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1

Selected aspects of the choice of live steam pressure in PWR nuclear power plant

Laskowski Rafał, Smyk Adam, Jurkowski Romuald, Ancé Julien, Wołowicz Marcin, Uzunow Nikołaj

Archives of Thermodynamics

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2022

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Vol. 43, no 3

85--109

EN

In commercially available generation III and III+ PWR (pressurized water reactor) reactors, pressure of steam produced in steam generators varies in a relatively wide range from 5.7 to 7.8 MPa. Therefore, it is important to ask which value of steam pressure should be used for a specific unit, taking into account different location conditions, the size of the power system and conditions of operation with other sources of electricity generation. The paper analyzes the effect of steam pressure at the outlet of a steam generator on the performance of a PWR nuclear power plant by presenting changes in gross and net power and efficiency of the unit for steam pressures in the range of 6.8 to 7.8 MPa. In order to determine losses in the thermal system of the PWR power plant, in particular those caused by flow resistance and live steam throttling between the steam generator and the turbine inlet, results concerning entropy generation in the thermal system of the power plant have been presented. A model of a nuclear power plant was developed using the Ebsilon software and validated based on data concerning the Olkiluoto Unit 3 EPR (evolutionary power reactor) power plant. The calculations in the model were done for design conditions and for a constant thermal power of the steam generator. Under nominal conditions of the Olkiluoto Unit 3 EPR power unit, steam pressure is about 7.8 MPa and the steam dryness fraction is 0.997. The analysis indicates that in the assumed range of live steam pressure the gross power output and efficiency increase by 32 MW and 0.735 percentage point, respectively, and the net power output and efficiency increase by 27.8 MW and 0.638 percentage point, respectively. In the case of all types of commercially available PWR reactors, water pressure in the primary circuit is in the range of 15.5−16.0 MPa. For such pressure, reducing the live steam pressure leads to a reduction in the efficiency of the unit. Although a higher steam pressure increases the efficiency of the system, it is necessary to take into account the limitations resulting from technical and economic criteria as well as operating conditions of the primary circuit, including the necessary DNBR (departure from nucleate boiling ratio) margin. For the above reasons, increasing the live steam pressure above 7.8 MPa (the value used in EPR units that have already been completed) is unjustified, as it is associated with higher costs of the steam generator and the high-pressure part of the turbine.

2

The Effect of Sonication Parameters on the Thickness of the Produced MoS2 Nano-Flakes

Taghavi Najme Sadat, Afzalzadeh Reza

Archives of Acoustics

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2021

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Vol. 46, No. 1

31--40

EN

Liquid Phase Exfoliation (LPE) is a common route to produce two-dimensional MoS2 nanosheets. In this research, MoS2 powder is exfoliated by an ultrasonic probe (sonicator) in a water-ethanol solution. It is reported that MoS2 as a prototype 2D Transition Metal Dichalcogenide, has a band gap that increases with a decreasing number of layers. There are some factors that affect the average band gap energy value and the thickness of the exfoliated flakes. We varied different parameters of the ultrasonic probe like power, pulse percentage and time duration of sonication to investigate the effects on the number of MoS2 layers. Our findings from the UV-Visible spectra, SEM, FESEM and TEM images indicate that the minimum thickness for these samples was acquired at 50% of the input power of the sonicator we used (∼65 W) and the optimum pulse percentage is 50%. The current study also found that the average amount of band gap increased with an increase in sonication time, and then remained unchanged after 60 minutes.

3

Thermodynamic analysis and analytical simulation of the Rallis modified Stirling cycle

Ranjan Ravi Kant, Verma Suresh Kant

Archives of Thermodynamics

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2019

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Vol. 40, no 2

35--67

EN

A Stirling cycle was developed by Rallis considering the adiabatic behaviour instead of isothermal behaviour of working fluid inside the expansion/compression volume, since the isothermal processes are very difficult to be realised in actual practice due to irreversibilities. In order to increase the performance of Rallis Stirling cycle engine, two modified versions of Rallis Stirling cycle engine model have been proposed and developed, called as Rallis modified Stirling cycle engine (RMSE). In this paper, the thermodynamic analysis of the developed models have been carried out and the simulated results are compared with the Rallis ideal model of Stirling cycle engine, as this model describes more accurately the thermodynamic cycle of practical Stirling machines. The results reveal the fact that the thermal efficiency of RMSE I model is enhanced by 38.06% and that of RMSE II model by 48.42%, whereas the power output is increased by 58.05% and 78.19% in case of RMSE I and RMSE II model respectively, when compared with the Rallis ideal adiabatic model of Stirling engine.

