Volume 1, No. 14 (2008)
Articles
VIRTUAL INSTRUMENT FOR FREQUENCY’S QUALITY INDEXES SURVEILLANCE
ABABEI ŞTEFAN, DAN ROTAR
In this paper there are presented a virtual instrument for frequency’s quality indexes surveillance. The virtual instrument is a application realised in Lab VIEW 3.1, and data is collected through a PC-LPM-16 acquisition board. The program has two main components: one for frequency measurement and one for frequency’s quality indexes calculus. The nominal frequency is fixed by operator on the front panel of the virtual instrument. The precision of measurement is better then 1%.
NUMERIC FREQUENCY METER WITH PLC
ABABEI ŞTEFAN, DAN ROTAR
In this paper is presented a numeric frequency meter that is realized with faze fittings circuit (?E 565). The realized frequency meter is destined to control the network frequency around the frequency of 50Hz. To display the value of the frequency two display devices with a common cathode VQE23F are used. Each display device contains two seven segments display cells. Frequency’s from 40 to 60 Hz can be measured which can then be displayed with two decimals.
NEW TECHNOLOGIES OF COAL COMBUSTION
ANITEI FLORIN 1), SAJIN TUDOR 1), CRACIUN ALEXANDRU 2), BUZDUGA ROXANA STEFANIA 1)
The paper presents the complete combustion processes for solid fuels. The incomplete combustion (or pyrolysis) is described to aid in understanding waste processing concepts that are based on this interesting but less common concept in waste pyroprocessing. The oil market risk insurance program provides a self-funding means to overcome a significant barrier to the rapid development of a new and needed domestic technology of thick fuel liquid fuel described in this paper.
PROPERTIES OF WATER-OIL FUEL EMULSIONS AND OF WATER-COAL FUEL SUSPENSIONS AND TECHNOLOGIES FOR ITS PREPARATION
ANITEI FLORIN 1), SAJIN TUDOR 1), CRACIUN ALEXANDRU 2) BUZDUGA ROXANA STEFANIA 1)
The properties of water-oil fuel emulsions and of water-coal fuel suspensions and technologies for its preparation are presents in this paper. The water-fuell emulsion and suspensions are a new types of liquid artificial fuel which physic and chemical properties, burning and heat transfer particularities are different in comparision with traditional fuel ones.
SOME ASPECTS ABOUT THE INFLUENCE OF FOULING TO STEAM CONDENSER OF A POWER PLANT
BADEA ADRIAN, GRIGORE ROXANA
Condenser performance and reliability have a significant impact on the electric generation of a power plant. Steam condensers are prone to fouling and the reduction in heat transfer that results almost invariably has an impact on product cost. Fouling on the heat transfer surfaces increase the thermal resistance, thus reducing the heat transfer performance and it is possible to appear failures. The paper presents theoretical considerations about mechanism of fouling in steam condensers, models for fouling evolution in time and the effects of fouling to effectiveness of condenser and power plant efficiency.
CONTRIBUTION TO OPTIMISE AN INTELLIGENT MECHANIC-ELECTRIC CONVERSION OF CLEAN ENERGY (WIND)
BENCHE VICTOR, UNGUREANU VIRGIL-BARBU, ŢÂRULESCU RADU
It is presented an applied brief study concerning the possibility for optimal obtaining an electrical power of 1 MW for a mean wind energy flux of 0.7 kW/m2 (a wind speed of 10.5m/s), using a high performance modern three-blade wind turbine having dimensional limits like the Danish wind turbine V63-1.5 MW (for wind speed ), equi-power and equi-speed, using the NACA-23015 lift airfoil. The optimisation is presented by an original analytical relation between wind speed, lift surface area and the proposed power that minimise the fluid energy loss and the axial push force, assuring the maximum mechanic-electric conversion.
