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Conjugated control of triple active bridge converter with common HFT
PublikacjaPaper presents synthetic analyses of single input, dual output DC/AC/DC converter with common high frequency transformer. Rise the problem of cross-coupling power flows between secondary terminals, under asymmetrical control operating condition. It also proposes a new approach to converter control, based on conjugated phase shift modulation and defines its limitations. Finally, the developed control technique was verified by simulation...
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Regulator przepływu
PublikacjaW artykule opisano konstrukcję i wyniki badań prototypu regulatora przepływu charakteryzującego się brakiem sprężyny. W regulatorze zawór różnicowy zastąpiono zaworem stosunku ciśnień. Charakterystyki przepływowe regulatora mają przebieg niezależny od obciążenia. Nastawa regulatora odbywa się poprzez obrót hydrostatycznie odciążonej tulei dławiącej, wewnątrz której umieszczony jest suwak główny i suwak pomocniczy zaworu stosunku...
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Magneto-thermal convection of low concentration nanofluids
PublikacjaThe main aim of this paper was to analyze possible utilization of the low concentration nanofluids and the magnetic field to enhance heat transfer. The studied fluids were based on water with an addition of copper particles (40-60 nm diameter). They belonged to the diamagnetic group of materials. As a first attempt to stated target the analysis of enclosure placed in the maximal value of square magnetic induction gradient was carried...
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Pin Angle Thermal Effects on Friction Stir Welding of AA5058 Aluminum Alloy: CFD Simulation and Experimental Validation
PublikacjaThe friction stir welding (FSW) of tool pin geometry plays a critical role in the final properties of the produced joint. The tool pin geometry directly affects the generation of heat and the flow of internal materials during the FSW process. The effects of the FSW tool pin angle on heat generation and internal flow have not been quantitatively investigated in detail. In this manuscript, a validated Computational Fluid Dynamic...
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A Computational Analysis of the Aerodynamic and Aeromechanical Behavior of a Thermo-Well for Steam Temperature Measurement in a Steam Turbine
PublikacjaThe goal of the paper is twofold: firstly, it presents computational fluid dynamics analysis for finding maximum unsteady flow forces (and their frequencies) acting on a thermo-well for measuring steam temperature in a steam turbine control stage and secondly, it presents computational solid dynamics analysis of possibility of entry into resonance of the thermowell structure. There have been analyzed two cases of flow with changing...
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Water-lubricated stern tube bearing - experimental and theoretical investigations of thermal effects
PublikacjaThe paper presents research results of thermal phenomena accompanying operation of a water-lubricated stern tube bearing with axial grooves. Experimental tests revealed, that intensity of forced axial flow has strong influence on bush temperature. Numerical simulations focused on investigation of the thermal phenomena under operation of water-lubricated journal bearing showed, that restricted axial flow promotes backflow of the...
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Influence of nanoparticle concentration on convective heat transfer of water-Al2O3 nanofluids inside horizontal tubes
PublikacjaNanofluids came to be seen as a new generation of coolants, especially in single-phase systems. Conducted experiments indicate that the increase in thermal conductivity is not the only reason for the intensification of heat transfer when using nanofluids. Preliminary results of the experimental investigation of the forced convection heat transfer of water-Al2O3 nanofluids inside stainless steel tube with 8 mm internal diameter...
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Biobatteries and biofuel cells with biphenylated carbon nanotubes
PublikacjaSingle-walled carbon nanotubes covalently biphenylated are used for the construction of cathodes in a flow biobattery and in flow biofuel cell. Zinc covered with a hopeite layer is the anode in the biobattery and glassy carbon electrode covered with bioconjugates of single-walled carbon nanotubes with glucose oxidase and catalase is anode of the biofuel cell. The potentials of the electrodes are measured vs. the Ag/AgCl reference...
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Driving a new perspective Professor Zygmunt Paszota, faculty of ocean engineering and ship technology, Gdansk University of Technology, Poland, explains a new approach to the Sankey Diagram for drive motors
PublikacjaThe paper presents the necessity of replacing the traditional, commonly accepted but erroneous, Sankey diagram of power decrease in the direction of power flow by the diagram, proposed by the Author, of power increase in the direction opposite to the direction of power flow. The proposed view of losses and energy efficiency should be applied to all types of drive motors and drive systems. The presented proposals open a new perspective...
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comparison of circular and rectangular narrow esps with longitudinal wire electrode
PublikacjaDiesel engines emit fine particles, which are harmful to human and animal health. There are several methods for decrease particulate emission from a diesel engines, but up to now, these methods are not enough effective or very expensive. An electrostatic precipitation was proposed as an alternative method for control of a diesel particulate emission. Therefore, narrow electrostatic precipitators (ESPs) have become a subject of...
