Wyniki wyszukiwania - BazTech

1

Evaluation of the Effect of Uncertainties on the Acoustic Behavior of a Porous Material Located in a Duct Element Using the Monte Carlo Method

Hannachi Hanen, Trabelsi Hassen, Kani Marwa, Taktak Mohamed, Chaabane Mabrouk, Haddar Mohamed

Archives of Acoustics

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2023

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Vol. 48, No. 1

81--91

EN

When studying porous materials, most acoustical and geometrical parameters can be affected by the presence of uncertainties, which can reduce the robustness of models and techniques using these parameters. Hence, there is a need to evaluate the effect of these uncertainties in the case of modeling acoustic problems. Among these evaluation methods, the Monte Carlo simulation is considered a benchmark for studying the propagation of uncertainties in theoretical models. In the present study, this method is applied to a theoretical model predicting the acoustic behavior of a porous material located in a duct element to evaluate the impact of each input error on the computation of the acoustic proprieties such as the reflection and transmission coefficients as well as the acoustic power attenuation and the transmission loss of the studied element. Two analyses are conducted; the first one leads to the evaluation of the impacts of error propagation of each acoustic parameter (resistivity, porosity, tortuosity, and viscous and thermal length) through the model using a Monte Carlo simulation. The second analysis presents the effect of propagating the uncertainties of all parameters together. After the simulation of the uncertainties, the 95% confidence intervals and the maximum and minimum errors of each parameter are computed. The obtained results showed that the resistivity and length of the porous material have a great influence on the acoustic outputs of the studied model (transmission and reflection coefficients, transmission loss, and acoustic power attenuation). At the same time, the other physical parameters have a small impact. In addition, the acoustic power attenuation is the acoustic quantity least impacted by the input uncertainties.

2

Experimental and Numerical Study of Photo Voltaic Thermal Phase Change Material Heat Transfer Augmentation with Encapsulation of Embedded Material/Fins

Kameswara Rao Dommeti, Reddy Keesari Sudhakar, Subba Rao V. V.

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 4

149--161

EN

Nonconventional energy sources like natural gas, coal, fossil fuels and petroleum are using extensively, leads to clean energy / renewable energy importance. Power generation with burning of fossil fuels can be changed using solar energy input source. Solar radiation incident on Photo voltaic Thermal (PVT) panel raises its temperaturę which tends to decrease the electrical output. Heat enhancement in Photo voltaic Thermal (PVT) panel can be reduced by attaching Phase Change Material (PCM) container on rear side of PV panel which increases the PVT efficiency. Novel technique and promising media for better thermal energy storage using PCM with fins, porous materials. Thermal conductivity of PCMs was low creates problem for energy storage and rate of retrieval. Improvement of thermal conductivity in PCMs and heat transfer enhancement can be done efficiently with the help of fins and porous materials of different designs. Present study provides optimum design of PCM container depth, fin height along with length of fin. Enhancement of heat transfer in Photo voltaic Thermal- Phase Change Material (PVT-PCM) will done by addition of Nano particles (Tio2, Sio2 and Al etc.)of high thermal conductivity along with PCM. Porous materials / fins can be made with metallic based materials nickel, copper, aluminum and carbon materials like graphite. These porous materials gave good results and efficient in heat transfer / thermal conductivity enhancement by 50–600 times than the conventional one. This paper gives the recommendations and conclusions to discuss research gap in this area PCM heat transfer enhancement to reduce the PVT panel temperature.

3

Identification of the Thermal Constants of the DPL Heat Transfer Model of a Single Layer Porous Material

Strąkowska Maria, Więcek Bogusław, De Mey Gilbert

Pomiary Automatyka Robotyka

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2021

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R. 25, nr 2

41--46

EN

This paper deals with parameters’ identification of the Dual Phase Lag (DPL) thermal model of a 3D printed porous materials. The experiments were performed for two porous materials with different filling factors. The Laplace transform was applied for the heat transfer equation and together with different optimization methods it allowed to identify the thermal time constants of the DPL model. Several optimization methods were tested with known parameters in order to confirm the correctness of the parameters’ estimation.

