integral analysis method to problems having regions of finite permeability.
Źródło:
Archives of Electrical Engineering; 2011, 60, 4; 519-529
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Permeability changes of coal cores and briquettes under tri-axial stress conditions
Przepuszczalność rdzeni oraz brykietów węglowych w trójosiowym stanie naprężenia
Autorzy:
Wierzbicki, M.
Konecny, P.
Kozusnikova, A.
Powiązania:
https://bibliotekanauki.pl/articles/219808.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
węgiel
przepuszczalność gazowa
naprężenie trójosiowe
brykiety węglowe
coal
gas permeability
tri-axial stress
coal briquettes
Opis:
The paper is dealing with the permeability of coal in triaxial state of stress. The permeability of coal, besides coal’s methane capacity, is the main parameter determining the quantity of methane inflow into underground excavations. The stress in a coal seam is one of the most important factors influencing coal permeability therefore the permeability measurements were performed in tri-axial state of stress. The hydrostatic three-axial state of stress was gradually increased from 5 MPa with steps of 5 MPa up to a maximum of 30 MPa. Nitrogen was applied as a gas medium in all experiments. The results of the permeability measurements of coal cores from the “Zofiówka” mine, Poland, and three mines from the Czech Republic are presented in this paper. As a “reference”, permeability measurements were also taken for coal briquettes prepared from coal dust with defined porosity. It was confirmed that the decreasing porosity of coal briquettes affects the decreasing permeability. The advantage of experimentation on coal briquettes is its good repeatability. From the experimental results, an empirical relation between gas permeability and confining pressure has also been identified. The empirical relation for coal briquettes is in good correspondence with published results. However, for coal cores, the character of change differs. The influence of confining pressure has a different character and the decrease in permeability is stronger due to the increasing confining pressure.
Przepuszczalność węgla, oprócz pojemności sorpcyjnej względem metanu jest głównym parametrem określającym dopływ metanu do podziemnych wyrobiskach górniczych. W warunkach naturalnych wartość przepuszczalności jest ściśle związana ze stanem naprężenia w pokładzie węgla. W pracy przedstawiono wyniki pomiarów przepuszczalności wykonanych w trójosiowym stanie naprężenia. Hydrostatyczny trójosiowy stan naprężenia stopniowo zwiększano od 5 MPa do maksymalnie 30 MPa z krokiem wynoszącym 5 MPa. Maksymalne ciśnienie hydrostatyczne odpowiada ciśnieniu hydrostatycznemu jakie występuje w górotworze nienaruszonym na głębokości około 1200 m. Pomiary przeprowadzono z zastosowaniem azotu na czterech rodzajach rdzeni węglowych. Trzy z nich pochodziły z kopalń czeskich (ČSM, Paskov, František) a czwarty z polskiej kopalni „Zofiówka“. Własności węgli i miejsca ich pobrania zestawiono w tablicy 1. Dodatkowo, dla celów porównawczych wykonano pomiary przepuszczalności na materiale „wzorcowym” jakim są brykiety węglowe. Brykiety te wykonano metodą prasowania w urządzeniu pokazanym schematycznie na rys. 2. Własności brykietów zestawiono w tablicy 2, gdzie podano ich gęstości helowe, objętościowe oraz porowatości. Zmienność przepuszczalności wywołana zmianą naprężenia hydrostatycznego może być opisana równaniem empirycznym (3). Wartości przepuszczalności początkowej (dla σ = 0) oraz współczynników B z równania 3, dla różnych porowatości brykietów zestawiono w tablicy 3. Zaletą eksperymentów na brykietach węglowych jest ich powtarzalność. Zmienności przepuszczalności wywołane obciążeniem hydrostatycznym próbek, dla brykietów węglowych oraz rdzeni pokazano na wykresach z rysunku 4. W przypadku rdzeni węglowych zmienność przepuszczalności jest znacznie większa, co wynika prawdopodobnie z występowania szczelin i spękań widocznych na rys 1. Szczeliny te, jako główne drogi transportowe dla gazu przy niskich obciążeniach ulegają zaciśnięciu i część transportu gazu przenosi się do przestrzeni porowej.
Źródło:
Archives of Mining Sciences; 2014, 59, 4; 1131-1140
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental study on the effects of vibrational frequency on the permeability of gas-containing coal rocks
Autorzy:
Bairu, Zhu
Yang, Song
Beining, Wu
Yongqi, Li
Powiązania:
https://bibliotekanauki.pl/articles/1853881.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wibracje
przepuszczalność
ciśnienie gazu
gas-containing coal rock
low-frequency vibration
gas pressure
permeability
sensitivity coefficient
Opis:
Low-frequency mechanical vibrations can trigger disasters such as coal-gas outbursts. An in-house “vibration-triaxial stress-seepage” experimental apparatus was used to measure the gas flow rate of rock specimens with varying vibrational frequency, gas pressure, and confining pressure. The results of these tests were then used to derive expressions that describe how the permeability of gas-containing coal rocks is related to these aforementioned factors. In addition, sensitivity coefficients were defined to characterise the magnitude of the permeability response to each permeability-affecting factor (i.e., vibrational frequency and gas pressure). The following insights were gained, regarding the effects of vibrational frequency on the permeability of gas-containing coal rocks: (1) If gas pressure and confining pressure are fixed, the permeability of gas-containing coal rocks rapidly increases, before gradually decreasing, with increasing vibrational frequency. Thus, the permeability of the gas-containing coal rock is always larger with vibrations than without. (2) If vibrational pressure and confining pressure are fixed, the relationship between the permeability of gas-containing coal rocks and gas pressure is consistent with the “Klinkenberg effect,” i.e., the permeability initially decreases, and then increases, with increasing gas pressure. (3) The change in permeability induced by each unit change in gas pressure is proportional to the gas pressure sensitivity coefficient. (4) The change in permeability induced by each unit change in vibrational frequency is proportional to the vibrational frequency sensitivity coefficient.
Źródło:
Archives of Mining Sciences; 2021, 66, 2; 265-278
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
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