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HMSE: A tool for coupling MODFLOW and HYDRUS-1D computer programs
PublikacjaA new software HMSE has been developed to facilitate external coupling between two well-known programs for subsurface flow modeling: MODFLOW-2005 (saturated zone flow) and HYDRUS-1D (unsaturated zone flow). Two coupling schemes have been implemented. In the first case the groundwater recharge flux is calculated by HYDRUS-1D assuming a fixed water table position and then passed to MODFLOW input files. In the second case the water...
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TERMODYNAMIC CALCULATIONS OF TURBINE STEAM PARAMETERS
PublikacjaIn this work a heat balance was made for the nominal conditions of a block working with 18K370 turbine. For the parameters obtained, the thermal-flow calculations of the steam turbine were performed, maintaining the actual geometry of its flow system. Based on the nominal values obtained, iterative thermal and flow calculations were made for both the heat cycle of the power plant block and the steam turbine itself, seeking to obtain...
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Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines. Part I: Steady-state processes
PublikacjaThe article presents a possible method of detecting failures in the flow section and supply system of a naval gas turbine engine based on the exhaust gas temperature measured behind the gas generator. This temperature is a basic diagnostic parameter use for evaluating the technical state of the turbine engine in operation, and is monitored during engine start-ups, accelerations and decelerations of rotor units, and steady-load...
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Model neuronowy jako alternatywa dla numerycznego modelu okołodźwiękowego przepływu pary przez palisadę turbinową.
PublikacjaWystępowanie skośnej fali uderzeniowej w przepływie pary przez palisadę turbinową stanowi zagrożenie dla bezpiecznej pracy turbiny oraz dla jej elementów konstrukcyjnych. Detekcja oraz lokalizacja fali uderzeniowej, a także rozpoznanie przyczyny jej powstawania, nie są możliwe do osiągnięcia na drodze pomiarowej. Analizę zjawisk zachodzących wewnątrz kanału przepływowego umożliwiają natomiast modele numeryczne oraz neuronowe. Zaletą...
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Chip suction system in circular sawing machine: empirical research and computational fluid dynamics numerical simulations
PublikacjaThe experimental analysis of the wood chip removing system during its redesigning in the existing sliding table circular saw and computational fluid dynamic (CFD) numerical simulations of the air flow process is presented in the paper. The attention was focused on the extraction hood and the bottom shelter of the actual existing system. The main aim was to perform experimental research on the pressure distribution inside the...
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Research of the changeability of the vessels traffic intensity of inland waterways – case study for Lower Vistula
PublikacjaThe article presents an analysis of the changeability of traffic intensity of inland waterway vessels in the Vistula Delta. The concept of traffic intensity was defined, traffic flows and disturbances were identified in the studied area. The characteristics of the inland waterway traffic model are presented. The results of the analysis indicate the need to carry out modernization of inland waterways for the needs of inland waterway...
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NUMERYCZNE MODELOWANIE HYDRODYNAMIKI JAKO NARZĘDZIE WSPOMAGANIA PROJEKTOWANIA REKREACYJNYCH I SPORTOWYCH OBIEKTÓW WODNYCH
PublikacjaW artykule opisano zastosowanie obliczeń numerycznych w procesie projektowania, analizy działania oraz oceny bezpieczeństwa użytkowania wodnych obiektów rekreacyjnych i sportowych. Użytkownicy aquaparków, sportowcy, a szczególnie kibice, oczekują wyjątkowych doznań na obiektach wodnych z jednoczesną gwarancją bezpieczeństwa. Na te kwestie duży wpływ ma hydrodynamika przepływu. Aby właściwie dobrać parametry geometryczne i hydrauliczne...
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The impact of the shape of deep drilled well screen openings on the filtration process in full saturation conditions
PublikacjaThe authors propose a supplementary method of modelling seepage flow around the deep drilled well screen. The study applies 3D numerical modelling (FEM) in order to provide an in-depth analysis of the seepage process. The analysis of filtration parameters (flow distribution q(x,t) and pressure distribution p) was conducted using the ZSoil.PC software system. The analysis indicates that the shape of perforation is of secondary importance...
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Trailing-Edge Separation Control of a NACA 0015 Airfoil Using Dielectric-Barrier-Discharge Plasma Actuators
PublikacjaThis paper presents a part of the works conducted in the Plasmaero European project (task 3.1), where the trailing-edge flow separation of a NACA 0015 airfoil has been controlled using four different dielectric barrier discharge (DBD) actuator types at three institutions across Europe. The results show that it is possible to enhance the aerodynamic performance of aircraft at speeds up to 40 m/s. Dielectric-barrier-discharge vortex...
