Wyniki wyszukiwania - BazTech

1

Effect of evaporation rate and substrate temperature on optical, structural, and electrical properties of ZnTe:Sb films deposited by thermal evaporation of Zn, Te, and Sb sources

Aqili Akram, Al-Reyahi Anas Y., Maghrabi Mufeed

Materials Science Poland

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2025

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Vol. 43, No. 2

78--86

EN

Antimony (Sb)-doped ZnTe films were deposited onto amorphous glass substrates via thermal evaporation of elemental sources. This study aims to investigate the effects of the Sb evaporation rate and glass substrate temperature on the various physical properties of the prepared films. Structural analysis was conducted using X-ray diffraction, and the elemental composition was determined using energy dispersive X-ray spectroscopy attached to a scanning electron microscope. Optical transmittance spectra, recorded across the 400–2,000 nm wavelength range, were used to assess the film thickness, surface roughness, refractive index, and optical bandgap. DC conductivity measurements were performed under vacuum within a temperature range of 30–170°C. The results showed a significant increase in the conductivity of the films (by several orders of magnitude), accompanied by a clear change in the optical properties as a result of increasing Sb content in the films. Additionally, the substrate temperature was found to have a substantial effect on the physical characteristics of the films.

2

Improvement of Thermophysical Characteristics of Polymer Coatings for Protecting Water Transport by Using a Mixture of Discrete Organic Fibers

Sapronov Oleksandr, Buketov Andriy, Sapronova Lyudmila, Mokiy Oleksandr, Vorobiov Pavlo, Banha Mykhailo, Straka Ľuboslav

Management Systems in Production Engineering

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2025

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nr 4 (33)

576--585

EN

This work presents the technological aspects of the reinforcement of the thermosetting binder to improve the thermophysical characteristics of polymeric materials and protective coatings based on them. Epoxy binder ED-20 was used to form polymer materials, which were polymerized with polyethylene polyamine (PEPA) in the ratio: 100 parts by weight of ED-20 epoxy oligomer and 10 parts by weight of PEPA hardener. A mixture of discrete organic fibers with the content of q = 0.25-2.00 wt.% was used to improve the thermophysical properties of polymer materials. The key parameters for determining the temperature range for the future operation of the designed composite materials without changing their properties were defined by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The maximum temperature of the mass loss beginning is Т0 = 624.0°K; the relative mass loss is εm = 65.7%; the initial temperature of the exoeffect is Тn = 475.5°K; and the maximum temperature of the exoeffect peak is Tmax = 545.5°K. The mathematical calculation of the activation energy of thermal destruction was performed to determine the resistance to the degradation of chemical bonds under the temperature influence. It has been proven that composites filled with a discrete organic fiber mixture with the content of q = 0.75 wt.% are characterized by the maximum activation energy (Ea = 167.2 kJ/mol), which indicates the thermal stability of reinforced composites.

3

A three-component model of kerogen kinetics on the example of the Menilite Beds

Słoczyński Tomasz, Matyasik Irena, Spunda Karol

Geology, Geophysics and Environment

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2025

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Vol. 51, no. 1

27--42

EN

This paper presents the concept of constructing three-component kinetic models of kerogen. The method was developed based on the kinetic mass model constructed from Rock-Eval pyrolysis and Py-GC analysis results. The parameters of the discrete function describing the distribution of activation energy (Ea) and the constant values of the reaction rate (A) for the mass model were optimized based on the results of Rock-Eval pyrolysis in the Kinetics15 program. With aid of multistage isothermal pyrolysis of Py-GC performed for the same duration at different temperatures, the percentages of each hydrocarbon fraction obtained during the successive stages of pyrolysis were determined. The determined fractions were assigned an appropriate (resulting from the mass model) value of activation energy. The multi-component kinetic model of kerogen constructed in this way enabled the calculation of the shares of individual hydrocarbon fractions generated at different stages of thermal transformation of the source rocks. Simulations of the composition of generated hydrocarbons for the developed model were carried out in the PetroMod Kinetic Editor. The results of the simulation justified the creation of multi-component kinetic models for each of the potential source formations located in the study area. Their implementation into the petroleum system model makes it possible to not only forecast the total amount of generated hydrocarbons but also the dynamics of the generation process and the shares of the generated fractions at various stages of thermal transformation of the source rocks. The research material consisted of Menilite source rocks samples, which are considered to be the main source of hydrocarbon accumulations in the Outer Carpathians.

