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EN
Agricultural residues rich in lignocellulosic biomass are low-cost and sustainable adsorbents widely used in water treatment. In the present research, thermodynamics, kinetics, and equilibrium of nickel(II) and lead(II) ion biosorption were studied using a corncob (Zea mays). The experiments were performed in a batch system evaluating the effect of temperature and dose of adsorbent. Langmuir and Freundlich isotherms were used to study the equilibrium. Thermodynamic and kinetic parameters were determined using kinetic models (pseudo-first order, pseudo-second order, Elovich). Biosorbent characteristics were studied by Fourier-transform infrared spectroscopy, Scanning Electron Microscopy and Energy-dispersive X-ray spectroscopy. It was found that the hydroxyl, carboxyl, and phenolic groups are the major contributors to the removal process. Besides, Pb(II) ions form micro-complexes on the surface of the biomaterial while Ni(II) ions form bonds with active centers. It was found that the highest Ni(II) removal yields were achieved at 0.02 g of adsorbent and 70°C, while the highest Pb(II) removal yields were achieved at 0.003 g and 55°C. A maximum Ni(II) adsorption capacity of 3.52 mg∙g–1 (86%) and 13.32 mg∙g–1 (94.3%) for Pb(II) was obtained in 250 and 330 min, respectively. Pseudo-first order and pseudo-second order models best fit experimental data, and Langmuir and Freundlich models well describe the isotherm of the process. Thermodynamic parameters (ΔH0, ΔG0, ΔS0) suggest that the adsorption process of both cations is exothermic, irreversible, and not spontaneous.
PL
Wydaje się, że temat jest banalnie prosty, że użytkownicy mają odpowiednią wiedzę, aby swoje instalacje chłodnicze prowadzić optymalnie z niskim zużyciem energii. Jednak jeśli przyjrzymy się jak naprawdę one pracują to nieraz musimy przyznać, że do optymalnych warunków jest jeszcze bardzo daleko. Autor od kilkunastu lat zajmuje się m. in. działalnością szkoleniową i swoje wnioski wysnuwa także z rozmów z kursantami, którzy stosunkowo często po raz pierwszy słyszą jak dobierać parametry pracy swoich sprężarek. Warto zauważyć, że prawidłowe parametry muszą być określone już na etapie projektowania instalacji.
EN
At the first glance the question is very simple and it seems that the users have enough knowledge to operate their refrigerating plants with a low energy consumption. But in fact the working parameters are very often far from the optimal values. The author presents his conclusions based on his long training activity and questions of the participants. It is worth to notice that correct working parameters of any refrigeration system have to be determined already in the designing process.
EN
In this work, the thermal efficiency in an engine with the Atkinson cycle was determined. The authorsof the work showed a significant increase in the overall efficiency of the engine operating according to the Atkinson cycle in relation to the engine working according to the Otto, Diesel and Sabathe cycles. The article presents the results of simulation studies on the efficiency of an internal combustion engine operating according to the Atkinson cycle and comparative cycles: Otto, Diesel, and Sabathe. The simulation tests were carried out taking into account the type of the theoretical working factor ofthe thermal cycles. The work has determined the degree of isobaric volume change in the Atkinson cycle and its influence on the theoretical efficiency of the cycle.
PL
W niniejszym artykule dokonano teoretycznej analizy wyznaczania sprawności ogólnej silnika cieplnego pracującego według obiegu Atkinsona. Autorzy pracy wykazali wystąpienie znaczącego wzrostu sprawności ogólnej silnika pracującego według obiegu Atkinsona w stosunku do silnika pracującego według obiegów Otto, Diesla i Sabathe’a. W artykule przedstawione zostały wyniki badań symulacyjnych dotyczących sprawności silnika spalinowego pracującego według obiegu Atkinsona oraz porównawczo obiegów: Otta, Diesla i Sabathe. Badania symulacyjne przeprowadzone zostały w uwzględnieniem rodzaju czynnika roboczego teoretycznego obiegu cieplnego. W pracy został wyznaczony stopień izobarycznej zmiany objętości w obiegu Atkinsona oraz jego wpływ na sprawność teoretyczną obiegu.
