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Calculation method for flow boiling and flow condensation of R134a and R1234yf in conventional and small diameter channels
PublikacjaThe paper presents the results of calculations performed using the authors’ model to predict the heat transfer coefficient during flow boiling for two refrigerants R134a and R1234yf. The experimental data from various past studies have been collected and the calculations have been conducted for the full range of quality variation and a wide range of mass velocity. The aim of the study was to test the sensitivity of the in-house...
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The energy approach to fatigue crack growth of S355 steel welded specimens subjected to bending
PublikacjaThe study presents the results of the research on the rate of fatigue crack growth subjected to bending in the ferritic-pearlitic structure. The studies were carried out at a constant amplitude of the moment and at various values of the load ratios R and at the operating frequency of the machine of 28.4 Hz. Flat specimens made of S355 steel and with fillet welds and with double-sided blunt external notches as well as concave...
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Theoretical Organic Rankine Cycle efficiency depending on different thermodynamic work variables.
PublikacjaOne of promising technologies of utilizing low- temperature waste heat is through ORC (Organic Rankine Cycle) system implementation. A primary objective in designing in-stallations based on such systems is to maximize the installation's work efficiency. On the other hand, ecological factors are commonly considered a natural barrier in introducing new, often very expensive technologies. Ecological effect of a potential modernization...
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Cavitation Erosion Resistance Influence of Material Properties
PublikacjaThe cavitation erosion is the phenomena that causes degradation of fluid flow machinery components due to repetitive implosion of cavitation bubbles adjacent to the solid surface. Cavitation erosion is a complex phenomenon, which includes not only hydrodynamic factors of liquid, but also properties of erodible material e.g. microstructure, hardness or Young modulus. In order to reduce the negative impact of erosion on machine components,...
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Approximation of Fractional Order Dynamic Systems Using Elman, GRU and LSTM Neural Networks
PublikacjaIn the paper, authors explore the possibility of using the recurrent neural networks (RNN) - Elman, GRU and LSTM - for an approximation of the solution of the fractional-orders differential equations. The RNN network parameters are estimated via optimisation with the second order L-BFGS algorithm. It is done based on data from four systems: simple first and second fractional order LTI systems, a system of fractional-order point...
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Evolution of Physical Properties of RE 3 Ni 5 Al 19 Family (RE = Y, Nd, Sm, Gd, Tb, Dy, Ho, and Er)
PublikacjaSingle crystals of RE3Ni5Al19 series (RE = Y, Nd, Sm, Gd, Tb, Dy, Ho, and Er) are grown using the Al self-flux method. The crystal structure is examined by both single crystal and powder X-ray diffraction. Physical properties are studied for the first time for RE3Ni5Al19 (RE = Y, Nd, Gd, Tb, Dy, Ho, and Er) by means of magnetic susceptibility, electrical resistivity, and heat capacity measurements. Complex magnetic behaviors, with...
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Efficiency and proportions of waste tyre pyrolysis products depending on the reactor type—A review
PublikacjaThis article discusses the current use of different pyrolytic reactors, their constructions and operating principles regarding the yields of main products of waste tyre pyrolytic recycling. Whether one makes a larger or smaller profit, or even a loss due to a surcharge being levied on waste tyre recycling, depends on the sale of the pyrolysis products (gas, char, oil), the proportions and market prices of which differ. The cheapest...
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Quasi-one-dimensional exchange interactions and short-range magnetic correlations in CuTeO4
PublikacjaCuTeO4 has been proposed as a crystallographically distinct, yet electronic structure analog, of the superconducting cuprates. Here, we present a detailed characterization of the physical properties of CuTeO4 to address this proposal. Fitting of magnetic susceptibility data indicates unexpected quasi-one-dimensional, antiferromagnetic correlations at high temperature, with a nearest-neighbor Heisenberg exchange of 1=164(5) K....
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Molecular Dynamics simulations of thermal conductivity of penta-graphene
PublikacjaThe thermal conductivity of penta-graphene (PG), a new two dimensional carbon allotrope and its dependence on temperature, strain, and direction are studied in this paper. The thermal conductivity of PG is investigated using a non-equilibrium molecular dynamics simulation (NEMD) with the Two Region Method by applying the optimized Tersoff interatomic potential. Our study shows that the thermal conductivity of PG (determined for...