THE ANALYSIS OF SOME HYDRAULIC POSSIBILITIES FOR ENERGY RECOVERY-STORAGE OF THE VEHICLES VARIABLE MOVEMENT
BENCHE VICTOR 1, UNGUREANU VIRGIL-BARBU 2, RADU ŢÂRULESCU 2, STELIAN ŢÂRULESCU 4
In the paper is analyze the hydraulic possibilities for energy recovery-storage of the vehicles variable (rectilinear, horizontal and curvilinear) movement on the base of some hydraulic scheme, using hydraulic pistons with large inner surfaces S, which is generating important pressure forces, used for actuating of some rotary volume pumps, multiplier of pressure, charged from a central tank with liquid, placed on the height h, with the flow rate Q in time t of the relative movement. In the accumulator is stocked hydraulic energy with multiplied pressure pacc and flow rate Qacc (fraction of the flow rate Q). There are making evident the determinant influence factors and the practical possibilities of energy recovery degree increasing. In the study is showed a numerical application.
MATHEMATICAL MODEL OF WATER-OIL EMULSION BURNING PROCESS
BUZDUGA ROXANA STEFANIA 1, SAJIN TUDOR 1, CRACIUN ALEXANDRU 2, ANITEI FLORIN 1
The paper presents the mathematical model of the processes involved in combustion of water-in-oil emulsion and the examination of the past research efforts in the field of oil combustion The model uses the oil properties and the emulsion characteristics, such as the water percentage present in the emulsion and the surrounding conditions as input data. The mathematical model is solved numerically using finite difference method.
PREPARATION AND BURNING OF WATER-IN-LIQUID FUEL EMULSION
BUZDUGA ROXANA STEFANIA 1, SAJIN TUDOR 1, CRACIUN ALEXANDRU 2, ANITEI FLORIN 1
The basis of liquid combustion and the particularities of water-in-liquid fuel emulsion burning are presented in this paper.
AIR EXHAUSTER WITH HIGH TOXIC GASES AND DUST CONTENT, BASED ON TWO-PHASE EJECTORS
OVIDIU MIHAI CRĂCIUN, RADU ŢÂRULESCU
In this paper is presented a hydro – pneumatic device based on biphasic ejectors, having as motor fluid water, with agents for toxic gases neutralization. Because of this mixture, motor fluid with toxic air (having a high toxic gases and dust content), it is accomplish, beside the dust restraining, a chemical purification of the air, having the possibility of air recirculation.
THEORETICAL STUDY ABOUT THE MAKING AND USING ENERGY
FLORESCU IULIAN, DANIELA FLORESCU
The tendency of the last decades in making and using the energy was given by the low prices of the energy based on hydrocarbons and it lead to the making of a general model of production and consumption based on an emphasized wastage of energy imposed by the existing, massive resources and by the convenient prices.
JUNKS` S THERMO CAPITALIZATION
FLORESCU IULIAN, DANIELA FLORESCU
The increase of the caloric power of the communal junks on the one hand and their heterogeneous structure on the other hand make possible the exploitation of their thermo energetic potential, especially if one can take into account the positive aspects of the ecologic impact. Another aspect refers to the diminishing of the surfaces used for gathering the refuse.
SIZING OF A STAND-ALONE PEM FUEL CELL POWER SYSTEM PART I: LOAD DATA ANALYSIS, DESIGN SPECIFICATIONS AND FUEL CELL DESIGN
MARIAN GAICEANU
This paper intends to be a real useful tool into designing the fuel cell power systems for stationary applications. A complete methodology, sustained with a certain system example is shown. This tool can calculate the necessary power for the overall system, followed by the design of each fuel cell power system’s component having the maximum load power as main data input. Because the changes in the electrical load are faster than in the fuel cell process, the storage elements are necessary. In order to design the storage elements of the system, the real ac and dc load profiles of a certain application have been used. The single phase inverter, 220Vac, 50Hz in stand-alone operating mode has been established through an adequate analysis of the load profiles. The fuel cell stack voltage, Vfc, has 48Vdc, as nominal value. The dc bus voltage level (48Vdc) was chosen by taking into account the fuel cells manufactures. Therefore, the voltage level must be increased to 220Vac. Moreover, the galvanic isolation is required. The isolation aspect is covered by using an adequate push-pull converter. In this way the voltage level is increased to 400Vdc. The second energy conversion is mandatory. By using a half bridge inverter topology, the 220 Vac-50Hz desired voltage level is obtained. The hydrogen necessary for the proton exchange membrane (PEM) fuel cell stack is obtained from the reformer. The fuel cell polarization curve has been modeled by using the Amphlett model. In order to charge the battery pack, a bidirectional half-bridge dc-dc converter has been used. The main requirement in sizing of the battery stack is to support accordingly the start-up of the fuel cell stack. In the same time, the battery must support the auxiliary system consumption in order to supply the fuel cell during operation. The detailed energy analysis, the components sizing and output results from this tool are presented.