4

ANN-enhanced determination and numerical model integration of activation energy and Zener–Hollomon parameter to evaluate microstructure evolution of AA6082 wheel forging

Saputro Imang Eko, Lin Chun-Nan, Mardiono Intan, Chen Hsuan-Fan, Chen Junwei, Ho Marlon, Fuh Yiin-Kuen

Archives of Civil and Mechanical Engineering

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2025

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Vol. 25, no. 1

art. no. e9, 2025

EN

This study presents the integration of two Arrhenius-constitutive model parameters, activation energy (Q) and the Zener–Hollomon parameter (Z), into a numerical model to evaluate their correlation with the microstructural evolution of AA6082 wheel forging. Isothermal tests powered by a Gleeble machine were conducted to establish the constitutive model of AA6082 material, with deformation temperatures and strain rates varying between 350–560 °C and 0.05–15 s⁻1, respectively. Two types of Arrhenius methods were employed: strain-compensated Arrhenius and artificial neural network (ANN)-enhanced Arrhenius. The key difference between the two methods is that the former ignores the effects of deformation temperature and strain rate when determining the activation energy (Q) value, while the latter considers these factors. Integrating activation energy and Zener–Hollomon parameters into a numerical model by directly inputting the mathematical equation from the strain-compensated Arrhenius method resulted in significant overfitting at certain nodes and elements. To address this issue, a new approach using trilinear interpolation and behavior-based clamping methods on Q values generated by the ANN–Arrhenius method proved effective. Additionally, the ANN–Arrhenius method demonstrated superior accuracy, reducing the prediction’s average absolute relative error (AARE) from 3.14% (strain-compensated Arrhenius method) to 1.10%. A comparative study of the distribution of Q and Z values in numerical model simulations, alongside average grain size and shape examined with an optical microscope, revealed that the Q and Z parameters are beneficial for predicting grain characteristics in final workpieces. This study aims to bridge the gap in implementing activation energy and Zener–Hollomon parameters in more realistic forging scenarios and with more complex workpiece designs.

5

Mathematical model of thin layer drying of purple yam by infrared assisted heat pump drying

Duc Le Anh, Hay Nguyen, Kien Pham Van, Tan Nguyen Thanh, Cuong Dang Quoc

Agricultural Engineering

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2025

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Vol. 29, No. 1

63--78

EN

This study focused on the thin-layer drying of yam by infrared-assisted heat pump drying to determine the thin-layer drying model, the effective moisture diffusivity, and the activation energy of moisture within the yam. The thin-layer drying experiment was conducted with input drying parameters such as drying temperatures of 40, 45, and 50°C, drying air velocity of 2.5 m·s-1, and infrared power of 250, 300, and 350 W. In order to determine a suitable thin-layer drying model for describing the yam drying process, six different thin-layer drying models (Lewis, Page, Modified Page, Henderson and Pabis, Wang and Singh, and Midilli) were chosen for nonlinear regression with the experimental drying data. The Midilli model was found to be the most suitable drying model for describing the thin-layer drying of yam. The average effective moisture diffusivity was in the range of 4.184×10-9 to 8.142×10-9 m2·s-1, and the activation energy was in the range of 16.78 to 21.01 kJ·mol-1 over the proposed range of drying input parameters.

PL

Celem badania jest opracowanie modelu suszenia cienkowarstwowego ignamu fioletowego za pomocą pompy ciepła z promieniowaniem podczerwonym i określenie efektywnej dyfuzyjności wilgoci zawartej w fioletowym ignamie oraz energii jej aktywacji. Eksperyment suszenia cienkowarstwowego przeprowadzono przy następujących parametrach wejściowych: temperatury suszenia: 40, 45 i 50°C, prędkość powietrza suszącego: 2,5 m·s-1 a moc promieniowania podczerwonego: 250, 300 i 350 W. Aby określić taki model suszenia cienkowarstwowego, który opisywałby proces suszenia ignamu fioletowego przeprowadzono nieliniową regresję danych eksperymentalnych z wykorzystaniem sześciu różnych modeli suszenia cienkowarstwowego (Lewis, Page, zmodyfikowany Page, Henderson i Pabis, Wang i Singh oraz Midilli). Najbardziej odpowiednim modelem okazał się model Midilli. Średnia efektywna dyfuzyjność wilgoci w tym modelu mieściła się w zakresie od 4,184×10-9 do 8,142×10-9 m2·s-1, natomiast energia aktywacji wynosiła od 16,78 do 21,01 kJ·mol-1 w analizowanym zakresie parametrów suszenia.

