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    Wyświetlanie 1-10 z 10
    Tytuł:
    Modelling of fluidized bed biomass gasification in the quasi-equilibrium regime for preliminary performance studies of energy conversion plants
    Autorzy:
    Kalina, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/185441.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    biomasa
    fluidyzacja
    termodynamika
    biomass
    fluidized bed
    thermodynamics
    Opis:
    Thermodynamic equilibrium-based models of gasification process are relatively simple and widely used to predict producer gas characteristics in performance studies of energy conversion plants. However, if an unconstrained calculation of equilibrium is performed, the estimations of product gas yield and heating value are too optimistic. Therefore, reasonable assumptions have to be made in order to correct the results. This paper proposes a model of the process that can be used in case of deficiency of information and unavailability of experimental data. The model is based on free energy minimization, material and energy balances of a single zone reactor. The constraint quasiequilibrium calculations are made using approximated amounts of non-equilibrium products, i.e. solid char, tar, CH4 and C2H4. The yields of these products are attributed to fuel characteristics and estimated using experimental results published in the literature. A genetic algorithm optimization technique is applied to find unknown parameters of the model that lead to the best match between modelled and experimental characteristics of the product gas. Finally, generic correlations are proposed and quality of modelling results is assessed in the aspect of its usefulness for performance studies of power generation plants.
    Źródło:
    Chemical and Process Engineering; 2011, 32, 2; 73-89
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An approach to modeling and thermodynamic analysis of modern power engineering systems
    Autorzy:
    Kozaczka, J.
    Kolat, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/185820.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    CCS
    energia
    termodynamika
    modelowanie
    power engineering
    energy
    thermodynamics
    Opis:
    The new efficient method of modeling and thermodynamic analysis of power engineering systems has been presented. With its help a comparison of different structures and investigation of the influence of a particular constituent process onto the whole system efficiency is possible. The shaft work or the energy is the main thermodynamic quantity taken into account in analyses, and the appropriate dimensionless modeling parameter has been introduced.
    Źródło:
    Chemical and Process Engineering; 2011, 32, 4; 401-410
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Developing novel correlations for calculating natural gas thermodynamic properties
    Autorzy:
    Farzaneh-Gord, M.
    Rahbari, H.R.
    Powiązania:
    https://bibliotekanauki.pl/articles/185843.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    termodynamika
    gaz ziemny
    natural gas
    thermodynamics
    novel correlations
    real time properties
    Opis:
    Natural gas is a mixture of 21 components and it is widely used in industries and homes. Knowledge of its thermodynamic properties is essential for designing appropriate processes and equipment. This paper presents simple but precise correlations of how to compute important thermodynamic properties of natural gas. As measuring natural gas composition is costly and may not be effective for real time process, the correlations are developed based on measurable real time properties. The real time properties are temperature, pressure and specific gravity of the natural gas. Calculations with these correlations are compared with measured values. The validations show that the average absolute percent deviation (AAPD) for compressibility factor calculations is 0.674%, for density is 2.55%, for Joule-Thomson coefficient is 4.16%. Furthermore, in this work, new correlations are presented for computing thermal properties of natural gas such as enthalpy, internal energy and entropy. Due to the lack of experimental data for these properties, the validation is done for pure methane. The validation shows that AAPD is 1.31%, 1.56% and 0.4% for enthalpy, internal energy and entropy respectively. The comparisons show that the correlations could predict natural gas properties with an error that is acceptable for most engineering applications.
    Źródło:
    Chemical and Process Engineering; 2011, 32, 4; 435-452
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Non-linear optimization of high-pressure gas networks with respect to hydrate control
    Nieliniowa optymalizacja sieci gazowej wysokiego ciśnienia z uwzględnieniem zapobieganiu hydratów
    Autorzy:
    Osiadacz, A. J.
    Uilhoorn, F. E.
    Chaczykowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/219876.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    hydraty gazowe
    modelowanie matematyczne
    termodynamika
    optymalizacja
    równowagi fazowe
    phase equilibria
    gas hydrates
    mathematical modelling
    thermodynamics
    optimization
    Opis:
    In this paper, gas pipeline optimization includes constraints resulting from hydrate prevention. The key is to seek for the optimal settings of both: the compressor units and hydrate combating method at minimum fuel consumption subject to security of supply and hydrate prevention. A case study is conducted on the Polish section of the Yamal pipeline and an arbitrarily selected partial onshore and offshore pipeline. Three different configurations are investigated: (i) cooling the compressed gas, (ii) no cooling and (iii) line heating immediately after the compressor station. For each configuration, the fuel consumption of the compressors is minimized and in order to prevent hydrate formation, the outlet temperature of the line heater, allowable water vapour in the gas and methanol concentration are calculated for each pipe section. The hydrate model is based on the statistical mechanical approach of Van der Waals and Platteeuw and applicable for systems that contain water (free or dissolved in gas), methanol and mixed gases both hydrate and non-hydrate formers.
    W artykule omówiono zagadnienie optymalizacji gazowego systemu przesyłowego uwzględniając dodatkowo ograniczenia wynikające z warunków tworzenia się hydratów. Kryterium optymalizacji to minimum zużycia paliwa w tłoczniach gazu. Badania przeprowadzono na polskiej części gazociągu jamalskiego dla trzech przypadków pracy tłoczni: chłodzenie gazu w tłoczni, brak chłodzenia oraz podgrzewanie gazu za stacją przetłoczną. Dla każdego wariantu, zużycie paliwa przez sprężarki jest minimalizowane oraz w celu przeciwdziałania tworzenia się hydratów, temperatura wyjściowa podgrzewacza jest obliczana a także obliczana jest zawartość pary wodnej i metanolu w gazie dla każdej sekcji gazociągu. Zastosowany model hydratu jest oparty na modelu Van der Waalsa oraz Platteeuw.
    Źródło:
    Archives of Mining Sciences; 2012, 57, 3; 627-643
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of adsorption of Cd(II) and Pb(II) ions on pure and chemically modified fly ashes
    Autorzy:
    Soco, E.
    Kalembkiewicz, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/185273.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    heavy metal
    coal fly ash
    adsorption
    kinetics
    thermodynamics
    popioły lotne z węgla kamiennego
    adsorpcja
    kinetyka
    termodynamika
    Opis:
    The study investigates chemical modifications of coal fly ash (FA) treated with HCl or NH4 HCO3 or NaOH or Na2 edta, based on the research conducted to examine the behaviour of Cd(II) and Pb(II) ions adsorbed from water solution on treated fly ash. In laboratory tests, the equilibrium and kinetics were examined applying various temperatures (293 - 333 K) and pH (2 - 11) values. The maximum Cd(II) and Pb(II) ions adsorption capacity obtained at 293 K, pH 9 and mixing time 2 h from the Langmuir model can be grouped in the following order: FA-NaOH > FA-NH 4 HCO 3 > FA > NaOH2edta > FA-HCl. The morphology of fly ash grains was examined via small-angle X-ray scattering (SAXS) and images of scanning electron microscope (SEM). The adsorption kinetics data were well fitted by a pseudo-second-order rate model but showed a very poor fit for the pseudo- first order model. The intra-particle model also revealed that there are two separate stages in the sorption process, i.e. the external diffusion and the inter-particle diffusion. Thermodynamics parameters such as free energy, enthalpy and entropy were also determined. A laboratory test demonstrated that the modified coal fly ash worked well for the Cd(II) and Pb(II) ion uptake from polluted waters.