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Effects of Noncontact Shoulder Tool Velocities on Friction Stir Joining of Polyamide 6 (PA6)
PublikacjaIn this study, the effects of the traverse and rotational velocities of the noncontact shoulder tool on the heat generation and heated flux during the friction stir joining of high-density polyamide 6 (PA6) polymer were investigated. The computational fluid dynamics (CFD) method was employed to simulate the thermomechanical phenomena during the friction stir joining (FSJ) process of PA6. A developed model was used to consider the...
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Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness
PublikacjaThe shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil,centrifugal force is acting on the moving fluid due to the curvature of thetube results in the development. It has been long recognized that the...
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Improvement of radiotracers experiments in mass transfer processes
PublikacjaThe greatest part of industrial mass transfer is based on continuous transportation of different substances throughout especially constructed installations. In that kind of practice, a flow of such mass in each part determines the process unit and can be described by the residence time distribution (RTD) of the substance inside this unit. This parameter may be evaluated by the properly arranged tracer experiment. It is worthwhile...
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A finite element analysis of thermal energy inclination based on ternary hybrid nanoparticles influenced by induced magnetic field
PublikacjaThe use of hybrid nanoparticles to improve thermal processes is a key method that has implications for a variety of interventions utilized in many sectors. This paper aimed to look into the impacts of ternary nanoparticles on hyperbolic tangent materials to establish their thermal characteristics. Flow describing equations have been explored in the presence of heat production, non-Fourier heat flux, and an induced magnetic field....
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ENHANCED MASTER CYCLE - SIGNIFICANT IMPROVEMENT OF STEAM RANKINE CYCLE
PublikacjaThe present paper focuses on an enhancement of the Master Cycle. In the first part, the paper presents a classical Master Cycle which is a modification of the double reheat Rankine cycle. This modification allows to slightly increase efficiency, resolves problems caused by superheated steam on bleeds and decreases mass flow rate of steam directed to reheat. These improvements include the implementation of a tuning turbine from...
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Experimental investigation on straight and u-bend double tube heat exchanger with active and passive enhancement methods
PublikacjaAuthors in this work want to demonstrate the possibility to increase the heat transfer efficiency by using simple wire coil inserts to create turbulent flow in the boundary layer as well as air blowing into the annulus of the pipe. In the study, Wilson plot approach was applied in order to estimate heat transfer coefficients for all heat exchanger (HX) configurations. The study focuses on experimental values of heat transfer coefficient...
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Acoustic heating produced in the boundary layer
Publikacja: Instantaneous acoustic heating of a viscous fluid flow in a boundary layer is the subject of investigation. The governing equation of acoustic heating is derived by means of a special linear combination of conservation equations in the differential form, which reduces all acoustic terms in the linear part of the final equation but preserves terms belonging to the thermal mode. The procedure of decomposition is valid in a weakly...
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Hazards of a flooding event in the city of Gdansk and possible forms of preventing the phenomenon – case study
PublikacjaThe main objective is to examine the urban flood hazard in the city of Gdansk and to determine the possibilities of preventing this phenomenon. Hydrological and hydraulic modeling was used for the case study analysis of urban flood in Strzyża basin, applying the HEC-HMS and HEC-RAS systems. The result of modeling with the assumption of torrential rainfall with a duration of t = 1 h (from 35 to 58 mm) is the probability of pluvial...
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Cavitation Erosion of P110 Steel in Different Drilling Muds
PublikacjaThe P110 steel specimens were subjected to ultrasonic cavitation erosion in different compositions of drilling muds and surfactant additive. The test procedure was based on ASTM-G-32 standard recommendations. API 5CT-P110 steel is used for pipes in oil and gas industry. The harsh environment and high velocity of flows poses corrosive and erosive threat on materials used there. The composition of drilling fluid influences its rheological...
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Impact of maintenance of floodplains of the Vistula River on high water levels on the section from Włocławek to Toruń
PublikacjaThis article describes the methodology of hydraulic calculations to estimate the water levels in open channels for steady gradually varied flow. The presented method has been used to analyse the water level on the Vistula River from Włocławek cross-section to Toruń cross-section. The HEC-RAS modelling system has been used for parameterization of the river channel and floodplains, as well as for flow simulation. The results obtained...
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Application of Monte-Carlo method to modelling influence of selected soil heterogeneity on macrodispersion of pollutants in unsaturated soil medium
PublikacjaThe influence of soil heterogeneity on miscible solute transport in soil is analyzed. The transport process is simulated numerically using the Monte-Carlo method. This paper shows how different types of soil heterogeneity influence the process of contaminant spreading. If independent flow paths exist in the soil, the degree of the mixing of pollutants in the outflow from the soil profile is larger. If the preferential flow paths...