6

Porównanie wpływu stopnia zawilgocenia na charakterystyki czasowe prądów polaryzacji i depolaryzacji półsyntetycznej izolacji celulozowo-aramidowej NOMEX ® 910 impregnowanej estrem syntetycznym i naturalnym

Krotowski Adam, Wolny Stefan

Przegląd Elektrotechniczny

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2024

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R. 100, nr 11

216--220

PL

W artykule zaprezentowano wyniki badań laboratoryjnych analizujących wpływ stopnia zawilgocenia na charakterystyki prądów polaryzacji i depolaryzacji próbek izolacji transformatorowej wykonanych na bazie hybrydowego, celulozowo-aramidowego papieru elektroizolacyjnego NOMEX®910 zaimpregnowanego estrem syntetycznym MIDEL®7131 lub cieczą biopochodną Nytro® BIO 300X. Wynikiem przeprowadzonej analizy są funkcje regresji energii aktywacji oraz dominujących stałych czasowych komponentów składowych celulozowo aramidowej izolacji NOMEX®910 z uwzględnieniem temperatury oraz stopnia zawilgocenia włókien celulozy.

EN

This article presents the results of laboratory tests analyzing the effect of the degree of moisture on the characteristics of polarization currents and depolarization of samples of transformer insulation made on the basis of hybrid cellulose-aramid electrical insulating paper NOMEX®910 impregnated with synthetic ester MIDEL®7131 or the bio-based liquid Nytro® BIO 300X. The result of the analysis, is the regression functions of the activation energy and the dominant time constants of the components of the cellulose-aramide insulation NOMEX®910, taking into account the temperature and degree of moisture of the cellulose fibers.

7

The kinetic study of refractory silver ore in acidified potassium chloride - hypochlorite media

Canıeren Ömer, Kurama Haldun, Karagüzel Cengiz

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 6

art. no. 199374

EN

In this study, the dissolution of refractory silver ore samples obtained from the Kütahya Gümüşköy region in the HCl/NaOCl and KCl system was investigated. Chemical and morphological analyzes of the sample show that the ore consists mainly of quartz, dolomite, barite and clay. Silver is dispersed as free fine particles or locked in barite and quartz minerals. The leaching tests were carried out under ambient conditions with direct contact of the solvent reagent with the sample. Reaction temperature, time, and KCl concentration were examined as leaching parameters to elucidate their effects on silver extraction. The results obtained in leaching tests indicated that the dissolution of silver occurs very quickly, almost linearly, within the first minute of the reaction. After this point, the dissolution rate decreases and reaches equilibrium after 10 minutes. It was found that increasing both temperature and KCl concentrations have a positive effect on extraction. These effects become more evident in the first stage, especially at high salt concentrations (1 M). The experimental results showed that the highest silver extraction of 53.15% was obtained under the following conditions: Temperature of 85oC, leaching time of 10 min, concentrations of 0.5 M and 0.1 M for KCl and NaOCl, respectively, the solid ratio of 30%, and particle size (d80) 15 μm. The kinetics of AgCl dissolution was specificially studied using aforementioned leaching system as well. The reaction rates, kinetic orders and activation energies were calculated. Correspondingly, a general kinetic model describing leaching systems based on shrinking core was proposed as a rate-controlling model for the dissolution mechanism.

8

Effect of the type of ion-exchange resin on Mn2+ adsorption in the presence of competing cations

Amengol Bruna P. C., Pires Renata. C., Leão Versiane A.