    Źródło:
    Chemical and Process Engineering; 2016, 37, 2; 215-234
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of thermodynamic mechanism of interfacial adsorption on purifying air-conditioning engineering under intensification of electric field
    Autorzy:
    Chen, Y.-Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/240795.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    interfacial adsorption
    thermodynamics
    Gibbs
    purifying air-conditioning engineering
    electric field
    adsorpcja międzyfazowa
    termodynamika
    oczyszczanie
    klimatyzacja
    pole elektryczne
    Opis:
    As a kind of mass transfer process as well as the basis of separating and purifying mixtures, interfacial adsorption has been widely applied to fields like chemical industry, medical industry and purification engineering in recent years. Influencing factors of interfacial adsorption, in addition to the traditional temperature, intensity of pressure, amount of substance and concentration, also include external fields, such as magnetic field, electric field and electromagnetic field, etc. Starting from the point of thermodynamics and taking the Gibbs adsorption as the model, the combination of energy axiom and the first law of thermodynamics was applied to boundary phase, and thus the theoretical expression for the volume of interface absorption under electric field as well as the mathematical relationship between surface tension and electric field intensity was obtained. In addition, according to the obtained theoretical expression, the volume of interface absorption of ethanol solution under different electric field intensities and concentrations was calculated. Moreover, the mechanism of interfacial adsorption was described from the perspective of thermodynamics and the influence of electric field on interfacial adsorption was explained reasonably, aiming to further discuss the influence of thermodynamic mechanism of interfacial adsorption on purifying air-conditioning engineering under intensification of electric field.
    Źródło:
    Archives of Thermodynamics; 2016, 37, 4; 105-119
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fundamental study of the photocatalytic reduction of CO2: A short review of thermodynamics, kinetics and mechanisms
    Autorzy:
    Gandhi, Romil
    Moses, Aashish
    Baral, Saroj Sundar
    Powiązania:
    https://bibliotekanauki.pl/articles/2173433.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    CO2 to fuels
    hydrocarbon production
    thermodynamics
    photocatalysis
    mechanism
    CO2 do paliw
    produkcja węglowodorów
    termodynamika
    fotokataliza
    mechanizm
    Opis:
    On the off chance that methods which reduce the global CO2 content are unavailable and inefficient, the increasing CO2 levels will lead to a synchronized rise in temperature across the world. The conversion of this abundant CO2 into hydrocarbons like CH4, CH3OH, CO, HCOOH and hydrogen fuel using different techniques and their use for power could assist with the world’s energy deficiency and solve the CO2 reduction-energy nexus. In this study, photocatalytic CO2 conversion by sunlight will be of primary focus since this bears a resemblance with the regular photosynthesis phenomenon. This work also portrays the writings that have narrated the development of mixtures of two or more carbon ions (C2 ̧) within the photocatalytic reduction of CO2. This paper thus comprises the energy required for CO2 photoreduction, the kinetics mechanisms and thermodynamics requirements. The reaction of CO with water and the hydrogenation of CO2 are covered to understand the gap of Gibb’s free energy between both of the reactions. Likewise, the summary of different metal-based co-catalysts, metal-free co-catalysts and their selectivity towards CO2 reduction by photocatalysis and reduction of CO2 into various hydrocarbons, fuel and materials have also been examined.
    Źródło:
    Chemical and Process Engineering; 2022, 43, 2; 223--228
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Efficiency optimization of a closed indirectly fired gas turbine cycle working under two variable-temperature heat reservoirs
    Autorzy:
    Ma, Z.
    Wu, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/240010.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    obieg
    technologie bioenergetyczne
    termodynamika
    turbina gazowa
    wymiennik ciepła
    Bioenergy technology
    Cycle performance
    finite time thermodynamics
    High temperature heat exchanger
    Indirectly fired gas turbine
    Opis:
    Indirectly or externally fired gas turbines (IFGT or EFGT) are interesting technologies under development for small and medium scale combined heat and power (CHP) supplies in combination with micro gas turbine technologies. The emphasis is primarily on the utilization of the waste heat from the turbine in a recuperative process and the possibility of burning biomass even "dirty" fuel by employing a high temperature heat exchanger (HTHE) to avoid the combustion gases passing through the turbine. In this paper, finite time thermodynamics is employed in the performance analysis of a class of irreversible closed IFGT cycles coupled to variable temperature heat reservoirs. Based on the derived analytical formulae for the dimensionless power output and efficiency, the efficiency optimization is performed in two aspects. The first is to search the optimum heat conductance distribution corresponding to the efficiency optimization among the hot- and cold-side of the heat reservoirs and the high temperature heat exchangers for a fixed total heat exchanger inventory. The second is to search the optimum thermal capacitance rate matching corresponding to the maximum efficiency between the working fluid and the high-temperature heat reservoir for a fixed ratio of the thermal capacitance rates of the two heat reservoirs. The influences of some design parameters on the optimum heat conductance distribution, the optimum thermal capacitance rate matching and the maximum power output, which include the inlet temperature ratio of the two heat reservoirs, the efficiencies of the compressor and the gas turbine, and the total pressure recovery coefficient, are provided by numerical examples. The power plant configuration under optimized operation condition leads to a smaller size, including the compressor, turbine, two heat reservoirs and the HTHE.