PL
W artykule przeanalizowano współczesne systemy elewacji z zastosowaniem przestrzeni wentylacyjnej, tj. elewacje podwójne typu DSF i elewacje wentylowane. Skupiono się na analizie współczesnej wiedzy z zakresu efektywności termicznej tych elewacji oraz wykorzystania ich w klimacie umiarkowanym ze względu na oszczędności energii. Przeanalizowano również możliwość dalszego rozwoju elewacji z zastosowaniem przestrzeni wentylacyjnej.
EN
The article analyzes contemporary facade systems with ventilation space i.e. double skin façades and opaque ventilated façades. The article analyzes contemporary knowledge of thermal efficiency of these façades and their use in a temperate climate due to energy savings. The possibility of further development of such elevations was analyzed.
PL
Celem niniejszego artykułu była realizacja analizy wytrzymałościowej nowego systemu ogrzewania podłogowego wykorzystującego modułowe panele grzejne nowej generacji. Praca obejmowała analizę wpływu termicznych obciążeń eksploatacyjnych na właściwości mechaniczne paneli grzejnych. Realizowana była metodami numerycznymi z zastosowaniem metody elementów skończonych w programie PLM Femap oraz LS Dyna. Do zamodelowania właściwości materiałowych drewna użyto m.in. modelu materiału ortotropowego pn. Wood ( nr 143).
EN
The aim of this work was to carry out strength analysis of a new underfloor heating system using modular heating panels. The work included the analysis of the impact of thermal operating loads on the mechanical properties of new generation heating panels. It was implemented using numerical methods using the Finite Element Method in the PLM Femap program and LS Dyna. The material model Wood (143) available in the LS Dyna program was used to model wood material properties.
EN
An equiatomic multi-component alloy Ni20Ti20Ta20Co20Cu20 (at.%) was obtained using vacuum arc melting. In order to characterize such an alloy, microstructure analysis has been performed using Scanning and Transmission Electron Microscopy, Electron Backscattered Diffraction, X-ray Diffraction and Energy Dispersive X-ray Spectroscopy techniques. Microstructure analysis revealed the presence of one rhombohedral and two cubic phases. Energy Dispersive X-ray Spectroscopy measurements revealed that both observed phases include five chemical elements in the structure. Using Rietveld refinement approach the lattice parameters were refined for the observed phases.
EN
Liquefied natural gas (LNG) qualifies as sustainable and secure marine fuel that is reliable in supply. The international standards (IGF Code) and classification regulations have been aligned. First experiences in ship operations and design are now available. Initial reports from the practical ship operations show that the lack of knowledge and misjudgements of original equipment manufacturers (OEM’s), suppliers, consulting services and flag state authorities have led to operational restrictions or expensive retrofitting. The aim of this paper is to illustrate first experiences and operating instructions using this new and different marine fuel; derive recommendations for instructions for education and training programmes at maritime colleges, universities and business partners; present action recommendations for future operational concepts.
PL
W części pierwszej artykułu („TCHiK” nr 3/2018) przedstawione zostały wyniki obliczeń i wnioski dotyczące charakterystyki cieplnej dla wybranego, wolnostojącego budynku mieszkalnego. Na ich podstawie Autor ocenił, które przegrody budowlane tego obiektu wymagają szybkiej poprawy termicznej. W części drugiej publikacji zwrócona została uwaga na aspekt ekonomiczny termomodernizacji przyjętego do analizy domu. Podano w niej koszty przeprowadzenia tego procesu i spośród kilku rozważanych wariant wybrano najkorzystniejszy. Przedstawione zostało zapotrzebowanie na energię cieplną analizowanego budynku po jego termomodernizacji.
EN
In the first part of the paper („TCHiK” No 3/2018) calculation results and conclusions on thermal characteristic for the analysed building have been presented. The most urgent modernization actions have been pointed. In the second part the chosen variant of thermomodernization is discussed. Heat demand of the analysed building after modernization is determined.