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 2

art. no. 187844

EN

Present in soils, ground and surface waters, manganese is among the most common metals in Earth crust. It is also an essential trace element to the functioning of several enzymes in the human body. However, exposure to high manganese concentrations can also be harmful to humans with psychiatric and motor effects and therefore, manganese concentrations in drinking water and also industrial effluents are regulated. In the current work, the adsorption of Ca2+, Mg2+ and Mn2+ on three different ion-exchange resins: (i) aminophosphonic acid - chelating (Purolite S950), (ii) polyacrylic weak acid cation (Purolite C104E) and (iii) polystyrene strong acid cation (Purolite C100) was investigated. The results revealed that Purolite S950 had the highest Mn2+ uptake (37.9 mg/mL-resin or 0.69 mmol/mLresin) as compared to Ca2+ (3.2 mg/mL-resin or 0.08 mmol/mL-resin) and Mg2+ (~0 mg/mL-resin) and was selected for further kinetics and equilibrium studies. The results indicated Purolite S950 as particularly suited to be applied in the treatment of neutral mine waters with high Mg/Mn ratios. Additionally, Purolite S950 showed a small affinity for Ca2+ and therefore an efficient Mn2+ removal will depend on the Ca/Mn ratio of the mine water under treatment. According to the kinetic analysis, manganese sorption on Purolite S950 was described by the pseudo-second order model (r2 > 0.98) with an activation energy of 6.34 kJ/mol and thus pore-difussion was the rate controlling step of the process. In terms of equilibrium studies, manganese sorption on Purolite S950 followed the Langmuir model with maximum loadings of up to 41.5 mg/mL-resin. The thermodynamic modelling indicated an exothermic process (-85.0 kJ/mol, as standard enthalpy) with a standard entropy of -274 J/mol×K, which was ascribed to the release of two adsorbed H+ ions for each Mn2+ ion taken up from solution.

9

Stabilization of Sewage Sludge from North Moroccan Wastewater Treatment Plants Using Convective Indirect Solar Drying

Bougayr El Houssayne, Bahammou Younes, Fantasse Azeddine, Lakhal El Khadir, Berroug Fatiha, Bouziane Abdelkhalek, Idlimam Ali

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 10

1--16

EN

The significant production of sewage sludge by wastewater treatment plants on a global scale and the lack of correspondence between housing development and the expansion of sanitation infrastructure indicate a genuine concern regarding environmental preservation. This study addresses the crucial issue of effective sewage sludge management and its environmental impact. In the context of searching for new drying methods that optimize energy use and effectively stabilize sewage sludge, this work investigated the drying behavior of sewage sludge from treatment plants in two northern Moroccan cities using a prototype of an indirect forced convection solar dryer. The drying experiments enabled the determination of drying kinetics as well as highlighted the influence of temperature and humidity on the drying rate. The characteristic drying curve (CDC) and its mathematical expression were determined using Van Meel’s formalism. Thermal diffusivity of wastewater sludge during drying was also investigated. Using Fick’s diffusion model, diffusion coefficients ranged between 0.59 × 10-9 m2/s and 1.43 × 10-9 m2/s, demonstrating an increase in effective diffusivity with rising temperature. The Arrhenius equation provided activation energy values of 16.80 kJ/mol for Oujda samples and 19.72 kJ/mol for Nador samples, indicating the effect of temperature on effective diffusivity. A new equation based on the Midilli-Kucuk model was proposed to predict the drying behavior under untested aerothermal conditions, considering drying temperature and the initial dryness. This study offers a comprehensive analysis of the drying kinetics and effective diffusivity of sewage sludge, providing valuable insights for designing large dryers for sludge management in WWTPs. This approach presents an optimal solution for drying and stabilizing sludge, contributing to environmental preservation efforts.

10

A study of starch hydrolysis by α–amylase from porcine pancreas with deactivation of enzyme

Miłek Justyna, Grubecki Ireneusz, Tomczak Wirginia

Chemical and Process Engineering : New Frontiers

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2024

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Vol. 45, nr 2

art. no. e57

EN

The demand of energy and the search for alternative energy sources are the reason why scientists are interested in starch hydrolysis. The aim of the work was to experimental study of the hydrolysis of starch by α–amylase from porcine pancreas with α–amylase deactivation. Based on the experiments data, the parameters of starch hydrolysis by α– amylase with deactivation of enzyme was estimated. A mathematical model of temperature impact on the activity of α–amylase from porcine pancreas was used. It has been estimated that the activation energy Ea and the deactivation energy Ed were equal to 66 ± 4 kJ/mol and 161 ± 12 kJ/mol, respectively. Additionally, specific constant of starch hydrolysis k 0 and specific constant of α–amylase deactivation k d0 were calculated. The optimum temperature Topt equal to 318 ± 0.5 K was obtained from mathematical model. The obtained values of Ea, Ed, k 0 and k d0 parameters were used to the model starch hydrolysis by α–amylase from porcine pancreas at 310 K and 333 K.