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Green energy extraction for sustainable development: A novel MPPT technique for hybrid PV-TEG system
PublikacjaThe Photovoltaic (PV) module converts only a small portion of irradiance into electrical energy. Most of the solar energy is wasted as heat, resulting in a rise in PV cell temperature and a decrease in solar cell efficiency. One way to harvest this freely available solar thermal energy and improve PV cell efficiency is by integrating PV systems with thermoelectric generators (TEG). This cogeneration approach of the hybrid PV-TEG...
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Generalized regression neural network and fitness dependent optimization: Application to energy harvesting of centralized TEG systems
PublikacjaThe thermoelectric generator (TEG) system has attracted extensive attention because of its applications in centralized solar heat utilization and recoverable heat energy. The operating efficiency of the TEG system is highly affected by operating conditions. In a series-parallel structure, due to diverse temperature differences, the TEG modules show non-linear performance. Due to the non-uniform temperature distribution (NUTD) condition,...
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The Environmental Benefits of Photovoltaic Systems: The Impact on the Environment in the Production of Photovoltaic Systems: With a Focus on Metal Recovery
PublikacjaGreenhouse gases (GHGs) such as carbon dioxide, nitrous oxide and methane, trap heat and energy, thus preventing solar radiation from escaping back into space. As the quantity of greenhouse gases in the atmosphere increases so does the trapped heat and corresponding global temperature. As a result, storms become more violent, droughts more prevalent, glaciers melt, and sea levels rise, to name but a few effects of a rapidly changing...
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Rozprzestrzenianie się w podtorzu skutków katastrof kolejowych z udziałem materiałów niebezpiecznych
PublikacjaDuża część przewozów materiałów niebezpiecznych prowadzona jest koleją. W związku z tym bezpieczeństwo tych przewozów nabiera coraz większego znaczenia. Każda katastrofa z udziałem materiałów niebezpiecznych ma negatywny wpływ na uczestników tego zdarzenia oraz na otaczające środowisko, bowiem jej zasięg na ogół nie jest lokalny. Z tego wynika, że w przypadku zaistnienia katastrofy należy minimalizować jej skutki oraz w dalszych...
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Analiza sterowania ułamkowego PIλDμ mocą reaktora jądrowego
PublikacjaW artykule przedstawiono syntezę regulatora PIλDμ niecałkowitego rzędu dla potrzeb sterowania mocą reaktora jądrowego lekko wodnego określanego, jako typu PWR (Pressurized Water Reactor). W tym celu wykorzystano nieliniowy model matematyczny reaktora PWR o parametrach skupionych obejmujący procesy generacji i wymiany ciepła oraz termicznych efektów reaktywnościowych. Nastawy regulatora PIλDμ niecałkowitego rzędu dobrano w sposób...
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The properties of reduced Bi-Ge-O glasses for thermoelectric devices
PublikacjaThe bismuth-germanate glasses have been investigated to examine their applicability for thermoelectric devices. In order to increase their electrical conductivity, the 25Bi2O3–75GeO2 glass samples have been reduced at 340-380°C for 10 hours in hydrogen. It has been shown that such heat treatment in H2 leads to the reduction of metal ions Bi3+ and Ge4+ into neutral atoms and the formation of metal grains both in an amorphous glass...
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Experimental investigation of domestic gas boiler fitted with ORC module
PublikacjaIn the paper the prototype of innovative domestic cogenerative ORC system, consisting of a conventional gas boiler and a small size axial vapour microturbines (in-house designed for ORC and the commercially available for Rankine cycle (RC)), evaporator and condenser were scrutinised. In the course of study the fluid working temperatures, rates of heat, electricity generation and efficiency of the whole system were obtained. The...
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Novel Analytic-Numerical Model of Free Convection: with Leading Edge Considered
PublikacjaA novel solution of the free convection boundary problem is represented in analytical form for velocity and temperature for an isothermal vertical plate, as an example. These fields are built as a Taylor Series in the x coordinate with coefficients as functions of the vertical coordinate (y). We restrict ourselves by cubic approximation for both functions. The basic Navier-Stokes and Fourier-Kirchhoff equations and boundary conditions...