EN
The performance of electro-flotation with aluminum electrodes for the removal of different dyes from synthetic aqueous solutions and real wastewater was studied. Parameters affecting the electro-coagulation-flotation process, such as pH, initial dye concentration, treatment time and temperature were investigated. The maximum dye removal from synthetic solutions was achieved at pH 7. The order of the dye removals is nonionic>cationic>anionic. The removal process follows pseudo first-order kinetics and the adsorption follows both physical and chemical adsorptions which is exothermic. Negative values of entropy change, ΔS°, and Gibbs free energy change, ΔG°, indicate that this adsorption process is spontaneous and less favorable at high temperatures. Treatment of a real wastewater from textile dyeing factory showed that the removal efficiency was ranging between 92-99% for all constituents. The energy consumption is 0.0167 kWh/dm3.
11
Content available Development of ORC’s for micro power generation
EN
In the paper, new trends in development of micro power generation of heat and electricity are presented. New type of CHP for domestic usage is developed in the Institute of Fluid-Flow Machinery PAS and methods of its design are presented. The most promising trends in equipment of ORC cycle for this purpose were discussed. Main attention was focused on micro-heat exchangers design based on micro-channels and micro-jets. In our opinion future development of high power heat exchangers will be based on nets micro-heat exchangers.
EN
1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is a kind of insensitive high explosive that can be used as an energetic material in nuclear weapon and space applications. In this work, we have studied the effect of aging on the properties of TATB from a 20 year old lot that had been in direct contact with casing and natural environment conditions. The kinetics was studied using the temperature at the maximum reaction rate (peak) and isoconversional methods from TGA and DTA data obtained at five heating rates under a nitrogen atmosphere. The properties investigated for thermal stability indicate that there is no change in the properties during prolonged exposure in natural environment conditions. The activation energy calculated by the Kissinger method was 179.9 kJ·mol−1 by DTG and the 176.9 kJ·mol−1 by DTA. The experimental results of kinetic analysis obtained by isoconversional methods are in good agreement and very close to each other. In the analysis of reaction mechanisms, the reaction models could be probably best described by a surface contraction mechanism using the Coats-Redfern and Criado methods. The thermodynamic parameters such as Gibbs free energy, enthalpy and entropy of activation were also investigated. The self-accelerating decomposition temperature (TSADT) and critical temperature for thermal explosion (Tb) were also calculated.
PL
W artykule omówiono sposób formułowania relacji konstytutywnych materiałów sprężysto-plastycznych z uwzględnieniem uszkodzenia na podstawie dwóch potencjałów: potencjału energetycznego i potencjału dyssypacji. Uzyskany model materiałowy jest termodynamicznie spójny, o ile przyjęte funkcje spełniają określone warunki. Przedstawiona metoda została zilustrowana przykładem jednowymiarowym oraz przykładem relacji trójwymiarowych z wykorzystaniem warunku plastyczności Beltramiego-Michella.
EN
In the paper a thermomechanical framework for modelling elastoplastic damaged materials is presented. Basic assumptions and concepts are given, leading to formulation of constitutive equations using two potentials only: Helmholtz free energy and dissipation potential. Consecutive steps of the procedure are shown for simplified one-dimensional case, followed by three-dimensional example concerning Beltrami-Michell failure condition.
EN
Although Ag-Pt system is crucial for several technological applications, investigations of the thermodynamic properties of this system are limited. In the present study, activity of silver at various temperatures in the platinum rich solid solution was measured by a solid electrochemical method and employing AgI as the solid electrolyte. The EMF was determined using a galvanic cell (–)|Ag|AgI|Ag – Pt alloy|C|Pt (+), which provided novel experimental data on thermodynamic properties of a Ag-Pt alloy. Activity, partial molar of Gibbs energy, enthalpy and entropy of silver in a solid solution containing 1 at % Ag between 573 and 673 K have been calculated. The results indicated that the activity of silver obtained in the present study shows a large positive deviation from the ideal Raoultian behavior. Microstructures of alloys with different compositions were also compared.