    Źródło:
    Archives of Thermodynamics; 2011, 32, 2; 3-20
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of mass transfer in marine engine with prechamber combustion spark ignition system
    Autorzy:
    Pielecha, Ireneusz
    Powiązania:
    https://bibliotekanauki.pl/articles/2128135.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    marine engine
    prechamber combustion spark ignition
    combustion process modeling
    combustion thermodynamics
    silnik morski
    zapłon iskrowy spalania w komorze wstępnej
    modelowanie procesu spalania
    termodynamika spalania
    Opis:
    The development of combustion systems construction is associated with the possibility of increasing the thermal or overall efficiency of an internal combustion engine. The combustion systems currently in use (mainly related to direct fuel injection) are increasingly being replaced by hybrid systems, including direct and indirect injection. Another alternative is the use of prechambers in new combustion systems. This article concerns the thermodynamic aspect of this issue – namely, the assessment of the inter-chamber f low of a marine engine equipped with a prechamber combustion spark ignition system. The research was carried out using mainly one-dimensional simulation apparatus, and detailed analyses were presented using three-dimensional modeling. The tests included the engine model at medium load. Differences in mass f lows were shown at different diameters and different numbers of holes from the preliminary chamber (while maintaining the same cross-sectional area). Similar values of excess air coefficient during ignition of the fuel dose in the prechamber were observed, which resulted in changes in the f low between the prechamber and the main chamber. The differences in mass f low affected the temperatures achieved in the individual combustion chambers. Based on three-dimensional analyses, the mass transfer rate between the chambers and the temperature distribution were assessed during fuel ignition initiated in the prechamber.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 2; e136744, 1--8
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of mass transfer in marine engine with prechamber combustion spark ignition system
    Autorzy:
    Pielecha, Ireneusz
    Powiązania:
    https://bibliotekanauki.pl/articles/2173605.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    marine engine
    prechamber combustion spark ignition
    combustion process modeling
    combustion thermodynamics
    silnik morski
    zapłon iskrowy spalania w komorze wstępnej
    modelowanie procesu spalania
    termodynamika spalania
    Opis:
    The development of combustion systems construction is associated with the possibility of increasing the thermal or overall efficiency of an internal combustion engine. The combustion systems currently in use (mainly related to direct fuel injection) are increasingly being replaced by hybrid systems, including direct and indirect injection. Another alternative is the use of prechambers in new combustion systems. This article concerns the thermodynamic aspect of this issue – namely, the assessment of the inter-chamber f low of a marine engine equipped with a prechamber combustion spark ignition system. The research was carried out using mainly one-dimensional simulation apparatus, and detailed analyses were presented using three-dimensional modeling. The tests included the engine model at medium load. Differences in mass f lows were shown at different diameters and different numbers of holes from the preliminary chamber (while maintaining the same cross-sectional area). Similar values of excess air coefficient during ignition of the fuel dose in the prechamber were observed, which resulted in changes in the f low between the prechamber and the main chamber. The differences in mass f low affected the temperatures achieved in the individual combustion chambers. Based on three-dimensional analyses, the mass transfer rate between the chambers and the temperature distribution were assessed during fuel ignition initiated in the prechamber.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 2; art. no. e136744
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-10 z 10

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