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Experimental research on water lubricated marine stern tube bearings in conditions of improper lubrication and cooling causing rapid bush wear
PublikacjaWater lubricated bearings are popular in sliding bearings of marine propeller shafts, turbines and pump shafts. Such popularity is partly due to their simple construction which also means a relatively affordable price. In practical experience one may also observe cases of rapid wear or even malfunctions of this bearings, some of which may be caused by insufficient flow of lubricant leading to overheating. The conducted...
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Comparative study of selected fluids for use in supercritical Organic Ranking Cycles
PublikacjaIn view of increasing interest in improving energy efficiency of energy conversion devices, there is an increasing requirement of combined production of heat and electricity as well as demand for increased implementation of renewable energy resources. The micro cogenerative units utilizing the Organic Rankine Cycle are focusing the attention of many research centres around the world. In the present paper calculations of ORC cycles...
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Interaction of Acoustic and Thermal Modes in the Gas with Nonequilibrium Chemical Reactions: Possibilities of Acoustic Cooling
PublikacjaNonlinear generation of thermal mode during propagation of dominative sound in a chemically reacting gas is considered. The dynamic equation of excess temperature associated with the thermal mode is derived. It is instantaneous and includes quadratic nonlinear acoustic source reflecting the nonlinear character of interaction between acoustic and non-acoustic types of gas motion. Both periodic and aperiodic sound may be considered...
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Cluster-spin-glass behavior in new ternary RE2PtGe3 compounds (RE = Tb, Dy, Ho)
PublikacjaTwo new ternary germanides Tb2Pt1.2Ge2.8, Dy2Pt1.15Ge2.85 and one already known germanium Ho2Pt1.1Ge2.9.were synthesized using an arc melting technique. The obtained samples were investigated by powder X-ray diffraction, which indicated that all of them crystallized in a hexagonal structure with P6/mmm (no. 191) space group. This structure is a disordered variant of the AlB2 aristotype that favors the formation of a spin-glass-like...
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Interaction of Acoustic and Thermal Modes in the Vibrationally Relaxing Gases. Acoustic Cooling
PublikacjaThe dynamic equation which governs an excess temperature associated with the thermal mode in vibrationally relaxing gas is derived. The nonlinear transfer of acoustic energy to the energy of the thermal mode in a relaxing gas causes slow variation of temperature with time. The nal dynamic equation is instantaneous. All types of sound, including aperiodic, may be considered as an acoustic source of corresponding heating or cooling....
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PARAMETRIC ANALYSIS OF THE EFFICIENCY OF THE COMBINED GAS-STEAM TURBINE UNIT OF A HYBRID CYCLE FOR THE FPSO VESSEL
PublikacjaA thermal diagram of the combined gas‒steam turbine unit of a hybrid cycle, which is an energy complex consisting of a base gas turbine engine with a steam turbine heat recovery circuit and a steam-injected gas turbine operating with overexpansion, is proposed. A mathematical model of a power plant has been developed, taking into consideration the features of thermodynamic processes of simple, binary, and steam-injected...
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Influence of hydrogen on a nanocrystalline high-entropy oxide with application potential in hydrogen technologies
PublikacjaThe influence of hydrogen on a (Co0⋅2Cu0⋅2Mg0⋅2Ni0⋅2Zn0.2)O HEO with a rock salt structure was studied. Two forms of this HEO (nanopowder and sinter) were prepared via mechanochemical synthesis (MS) and additional heat treatment, respectively. The chemical stability of the synthesized samples in a pure hydrogen atmosphere was investigated using Sievert’s technique. High-pressure hydrogenation at 250 ◦C had no noticeable effect...
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Superconductivity of Ta-Hf and Ta-Zr alloys: Potential alloys for use in superconducting devices
PublikacjaThe electronic properties relevant to superconductivity are reported for bulk Ta-Hf and Ta-Zr body centered cubic alloys, in a large part to determine whether their properties are suitable for potential use in superconducting qbits. The body centered cubic unit cell sizes increase with increasing alloying. The results of magnetic susceptibility, electrical resistivity, and heat capacity characterization are reported. While elemental...