PL
Sprężone gazy i pary znajdują szerokie zastosowanie w różnych gałęziach przemysłu, m. in. w przemyśle spożywczym, chłodnictwie i transporcie. Do najczęściej sprężanych płynów można zaliczyć np.: powietrze, czynniki chłodnicze, amoniak, azot, tlen, dwutlenek węgla, hel, argon, metan. Ze względu na wymagane parametry w zależności od przeznaczenia sprężane gazy dzieli się na: gazy techniczne, medyczne i spożywcze. W prezentowanym cyklu artykułów znajdą się m. in. niezbędne w codziennej eksploatacji informacje z termodynamiki gazów, wymiany ciepła, działania urządzeń i instalacji gazów medycznych, obsługi tych instalacji oraz obsługi butli gazowych. Ponadto znajdą się w nim również informacje dotyczące wykonania tych instalacji i bezpieczeństwa ich użytkowania.
EN
Compressed gases and vapours are widely used in many branches of industry, such as food processing, refrigeration and transport. The most common compressed media are: air, refrigerants, ammonia, nitrogen, oxygen, carbon dioxide, helium, argon, methane. Taking into account desired parameters and application area, technical, medical and food processing compressed gases can be distinguished. The series of papers deals - except others - with necessary from the practical point of view information on thermodynamics of gases, heat transfer, working principles of devices and installations for medical gases, as well as operation of these installations and gas cylinders. Manufacturing technologies and safety aspects are also described.
EN
This article proposes a concept of new method for supporting the identification of solids and their thermal parameters. This concept is based on the idea of implementation of metrological methods and solutions known from hot-wire anemometry in applications for supporting the thermal identification of solids. The idea of the method is based on the fact that measuring head of the probe, comprising a resistance – temperature transducer heated by electric current, is continuously maintained in a stable thermal contact with the tested material, while the temperature of the resistance – temperature transducer is controlled by the constant – temperature controlled system. The characteristic parameters of the head – material system are determined based on measurement of the flux of heat transferred from the head in its various states of heating. These parameters are compared to parameters obtained for different materials used as standards during the system calibration process, which allows for a measured parameters to be correlated with calibration ones, classifying ultimately the tested material into specific class of materials. Selected methods of artificial intelligence can be applied here. In complex solutions it is possible to use measuring heads comprising higher number of resistance – temperature transducers, both passive and active ones, an array of measuring heads, complex algorithms of thermal excitations and interpretation of measured signals or the analysis of thermal waves propagation in a tested material.
PL
Autor pracy proponuje nową koncepcję metody wspomagania identyfikacji ciał stałych oraz ich parametrów cieplnych. Koncepcja ta oparta jest o ideę implementacji metod i rozwiązań metrologicznych znanych z termoanemometrii w zastosowaniach do wspomagania identyfikacji termicznej ciał stałych. Podstawowa idea proponowanej metody pomiarowej polega na tym, że głowica pomiarowa zawierająca nagrzewany prądem elektrycznym rezystancyjny przetwornik temperatury utrzymywana jest w stabilnym kontakcie termicznym z badaną substancją, a poziom temperatury rezystancyjnego przetwornika temperatury zadawany jest poprzez sterowany układ stałotemperaturowy. Na podstawie pomiaru strumienia ciepła odbieranego z głowicy w różnych stanach nagrzania wyznaczane są parametry charakterystyczne układu głowica – substancja. Parametry te porównywane są z parametrami uzyskanymi dla różnych substancji w procesie wzorcowania układu, co pozwala na określenie korelacji parametrów wzorcowych i mierzonych, a tym samym na zaklasyfikowanie badanej substancji do danej klasy materiałów. Korzystne może tu być zastosowanie metod sztucznej inteligencji. W rozbudowanych rozwiązaniach możliwe jest zastosowanie w głowicy większej ilości rezystancyjnych przetworników temperatury, zarówno pasywnych jak i aktywnych, stosowanie matrycy głowic, zastosowanie złożonych algorytmów wymuszeń termicznych i interpretacji sygnałów mierzonych, jak również badanie propagacji fal termicznych w badanej substancji.