PL

Artykuł przedstawia nową metodę identyfikacji parametrów termicznych modelu Dual Phase Lag (DPL) materiałów porowatych drukowanych na drukarce 3D. Eksperymenty przeprowadzono dla dwóch materiałów porowatych o różnych współczynnikach wypełnienia. Do rozwiązania równań przepływu ciepła zastosowano transformację Laplaca, a następnie wykonano optymalizację w celu wyznaczenia wartości parametrów modelu w celu dopasowania ich do eksperymentu. Umożliwiło to identyfikację cieplnych stałych czasowych modelu DPL. Przetestowano również różne metody optymalizacji dla znanych wartości parametrów modelu w celu potwierdzenia poprawności identyfikacji.

4

Co warto wiedzieć o wodzie i jej działaniu na dachach

Patoka Krzysztof

Materiały Budowlane

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2021

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nr 3

34--35

5

Use of burshtyn TPP ash for the production of expanded gas concrete

Koshlak Hanna

Journal of New Technologies in Environmental Science

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2021

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Vol. 5, nr 2

82--88

EN

Production of not autoclave porous concrete, including small enterprises, industry of wall materials, which is now the most dynamically developing. One of the main problems in the production of gas concrete and concrete products is a comprehensive savings of cement, while ensuring high quality designs. Technology of gas concrete to date has at its disposal wide range of techniques that allow in specific conditions to reduce the specific consumption of cement without compromising technical properties of concrete. In recent years, for this purpose proposed in plasticized concrete mixtures using active mineral fillers. In this area gained considerable practical experience of application additives ash - removal, slags, carbonaceous materials, silica sand. Classical technology of these concrete based mainly on cement and unground sand. The use of TPP ash for cellular concrete is recommended by most of normative documents. The greatest effect is achieved by using high calcium ash.

6

The effect of capillary pumping on the course of cleaning porous materials containing liquid contaminants using supercritical fluids – A pore network study

Krzysztoforski Jan, Khayrat Karim, Henczka Marek, Jenny Patrick

Chemical and Process Engineering

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2021

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Vol. 42, nr 4

349-–368

EN

The role of capillary pumping on the course of cleaning porous materials containing liquid contaminants using supercritical fluids was investigated numerically. As a specific process to be modelled, cleaning of porous membranes, contaminated with soybean oil, using supercritical carbon dioxide as the cleaning fluid (solvent) was considered. A 3D pore-network model, developed as an extension of a 2D drying model, was used for performing pore scale simulations. The influence of various process parameters, including the coordination number of the pore network, the computational domain size, and the external flow mass transfer resistance, on the strength of the capillary pumping effect was investigated. The capillary pumping effect increases with increasing domain size and decreasing external flow mass transfer resistance. For low coordination numbers of the pore network, the capillary pumping effect is not noticeable at macro scale, while for high coordination numbers, the opposite trend is observed – capillary pumping may influence the process at macro scale. In the investigated system, the coordination number of the pore network seems to be low, as no capillary pumping effects were observed at macro scale during experimental investigation and macro-scale modelling of the membrane cleaning process.

7

Udział i znaczenie przepływu lepkiego w nieizobarycznej dyfuzji gazów przez materiały porowate

Boroń Dominika, Tabiś Bolesław

Przemysł Chemiczny

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2020

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T. 99, nr 12

1717--1722

PL

Przedstawiono wyniki ilościowej analizy dyfuzji nieizobarycznej przez materiały makroporowate. Na podstawie uogólnionego modelu gazu zapylonego dokonano oceny udziału przepływu lepkiego. Zaobserwowano zjawisko odwrócenia strumieni molowych, pojawiające się dla pewnej średnicy porów, nawet wówczas gdy dyfuzja następuje przy ustalonej różnicy ciśnień pomiędzy obydwiema stronami membrany. Podano sposób określenia tej średnicy. Zaproponowano uproszczoną metodę obliczania średniej lepkości gazów i dokonano jej oceny. Przedstawione równania modelu są słuszne dla dyfuzji K-składnikowej. Metodę zilustrowano na przykładzie roztworu dwuskładnikowego: argon, metan.

