Wyniki wyszukiwania dla: DESIGN OF TURBINES - MOST Wiedzy

Wyszukiwarka

Wyniki wyszukiwania dla: DESIGN OF TURBINES

Wyniki wyszukiwania dla: DESIGN OF TURBINES

  • Investigations of Aerodynamics of Tesla Bladeless Microturbines

    Publikacja
    • Ł. Jędrzejewski
    • P. Lampart

    - Journal of Theoretical and Applied Mechanics - Rok 2011

    The 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...

    Pełny tekst do pobrania w portalu

  • On the internal efficiency of a turbine stage: classical and CFD definitions

    Publikacja

    - Transactions of the Institute of Fluid-Flow Machinery - Rok 2012

    Almost 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...

  • Compact High Efficiency and Zero-Emission Gas-Fired Power Plant with Oxy-Combustion and Carbon Capture

    Publikacja

    - ENERGIES - Rok 2022

    Reduction of greenhouse gases emissions is a key challenge for the power generation industry, requiring the implementation of new designs and methods of electricity generation. This article presents a design solution for a novel thermodynamic cycle with two new devices—namely, a wet combustion chamber and a spray-ejector condenser. In the proposed cycle, high temperature occurs in the combustion chamber because of fuel combustion...

    Pełny tekst do pobrania w portalu

  • A study of a compact high-efficiency zero-emission power plant with oxy-fuel combustion

    Publikacja

    - Rok 2019

    This paper discusses the application of global trends in gas cycles technology using oxy-fuel combustion. This is followed by a demonstration of a design solution for a new cycle with two enhanced energy-converting devices, namely a wet combustion chamber and a spray-ejector condenser. The proposed gas and steam cycle unit is contained within a single turbine, whose benefits combine those offered by gas turbines (high inlet temperatures)...

  • Innovative Turbine Intake Air Cooling Systems and Their Rational Designing

    Publikacja

    - ENERGIES - Rok 2020

    The improved methodology of the engine intake air cooling system designing based on the annual effect due to cooling was developed. It involves determining the optimal value of cooling capacity, providing the minimum system sizes at maximum rate of annual effect increment, and its rational value, providing a close to maximum annual effect without system oversizing at the second maximum rate of annual effect increment within the...

    Pełny tekst do pobrania w portalu

  • Multi-objective optimization of the ORC axial turbine for a waste heat recovery system working in two modes: cogeneration and condensation

    Publikacja

    - ENERGY - Rok 2023

    Due to the demand of the district heating network and electric power grid ORC turbines can operate in the condensation and cogeneration modes. This approach requires the design of an expander which is characterized by high efficiency in each mode of operation. The paper is devoted to a multi-objective efficiency optimization of a one stage axial ORC turbine working on MM (Hexamethyldisiloxane). An Implicit Filtering algorithm (IF)...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • CONTROL OF THE WAVES IN A TOWING TANK WITH THE USE OF A BLACK-BOX MODEL

    The paper describes an adaptive control system of the waves, implemented in the Ship Design and Research Centre, CTO S.A. The purpose of generating the waves in the towing tank is the modelling of the environmental conditions during hydrodynamic model tests. The tests are performed on scale models of towed or free running ships, anchored structures like oil rigs or bottommounted structures, e.g. wind turbines. In the towing tank...

    Pełny tekst do pobrania w portalu

  • Strength analysis of a large-size supporting structure for an offshore wind turbine

    Publikacja

    The offshore wind power industry is the branch of electric energy production from renewable sources which is most intensively developed in EU countries. At present, there is a tendency to install larger-power wind turbines at larger distances from the seashore, on relatively deep waters. Consequently, technological solutions for new supporting structures intended for deeper water regions are undergoing rapid development now. Various...

    Pełny tekst do pobrania w portalu

  • Heat turbomachinery

    Kursy Online
    • K. Kosowski

    1. Steam turbine cycles. 2. Gas turbine cycles. 3. Combined gas-steam cycles. 4. Flows in nozzles. 5. Theory of turbine stages. 6. Multistage turbines. 7. Examples of turbine design.  