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Prowadzenie ruchu małej elektrociepłowni gazowej według kryterium efektu ekonomicznego
PublikacjaCechą charakterystyczną źródeł gazowych jest ich duża elastyczność ruchowa, w porównaniu do większości źródeł konwencjonalnych i odnawialnych. Cecha ta może i powinna być wykorzystywana do poprawy wskaźników ekonomicznych obiektu. W tym celu należy przeanalizować możliwości jakie daje prowadzenie ruchu źródeł nie w standardzie pracy z wymuszeniem zapotrzebowania na ciepło, ale właśnie maksymalnie wykorzystując elastyczność ruchową...
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Prowadzenie ruchu małego źródła kogeneracji gazowej według kryterium efektu ekonomicznego
PublikacjaCechą charakterystyczną źródeł gazowych jest ich duża elastyczność ruchowa, w porównaniu do większości źródeł konwencjonalnych i odnawialnych. Cecha ta może i powinna być wykorzystywana do poprawy wskaźników ekonomicznych obiektu. W tym celu należy przeanalizować możliwości jakie daje prowadzenie ruchu źródeł nie w standardzie pracy z wymuszeniem zapotrzebowania na ciepło, ale właśnie maksymalnie wykorzystując elastyczność ruchową...
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Koncepcja stanowiska oraz badania możliwości bezpompowego przetłaczania czynnika w rurce ciepła z pętlą obiegową. Część I - Wstęp-charakterystyka obiegu LHP
PublikacjaBezpompowa cyrkulacja czynnika roboczego występuje w rurkach ciepła z pętlą obiegową (LHP, ang. Loop Heat Pipe). Rurki ciepła oparte na pętli, to urządzenia dwufazowe służące do transportu ciepła, wykorzystujące grawitacyjne i kapilarne siły do wzbudzania obiegu czynnika roboczego. LHP stało się bardzo obiecującym urządzeniem, możliwym do wykorzystania w różnego rodzaju zaawansowanych urządzeniach pracujących naziemnie. W pierwszej...
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Characterization of structural, thermal and mechanical properties of bismuth silicate glasses
Publikacjahe influence of heating and reduction processes on the structural, thermal and mechanical properties of bismuth-silicate glasses has been investigated. Two compositions of glasses: 40Bi2O3–60SiO2 (Bi0.57Si0.43Ox) and 27Bi2O3–73SiO2 (Bi0.43Si0.57Ox) were fabricated by a typical melt quenching technique. Then the reduction in hydrogen at 380 °C for 20, 42 or 67 h was performed. It was found that a 50 μm-thick layer was formed on...
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Failure of austenitic stainless steel tubes during steam generator operation
PublikacjaThe article presents the failure process of austenitic stainless steels used in power devices, such as heat exchangers, steam generators, in terms of local corrosion: pitting, stress and intergranular corrosion, paying particular attention to welded joints area. The effect of steel chemical composition, microstructure, welding process and work environment was analyzed. The second part of the article presents the results of the...
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Non-adiabatic Effects in Pressure Drop Calculations in Flow Boiling and Flow Condensation in Minichannels
PublikacjaConsiderations presented in the paper relate both to the case of flow boiling and flow condensation in conventional channels as well as small diameter ones. Authors devoted all the possible attention that the modeling presented is applicable to the whole range of quality variation in both cases of condensation and boiling. The form of two-phase flow multiplier, which is a major factor in modeling presented here, should be capable...
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Experimental investigations and simulations of the microturbine unit with permanent magnet generator
PublikacjaIn dispersed power generation, low power devices are used for local combined generating of heat end electric power. There are developing concepts of micropower plants with electric generators driven by steam or gas microturbines. The paper presents the results of an experimental investigations of the microturbine set consists of the turbine with partial admission, permanent magnet generator and three phase AC-to-DC rectifier. The...
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The influence of the carbon equivalent on the weldability of high-strength low-alloy steel in the water environment
PublikacjaFrom many years, the high strength low alloy steels are often used for offshore constructions. This constructions, due to the environment in which they work, require more frequent repairs than the constructions from the land. For economic reasons, repairs take place in the underwater conditions, however water significantly decreases the weldability of steel. The paper presents the results of the CTS weldability test for S460ML...