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Effect of Vascular Lumen Reduction on the Performance and Energy Consumption of an Innovative Implantable LVAD
PublikacjaThis paper presents the results of a study on the effect of vascular lumen reduction on the performance of an innovative implantable LVAD (left ventricular assist device). It details the pressures in the individual cardiac chambers as a function of device frequency. In addition, mass flow rates and energy consumption of the device are examined, varying with lumen reduction and operating frequency. While the lumen reduction of the...
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Port Cities within Port Regions: Shaping Complex Urban Environments in Gdańsk Bay, Poland
PublikacjaPort cities located within various metropolitan or functional regions face very different development scenarios. This applies not only to entire municipalities but also to particular areas that play important roles in urban development—including ports as well as their specialized parts. This refers also to the various types of maritime industries, including the processing of goods, logistics operations, shipbuilding, or ship repairing,...
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Influence of metallic porous microlayer on pressure drop and heat transfer of stainless steel plate heat exchanger
PublikacjaThe experimental analysis of passive heat transfer intensification in the case of plate heat exchanger has been carried out. The metallic porous layer was created on the heat transfer surface of analyzed unit. The experiment was accomplished in two stages. In the first stage the commercial stainless steel gasketed plate heat exchanger was investigated, while in the second one – the identical heat exchanger but with the modified...
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Influence of water and mineral oil on the leaks in satellite motor commutation unit clearances
PublikacjaThe article describes the flow rates of mineral oil and water flowing, as working media, through the commutation unit of a hydraulic satellite motor. It is demonstrated that geometrical dimensions of commutation unit clearances change as a function of the machine shaft rotation angle. Methods for measuring the rate of this flow and the pressure in the working chamber are presented. The results of pressure measurements in the working...
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Experimental Research on Insufficient Water Lubrication of Marine Stern Tube Journal Bearing with Elastic Polymer Bush
PublikacjaWater-lubricated bearings with polymer bushes are steadily gaining popularity due to their advantages, including environmental friendliness, relatively simple construction and long-term operation. Nevertheless, in practice instances of damage to such bearings occur due to insufficient or absent flow of the lubricating agent. In this study, experimental tests established that elastic polymer bush bearing is capable of operating...
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Operational causes of fatigue failures within the passages of gas turbine engines
PublikacjaThe short profile of a fatigue wear process of gas turbine engine's constructional elements has been introduced in the article. The primary causes of a fatigue cracks formation within the mechanical system as well as within the passages of the engine have been showed. Especial attention was devoted to the low-cycle fatigue, what is associated with unsteady thermal-flow processes being worked out in the passages.The selected damages...
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Comparison of Mathematical Models of Torque Transmitted by Multi-disc Wet Clutch with Experimental Results
PublikacjaIn this article was described the methodology for the experimental study of flows in the prototype of a satellite hydraulic motor with a rotating body. The experimental tests of the motor were carried out at a low constant rotational speed in a wide range of pressure drop in this motor. The constant rotational speed of the motor was kept by a worm gear. Based on the test results, the leakage characteristics in the flat gaps of...
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Analiza parametrów płukania sieci wodociągowej metodą ukierunkowanego przepływu wody
PublikacjaEksperymenty prowadzone przez wiele lat podczas płukania sieci wodociągowej metodą jednokierunkowego przepływu wody umożliwiają weryfikację interakcji między jakością wypłukiwania nagromadzonych zanieczyszczeń oraz parametrami przepływu, liczbą cykli wymiany wody, a także zasięgiem płukania. Usuwanie zanieczyszczeń na początku przebiega zgodnie z szybko rosnącą krzywą, a następnie według funkcji malejącej. Taki przebieg jest spowodowany...
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A novel concept of enhanced direct-contact condensation of vapour- inert gas mixture in a spray ejector condenser
PublikacjaAn analytical model of direct steam condensation (DCC) in the novel idea of spray ejector condenser (SEC) in the presence of inert gas has been developed. It is based on continuity, momentum and energy equations for the steam-carbon dioxide mixture and direct contact condensation mechanisms due to heat transfer and concentration. Crucial in the process of DCC is atomisation of the motive fluid in the ejector. The effect of atomised...