  • Badanie dynamiki platform pływających morskich turbin wiatrowych z zastosowaniem metod numerycznej mechaniki płynów

    Publikacja

    - Rok 2024

    Praca dotyczy badania ruchu platform pływających pod morskie turbiny wiatrowe. Przedstawiono w niej główne metody obliczeń i przedyskutowano ich zastosowanie. Na przykładzie koncepcji konstrukcji 3-kolumnowej platformy typu Spar przedstawiono metodykę wykonywania obliczeń z zastosowaniem programu AQWA opartego na metodzie dyfrakcyjnej, rozszerzonego o współczynniki wynikające z lepkości wyznaczone za pomocą obliczeń RANSE-CFD....

    Pełny tekst do pobrania w portalu

  • Large hydrodynamic thrust bearing: Comparison of the calculations and measurements

    Hydrodynamic thrust bearings, used to carry axial loads in heavily loaded shafts of water power plants hydro turbines, can reach outer diameters even exceeding 5 m. In such large objects scale effect could be observed. According to this, allowable bearing specific load assuring safe operation of the bearings has to be decreased, which increases thrust bearing dimensions. This effect is caused by excessive thermal deflections of...

    Pełny tekst do pobrania w portalu

  • Technical and Economic Analysis of the Supercritical Combined Gas-Steam Cycle

    Publikacja

    Combined cycle power plants are characterized by high efficiency, now exceeding 60%. The record-breaking power plant listed in the Guinness Book of World Records is the Nishi-Nagoya power plant commissioned in March 2018, located in Japan, and reaching the gross efficiency of 63.08%. Research and development centers, energy companies, and scientific institutions are taking various actions to increase this efficiency. Both the gas...

    Pełny tekst do pobrania w portalu

  • Analysis of operations of combined STIG installation

    Publikacja
    • A. Chrzczonowski
    • K. Jesionek
    • J. Badur
    • P. Ziółkowski

    - Rok 2013

    Steam injection in gas turbines is interesting technology with good energetic and ecological properties of gas turbines. In these applications the heat of exhaust gases is used to produce steam, which is injected in the combustion chamber of a gas turbine. The steam injection increase the power and efficiency of the installation. there are some possibilities to increases the properties of STIG turbines, for example by meas of additional...

  • Systems Engineering Requirements for Rotating Machines (PG-00060237)

    Kursy Online
    • J. Szwedowicz

    Turbiny wiatrowe, gazowe, mikroturbiny, silniki lotnicze, turbosprężarki i inne systemy mechaniczne to przykłady maszyn wirujących, które wymagają wysoko wykwalifikowanych inżynierów. Powinni oni zrozumieć złożoność procesów projektowania i produkcji, w tym wytwarzania przyrostowego, oraz konserwacji prognostycznej opartej na inżynierii cyfrowej dla bezawaryjnej pracy silnika. Wind, gas, micro turbines, aircraft engines, turbochargers,...

  • Organic Rankine cycle as bottoming cycle to a combined Brayton and Clausius - Rankine cycle

    Publikacja

    A 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...

  • Analysis of Failures of High Speed Shaft Bearing System in a Wind Turbine

    Publikacja

    During the operation of wind turbines with gearbox of traditional configuration, consisting of one planetary stage and two helical stages high failure rate of high speed shaft bearings is observed. Such a high failures frequency is not reflected in the results of standard calculations of bearing durability. Most probably it can be attributed to atypical failure mechanism. The authors studied problems in 1.5 MW wind turbines of...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • A concept of zero-dimensional and three-dimensional thermodynamic modelling of steam storage in a steam cycle

    Publikacja

    - Rok 2020

    This work presents the thermodynamic model of steam storage in a steam cycle. The innovative steam storage is an integral part of the unit and thus responds quickly to changes in load. This enhances the primary control reserve while maintaining high efficiency of energy conversion. With regard to power plants, it improves the operational safety of generation units, as it prevents boiler and turbines overload in the case of steep...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Recovering Sound Produced by Wind Turbine Structures Employing Video Motion Magnification