SIZING OF A STAND-ALONE PEM FUEL CELL POWER SYSTEM PART II: THE BATTERY PACK AND HALF-BRIDGE POWER CONVERTER DESIGN
MARIAN GAICEANU
In the first part of this paper a stand-alone power system based on a proton exchange membrane fuel cell (PEM) fuel cell stack is designed using a developed tool. The fuel cell power system supplies electricity to the user load without being connected to the electric grid. This kind of power system is developed in the isolated regions. The load analysis, the design requirements and the PEM fuel cell stack design have been performed in the first part of this article. The aforementioned tasks have been implemented by using the Microsoft Excel software. In this way a dedicated design tool has been resulted. The advantages of using this tools are the rapid prototyping the stand-alone fuel cell power systems. The fuel cell power system consist of a reformer, PEM fuel cell stack, battery pack connected with a bidirectional half-bridge dc-dc converter, and power conditioning units (PCU) to give the adequate system topology. The generator sources (battery, fuel cell) are designed to meet the requirements of a user load. During the start-up of the fuel cell process, the user load is powered totally by a battery pack. A proton exchange membrane (PEM) fuel cell is used to keep the system’s reliability at the same level as for the conventional system while decreasing the environmental impact of the whole system. The PEM fuel cell consumes gases which are produced by a reformer to meet the user load demand. Power conditioning units are appropriate for the conversion and dispatch the energy between the components of the system.
SIZING OF A STAND-ALONE PEM FUEL CELL POWER SYSTEM PART III: DESIGN OF THE PUSH-PULL CONVERTER AND THE SINGLE-PHASE INVERTER
MARIAN GAICEANU
The third part of the paper concludes the design tool of a stand-alone power system based on a proton exchange membrane (PEM) fuel cell stack by means of Microsoft Excel. The design of the push-pull converter, single-phase inverter and of the output filter are described in separate sections of the paper. All the data are derived from the specific load conditions for the stationary application. The design tool is used in order to choose an adequate topology for the PEM fuel cell power system.
THE COLD WELDING ON COGGED SURFACES
GEORGESCU BOGDAN, GEORGESCU VALERIU
Welding by cold pressing on cogged surfaces, produces the joint of a component made from an easy deformable metal by pressing on the cogged surface of a harder metal component. Different welds between aluminium (the easy deformable component) and copper, brass, steel, stainless steel (harder component, cogged on the contact surface) can be obtained. The weld is obtained only by deforming the aluminium component at a deformation rate of 20…20%. The welding on cogged surfaces of materials with different plasticity makes possible the production of bimetallic or multilayer elements. The weld tensile strength is up to 10% of aluminium ultimate tensile strength, better results being obtained for the shearing strength. The weld contact electric resistance is negligible, recommending the process for producing dissimilar elements used in electrotechnics.
DECREASING OF THE ELECTRICAL ENERGY LOST USING WELDING ON COGGED SURFACES
GEORGESCU BOGDAN, GEORGESCU VALERIU
The welding on cogged surfaces between aluminium and copper to be useful so as to replace the mechanical aluminium-metal contact with the copper-metal contact. The possible applications in this respect have been analyzed for the following concrete directions: The welding of electric aluminium conductor bars; The sheathing of electric aluminium conductor bars; The sheathing of the aluminium clips. The contact electric resistance measurements made with a CA 10 Microhmeter indicates negligible values of 1-5 µ?. These values are constant in time during the exploitation of the electrical contact (tests during months of exploitations were also performed). The temperature in the contact area was measured with a Therma Cam PM 675 PAL thermographic camera. The efficiency of the sheathing is obvious if we were to consider the overheating inside the substation with only 3°C as compared to the 30-40°C normally existing there in the case of classical joints.