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Microwave treatment in waste rubber recycling – recent advances and limitations
PublikacjaEnvironmentally-friendly microwave heating is increasingly used in polymer chemistry and technology. The selectivity and highly efficiency in the heat transfer present a huge advantage in systems based on recycling, improving their productivity and economic competitiveness. In case of the industrial recycling of waste rubbers, especially end-of-life tires, microwave-induced devulcanization and pyrolysis are nowadays considered...
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Detailed studies of superconducting properties of Y2Pd1.25Ge2.75
PublikacjaWe report a successful synthesis of a high-purity intermetallic germanide Y2Pd1.25Ge2.75, crystallizing in the disordered variant of the AlB2-type structure. A single-phase sample was obtained via arc-melting by deliberately tuning the composition out of the ideal 2:1:3 ratio. Specific heat, electrical resistivity and magnetization measurements show that the compound is a weakly-coupled (λ e-p = 0.58) type-II superconductor with...
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Real-Time Basic Principles Nuclear Reactor Simulator Based on Client-Server Network Architecture with WebBrowser as User Interface
PublikacjaThe real-time simulator of nuclear reactor basic processes (neutron kinetics, heat generation and its exchange, poisoning and burn- ing up fuel) build in a network environment is presented in this paper. The client-server architecture was introduced, where the server is a pow- erful computing unit and the web browser application is a client for user interface purposes. The challenge was to develop an application running under the...
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Revitalisation Living Lab as a Format to Accelerate an Energy Transition in Polish Rural Areas: The Case Studies of Metropolitan Outskirts Gdańsk-Orunia and Lubań
PublikacjaThe paper deals with the issue of energy transition in the revitalization process dedicated to the rural and semi-rural areas of the Pomerania Region (PR). Two distinct areas, located in sub- and ex-urban zones of the Gdańsk-Gdynia-Sopot Metropolitan Area (OMGGS), in which bottom-up community initiatives have been playing a key role in the transformation, have been focused on. The village of Lubań (Municipality of Nowa Karczma)...
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Synthesis, structure and physical properties of new intermetallic spin glass-like compounds RE2PdGe3 (RE = Tb and Dy)
PublikacjaNew intermetallic compounds Tb2Pd1.25Ge2.75 and Dy2Pd1.25Ge2.75 have been synthesized using the arc-melting method. The crystallographic structure and magnetic, electronic transport, and thermal properties are reported. The crystal structure obtained from powder x-ray diffraction analysis suggests that these compounds crystallize in the AlB2-type structure (space group P6/mmm, no. 191) with lattice parameters a = 4.228 53(5)/4.230 54...
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Superconductivity on a Bi Square Net in LiBi
PublikacjaWe present the crystallographic analysis, superconducting characterization and theoretical modeling of LiBi, that contains the lightest and the heaviest nonradioactive metal. The compound crystallizes in a tetragonal (CuAu-type) crystal structure with Bi square nets separated by Li planes (parameters a = 3.3636(1)Å and c = 4.2459(2) Å, c/a = 1.26). Superconducting state was studied in detail by magnetic susceptibility and heat...
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Molecular identification and genotyping of Staphylococci: genus, species, strains, colnes, lineages, and interspecies exchanges
PublikacjaStaphylococci are increasingly recognized as etiological agents of many opportunistic human and animal infections, emphasizing the need for a rapid and accurate identification, even to a genotypical level of these bacteria. In the recent years, there has been a significant progress in typing and phylogenetic study of Staphylococcus species. Here, we describe molecular methods used in taxonomy as well as staphylococci characterization....
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Organic Rankine cycle as bottoming cycle to a combined Brayton and Clausius - Rankine cycle
PublikacjaA preliminary evaluation has been made of a possibility of bottoming of a conventional Brayton cycle cooperating with the CHP power plant with the organic Rankine cycle installation. Such solution contributes to the possibility of annual operation of that power plant, except of operation only in periods when there is a demand for the heat. Additional benefit would be the fact that an optimized backpressure steam cycle has the advantage...
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Wykorzystanie ciepła niskotemperaturowego do procesu suszenia peletu ze słomy z wykorzystaniem mikrostrugowego wymiennika ciepła
PublikacjaW artykule przedstawiono wpływ temperatury medium suszącego na zmiany względnej oraz bezwzględnej zawartości wilgoci podczas suszenia peletu ze słomy. Proces suszenia przeprowadzono przy stałym ciśnieniu atmosferycznym i różnych wartościach temperatury powietrza, jako czynnika suszącego, wynoszących odpowiednio: 40℃, 60℃, 80℃, 100℃ oraz 120℃. Badania eksperymentalne wykonywano na innowacyjnym stanowisku wyposażonym w mikrostrugowy...