    The recordings were made with a fast video camera and with a microphone. Using fast cameras allowed for observation of the micro vibrations of the object structure. Motion-magnified video recordings of wind turbines on a wind farm were made for the purpose of building a damage prediction system. An idea was to use video to recover sound & vibrations in order to obtain a contactless diagnostic method for wind turbines. The recovered signals...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Research of Emergency Modes of Wind Power Plants Using Computer Simulation

    Publikacja
    • M. Z. Qawaqzeh
    • O. Miroshnyk
    • T. Shchur
    • R. Kasner
    • A. Idzikowski
    • W. Kruszelnicka
    • A. Tomporowski
    • P. Bałdowska-Witos
    • J. Flizikowski
    • M. Zawada
    • K. Doerffer

    - ENERGIES - Rok 2021

    The aim of this study is to investigate changes in the wind power plant energy production parameters under the conditions of sudden wind changes and voltage drop. To achieve these goals, a simulation of operation of wind power plants was performed. Twelve wind turbines with variable rotational speed equipped with a Fuhrländer FL 2500/104 asynchronous double-fed induction generator (DFIG) were used, each with an installed capacity...

    Pełny tekst do pobrania w portalu

  • Analyzing Wind Energy Potential Using Efficient Global Optimization: A Case Study for the City Gdańsk in Poland

    Publikacja

    - ENERGIES - Rok 2022

    Wind energy (WE), which is one of the renewable energy (RE) sources for generating electricity, has been making a significant contribution to obtaining clean and green energy in recent years. Fitting an appropriate statistical distribution to the wind speed (WS) data is crucial in analyzing and estimating WE potential. Once the best suitable statistical distribution for WS data is determined, WE potential and potential yield could...

    Pełny tekst do pobrania w portalu

  • CFD analysis of fluid flow through the labyrinth seal

    Steam and gas turbines are some of the fundamental means of power generation. The energy efficiency of the turbines, however, is not satisfactory. Ever since the start-up of the first turbine in the world, engineers have been striving for their increased efficiency. Multiple solutions to the problem of steam loss in an operating turbine are available. The use of seals is one of them. Empirical methods or numerical calculations...

    Pełny tekst do pobrania w portalu

  • Accuracy Investigations of Turbine Blading Neural Models Applied to Thermal and Flow Diagnostics

    Publikacja

    Possibility of replacing computional fluid dynamics simulations by a neural model for fluid flow and thermal diagnostics of steam turbines is investigated. Results of calculations of velocity magnitude of steam for 3D model of the stator of steam turbine is presented.

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Subcritical Thermodynamic Cycles with Organic Medium and Isothermal Expansion

    Publikacja

    The efffciencies of the Organic Rankine Cycle (ORC) are not very high and only very seldom do they exceed 20%. The increase and optimization of initial parameters and certain modifications of the thermodynamic cycle make it possible to overcome these drawbacks. A new modified cycle has been described and analyzed in detail in the paper. Similarly to the Ericsson cycle for gas turbines, isothermal expansion in the turbine is suggested...

    Pełny tekst do pobrania w portalu

  • Manufacturing and Recycling Impact on Environmental Life Cycle Assessment of Innovative Wind Power Plant Part 1/2

    Publikacja

    - Materials - Rok 2021

    Wind power plants are considered as ecologically-clean source of energy. However, manufacturing processes cannot be treated that way. Manufacturing processes consume huge amount of electrical and thermal energy and significant amount of materials, e.g. steel, polymers, oils and lubricants. All of the above could be potentially harmful for environment. There are not many works and publications regarding life-cycle analysis of wind...