11

Investigation of the thermal degradation behavior of coal/biomass blends for kinetics analysis with sequential method implication

Shoaib Hafiz Muhammad, Qureshi Tayyab, Khan Ihtisham, Mahmood Hamayoun, Iqbal Tanveer

Architecture Civil Engineering Environment

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2024

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Vol. 17, no. 4

161--168

EN

Pakistan currently has a problem in the energy supply and demand. There is a large gap between supply and demand for electricity. The depletion of fossil fuels and environmental pollution factors also exist. These factors convert the intention to implement co-firing of coal and biomass. Being agricultural land and producing a significant amount of agricultural waste and have a little valuable use of this waste. Keeping in mind for effective use of this agro-waste the pyrolysis behavior of Pakistani local coal (LC), rice husk (RH), and their blends 75LC/25RH wt.%, 50LC/50RH wt.%, 25LC/75RH wt.% were studied using a thermogravimetric analyzer in a nitrogen environment with 10K/min heating rate. A sequential method approach is used to calculate kinetics parameters quickly and accurately. With the assumption of first-order reaction, calculation is performed. The research findings revealed that the addition of rice husk to the blends led to an increase in the activation energy for devolatilization, rising from 22.9 kJ/mol to 45.2 kJ/mol. However, the activation energy for char degradation decreased from 60.4 kJ/mol (100%LC) to 14.2 kJ/mol (100%RH) as the proportion of rice husk in the blends increased. Moreover, the rate of mass degradation also increased with higher amounts of rice husk in the blends. These results suggest that the decrease in char degradation activation energy allows for a reduction in operational temperature, thereby facilitating a reliable co-pyrolysis process. Such a process holds the potential to design a low-cost and effective gasification process, aiding in overcoming the energy challenges.

12

Rozkład nadtlenku wodoru podczas katalitycznego epoksydowania propylenu

Lina Wang, Cheng Shen, Yingfeng Duan, Wei Du, Yagang Zhang, Wenying Li

Przemysł Chemiczny

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2023

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T. 102, nr 10

1018--1021

PL

Jako katalizator epoksydowania propylenu za pomocą nadtlenku wodoru w wodnym roztworze metanolu zastosowano sito molekularne TS-1 (krzemian tytanu). Zbadano szybkość samoistnego rozkładu nadtlenku wodoru wtemp. 30-50°C. Znaleziono optymalne warunki (temp. reakcji 43°C, stężenie nadtlenku wodoru 10,3% mas., zawartość metanolu 65% mas.). Ustalono, że rozkład nadtlenku wodoru jest reakcją pierwszego rzędu. Wyznaczono stałą szybkości tej reakcji i jej energię aktywacji.

EN

Ti silicalite mol. sieve (TS-1) was used as catalyst for propylene epoxidation with H₂O₂ in aq. MeOH soln. The H₂O₂ self-decompn. rate at 30-50°C was studied. The optimum conditions were found (reaction temp. 43°C, H₂O₂ concn. 10.3% by mass, MeOH concn. 65% by mass). The H₂O₂ selfdecompn. was the first-order reaction. Its reaction rate const. and activation energy were detd.

13

Stagnation-point flow of Williamson fluid along a stretched plate with convective thermal condition and activation energy

Salawu S. O.

International Journal of Applied Mechanics and Engineering

|

2023

|

Vol. 28, no. 3

101--111

EN

The implication of a stagnation-point flow together with the influence of activation energy in a Williamson fluid, which consists of tiny particles, over an expansive plate is analyzed numerically. Conditions of convective heat and mass motion with features of irregular movement and thermal-migration of particles influenced by viscous dissipation and convective heat surface condition are checked in the study. The conversion of the model equations from the initially formulated partial derivatives to ordinary ones is implemented by similarity transformations while an unconditionally stable Runge-Kutta-Fehlberg integration plus shooting technique are then used to complete the integration. Various interesting effects of the physical parameters are demonstrated graphically and explained appropriately in order to make accurate predictions. Moreover, the accuracy of the solution is verified by comparing the values of the skin friction factor with earlier reported ones in literature under limiting constraints. It is worth mentioning that the velocity profiles flatten down as the magnitude of the magnetic field factors expands but this causes a boost in the fluid’s temperature. The concentration field also appreciates with activation energy but depreciates with chemical reaction and Schmidt number.