EN
Magnetic ZnFe2 O4  nanocomposite (ZnFe-NC) was used as an adsorbent for the removal of Rhodamine B (RB) from aqueous solution. The synthesized nanocomposite was characterized by XRD, SEM, HRTEM, BET and FTIR. The effects of various parameters such as initial RB concentration (5–25 mg L−1 ), pH (3.4–11.1) and temperature (20–60°C) were investigated. The adsorption capacity at equilibrium increased from 5.02 to 9.83 mg g−1 , with the increase in the initial concentration of RB from 5 to 25 mg L−1  at pH 7.0 and at 20°C. The experimental results indicated that the maximum RB removal could be attained at a solution pH of 4.4 and the adsorption capacity obtained was 6.02 mg g−1 . Kinetic adsorption data were analyzed using the pseudo-first-order kinetic model, the pseudo-second-order model and the intraparticle diffusion model. The adsorption kinetics well fitted using a pseudo-second-order kinetic model. The experimental isotherm data were analyzed using two isotherm models, namely, Langmuir and Freundlich. The results revealed that the adsorption behavior of the RB onto ZnFe-NC fitted well with the Langmuir isotherm model. In addition, various thermodynamic parameters, such as standard Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) have been calculated.
EN
Cr(VI) adsorption was studied for abundantly available low-cost lignocellulosic adsorbents in Pakistan namely, tobacco stalks (TS), white cedar stem (WCS) and eucalyptus bark (EB). Several process variables like contact time, adsorbent dose, pH, metal concentration, particle size and temperature were optimized in batch mode. EB showed high Cr(VI) adsorption of 63.66% followed by WCS 62% and TS 57% at pH 2, which is higher than most of the reported literature. Langmuir isotherm (R2  = 0.999) was well fitted into the equilibrium Cr(VI) data of EB, suggesting homogeneous active sites and monolayer coverage of Cr(VI) onto the EB surface. Freundlich (R2  = 0.9982) isotherm was better fitted to the equilibrium data of TS and WCS, revealing the adsorption sites with heterogeneous energy distribution and multilayer Cr(VI) adsorption. Moreover, the Cr(VI) adsorption of studied adsorbents followed the pseudo-second order kinetic model. Thermodynamic properties were investigated in two temperature ranges, i.e., T1  (303–313 K) and T2  (313–323 K). TS and EB showed the exothermic at T1 and endothermic reactions at T2 with entropy controlled adsorption at the solid-liquid interface, and WCS exhibited an opposite thermal trend with decreasing disorderness at solid-liquid interface as temperature rises. Gibbs free energy (ΔG>0) confirmed the non-spontaneous adsorption process for all studied adsorbents.
EN
Lattice dynamic and mechanical properties of hypothetical RbC and SrC compounds were investigated using the ab-initio pseudopotential method and a linear response scheme. The lattice dynamics was studied in the framework of the density functional perturbation theory (DFPT). The dynamical and mechanical stability of the hypothetical RbC and SrC compounds was proved in their equilibrium B1 structure. In addition, the same stability was confirmed in the B3 phase. The thermodynamic properties were also investigated. They exhibited the same trend in both phases, and followed the Debye model. These results were confirmed in the ferromagnetic state, which makes the investigated compounds promising candidates in the spintronic field.
20
EN
A new generalized hypothesis of elastic energy equivalence is proposed. The proposed generalized hypothesis is inclusive of all the existing different hypotheses of equivalence in continuum damage mechanics and all are obtained as special cases. Specifically, the hypothesis of elastic strain equivalence and the hypothesis of elastic energy equivalence are obtained as special cases of the generalized hypothesis proposed here. In addition, the generalized hypothesis has some unusual properties when the integer exponent n approaches infinity. In particular, it turns out that the strain energy density function is a vector for even values of the integer exponent. This conclusion is totally unexpected but an attempt is made to explain this result based on geometry.
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