    Pełny tekst do pobrania w portalu

  • An Impact of Environmental Disturbances on Combined Cycle Power Plant Control

    Publikacja

    Combined cycle power plants operate at thermal efficiency approaching 60 percent. In the same time their performance presents several problems that have to be addressed. E.g. gas turbines are very sensitive to backpressure exerted on them by the heat recovery steam generators as well as to ambient pressure and temperature.

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Turbomachinery - Background

    The "Turbomachinery - Background" is the first part of a series of monographs devoted to different aspects of rotating machines. The book presents the main fundamentals which are necessary for the different problems of steam, gas, wind and water turbines as well as pumps, compressors and propellers which will discussed in detail in the subsequent parts of the series.

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Comparative analysis of the theoretical models of ideal propulsor, ideal fluid brake, ideal screw propeller and ideal axial wind turbine

    Publikacja

    - Polish Maritime Research - Rok 2013

    The article presents a detailed discussion of four different fluid dynamics devices.These devices are presented with all relevant mathematical formulae regarding the forces, the power and the efficiency. It is demonstrated that application of the Betz theorem to axial wind turbines is not correct and it underestimates the maximujm achievable efficiency. This conclusion is supported by numerical calculations.

    Pełny tekst do pobrania w portalu

  • Strength analysis of the support structure of the offshore wind turbine

    Publikacja

    - Rok 2015

    The global power demand from renewable sources is growing. One of a very favorable solution which meets severe environmental protection requirements are the offshore wind turbines. The offshore wind energy sector has experienced very fast development over last decade. Offshore wind farms, in comparison with onshore applications, can provide increased efficiency with reduced noise, visual, transportation and installation con-flicts....

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Optimisation of cooperation of hybrid renewable energy sources with hydrogen energy storage toward the lowest net present cost

    Publikacja

    The paper presents the results of a technical and economic analysis of the power supply for a model industrial facility based on intermittent renewable energy sources in the form of wind turbines and photovoltaic modules, supplemented with hydrogen energy storage. The adopted power supply strategy assumed the maximisation of self-consumption of self-produced electricity. Six variants were considered, including two with an energy...

    Pełny tekst do pobrania w portalu

  • Control of the wind turbine generator

    Publikacja

    Wind power system consists of two main parts: wind turbine and electrical generator. Wind turbine converts the energy of the flowing air into mechanical energy, next generator converts this energy into electrical energy that is sent to the power system. These two processes should be realized with maximum efficiency and the following requirements for the control system can be formulated: opti-mal wind power conversion, compensation...

  • High-efficient, zero-emission energy production

    Publikacja

    - Rok 2013

    This paper presents innovative thermodynamiccycles with high-efficient, zero-emission energy production. The main aim of this work is to show the role of nano-phenomena in the enhancement of the power of thermodynamic cycles. For that purpose, the cycles using oxy-combustion and spray ejected condensation are first studied and, secondly hybrid cycles using fuel cells and gas turbines are presented. The role of nano-phenomena in...

  • Wymagania inżynierii systemów dla maszyn wirujących (PG-00060237)

    Kursy Online
    • J. Szwedowicz

    Turbiny wiatrowe, gazowe, mikroturbiny, silniki lotnicze, turbosprężarki i inne systemy mechaniczne to przykłady maszyn wirujących, które wymagają wysoko wykwalifikowanych inżynierów. Powinni oni zrozumieć złożoność procesów projektowania i produkcji, w tym wytwarzania przyrostowego, oraz konserwacji prognostycznej opartej na inżynierii cyfrowej dla bezawaryjnej pracy silnika. Kurs zapewnia fundamentalną wiedzę wymaganą w przemyśle...

  • Thermodynamic Cycle Concepts for High-Efficiency Power Plants. Part B: Prosumer and Distributed Power Industry

    Publikacja

    - Sustainability - Rok 2019

    An analysis was carried out for different thermodynamic cycles of power plants with air turbines. A new modification of a gas turbine cycle with the combustion chamber at the turbine outlet has been described in the paper. A special air by-pass system of the combustor was applied, and in this way, the efficiency of the turbine cycle was increased by a few points. The proposed cycle equipped with an effective heat exchanger could...