EN

Numerical studies of mass diffusion through porous materials were carried out for a two-component mixt. of Ar and CH4 gases. Using the generalized dusty gas model, an assessment of viscous flow contribution was performed. Reversing of molar fluxes were obsd. for certain pore diam. even at fixed transmembrane pressure difference. A method for detg. the diam. was given. A simplified method for detg. av. viscosity of gaseous mixts. was proposed and assessed. Presented model equations are valid for multicomponent diffusion.

8

Wymiana pary wodnej pomiędzy materiałami budowlanymi a powietrzem w pomieszczeniu

Mijakowski Maciej

Materiały Budowlane

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2019

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nr 1

34--36

PL

W artykule przedstawiono zagadnienia dotyczące transportu (wymiany) wilgoci pomiędzy powietrzem a higroskopijnymi materiałami budowlanymi i wyposażenia wnętrz. Opisano właściwości higroskopijne materiałów porowatych oraz uproszczony model wzajemnego oddziaływania materiału porowatego z otaczającym go powietrzem. Następnie scharakteryzowano wpływ materiałów wyposażenia wnętrz i przegród budowlanych na wilgotność powietrza wewnętrznego. Stanowi to podstawę do określenia możliwości wykorzystania pojemności higroskopijnej budynku do kształtowania warunków wilgotnościowych w pomieszczeniach.

EN

In the paper the issues the regarding transport (exchange) of moisture between air and hygroscopic building materials and interior furnishings have been presented. The hygroscopic properties of porousmaterials and a simplified model of interaction of porous material with the surrounding air have been described. Then, the influence of interior furnishing materials and building partitions on indoor air humidity has been characterized. This set the basis for determining the possibility of using the hygroscopic capacity of the building to shape the humidity conditions in the rooms.

9

Response surfaces in the numerical homogenization of non-linear porous materials

Beluch Witold, Hatłas Marcin

Engineering Transactions

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2019

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Vol. 67, iss. 2

213--226

EN

The paper deals with the numerical homogenization of structures made of non-linear porous material. Material non-linearity causes a significant increase in computational costs for numerical homogenization procedure. An application of the response surface methodology allows a significant reduction of the computational effort providing good approximation precision. Finite element method commercial software is employed to solve the boundary-value problem in both scales. Due to the significant reduction in computing time, the proposed attitude may be applied for different optimization and identification tasks for inhomogeneous, non-linear media, especially with the use of global optimization methods.

10

Effects of viscoelastic and porous materials on sound transmission of multilayer systems

Felhi H., Trabelsi H., Taktak M., Chaabane M., Haddar M.

Journal of Theoretical and Applied Mechanics

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2018

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Vol. 56 nr 4

961--976

EN

Multilayer structures allow obtaining good performance in acoustic insulation to eliminate unwanted noise in the medium and high frequencies in many applications such as building and transport industry. In this paper, the sound transmission of multilayer systems is studied using the Transfer Matrix Method (TMM). The studied multi-layered panels include elastic, viscoelastic and porous materials. Several configurations of multilayer systems are studied, and their corresponding transmission loss T L is computed. Also, the effects of porous material characteristics are studied to evaluate the impact of each parameter.

11

Bone tissue loads around titanium femoral implant and coated with porous layer

Bobik G., Żmudzki J., Majewska K.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 90, nr 2