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Efekty egoistycznych ataków na poziomie mac w sieciach ad hoc o topologii wieloskokowej
PublikacjaStacje sieci ad hoc mogą manipulować parametrami dostępu do medium transmisyjnego dla osiągnięcia nienależnie wysokiej jakości usług. Dla środowiska sieci ad hoc o topologii wieloskokowej rozważane są ataki na mechanizmy odłożenia transmisji i klasyfikacji ruchu, przeprowadzane zarówno w stosunku do przepływów źródłowych jak i tranzytowych. Wyniki pozwalają wstępnie ocenić efekty takich ataków oraz skuteczność mechanizmów obronnych.
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INFLUENCE OF SURFACE CURVATURE ON SESSILE DROPLET CONTACT ANGLE OF NANOFLUIDS
PublikacjaThis paper deals with change in contact angle of droplets of three nanofluids, i.e. water-Al2O3, water-TiO2 and water-Cu. Nanoparticles were tested at the concentration of 0.01%, 0.1%, and 1% by weight. Although dispersants were not used to stabilize the suspension, the solutions tested exhibited satisfactory stability. Ultrasonic vibration was used in order to stabilise the dispersion of the nanoparticles. Experimental measurements...
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On the internal efficiency of a turbine stage: classical and CFD definitions
PublikacjaAlmost entire fleet of steam turbines in Poland was designed between 1950 – 1980 with the use of the so-called zero dimensional (0D) calculation tools. For several years, design and modernization of the turbines occur in assistance with the state of the art methods that describe working fluid flow field based on 3D models and CFD codes. This cooperation between 0D and 3D codes requires exchange of overall, integral information...
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Experimental research on helical coil biomass boiler with oil as a heating fluid
PublikacjaThis paper presents an experimental research of helical coil biomass boiler with thermal oil heating agent. Heat exchanger consists of two coaxial helical coils swept by the flue gases. The burner is a single vertical retort connected to the fuel tank (wooden pellets). The boiler is a part of micro-power plant in which the heat from the boiler is exchanged with low-boiling HFE7100 to produce steam for a custom steam turbine. The...
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Clean gas technologies - towards zero-emission repowering of Pomerania.
PublikacjaThe main aim this work is to show the different thermodynamic cycles which improve efficiency and/or decrease emission like: Cheng cycle, Szewalski cycle, LOTHECO cycle, hybrid pSOFC/GT cycle, inverse Brayton cycle, low-emission cycle and zero-emission cycle. For that purpose, cycles and results of analysis are first studied and, secondly, new concept is presented. The role of coupled analysis 0D and 3D in cycle’s devices is also...
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Design and distribution of air nozzles in the biomass boiler assembly
PublikacjaDue to energy crisis as well as increasing pollution of the environment, renewable energy sources usage increases all over the world. These facts encouraged authors to start research over developing a uniform biomass boiler calculation model. This paper presents a design of biomass boiler assembly created for ORC (Organic Rankine Cycle) unit since these systems could achieve strong position in energy industry....
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Enhancement of the Brayton cycle efficiency by water or steam utilization
PublikacjaIn the paper, thermodynamic analysis of two modifications of a Brayton cycle into enhancement cycles with water/steam injection are discussed. The first one deals with a STIG modified system with both interstage compressed air cooling and air heating (heat regeneration) before combustion chamber. The second one, mainly devoted to higher steam/air ratio, is connected with separate steam production in a HRSG. The analysis has been...
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Kinetic analysis of the stage for a high speed steam turbine
PublikacjaThis article analyzes possibilites of resonances within a control stage for a high speed steam turbine. This stage hase been based on assembling of a single blade to a rotating disk and increasing of rigidity of the system by using of a bandage. In the analysis will be nd a possiblity of resonance frequency, and mistuning by showing safety working ranges. The calculations have bean used the3D modal and harmonic analysis by the...
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Experimental and theoretical study of surface cooling using a single microjet
PublikacjaPrzedstawiono wyniki badań eksperymentalnych intensyfikacji wymiany ciepła przy pomocy pojedynczych strug wody i powietrza.Uzyskana na podstawie wyników korelacja, opisująca współczynnik przejmowania ciepła, posłużyła do weryfikacji modelu opracowanego wcześniej przez Mikielewicza (2007).
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Experimental investigations of hydraulic jump created by a two-phase impin-ging jet on a solid surface
PublikacjaPrzedstawiono rezultaty badań eksperymentalnych powstawania uskoku hydraulicznego tworzonego przez dwufazową strugę uderzającą.
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Analysis of transient heat transfer operation in tube wall.Selected papers from the International Conference on Turbines of Large Output devoted to 100th Anniversary of Prof. Robert Szewalski Birthday.
PublikacjaW pracy przedstawiono zachowanie się wymiennika ciepła stosowanego w układzie regeneracji turbin parowych w niestacjonarnych warunkach pracy.