14

Austenite-grain-growth kinetics and mechanism in type 347H alloy steel for boiler tubes

Huda Zainul, Zaharinie Tuan, Aniszulaikha Ireen, Almitani Khalid

Advances in Materials Science

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2023

|

Vol. 23, nr 3(77)

79--97

EN

The research material (type 347H alloy steel) has been characterized using optical microscopy and an EDS/SEM system. Annealing experiments have been conducted at temperatures range of 600–1050°C for 30 min–20 h by using an atmosphere-controlled furnace. Normal grain growth with intermediate grain size has been related to the favouring of creep resistance to recommend the material suitable for boiler tubes at operating temperatures up to 750oC for long duration. The kinetics of grain growth in the 347H has been shown to behave similar to a pure metal in the initial stage of annealing in the range of 0–30 min, beyond which the grain-growth process was found to be suppressed due to second-phase (NbC) particle-pinning and solute drag effects. The grain-growth exponent n is computed to be in the range of 0.117–0.313; the deviation from ideal kinetic behavior (n=0.5) has been scientifically justified. The activation energy for grain growth Qg, for the investigated alloy, has been graphically computed and validated.

15

Energia aktywacji utworów warstw menilitowych i jej implikacje dla procesu generowania węglowodorów w Karpatach

Spunda Karol, Słoczyński Tomasz

Nafta-Gaz

|

2022

|

R. 78, nr 5

327--335

PL

W artykule zaprezentowano procedurę obliczeń energii aktywacji kerogenu utworów warstw menilitowych oraz implikacje wynikające z jej zróżnicowania dla przebiegu procesu generowania węglowodorów w karpackim systemie naftowym. Powstawanie węglowodorów w skałach następuje w wyniku rozpadu złożonych związków organicznych (głównie związków węgla, wodoru i tlenu) budujących kerogen na cięższe i lżejsze węglowodory frakcji olejowej i gazowej. Proces jest reakcją termokatalityczną, której dynamika determinowana jest między innymi przez energię aktywacji kerogenu. Energia aktywacji jest jednym z podstawowych parametrów wejściowych implementowanych do numerycznych modeli systemów naftowych, dlatego jej oznaczenie jest bardzo istotne dla rzetelnego odtworzenia tego procesu, zachodzącego w naturalnych warunkach geologicznych i w skali czasu geologicznego. Obliczeń energii aktywacji dokonano na podstawie wyników oznaczeń parametrów kinetycznych reakcji krakingu kerogenu, który to kraking przeprowadzono w kontrolowanych warunkach laboratoryjnych przy użyciu analizatora pirolitycznego Rock-Eval. Eksperyment polegał na nieizotermicznej pirolizie skał zawierających kerogen i rejestrowaniu szybkości reakcji (tempa generowania węglowodorów) w całym zakresie temperaturowym pirolizy. Energię aktywacji (Ea) i stałą Arrheniusa (A) obliczano z równania Arrheniusa, opisującego zależność stałych szybkości reakcji od temperatury. Do obliczeń wykorzystano model dyskretnej dystrybucji energii aktywacji (Ea) ze stałą wartością stałej Arrheniusa (A). Rozkład optymalizowano iteracyjnie metodą regresji liniowej i nieliniowej. Dla każdego z reagentów, o początkowej masie x0i, obliczono dyskretną wartość energii aktywacji (Eai). W tym przypadku i-ta reakcja równoległa odpowiadała wiązaniom chemicznym, które muszą zostać rozbite energią aktywacji (Eai) w cząsteczkach kerogenu. Optymalizacji rozkładu energii aktywacji dokonano przy użyciu oprogramowania Kinetics2015.