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Noncentrosymmetric superconductor with a bulk three-dimensional Dirac cone gapped by strong spin-orbit coupling
PublikacjaThe layered, noncentrosymmetric heavy element PbTaSe2 is found to be superconducting. We report its electronic properties accompanied by electronic-structure calculations. Specific heat, electrical resistivity, and magnetic-susceptibility measurements indicate that PbTaSe2 is a moderately coupled, type-IIBCSsuperconductor (Tc = 3.72 K, Ginzburg–Landau parameter κ = 17) with an electron-phonon coupling constant of λep = 0.74. Electronic-structure...
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LaNi1-xCoxO3-δ(x=0.4 to 0.7) cathodes for solid oxide fuel cells by infiltration
PublikacjaPerformance of LaNi 1-x Co x O 3−δ (LNC) (x=0.4 to 0.7) as a cathode in solid oxide fuel cell (SOFC) is evaluated. Symmetrical cathode/electrolyte/cathode cells for electrochemical testing are prepared by infiltration of yttria stabilized zirconia (YSZ) backbone with LNC solutions. It is showed that the cathode infiltrated with LaNi 0.5 Co 0.5 O 3−δ (LNC155) has the lowest polarization resistance and activation energy, 197 mΩ cm...
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Three phase transient model of wet coal pyrolysis
PublikacjaA one-dimensional transient mathematical model was developed to describe the thermal and flow phenomena during coal pyrolysis in a coke oven. The model was solved numerically using partly implicit methods for gas flow and heat transfer problems. It was successfully validated with industrial-scale measurements of temperature change in the middle-plane of the coke oven chamber. The evolution of temperature and pressure, distributions...
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The dying medium temperature impact on the final moisture content of pine wood at constant drying time
PublikacjaThe results of final moisture content of pine wood (Pinus sylvestris L.) after drying process are presented. The wood in the experiments was taken from the northern part of Pomeranian region in Poland. The drying process was performed in the experimental chamber equipped with the micro-jet heat exchanger. The air at temperatures of 40°C, 60°C, 80°C, 100°C and 120°C with relative humidity about 60% and atmospheric pressure was the...
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Stirling engines powered by renewable energy sources
PublikacjaStirling engine is a device that produces mechanical energy using heat from any source of energy, without the need of combustion of any fuel inside the device. Renewable energy sources, which are mostly low-temperature energy sources, can be used to produce mechanical and electrical energy in Stirling engines. The paper presents an overview of the existing prototype Stirling engines designed for using of low-temperature energy...
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Investigations of Aerodynamics of Tesla Bladeless Microturbines
PublikacjaThe paper presents an analysis of a Tesla bladeless turbine for a co-generating micro-power plant of heat capacity 20 kW, whichoperates in an organic Rankine cycle with a low-boiling medium. Numerical calculations of flow in several Tesla turbine models areperformed for a range of design parameters. Results of investigations exhibit interesting features in the distribution of flowparameters within the turbine interdisk space. The...
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Hydrogen effects in duplex stainless steel welded joints - electrochemical studies
PublikacjaIn this work results on the influence of hydrogen on passivity and corrosion resistance of 2205 duplex stainless steel (DSS) welded joints are described. The results were discussed by taking into account three different areas on the welded joint: weld metal (WM), heat-affected zone (HAZ) and parent metal. The corrosion resistance was qualified with the polarization curves registered in a synthetic sea water. The conclusion is that,...
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HYDROGEN PRODUCTION PERFORMANCE IN THERMOCATALYTIC REACTOR BASED ON THE INTERMETALLIC PHASE OF NI3AL
PublikacjaThe main aim of the following paper is mathematical modelling for momentum, heat and mass transfer, which is accompanied by chemical surface reactions of the flow of the mixture helium and methanol. The thermocatalytic devices used for decomposition of hydrocarbons incorporate vertical microchannels coupling at the ends and heated to 500 oC at the walls. The results of the experiment were compared with CFD calculations to calibrate...