    Pełny tekst do pobrania w portalu

  • Tesla Friction-Type Micro Turbine For Small-Scale Cogeneration

    Publikacja
    • Ł. Jędrzejewski
    • P. Lampart

    - RED. ZAGR. ANGIELSKI - Rok 2011

    Tesla turbine is rarely used in professional power installations due to its specific work characteristics and relatively low internal efficiency. However, it has some potential to be applied in micro-power plants operating in distributed co-generation systems, also working in an organic Rankine cycle. This paper presents results from numerical calculations of flow in three models of Tesla disk turbines assuming nitrogen as a working...

  • ENHANCED EVAPORATION OF THE DROPLETS OF CONDENSATE IN THE ASYMMETRICAL SHOCK WAVE ZONE

    In the low-pressure part of steam turbine, the state path usually crosses the saturation line in penultimate stages [4,5]. The formation and evolution of these droplets lower the performance of the wet stages of the turbines, and their effects on the efficiency are collectively known as wetness losses [4]. Nowadays, due to work of steam turbines at partial load, process of homogeneous and heterogeneous condensation still is current....

    Pełny tekst do pobrania w serwisie zewnętrznym

  • The thermal effort during marine steam turbine flooding with water

    Publikacja

    - AIP Conference Proceedings - Rok 2019

    The work discussed an extreme case of cooling a steam turbine. The ship's steam turbine was used as an example. In marine transport units with low-speed engines dominate, however, there are also units with steam turbines. An example of analysed marine steam turbine is shown in Fig. 1. When considering the issue of cooling steam turbines, it is necessary to estimate the extreme conditions that may occur during operation of the turbine....

    Pełny tekst do pobrania w portalu

  • A Method for Optimising the Blade Profile in Kaplan Turbine

    Publikacja

    - Rok 2011

    This paper introduces a method of blade profile optimisation for Kaplan-type turbines, based on modelling the interaction between rotor and stator blades. Rotor and stator blade geometry is described mathematically by means of a midline curve and thickness distribution. Genetic algorithms are then used to find a global optimum that minimises the loss coefficient. This allows for variety of possible blade shapes and configurations....

  • ENERGY STORAGE IN COMPRESSED AIR – SOLUTION SUPPORTING RENEWABLE ENERGY SOURCES

    This article presents a brief description of a power system, the current national power system daily load, the use of wind power as a renewable energy source and its share in the national load. It also discusses the methods for storing energy, their characteristics and possible solutions. The power storage and generation solution proposed in the article is based on the collaboration between a gas turbine and an air storage system....

    Pełny tekst do pobrania w portalu

  • The analysis of turbine propulsion systems in nuclear submarines

    Publikacja

    The article systematises submarines, which are presently in service, according to their propulsion types (both conventional and nuclear), power output, and submersion depth. Contemporary types of propulsion systems installed and used in submarines are discussed. Calculations were performed for the PWR (Pressurized Water Reactor) type nuclear propulsion system and the supercritical turbine propulsion system (supercritical reactor...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Thermodynamic Cycles of Air Microturbine Power Plants Working on Biomass Fuels

    The gas turbine engine is modified to work as an air turbine set which consists, in the simplest arrangement, of a compressor, a heat exchanger and a turbine. Air is a working medium for both: the compressor and the turbine. This kind of air turbine set can be applied in power plants working on biomass fuels. In this solution we can burn fuels of varying parameters in the external combustion chamber without any harmful effects...

  • Active Suppression of Nonstationary Narrowband Acoustic Disturbances

    Publikacja

    In this chapter, a new approach to active narrowband noise control is presented. Narrowband acoustic noise may be generated, among others, by rotating parts of electro-mechanical devices, such as motors, turbines, compressors, or fans. Active noise control involves the generation of “antinoise”, i.e., the generation of a sound that has the same amplitude, but the opposite phase, as the unwanted noise, which causes them to interfere...