THE ESTIMATION OF THE POWER AND ENERGY LOSSES IN ELECTRIC ENERGY DISTRIBUTION SYSTEMS
GEORGESCU GH, VARVARA VIOREL
The continuous growth of the number and installed power of the electric energy consumers and the growth of the density of consume in large urbanistic areas, led to the necessity of a durable development of the electric energy distribution systems. At present time, the estimation of the power and energy losses in the distribution systems is done with difficulty, mainly, because of the lack of instruments installed in the nodes of the networks that allow the continuous record of the loads. In the paper, there are presented two methodologies: the decomposition of the load curves into Fourier series and the sampling of the load curves. On these bases there were realized packages of software that estimate the power and energy losses in electric distribution systems. The input data need a low number of measurements in the network and the results have a good precision.
STUDY REGARDING SIMULATION AND MODELING OF STEAM CONDENSER
GRIGORE ROXANA, DRAGUSANU VASILE, LAZAROIU GHEORGHE, POPA SORIN
The steam condenser is a major component of a power plant cycle. In the space of the condenser, the steam which exhaust from the turbine is forced to give up its latent heat of vaporization. The condenser generates a vacuum which increases the amount of energy extracted from the steam by the turbine. The stability of operation and the efficiency of the power plant depend on the efficiency of steam condenser operation. These things go to developing a dynamic model of steam condenser.
PROGRAM FOR COMPUTATION WATER-STEAM THERMODYNAMICS PROPRIETIES
GRIGORE ROXANA, HAZI ANETA, POPA SORIN
The paper presents a program very useful for calculating the water and steam proprieties. The program , elaborate in programming language Borland Pascal has 4 procedures for superheated , saturated water and steam. Equations assure the computation of thermodynamic values with maximum deviations: ± 0,05 % for constant volume, ±1kJ/kg for enthalpy and ±0,0010kJ/kgK for entropy. Accuracy of the equations and consistency along the region boundaries are more than sufficient for engineering application.
MODELLING OF THE JOULE TYPE ELECTROTHERMAL CONVECTION IN CONDUCTING LIQUIDS
GROSU TUDOR 1, SAJIN TUDOR 2
The paper presents a theoretical analysis of the effect of Joule heating on the stability of mechanical equilibrium and development of electroconvective phenomena in liquids with conductivity on the order of 10-3-10-6 S/m. Distinguishing characteristics of Joule heating of these liquids consist in the appearance of an electric force proportional to the potential difference of the fourth power, in the existence of conditions of the liquid’s dominant tendency toward electrohydrodynamic equilibrium, and development of electrothermal convection of the Joule type, which is characterized by formation of layered structures such that nonstationary wave movements are observed near the electrodes, and stationary currents like Bénard cells in the core of the flow. Depending on the heat-exchange conditions at the boundaries with the electrodes, convection may occur in a limited region of the liquid with an inversion surface for the sign of the temperature gradient, or it may encompass the whole volume if certain conditions are observed. In our view, experimental checking of obtained dependences will make it possible to confirm the physical hypotheses in relation to electric convection of the Joule type and its practical use.
BLACK LIQUOR - SOURCE OF RENEWABLE ENERGY FOR THE PAPER MAKING INDUSTRY
HAZI ANETA, HAZI GHEORGHE
In the paper making industry black liquor, which results from the technological process, is an important renewable energy source. In this paper, the authors present, the first, use ways of black liquor for generation of thermal and electrical energy. After that, it is presented numerical results from a pulp and paper mill, standing out fuel saving and reduction of environmental pollution.
EXERGY EVALUATION OF THE COOKING PLANT
HAZI ANETA, HAZI GHEORGHE
Exergy analysis can lead us to improve thermal processes. The pulp and paper industry was chosen for this exergy analysis because of this sector’s high energy demand on both electricity and fuel oil. In this paper, the authors present the cooking process, the exergy evaluation of this process and numerical result for a cooking plant.
