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1
Content available remote Zagrożenia od wyładowań z powierzchni tkanin
PL
Zaproponowano uproszczony model układu uziemiony obiekt-naładowana tkanina, pozwalający na oszacowanie energii możliwej do uwolnienia z powierzchni tkaniny podczas wyładowania elektrostatycznego. Badano tkaninę syntetyczną zawierającą włókna przewodzące. Jako uziemiony obiekt przyjęto elektrodę kulistą, stosowaną w pomiarach ładunku przenoszonego. Przedstawiony model prowadzi do potęgowej zależności energii uwolnionej w trakcie wyładowania od gęstości wprowadzenia włókien przewodzących.
EN
A simplified model of the grounded object-charged fabric system was proposed. It allows to estimate the energy that can be released from the fabric surface during electrostatic discharge. The synthetic fabric containing conductive fibres was tested. A spherical electrode, used for charge transport measurements, was adopted as a grounded object. The presented model has led to the power type relation between released energy and the density of introducing conductive fibres.
PL
Impulsowe zakłócenia generowane podczas wyładowania atmosferycznego są przyczyną zakłócenia procesu eksploatacji elektronicznych systemów bezpieczeństwa (ESB). Prądy i napięcia występujące podczas wyładowania indukują w liniach dozorowych zakłócenia. Odpowiednia organizacja ESB na obszarze kolejowym i urządzenia przepięciowe to zabezpieczenie przed zakłóceniami. Występowanie zakłóceń podczas użytkowania systemu wymaga stosowania innego algorytmu do wyznaczania wskaźników oceny bezpieczeństwa.
EN
This paper presents the results of electromagnetic interference generated during lightning on the process of operation of security systems - ESB. Electric and magnetic fields which are generated during atmospheric discharge may have very high values near to the main channel of lighting discharge (1). The impulse of the electromagnetic field that occurs during this phenomenon, induces electromagnetic interferences (voltages and currents) having very high values (Fig. 1) also in power ground lines and in transmission buses of the ESB system. The pulse amplitudes of surge signals (main and return discharge) may affect operation of the ESB or cause total or partial damage. The ESB may be present at the set of different exploiting states, which result from “normal” or electromagnetic interferences exploitation process. The proper usage of the ESB in enormous railway is an absolutely complicated technical issue, where, in addition to the “normal” exploitation specified in technical standards, there are issues related to the problem of ensuring electromagnetic compatibility (3). The occurrence of electromagnetic interference with high power levels can lead to a catastrophic failure in the system of the ESS. The research allowed determining the effect of the pulse electromagnetic field generated during lightning on the test systems.
3
Content available remote Zero concentrate flow discharge membrane techniques for natural water treatment
EN
The main problem of modern RO and NF membrane techniques is the existence of concentrate flow that creates a problem of its utilization. Large amounts of RO/NF effluents are mainly attributed to fouling and scaling protection. Research of scaling and fouling mechanisms showed that these processes depend not only on hydraulic and hydrodynamic factors, but on membrane channel configuration as well. The novel concept of spiral wound module with the modified membrane channel (called “open channel”) is developed, fieldtested and introduced into practice. Fouling control is achieved due to the elimination of spacer and the implementation of an optimum hydraulic mode. Modification of channel provides the possibility to reach high recoveries and high supersaturation values due to strong stability of calcium carbonate solutions. The main principles of high recoveries and zero discharge are ensured by concentration of brine through re-circulation by 50-100 times by volume. Coagulated suspended matter after membrane flushes is collected, sedimented and finally dewatered. In case of hard water treatment the excessive calcium carbonate could be concentrated in membrane modules and subsequently precipitated, sedimented and dewatered. Several examples of water treatment flow diagrams are presented to demonstrate the principles of zero concentrate flow discharge.
PL
Podstawowym problemem współczesnych instalacji odwróconej osmozy i nanofiltracji jest powstawanie dużych ilości trudnego do zagospodarowania koncentratu. Problem ten nasila się w przypadku wystąpienia zjawisk fouling’u i scaling’u. Badania mechanizmu procesów fouling’u i scaling’u wykazały, że obok warunków hydraulicznych i hydrodynamicznych ma na nie wpływ konfiguracja kanałów ukierunkowujących przepływ przez membranę. Opracowano nową koncepcję modułu spiralnego z ukierunkowanym przepływem (nazywaną “open channel”) dzięki zastosowaniu odpowiednich przekładek w konstrukcji modułu membrany. Dobranie optymalnych parametrów hydraulicznych i eliminacja stref martwych pomogło w kontroli zjawiska foulingu i scalingu. Zastosowane rozwiązanie budowy modułów membranowych zapewnia możliwość uzyskania recurkulatu o dużym stężeniu dzięki silnej stabilności roztworu węglanu wapnia. Wysoki odzysk zapewnia 50-100-krotna recyrkulacja stężonej solanki. Zawiesina wypłukiwana z membran po koagulacji jest poddawana sedymentacji i odwadnianiu. Zaprezentowano kilka przykładowych schematów uzdatniania wody wykorzystujących przyjęte rozwiązania.