EN

The article presents the procedure for calculating the kerogen activation energy of rock of the Menilite Beds which are considered the main source rock of the Carpathian petroleum system. The formation of hydrocarbons in rocks occurs as a result of breakdown of complex organic compounds (mainly carbon, hydrogen and oxygen compounds) which build kerogen into heavier and lighter oil and gas hydrocarbons. This process is a thermocatalytic reaction, the dynamics of which is determined, inter alia, by the kerogen activation energy. The activation energy is one of the basic input parameters implemented into numerical models of petroleum systems. For this reason, the determination of the activation energy is very important for a reliable reconstruction of the hydrocarbon generation process in natural geological conditions and on the geological time scale. Activation energy calculations were made on the basis of the results of measurements of kinetic parameters of the kerogen cracking reaction, which (kerogen cracking) was carried out under controlled laboratory conditions using a Rock-Eval pyrolyser. The experiment consisted in non-isothermal pyrolysis of rocks containing kerogen and recording the rate of reaction (rate of hydrocarbon generation) over the entire temperature range of pyrolysis. The activation energy (Ea) and pre-exponential factor (A) were calculated using the Arrhenius equation describing the dependence of the reaction rate constants on the temperature. Discrete distribution of activation energies (Ea) model with a constant value of the pre-exponential factor (A) was used for the calculations. The energy distribution was optimized by iterative linear and non-linear regression. The discrete activation energy (Eai) was calculated for each reactant with an initial mass x0i. In this case, the “i-th” parallel reaction corresponds to chemical bonds that must be broken with an energy equal to Eai in the kerogen molecules. The activation energy distribution was optimized using the Kinetics2015 software.

16

Electrical characteristics of dry cement – based composites modified with coconut husk ash nanomaterial

Robert Ubong Williams, Etuk Sunday Edet, Ekong Sylvester Andrew, Agbasi Okechukwu Ebuka, Ekpenyong Nsikak Edet, Akpan Samuel Sunday, Umana Eme Aniefiok

Advances in Materials Science

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2022

|

Vol. 22, nr 2(72)

64--77

EN

Coconut husk is generated yearly as waste in large quantities but majorly under-utilized. Also, as a result of high embodied carbon, cement production is one of the largest contributors to construction sector carbon footprint. Since accumulation of unmanaged agro-waste like coconut husk has an increased environmental concern due to its pollution effect, recycling it into sustainable construction materials is a viable solution for future generation. In this study, experiments were performed to investigate the influence of coconut husk ash nanomaterial (CHAN) inclusion on electrical characteristics of plain cement paste (BCP) and mortar (CSM) samples at curing ages of 7 and 28 days. The results showed increase in electrical resistivity, thermal constant, and activation energy with curing duration for heating and cooling cycles of BCP and CSM. With inclusion of CHAN, the developed cement paste (CAP) and mortar (CASM) possessed lower values in all cases compared to their counterparts. Also, during heating at 28 days, both the CAP and CASM exhibited decrease in thermal constant. Though electrical resistance of all the samples varied inversely with temperature, CAP and CASM were found to possess greater potentials to make building structures intrinsically smart. Hence, in addition to solving disposal problems, utilization of coconut husks as described herein could enhance development of safe, inexpensive, and sustainable buildings that have large temperature sensing volume.

17

Study of thermal stability and energy of activation of epoxy composites with particles of synthesised powder mixture for increasing reliability of vehicles

Komsta Henryk, Vitenko Tetiana, Buketov Аndrii, Syzonenko Оlha, Bezbakh Оleh, Torpakov Andrii, Kruglyj Dmytro, Appazov Eduard, Popovych Pavlo, Rybicka Iwona

Zeszyty Naukowe. Transport / Politechnika Śląska

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2021

|

z. 110

73--86

EN

The prospective of the application of new materials on a polymer base is shown in this work. Given that developed composites can be efficiently used for protection of equipment that is operated at elevated temperatures, the impact of the nature and content of powder mixture, synthesised by high voltage electric discharge, on the thermophysical properties of epoxy composites were studied. Epoxy diane oligomer was chosen as the main component of the binder during the formation of the composites. Polyethylene polyamine hardener was used for cross-linking of epoxy composites, which allows hardening of materials at room temperatures. The selection of powder mixture, synthesised by high voltage electric discharge, for increase of thermophysical properties of developed materials was justified. More so, thermal stability and activation energy of epoxy composites were studied. Permissible limits of the temperature, at which developed materials can be used, were established based on the conducted tests of thermophysical properties of materials, filled by powder mixture, synthesised by high voltage electric discharge.