COMPLEX ASYMMETRIC REGIMES IN THE 110 KV NETWORK DUE TO RAR AUTOMATION
HAZI GHEORGHE, HAZI ANETA, MANOLIU CRISTINA, VERNICA SORIN
This paper analyzes a particularly case of complex asymmetric which appears in the 110 kV radial networks when monophase RAR works. It is determined working equations and they are solving for a numerical example. Finally, it is shown influence of impedance above fault place and success conditions for monophase RAR.
ENERGY SAVING IN SUGAR MANUFACTURING PROCESS
ION V. ION, ION DANA IOANA
This paper presents a thermo-energetic analysis of the processes in a sugar mill. This study is motivated by the deficiency of thermoenergetic studies on that processes and environmental impacts. This study provides solutions for rational energy use and optimizations according to the constraints imposed on juice concentration at evaporator outlet and the constraint imposed on power balance of the factory.
INTELLIGENT CONTROL SYSTEM OF A LOW POWER AUTONOMOUS WIND POWER STATION
LIVINTI PETRU, BRAILEANU CATALIN
This work is presenting an intelligent control system of an autonomous wind power station, of low power. This system is composed of a programmable logical controller (PLC), EASY 512-DC-RC produced by Moeller, a signal adaptor for the voltage measured on the terminals of a condenser, a stabilized voltage source of 24 V D.C. for supplying the PLC and an interface with miniature relays for connecting the load resistors.
SIMULATION, IMPLEMENTATION AND TESTING OF A NEW PWM INVERTER FOR SUPPLYING RELUCTANT MOTORS
CALIN MARGINEAN, TRIFA VIOREL, EMIL TRIFU
The paper deals with the aspects regarding the simulation, implementation, and testing of a new PWM inverter for reluctant motors, using an IR2101 driver from International Rectifier. Two types of reluctant motors are used, a variable reluctance motor(VRSM) and a switched reluctance motor(SRM). The simulation of the inverter using OrCAD environment and the acquired waveforms with LabVIEW environment in case of inverter testing are presented.
CHALLANGES OF FIBER OPTIC INFRASTRUCTURE USED IN WIDE AREA PROTECTION OF THE ROMANIAN POWER GRID
ION NEDELCU, VIZITEU IOAN, MARIA VIZITEU, GHEOGHE HAZI
The field of protection systems used in power systems is more and more dominated by computer based relays. In the power systems of Europe, but not only, the deregulation is appeared and works. Due to the operational demands imposed on transmission networks by this, it is clearly that wide-area measurements and their integration in protection and control systems becomes more then a necessity.Wide Area Protection (WAP) using fiber optic is one exemple of integration of communication in protection systems. Transelectrica SA ( Romanian Transmission Power Grid and System Operator), trough the Teletrans Sa (which ensure the operation and maintenance for telecomunication networks and systems owned by Transelectrica SA), has a strongly and robust communication architecture witch can be used for WAPaC (Wide Area Protection and Control) of Transmission Power Grig, in order to extend the system operational limits
DECISION TREE AND EXPERT SYSTEM FOR IMPROVE THE MANAGEMENT OF WATER
COSTICĂ NITU, EUSEBIU PRUTEANU *, DAN DĂSCĂLIŢĂ **
In this work the main goal is to design and develop a expert system, with special focus on water management and quality. It is remarkable the high quantity of information and knowledge patterns implicit in large databases coming from the monitoring of any system or dynamical environmental process. For instance, historical data collected about meteorological phenomena in a certain area, about the performance of a wastewater treatment plant, about characterizing environmental emergencies (toxic substances wasting).
THE USING OF ARTIFICIAL INTELLIGENCE IN THE RELIABILITY INDICES OPTIMISATION OF ELECTRICAL EQUIPMENT
C. PANCU, NEMEŞ C., BARABOI A., M. ADAM
In this paper a system based on artificial intelligence is proposed in order to optimisation the reliability indices of the electrical equipment. Using this method it obtains the distribution function type of the various failure of electrical equipment. This approach is much more efficient than the classic method if it knows a historical behaviour of analysed equipment..