PL
Przeprowadzono badania wpływu dodatku Ca(OH)2 do elektrody niklowej typu Ni(OH)2/NiOOH. Powoduje on zarówno podwyższenie potencjału końca ładowania, jak i zdolności przyjmowania ładunku. Elektrody zawierające 0,5–3% mas. Ca(OH)2 już po pierwszym cyklu wykazują większą sprawność procesu wyładowania/ładowania, w porównaniu z elektrodami nie zawierającymi tego związku. Dla elektrod zawierających 0,5–2% mas. Ca(OH)2 w pierwszym cyklu ładowania/wyładowania stwierdzono zwiększenie masowej pojemności właściwej wyładowania o ok. 10%, zaś w kolejnych cyklach wartość ta pozostaje, o co najmniej 5% wyższa w stosunku do elektrody bez dodatku tego związku.
EN
After the 1st cycle, the Ni(OH)2/NiOOH-based Ni electrodes contg. 0.5–3% Ca(OH)2 showed increasingly better charge acceptance, higher (by 20–40 mV) final charging potentials, and a higher charge/discharge efficiency. In the 0.5–2% Ca(OH)2 electrodes, the mass specific capacity was 10% higher in the 1st charge/discharge cycle and 5% higher in the subsequent cycles.
EN
The methane conversion into C2 hydrocarbons, carbon black, and hydrogen has been studied under non-equilibrium plasma conditions, using dielectric barrier discharges (DBD) and gliding discharges (GD) at low and medium temperatures at atmospheric pressure. It has been found that ethane is the main product of the filamentary DBD action in the mixtures CH4+Ar and the reaction rate depends mainly on the concentration of high-energy components being able to initiate the chemical transformations of methane. Using GD, two processes are observed: the methane conversion into unsaturated hydrocarbons C2 (mainly acetylene) and into carbon black. The energy density of GD and the methane concentration in initial gas mixtures (CH4+H2 and CH4+Ar) are the main parameters influencing the methane conversion rate and the unit energy consumption.
EN
The reactions of methane under the conditions of barrier discharges were studied in the mixtures: 1) 50% CH4+ 50% Ar, 2) 50%CH4+ 25%CO2+ 25% Ar, and 3) 50%CH4+ 50%CO2, under atmospheric pressure at about 50°C and about 300°C. Besides hydrogen, ethane was the main gaseous product of the reaction, with small additions of ethylene and acetylene. An increase of the overall methane conversion and conversion into C2 hydrocarbons was observed in cases where grains of quartz glass was packed in the discharge gap.
EN
A gliding-discharge plasma reactor with a spouted bed of granular materials was developed for the study of the methane conversion into C2 hydrocarbons. It was found that the presence of ceramic grains moving across the discharge zone increased the methane conversion into acetylene and decreased the unit energy consumption.
EN
Experiments concerning the applying of dielectric-metal mesh system in ozone synthesis process were carried out. The mixed surface-glow discharge was obtained. It was found that Teflon is especially interesting as a dielectric material although its life-time in conditions of ozone synthesis process is not long. Well developed discharge on Teflon surface was obtained. High ozone concentration was obtained.
EN
Non-thermal plasma of pulsed dielectric-barrier discharge (PDBD) was used for the decomposition of tetrachloromethane. The study was carried out using air or oxygen as carrier gas. The effect of the initial concentration of CCl4, flow rate of gas mixture and presence of the packing in the discharge gap on conversion rate of CCl4 was studied. The pulsed dielectric-barrier discharge combined with the packing of TiO2, Pt/SiO2 or SiO2 (quartz glass) has been applied for tetrachloromethane conversion. It has been concluded that the granular packing in the discharge gap increases the conversion rate of tetrachloromethane.
EN
The electrogeometric model is now widely used for the dimensioning of lightning protection systems of ground structures. This model has the advantage of taking into account the magnitude of the lightning current and its statistical distribution but has a weakness in that it does not include the shape of electrode of the ground structure. This paper describes a laboratory experiment to investigate the dependence of the striking distance of a descending negative discharge on the shape of the ground electrode/structure. A theoretical study, based on the Lemke streamer-leader model, is also described. In this study, the streamer discharge is assumed to grow into a stable leader in the space between two electrodes when the streamer reaches a critical length, associated with the shape and polarity of the energized electrode. The experimental model uses an air-water interface in which the water conductivity is varied. The experimental results agree with the theoretical predictions.