18

A study on the dissolution kinetics of iron oxide leaching from clays by oxalic acid

Arslan Volkan

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 3

97--111

EN

Clay is widely used in a number of industries due to its special properties like fine particle size, brightness and whiteness, chemical inertness, platy structure, etc. In this study, the general characteristics of clays have been investigated by XRF, XRD, FT-IR, TG-DTA and SEM. The presence of iron as an impurity decreases its commercial value due to giving unwanted colors to clay mineral. Therefore, the dissolution capacity of clay ore was investigated by oxalic acid leaching. Under optimized leaching conditions (0.8 M oxalic acid concentration, 85°C reaction temperature, 1.75 ambient pH, 106+75 µm particle size, 15% w/v solids concentration and 150 min. leaching time) with 250 rpm stirring, 83.90% of Fe2O3 was removed. The amount of iron oxide, the main impurity in the clay, has been reduced from 2.70 to 0.40%. The iron dissolution kinetics was mainly controlled by internal diffusion control of shrinking core model and activation energy, Ea, of 26.29 kJ/mol was obtained for the process. The results also showed that the studied clays have adequate characteristics for ceramics industry, earthenware and porcelain production.

19

Determination of the activation energy of a gasless pyrotechnic composition

Zakusylo Daryna

Materiały Wysokoenergetyczne

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2021

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T. 13

96--100

EN

This article presents the determining of some parameters of a gasless pyrotechnic composition. Thermo-analytical studies have been carried out. The activation energy of the gasless pyrotechnic composition was determined experimentally and by calculation. The flashpoint was 100 °C. The value of the activation energy of the pyrotechnic composition was 369.39 kJ/mol, which exceeds the activation energy of standard solid and liquid explosives by 2.4-2.8 times and makes it more stable. The change in the mass of the pyrotechnic composition during heating did not exceed 1%.

PL

Artykuł dotyczy zagadnień wyznaczania niektórych parametrów bezgazowej kompozycji pirotechnicznej. Przeprowadzono badania derywatograficzne. Energię aktywacji bezgazowej kompozycji pirotechnicznej wyznaczono doświadczalnie i obliczeniowo. Temperatura zapłonu wynosiła 100 °C. Wartość energii aktywacji kompozycji pirotechnicznej wyniosła 369,39 kJ/mol, co przewyższa energię aktywacji standardowych materiałów wybuchowych stałych i ciekłych 2,4-2,8 razy i czyni ją bardziej stabilną. Zmiany masy kompozycji pirotechnicznej pod wpływem temperatury nie przekraczają 1%.

20

Hydrothermal Carbonization Kinetics of Lignocellulosic Municipal Solid Waste

Putra Herlian Eriska, Djaenudin Djaenudin, Damanhuri Enri, Dewi Kania, Pasek Ari Darmawan

Journal of Ecological Engineering

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2021

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Vol. 22, nr 3

188--198

EN

Hydrothermal carbonization (HTC) is known as a thermochemical converting of wet biomass into a coal-like solid fuel (hydrochar). Hydrochar is easily crumbled. Because of hydrophobic properties, hydrochar is difficult to degrade by microorganisms. It has a calorific value comparable to lignite coal. In this study, hydrochar was made via converting the organic fraction of municipal solid waste through HTC at 190, 210, and 230°C for 30 min with feed to water ratio (FWR) 0.1, 0.2, 0.3. The feedstock processed includes food waste, paper, and wood waste, represented as a pseudo-component of the organic fraction of MSW. The high heating value (HHV), FTIR, as well as proximate and ultimate analyses were applied both to feedstock and hydrochar. The results showed that the energy density of hydrochar was elevated with increasing HTC temperature. The energy densification ratio and heating value increased by approximately 1.0–1.32 and 30%, respectively compared to raw feedstock. The lower yields of hydrochar were obtained at higher temperature. The typical char yields for lignocellulosic material range between 62–63 wt% at 190 °C and reduce to 54–57 wt% at 230 °C. Furthermore, a preliminary study of kinetic model for lignocellulose decomposition was conducted. This model was based on the mass loss rate of the lignocellulose compound in HTC of MSW. Three first-order reactions were given to illustrate the hydrochar yield at of 190, 210, and 230°C. The activation energy of lignocellulose decomposition was 76.26 kJ/mol, 51.86 kJ/mol, 12,23 kJ/mol for lignin, cellulose, and hemicellulose decomposition, respectively.