4

Ocena względnej mocy użytecznej silnika o zapłonie iskrowym na podstawie wartości parametrów termodynamicznych spalin i prędkości obrotowej wału korbowego

Markowski J., Pielecha J., Merkisz J., Nowak M.

Combustion Engines

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2015

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R. 54, nr 3

469--474

PL

Podczas badań emisji związków szkodliwych spalin w warunkach eksploatacji środków transportu przydatne są informacje dotyczące parametrów pracy silnika. Informacje te wykorzystywane są do zdefiniowania m.in. wartości obciążenia silnika podczas eksploatacji środka transportu. W większości pojazdów produkowanych obecnie wykorzystuje się do tych celów informacje z systemów diagnostycznych. Natomiast w badaniach emisji związków szkodliwych z silników tłokowych stosowanych w małych samolotach jest to utrudnione, ponieważ nie wszystkie samoloty są wyposażone w pokładowe rejestratory parametrów lotu. Dlatego w przeprowadzonych badaniach emisji zanieczyszczeń z tłokowych napędów samolotów poszukiwano narzędzia, umożliwiającego dokonanie oceny obciążenia silnika podczas prowadzonych pomiarów w warunkach eksploatacji. W artykule przedstawiono propozycję algorytmu dotyczącego oceny wartości obciążenia tłokowego silnika lotniczego o zapłonie iskrowym na podstawie wartości temperatury spalin i prędkości obrotowej wału korbowego.

EN

During the research of exhaust emission under operating conditions of means of transport the engine's parameters are highly useful information. That information is used to define values of the engine load during the operation of the means of transport. In most vehicles produced nowadays the information from diagnostic systems is used for this purpose. The other hand, emissions testing of harmful compounds from piston engines used in small aircrafts is difficult because not all aircraft are equipped in on-board flight data recorders. Therefore, in the area of emissions from aircraft piston engines appeared the necessity of creation tool allowing evaluation engine load during the measurements under operating conditions. The article includes an algorithm for the assessment of the load values of aircraft's spark-ignition engines based on exhaust gas temperature and rotation speed of the crankshaft.

5

Nowe bloki energetyczne oparte na paliwie węglowym i gazie o mocy powyżej 400 MW, ich rola w krajowym systemie elektroenergetycznym

Lacroix L.

Prace Naukowe Politechniki Śląskiej. Elektryka

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2014

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z. 2-3

7--20

PL

Niniejszy artykuł opisuje aktualnie budowane i planowane do budowy bloki energetyczne oparte na paliwie węglowym - węglu kamiennym i węglu brunatnym oraz na paliwie gazowym. Głównym celem tych inwestycji jest zastąpienie wycofywanych bloków, by móc utrzymać zbilansowanie systemu elektroenergetycznego z odpowiednią nadwyżką zainstalowanej mocy. Powody wycofania pewnej ilości istniejących bloków podane są w dalszej części artykułu. W artykule opisano skrótowo nową technologię wytwarzania pary w kotłach o tzw. parametrach nadkrytycznych, podwyższających znacznie sprawność bloków węglowych w stosunku do technologii obecnie stosowanej. Artykuł ukazuje też pewne zagrożenia dla pracy bloków o poziomie mocy powyżej 850 MW w okresie występowania tzw. dolin obciążenia dobowego systemu elektroenergetycznego. W artykule wspomniano też o Dyrektywie unijnej IED, która nakazuje ograniczenia emisji szkodliwych substancji (gazów) do atmosfery, głównie chodzi tu o szkodliwe gazy, jak: dwutlenek siarki czy wielotlenki azotu oraz dwutlenek węgla.

EN

This article describes the construction and the plans for the construction of power units based on carbon fuel - coal and lignite and the gaseous fuel. The main objective of these investments is to replace the withdrawn blocks to be able to maintain a balance of power system with adequate surplus installed capacity. The reasons for the withdrawal of a certain amount of existing units are described later in the article. The article briefly describes the new technology of steam generation in boilers of the socalled. supercritical parameters, which increase significantly the efficiency of coal-fired units in relation to the technology currently used. The article presents a certain threat to the operation units on the level of power above 850MW at the time of the so-called (off peak ). valleys of daily load of the power system The article also mentioned about the IED European Directive, which requires the limitation of emissions of harmful substances (gases) into the atmosphere, mainly it is a harmful gases: as sulfur dioxide or nitrogen multioxides and carbon dioxide.