77--84

EN

Purpose: Difference in the mechanical properties of bone and stiffer femoral implant causes bone tissue resorption, which may result in implant loosening and periprosthetic fractures. The introduction of porous material reduces the stiffness of the implant. The aim of the study was to analyse the influence of porous shell of femoral revision implant on bone tissue loading distribution with use the finite element method. Design/methodology/approach: Load transfer in the femur has been investigated using the finite element method (Ansys). Cementless implant models were placed in the anatomical femur model. Femur model included sponge bone and cortical bone. The solid implant was compared with the implant containing porous material in 70% in outer layer with a thickness of 2 mm. Load of 1500 N during gait was simulated. In addition, the forces of the ilio-tibial band and the abductor muscles were implemented, as well as the torque acting on the implant. Findings: Increase of stress for the porous model was found. The underload zones in bone have been reduced. Loading distribution was slightly more favourable, albeit rather in cortical bone. Stress value in cancellous bone around cementless implant margin has increased to a level that is dangerous for bone loss. Stress in the implant was not dangerous for damage. The stress distribution was different in the implant neck zone where the porous shell borne a little less load and high stress was shifted to the stiffer core. Research limitations/implications: Variable conditions for fitting the stem to the bone as well as the friction conditions were not investigated. Practical implications: Stress values in the spongy bone around the insertion edge of the cementless implant are consistent with long-term clinical results of the bone atrophy in 1 and 2 Gruen`s zones around the fully porous implants. Originality/value: The advantage of fully porous coated implant was the decrease of risk of trabecular bone tissue resorption around the implant tip and the increase of risk of trabecular bone tissue resorption around insertion edge of the implant.

12

Zeolitization characteristics of fly ash and its use to manufacture porous materials

David E., Şandru C., Armeanu A.

Archives of Materials Science and Engineering

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2018

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Vol. 90, nr 2

56--67

EN

Purpose: At thermal power plants the fly ash (FA) is stored either through dry or wet disposal systems. These storage practices result in different features for fly ashes, such as their interaction with alkalis and hence the potential of zeolite synthesis will be different. With the aim to demonstrate this, it was conducted some investigations to study the physical, chemical, morphological and mineralogical characteristics of the fly ash residues, then were used to synthesis zeolites by a double stage fusion-hydrothermal method. Design/methodology/approach: The raw and converted fly ash samples were characterized with respect to their composition, crystallinity and morphology, by SEM and XRD analysis. The effects of environment conditions and process parameters on the zeolitization process were studied and analysed. Findings: The analysis of these residues showed that dry ash attains a high cation exchange capacity (CEC) and SiO2 /Al2O3 ratios, which is in agreement to the formation of fly ash zeolites as compared to its counterpart. The experimental results indicate that the fusion temperature does not influence on the synthesis mechanism in range of 500-800 (°C) having only an effect of acceleration. The increasing of alkaline activator/fly ash ratio enhances the zeolitization degree. Research limitations/implications: The scientific basis for the issues on the zeolitization characteristics of fly ash and its use to manufacture porous materials calls yet for further elucidation and development. Practical implications: This study helps to establish the superiority of dry ash over wet ash for synthesizing porous materials and their enhanced quantity and quality. Originality/value: A new route for the fly ash use is demonstrated and this can become an unavoidable task for porous material manufacturing, a viable way to manage this industrial waste and to protect the environment.

13

Experimental and numerical two- and three-dimensional investigation of porosity morphology of the sintered metallic material

Madej L., Legwand A., Mojzeszko M., Chraponski J., Roskosz S., Cwajna J.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 4

1520--1534

EN

A through scale investigation of a porosity shape and morphology after sintering of the Distalloy AB powder is the goal of the paper. First, the classical two dimensional analysis of porosity geometrical aspects is presented with the use of the systematic scanning technique (SST) and the light microscopy (LM). Then, a three dimensional investigation is realized with the non-destructive computed tomography (CT) technique. Advantages and limitations of the approach are evaluated within the work. Finally, to investigate small pores which are beyond the computed tomography resolution, the destructive serial sectioning technique was applied. The developed three dimensional reconstruction algorithm of two dimensional images of obtained cross sections is also presented. Finally, an example of possible practical application of obtained three dimensional digital representation of porosity in sintered samples, during the finite element (FE) modelling of deformation conditions is presented.