THERMAL PERFORMANCE OF PARABOLIC CONCENTRATING COLLECTORS
PARASCHIV SPIRU
For many applications it is desirable to deliver energy at temperature higher than those possible with flat-plate collectors. Decreasing the area from which heat losses occur can increase energy delivery temperatures. This is done by interposing an optical device between of source of radiation and the energy-absorbing surface. He small absorber will have smaller heat losses compared to a flat-plate collector at the same absorber temperature. This paper present a method to evaluate the thermal performance of parabolic concentrating collectors.
A MATHEMATICAL MODEL FOR THE ESTIMATION OF DAILY SUNSHINE DURATION
PARASCHIV SPIRU, PARASCHIV SIMONA LIZICA, ION V. ION
Solar energy systems require detailed information concerning the availability of solar radiation. The total amount of solar energy depends upon the season of the year and sky conditions during day time. The performance calculations of solar energy systems are sometimes carried out on an hourly basis. To make such performance calculations for a system, it is necessary to have an idea of the hourly values of the radiation.The present article shows a methodology of calculation of the: solar altitude and azimuth angles at solar noon and sunrise and sunset times in any location in a specific day.
COMMENT L’INEVITABLE INCERTITUDE PARAMETRIQUE AFFECTE L’OPTIMALITE DES POLITIQUES DE MAINTENANCE
PIERRAT LAMBERT 1, VIZITEU IOAN 2
Par suite de son impact technico-économique, la définition d’une politique de maintenance optimale est un aspect important dans le contexte de la sureté de fonctionnement. Le but de ce papier est de mettre en évidence les limites des modeles de maintenance des lors qu’ils s’appliquent a des situations réalistes caractérisées par d’inévitables incertitudes. Dans la premiere partie, on met en évidence une relation entre la disponibilité et l’entropie d’information, puis on analyse l’influence de la complexité fonctionnelle et des incertitudes paramétriques sur la disponibilité d’un systeme markovien stationnaire. Dans la seconde partie, on présente trois modeles relatifs a des politiques de maintenance optimale : périodicité optimale d’une maintenance préventive basée sur l’âge, périodicité optimale de test d’un dispositif de secours et cout critique optimal d’une réparation minimale. On montre que l’incertitude des parametres technico-économiques se propage a travers les modeles et amoindrit l’acuité de l’optimum théorique. En conclusion, on suggere de rechercher un compromis entre la complexité des modeles et l’incertitude des informations accessibles.
EXPERIMENTAL IDENTIFICATION OF THE EQUIVALENT CIRCUIT USED FOR THE PHOTOVOLTAIC POWER SYSTEM SIMULATION
PIERRAT LAMBERT 1, WANG YAW-JUEN 2
In order to analyse a photo-voltaic power system we can use the following methods: analytical, circuit simulation or experimental. In this paper we propose to measure the current-voltage characteristics of a photo-voltaic cell influenced by temperature and radiation intensity using a low-frequency signal injection method. This one permits to obtain the parameters of an equivalent cell circuit used in the circuit simulation software EMTP. Comparison of measured and simulated data at quasi steady-state and dynamic conditions has been carried out. We present briefly an application case concerning the determination of a photo-voltaic module characteristics under partial shading. This proposed method can be useful for further studies of photo-voltaic power systems such as array modelling, array fault analysis, isolated network operation, etc
LIMITES DU FACTEUR DE FORME CARACTERISANT LE POTENTIEL ENERGETIQUE D’UN SITE EOLIEN
PIERRAT LAMBERT
L’énergie éolienne est caractérisée par la variabilité intrinseque de la vitesse du vent. Une turbine éolienne a pour but d’extraire l’énergie aéraulique maximale disponible, compte tenu de la distribution statistique de la vitesse du vent sur le site considéré. Le potentiel énergétique d’un site peut etre défini par un facteur énergétique (Energy Pattern Factor) qui dépend des lois de la mécanique des fluides et de la variabilité de la distribution de la vitesse. Pour tenir compte de la diversité des situations possibles, la distribution classique de Rayleigh est étendue a celle de Weibull. Ceci permet d’obtenir l’expression analytique exacte du facteur énergétique et de borner sa valeur dans une plage réaliste. Une analyse comparative entre valeurs théoriques et expérimentales collectées dans la littérature montre la validité de l’approche proposée.