6

Stability Performance Analysis for Variable-Speed Variable-Pitch WECS Based on Dynamic Feedforward Neural Network Control

Li T., Ji Z.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 7b

243--247

EN

Wind energy conversion system (WECS) is a complex nonlinear system, when the wind speed is above the rated value. For a smooth integration of wind generators into the utility grids, two subsystems are built for the WESC based on two-time-scale. NNPID compensator is designed to compensate slow dynamics blade pitch angle, in order to reduce fluctuations of the power output. Compensator for the slow dynamics blade pitch angle is designed based on dynamic feedforward neural network (DFNN), its approximation capabilities are verified by the SCADA (supervisory control and data acquisition) wind farm data collected. Control performances of the DFNN with different structure are compared and analysed, results show that the method can effectively reduce the interference caused by disturbed parameters of the WECS. Safety of the system is improved, and a better idea is provided for application of the DFNN in wind power systems field.

PL

System konwersji energii wiatrowej jest szczególnie złożony gdy prędkość wiatru przekracza założone wartości. Zaproponowano dynamiczny układ sterowania z siecią neuronową DFNN. Osiągnięto lepsze bezpieczeństwo pracy systemu i zmniejszenie zakłóceń.

7

Power output of a wind turbine in tubular housing equipped with a diffuser

Romański L.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2008

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nr 11

277-282

EN

This paper presents the results of a study conducted on a model wind turbine in tubular housing equipped with a diffuser. The impact of the diffuser's diameter and length on the wind turbine's power output was tested. The highest output was reported when the ratio of the diffuser's inlet and outlet diameter was 1.7 and relative diffuser length reached approximately 0.6.

PL

W artykule przedstawiono wyniki badań modelu siłowni wiatrowej pracującej w obudowie rurowej z zainstalowanym dyfuzorem. Testowano wpływ średnicy i długości dyfuzora na generowaną przez tę siłownię moc. Najwyższe wartości mocy uzyskano wówczas, gdy stosunek średnicy wlotowej do wylotowej dyfuzora wynosił 1,7, a względna długość dyfuzora około 0,6.

8

Wpływ parametrów geometrycznych obudowy rurowej na moc siłowni wiatrowej

Romański L., Charkiewicz M.

Inżynieria Rolnicza

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2008

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R. 12, nr 5(103)

213-219

PL

W pracy przedstawiono wyniki badań efektów pracy siłowni wiatrowej umieszczonej w obudowie rurowej. W porównaniu do siłowni wolnostojącej generuje ona około 50% większą moc prądu elektrycznego. Obudowy rurowe instalowane przed jak i za wirnikiem powinny być jak najkrótsze. Wartość szczeliny obwodowej nie może przekraczać 1 mm.

EN

The paper presents results of the research on operation effects of wind power plant built-in in a tubular housing. Compared to a free-standing wind power plant, it generates approximately 50% higher power output of electric current. Tubular housings installed before and past the windwheel shall be as short as possible. Circumferential gap size shall not exceed 1 mm.

9

Analysis of parameters for determining power output of rail traction vehicles

Sikory J.

Logistyka

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2007

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nr 3

CD-CD

EN

This contribution focuses on the characteristics of common patterns of demand specifications for rail traction vehicles operating at industrial locations; followed by the analysis of track conditions on routes given by the operator and the analysis of trains travelling at low speed. In conclusion, the paper gives a graphical representation of the parameters that have been designed for determining the power demand from the diesel engine in the rail traction vehicle.

10

Metoda monitorowania plonu roślin przez pomiar mocy na WOM ciągnika podczas zbioru kukurydzy sieczkarnią polową

Lisowski A., Klonowski J., Sypuła M., Nowakowski T., Chlebowski J.

Problemy Inżynierii Rolniczej

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2004

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R. 12, nr 3

13--20

PL

Podczas badań stwierdzono, że uwzględnienie stanu technicznego maszyny wymaga pomiaru mocy dla dwu stanów: pod obciążeniem i na biegu jałowym. Uzasadniono, że podczas pomiaru mocy potrzebny jest również ciągły pomiar prędkości ruchu agregatu ciągnik-sieczkarnia i wilgotności roślin. Wymagana jest także informacja o przełożeniu między prędkością obrotową wału napędzającego i napędzanego, liczbie noży na tarczy zespołu rozdrabniającego oraz szerokości i liczbie zbieranych rzędów roślin kukurydzy.

EN

Paper presented the method of monitoring the yield of green maize harvested with a tractor driven forage harvester. The method is based on measuring the tractor PTO power output. It was stated that to recognize the technical condition of the machine, power measurements have to be taken at two states - under loading and at idle running. The power output measurements should be accompanied by continuous monitoring of the tractor-forage harvester speed and testing moisture content of plants harvested. The technical parameters such as rotational speed ratio of driving and driven shafts, the number of knives on chopper flywheel, spacing and number of harvested plant rows, are also necessary to be known.