14

Porous material effect on gearbox vibration and acoustic behavior

Letaief M. R., Walha L., Taktak M., Chaari F., Haddar M.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 4

1381--1395

EN

In this paper, we define a resolution method to study the effect of a porous material on vibro-acoustic behavior of a geared transmission. A porous plate is coupled with the gearbox housing cover. The developed model depends on the gearbox characteristic and poroelastic parameters of the porous material. To study the acoustic effect of the housing cover, the acoustic transmission loss is computed by simulating numerically the elastic-porous coupled plate model, and the numerical implementation is performed by directly programming the mixed displacement-pressure formulation. To study the vibration effect, the bearing displacement is computed using a two-stage gear system dynamical model and used as the gearbox cover excitation. Numerical implementation is performed by direct programming of the Leclaire formulation.

15

Physical model of simultaneous disparaging and dehydration of fine porous material in thermal vacuum installation

Kutovyi V. O., Lutsenko A. S., Skoromnaya S. F., Tkachenko V. I.

Journal of New Technologies in Environmental Science

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2017

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Vol. 1, nr 4

142--149

EN

Carbon materials represent difficult chemical compounds [1, 2]. They demand not only dispergating (crushing), and dehydration (removal of moisture) [3], but also cleanings of harmful impurity which negatively influence the environment at their further use in the industry. Now there are many installations and techniques of dehydration and dispergating of rheological material, including coals of different types. Comparative analysis of standard technologies and technology of thermal vacuum dehydration and dispergating of brown coal carried out. The experimental technique of dehydration and dispergating of brown coal described. Temperature, pressure, time of dehydration and dispergating of brown coal are determined. The physical model of simultaneous dehydration and dispergating of fine porous material offered. Dispergating of the dried-up material described by means of two models of disintegration of a part in the course of drying: discrete and continuous. It shown that at the initial stage of drying the maximum difference on the mass of the extracted water calculated on two models makes size about 7%. On big times of drying dependence of amount of the extracted water on time for the models considered above is almost identical. Calculations show that rapid withdrawal of water from a sample explains rather intensive process of crushing of the dried-up material at the initial stage of drying. At the same time with excess of temperature of the heater by 1.68 times over temperature of boiling of water with the lowered part pressure in the same number of times are crushed quicker. Comparison of theoretical calculations with experimental data shows adequacy of the offered models of dehydration and dispergating of fine rheological material.

16

Multiscale identification of parameters of inhomogeneous materials by means of global optimization methods

Beluch W.

Engineering Transactions

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2017

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Vol. 65, iss. 1

19--24

EN

This paper deals with the identification of material parameters at a microscale on the basis of measurements at a macroscale. Inhomogeneous materials such as composites and porous media are considered. Numerical homogenization with the use of a representative volume element is performed to obtain a macroscopically homogenized equivalent material. The evolutionary algorithm is applied as the global optimization method to solve the identification task. Modal analysis is performed to collect data necessary for the identification. Different ranges of measurement errors are considered. A finite element method is employed to solve a boundary-value problem for both scales.

17

Modelowanie przepływu cieczy przez materiały porowate o różnej mikrostrukturze

Stec J., Filipek R.

Cement Wapno Beton

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2017

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R. 21/83, nr 6

489--506

PL

W pracy przedstawiono sformułowania modeli transportu w ośrodku porowatym w skali mikro i makro. Jako model mikro ośrodka porowatego przyjęto układ nieruchomych kul reprezentujący ziarna, o rozkładzie dwumodalnym. Na podstawie obliczeń w skali mikro, stosując stacjonarne równanie Stokesa dla cieczy nieściśliwej, wyznaczono maksymalne prędkości oraz przepływy dla poszczególnych mikrostruktur w funkcji promienia małego ziarna oraz porowatości. Obliczono również krętość poszczególnych mikrostruktur. Przedstawiono metodę wyznaczania przepuszczalności układu, która jest uśrednionym parametrem opisującym ośrodek porowaty w skali makro. Zaprezentowana metoda może być stosowana w modelowaniu procesów transportu dla materiałów o rzeczywistej mikrostrukturze.

EN

In the paper authors present the formulation of transport models in porous medium in both micro and macro scale. System of spheres, representing grains, with bimodal radius distribution were used as a model of porous medium in micro scale. Based on calculation in micro scale, using stationary Stokes' equation for incompressible fluid, the maximum velocity and flows were calculated for each microstructure as a function of small grains size as well as porosity. Tortuosity for each microstructure was also calculated. Method for permeability determination, which is an average parameter describing porous medium in macro scale, was presented. Presented method might find application in modelling of transport for materials with real microstructure.