ELECTRIC FIELD MEASUREMENT FOR LOW VOLTAGE AUTOMATIC CIRCUIT BREAKER
POPA SORIN EUGEN
In this paper I present the measurement of the electrical field around the low voltage automatic circuit breaker in different scenarios. The measurements are taken from two axes, and will be compared with values obtained from mathematical simulations. The methods that are used are elaborated by the author in his doctoral paper work.
INFLUENCE OF THE SUN POSITION AND SOLAR IRRADIATION OVER PHOTOVOLTAIC POWER PRODUCTION
POPA SORIN EUGEN, PUIU PETRU GABRIEL, ANGHELUŢ MARIUS
In this paper we present a mathematical algorithm used to determine the photovoltaic power depending of position of the sun and the solar irradiation. The algorithm can be used to simulate the sun position, the solar irradiation and the electrical power production of an particular photovoltaic cell panel.
LIFE-CYCLE ANALYSIS OF TRANSFORMERS OF TRANSFORMING STATIONS AND POSTS
POPESCU CRISTINEL
Transformers of electric transforming stations and posts represent the most precious equipments, reason that requires attempts and due prophylactic measurements in order to forecast the life-cycle of transformers. The establishment of the allowable overcharge and of its life-cycle in the rush our of systematical and accidental charge has a specially practical importance for the exploitation of electric transformers of electric transforming stations and posts.
SENSORLESS CONTROL OF THE INDUCTION MACHINE BY USING A KALMAN OBSERVER
MIHAI PUIU – BERIZINŢU, ANGHELUŢ MARIUS
This paper work presents a method to receive in a sensorless way the rotor speed and the rotor flux of an induction machine by using a Kalman observer. There is presented the Kalman filter general theory and its applying way for the implementation of an optimal recursive observer, named Extended Kalman Filter (EKF). The observer with EKF for the rotor speed and flux estimation is simulated by using MATLABSIMULINK files, and the conclusions of the simulation study are presented.
ENVIRONMENTAL BENEFITS OF BIODIESEL
IRINA-GABRIELA ROŞCAN
Since the beginning of the 1980s a number of studies on the energy and environmental efficiency of alternative fuels was carried out. Most of the studies caused hot discussions among proponents and opponents on an expert level but also in the public. Atmospheric and environmental deterioration due to large consumption of fossil fuels has become an environmental problem taken up on a global scale. Resolving this problem, together with global warming by CO2, has become one of the foremost issues in modern society. În recent years, in particular, attention has focused on diesel vehicle emissions as a major cause of atmospheric deterioration. Policies are being advanced to reduce the burden on the atmosphere and the environment both in terms of fuel and in terms of fuel-burning equipment.
BUILDING ENERGETIC EFFICIENCY ESTIMATION USING THE NEURAL NETWORK TECHNOLOGY
DAN ROTAR, ABABEI ŞTEFAN
The building energy consumption represents an important domain of study because of these implications to social, economic and environmental issues. Many complex tasks can be solved using the artificial intelligence methods. The paper describes the building energy consumption evaluation with aid of neural network solutions. Based on the known building behavior data the neural network is trained for evaluation of different solutions for the new building. This new method reduces the building design duration and saving spends founds.
VIRTUAL INSTRUMENT WITH PIC 12F675
DAN ROTAR, ABABEI ŞTEFAN
Virtual instrumentation achieved mainstream adoption by providing a new model for building measurement and automation systems. Keys to its success include rapid PC advancement; explosive low-cost, high-performance data converter (semiconductor) development; and system design software emergence. The paper presents a virtual instrument achieved with the PIC 12F675 microcontroller. The implementation method and the results achieved are presented.
AIR POLLUTANTS REMOVAL AT BURNING OF WATER-FUEL EMULSIONS AND SUSPENSIONS
SAJIN TUDOR 1, CRACIUN ALEXANDRU 2, ANITEI FLORIN 1, BUZDUGA ROXANA STEFANIA 1
The particularities, economic and ecologic indexes and experimental data of study of the water-heavy oil emulsions and of the water-coal suspensions burning process on a test installation are presents in this paper.