    Pełny tekst do pobrania w portalu

  • Organic Supercritical Thermodynamic Cycles with Isothermal Turbine

    Publikacja

    Organic Rankine cycles (ORC) are quite popular, but the overall efficiencies of these plants are rather very low. Numerous studies have been conducted in many scientific centers and research centers to improve the efficiency of such cycles. The research concerns both the modification of the cycle and the increase in the parameters of the medium at the inlet to the turbine. However, the efficiency of even these modified cycles rarely...

    Pełny tekst do pobrania w portalu

  • Conditions for increasing the recognition of degradation in thermal-flow diagnostics, taking into account environmental legal aspects

    Publikacja

    - Journal of Power Technologies - Rok 2023

    The ever-increasing demand for electricity and the need for conventional sources to cooperate with renewable ones generates the need to increase the efficiency and safety of the generation sources. Therefore, it is necessary to find a way to operate existing facilities more efficiently with full detection of emerging faults. These are the requirements of Polish, European and International law, which demands that energy facilities...

    Pełny tekst do pobrania w portalu

  • Shape Optimisation of Kaplan Turbine Blades Using Genetic Algorithms

    Publikacja

    - Rok 2017

    This monograph is a comprehensive guide to a method of blade profile optimisation for Kaplan-type turbines. This method is based on modelling the interaction between rotor and stator blades. Additionally, the shape of the draft tube is investigated. The influence of the periodic boundary condition vs. full geometry is also discussed. Evolutionary algorithms (EA) are used as an optimisation method together with artificial neural...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Experimental research on water lubricated marine stern tube bearings in conditions of improper lubrication and cooling causing rapid bush wear

    Water 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...

    Pełny tekst do pobrania w portalu

  • Inlet air fogging of marine gas turbine in power output loss compensation

    The use of inlet air fogging installation to boost the power for gas turbine engines is widely applied in the power generation sector. The application of fogging to mechanical drive is rarely considered in the literature [1]. This paper will cover some considerations relating to its application to gas turbines in ship drive. There is an important evaporative cooling potential throughout the world when the dynamic data is evaluated,...

    Pełny tekst do pobrania w portalu

  • Flow Analysis of a Kaplan Turbine

    Publikacja

    - Rok 2017

    This monograph is a guide to a method of experimental and numerical flow investigations for Kaplan - type turbines. The numerical calculations were compared with the test results of the model Kaplan turbine. The tests were carried out on the model test rig in the Gdańsk University of Technology. The turbine has been thoroughly experimentally investigated, resulting in the identification of optimum setting combination of the stator...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Application of microturbines in CHP systems with reciprocating engines

    Publikacja

    The analysis was carried out for Combined Heat and Power generation systems with micro-turbines power plants working on heat rejected from the reciprocating engine. The calculations were performed for GE Jerbacher engines of J320 GS- C05, J320 GS- C25 and J416 GS- B05 types. We considered different working media (both wet and dry fluids): water, ammonia, ethanol, methanol, methylacetylene (propyne), dimethyloether, sulphur dioxide,...

  • COMPARISON OF TWO MODELS OF CONDENSATION

    Publikacja

    - Rok 2014

    In the low-pressure part of steam turbine, the state path usually crosses the saturation line in penultimate stages. At least last two stages of this part of turbines operate in two –phase region. The liquid phase in this region in mainly created in the process of homogeneous and heterogeneous condensation. Several observations confirm however, that condensation often occurs earlier than it is predicted by theory i.e. before the...

  • RESEARCH ON HYDRODYNAMIC PEEK JOURNAL BEARINGS LUBRICATED WITH WATER AND OIL

    The main purpose of the research was to determine the possibilities and experimentally test the benefits of replacing conventional oil lubrication with ecological water lubrication. Tests were carried out on a test rig for hydrodynamic radial bearings under conditions representative of the expected applications for the bearing in water turbines. Bearings made from the polymer material PEEK (polyether ether ketone) were tested under static...

    Pełny tekst do pobrania w portalu