18

Wpływ struktury powierzchni granulatu skrobi termoplastycznej na kinetykę adsorpcji pary wodnej

Muszyński S., Świetlicki M., Oniszczuk T., Kwaśniewska A., Świetlicka I., Arczewska M., Oniszczuk A., Bartnik G., Kornarzyński K., Gładyszewska B.

Przemysł Chemiczny

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2016

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T. 95, nr 4

865--869

PL

Dokonano oceny wpływu struktury powierzchni granulatu skrobi termoplastycznej (TPS) wytworzonej na bazie skrobi pszennej, kukurydzianej i ziemniaczanej na kinetykę adsorpcji pary wodnej. Strukturę tę modyfikowano poprzez zmianę prędkości obrotowej ślimaka ekstrudera, zmieniając gęstość pozorną (objętościową), gęstość rzeczywistą, porowatość całkowitą i względną objętość porów. Badanie prowadzono przez 72 h w środowisku o wilgotności względnej 75,3% w temp. 20°C, wyznaczając przebieg kinetyki adsorpcji pary wodnej w funkcji czasu oraz zmian szybkości adsorpcji pary wodnej w funkcji zawartości wody. Na podstawie przeprowadzonej analizy wykazano wpływ rodzaju użytej skrobi oraz parametrów technologicznych procesu ekstruzji na adsorpcję pary wodnej przez granulat TPS.

EN

Wheat, maize and potato starches were converted to thermoplastic starch (TPS) with glycerol by extrusion, pelletized at changing the speed of extruder screw and studied for apparent d., true d., total porosity, and sp. pore vol. The TPS pellets were studied for water adsorption from air at 20°C and relative humidity 75.3% for 72 h to det. the adsorption kinetics. The lowest hydrophilicity of TPS was found for the pellets extruded at highest speed of extrusion screw (120 rpm).

19

Assessment of process conditions associated with hydrodynamics of gas flow through materials with anisotropic internal structure

Wałowski G., Filipczak G.

Journal of Sustainable Mining

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2016

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Vol. 15, iss. 4

156--169

EN

The results of experimental research concerning the assessment of the permeability of porous materials with respect to gas flow are presented in this paper. The conducted research applied to, among others, chars (acquired from the UCG thermal process) with an anisotropic gap-porous structure and - for comparative purposes - model materials such as pumice and polyamide agglomerates. The research was conducted with the use of a special test stand that enables the measuring of gas permeability with respect to three flow orientations compared with symmetric cubic-shaped samples. The research results show the explicit impact of the flow direction on the permeability of chars, which results from their anisotropic internal structures. The suitability of calculation methods employed to calculate the hydrodynamics of the gas flow through porous materials was also evaluated.

20

Oczyszczanie polimerowych materiałów porowatych przy użyciu płynów w stanie nadkrytycznym

Krzysztoforski J., Henczka M.

Inżynieria i Aparatura Chemiczna

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2016

|

Nr 1

26--27

PL

W pracy przedstawiono wyniki badań doświadczalnych oraz symulacji numerycznych procesu oczyszczania polimerowych materiałów porowatych przy użyciu płynów w stanie nadkrytycznym. Zbadano wpływ parametrów operacyjnych na przebieg procesu oraz opracowano i wstępnie zweryfikowano model matematyczny, który może być wykorzystany do symulacji i optymalizacji procesu oraz do projektowania aparatury wysokociśnieniowej. Wykazano, że płyny w stanie nadkrytycznym stanowią efektywne rozpuszczalniki w procesach oczyszczania polimerowych materiałów porowatych.

EN

Experimental results and numerical simulations of porous polymer material cleaning process using supercritical fluids are presented in the paper. An influence of process parameters on the process course was investigated and a mathematical model was developed and validated. The model can be used for process investigation and optimization, and also for high pressure equipment design. It was proven that supercritical fluids are effective solvents in porous polymer material cleaning processes.