DEVELOPMENT OF NEW TECHNOLOGY OF BURNING AND POLLUTANTS REMOVAL IN ELECTRIC AND MAGNETIC FIELDS ON BASIS OF GASEOUS COMBUSTION
SAJIN TUDOR 1, CRACIUN ALEXANDRU 2, BOTEZ CLEOPATRA 3
The basis of gaseous combustion and the development of new technology of burning and pollutants removal in electric and magnetic fields are presented in this paper.
ELECTROPLASMOCHEMICAL TECHNOLOGIES OF THE ORGANIC FUELS COMBUSTION(FIRING) AND OF THE POLLUTANT EMISSIONS REDUCTION
SAJIN TUDOR 1, CRACIUN ALEXANDRU 2, BOTEZ CLEOPATRA 3, PUIU PETRU GABRIEL 1, SILAV ROXANA STEFANIA 1, ANITEI FLORIN 1
This paper work presents new electroplasmochemical technologies of the fuel composition preparation, of the flame direction and of the sulphur and nitrogen oxides conversion into mineral fertilizers. The experts debugged an efficient electroplasmochemical method regarding the thermal, kinetic and geometric characteristics setting of the flame and of the incomplete firing reducing.
THE GAS RESOLUTION AT THE PULSES DISCHARGE
SAJIN TUDOR 1, BOTEZ CLEOPATRA 2, CRACIUN ALEXANDRU 3, PUIU PETRU GABRIEL 1, SILAV ROXANA STEFANIA 1, ANITEI FLORIN 1
In this paper work there are presented the study experimental and theoretic results of the gasses resolution and synthesis processes under the pulses discharge. These results are the base of a new electroplasmochemical technology regarding the gasses processing, that could be applied at the fuel mixture preparation, in the firing and depollution of the firing gasses processes.
METHODS OF WATER CLEAVAGE INTO OXYGEN AND HYDROGEN (STATE OF THE ART)
SAJIN TUDOR 1, CRACIUN ALEXANDRU 2, CULEA GEORGE 1, CULEA CĂTĂLINA 1, ANITEI FLORIN 1
This paper is referring to modern systems, in particular to photo-electrochemical cells for water cleavage into hydrogen and oxygen, wherewith it is realized the pure ecologic cycle of solar energy conversion.
NEW SOLUTIONS FOR THE PERFORMANCES IMPROVEMENT OF SOLAR PLANTS FOR WATER CLEAVAGE INTO OXYGEN AND HYDROGEN
SAJIN TUDOR 1, CRACIUN ALEXANDRU 2, CULEA GEORGE 1, CULEA CĂTĂLINA 1, ANITEI FLORIN 1
This paper is referring to photo-electrochemical systems for water cleavage into hydrogen and oxygen, wherewith it is realized the pure ecologic cycle of solar energy conversion. It was obtained the patents for two installation realized in scheme of tandem photo-electrochemical cells. Its performances consist in increasing yield of solar energy conversion in chemical energy of the water decomposition components which can amount from 8-10% to 30% values.
UNBALANCED OPERATION OF TRANSFORMERS AND ELECTRICAL ENERGY LOSSES
TOADER C., POSTOLACHE P., GOLOVANOV N., FLORICĂU D.
In the paper is presented a useful method for electric energy losses evaluation in two-winding transformers. An adequate mathematical model for the case of several transformers working within the same power station is developed, by supposing an unbalanced transformers load.
HEAT PIPE HEAT EXCHANGERS USED IN WASTE HEAT RECOVERY SYSTEMS
UNGUREANU VIRGIL-BARBU *, HORNEŢ MIRCEA **
It is presented an applied brief study concerning the possibility of heat pipe heat exchanger utilization in waste heat recovery systems and there are emphasized advantages of this kind of heat exchanger. A numeric comparison is carried out in order to prove the superiority of the forced convection heat transfer for fluids passing across pipes, like both regions of the heat pipe.