PL
W projektowaniu układów ochrony odgromowej budowli naziemnych wykorzystuje się szeroko modele elektryczno-geometryczne. Ich zaletą jest możliwość uwzględnienia wartości prądu wyładowania i jego rozkładu statystycznego, wadą - niemożliwość analizy wpływu kształtu elektrod uziemieniowych. Artykuł przedstawia badania laboratoryjne zależności długości drogi przeskoku udaru o biegunowości ujemnej od kształtu elektrody uziemieniowej. Przedstawiono również analizę teoretyczną problemu w oparciu o model strimerowo-liderowy Lemkego. W analizie tej założono, że wyładowanie strimerowe przechodzi w ustabilizowane wyładowanie liderowe w przestrzeni międzyelektrodowej gdy strimer osiąga długość krytyczną, zależną od kształtu i biegunowości elektrody uziemieniowej. W modelu laboratoryjnym wykorzystano układ woda-powietrze ze zmienną konduktywnością cieczy. Wyniki badań laboratoryjnych są zgodne z analizą teoretyczną.
12
Content available remote Plasma-catalytic processing for environmental protection
EN
Plasma-catalytic processing may be an efficient way for the decomposition of tetrachloromethane and nitrous oxide. The silent and the gliding discharges combined with a catalytic bed have been applied. The gliding arc discharge combined with TiO" SiO2 (ąuartz glass), and y-Al,O, beds packing has been used for nitrous oxide processing in oxygen. The silent discharge stabilized dielectric barrier combined with TiO, bed packing has been applied for tetrachloromethane conversion to chlorine in argon and oxygen. The conversion ratę of nitrous oxide, as well as the coiwersion ratę of nitrous oxide to NO, was studied as a funetion of specific energy. The conversion ratę of nitrous oxide to elements and NO and the conversion ratę of nitrous oxide to NO increased when granular dielectric materials TiO,, SiO, (ąuartz glass), and y-Al,O3 were introduced into the discharge space. The effect of interelectrode space filling with granulated TiO2 on conversion ratę of CC14 to chlorine in silent discharge was observed.
EN
The results of researches concerning characteristics of discharges in homogeneous electric field with the application of composite electrodes made of the layers of polyester film as a dielectric and integrated with a mixture of powder carbon or graphite are presented. The effect of the kind and thickness of an electrode and of the gap size on ozone synthesis course has been analyzed.
EN
The effect of essential parameters (active power consumption and temperature of electrodes) on the process of ozone synthesis was studied in temperature range 1- 50' C. A catalytic effect of granular dielectric packing, placed in the discharge gap, on the process efficiency was observed. High concentrations of ozone were obtained in presence of dielectric packing when the discharge (glass) electrodes were cooled down to 1st.C.
EN
In this paper results of modelling of chemical processes in a mixture of Nz:O2:COz:H2O:NO subjected to a corona, discharge streamer are presented. The results show that NOx are decomposed mainly in reactions with OH and HO2 radicals generated from the water vapour.
EN
A simplified kinetic model of ozone synthesis in a silent discharge is presented. The influence of the discharge gap width on the ozone concentration and the energetic efficiency achieved has been calculated for this model. From the calculations it appears that, in agreement with the results of experiments and industrial practice, better results are obtained in an ozonizer with a smaller gap. This is an effect only of higher heat transfer rate resulting in a lower temperature in the discharge gap.
EN
In this paper experimental results of investigation of NOx removal from humid N2:02(5%):C02(15%):NO(400 ppm) mixture subjected to a positive pulsed corona discharge in a wire-to-cylinder reactor are presented. The experimental results show that NOx removal in the dry operating gas is less effective than when it is humid. The NOx removal was about 50% in the optimal conditions (9.5% of water vapour).
EN
A new type of reactor for plasma chemical vapour deposition from organic precursors, activated by audio frequency, is presented. It was found that ion bombardment process and plasma chemical processes are completely separated in the system and they can be idenpendently controlled. This feature makes it possible to produce two types of twin films, namely amorphous insulators (a-I) and amorphous semiconductors (a-S), using the same original compound and a continuous deposition process. The type of deposited material can be selected by only small changes of a coupling capacitance in the system. It seems that the reactor offers new possibilities for thin film technology consisting in preparation of novel class of layer structures formed from twin films of a-I and a-S.
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