Dragos Astanei

A correlation between the rotational temperature and the electrical energy of a cold plasma type electrical discharge produced by a double spark-plug

To improve the combustion process of the air-fuel mixture into the combustion chamber of the engines, an ignition system based on a three electrodes spark-plug and a microcontroller based supply has been proposed. The benefits which can be achieved by using the new system are: reduction the amount of some pollutants such as unburned hydrocarbons from the exhaust gases, improving the engines efficiency, fuel consumption decreasing and also some unwanted engine processes (misfires, hesitations, detonations, stutters and stumbles) can be avoided. The first phase of the validation process of the new ignition system was to perform a diagnosis of the plasma produced using the new spark plug and to compare the results with the ones obtained from the diagnosis of the plasma produced by a classical spark plug. Also the electrical parameters were measured for both the spark plugs and for different waveforms of the control signals. In this paper we present a correlation between the rotational temperatures of the plasma and the energy consumed by the discharges produced using the classical and the double spark plugs. The spectra used to determine the rotational temperatures have been recorded in air at atmospheric pressure using a spectrometer equipped with a CCD camera. The electrical discharge voltage and current measurement used to calculate the energy of the discharge have been made in air using a high voltage probe and a shunt resistance.

About the operation of the cold plasma GlidArc type reactors with rotary discharge and auxiliary electrodes

The cold plasma type electrochemical reactors are more often used for different applications such air or solutions decontamination, surfaces treatment and in some cases for bio-decontamination or even sterilization [1]. In the last decade, in the medicine field, several applications have been developed which assure bio-compatibility of the implant materials or even are used to treat living tissues (postsurgical or for skin disorders). The utilizations of the auxiliary electrodes in the construction of the GlidArc reactors confer on them the possibility to command and to control the main discharge, obtaining in this way certain benefits for the applications which use such devices [2], [9], [11]. Following the innovative solutions of the GlidArc type electrochemical reactors with auxiliary electrodes and planar discharge, volumic discharge or rotary discharge proposed by our research team, [3], [4], this paper aims are to present a appropriate mathematical model regarding the operation of the reactors with rotary discharge and auxiliary electrodes. In this way can be defined the fact that there is only one possible position of the auxiliary electrodes for which the command and the control of the discharge can be assured in the case of the reactors with rotary discharge comparing with the case of the reactors with planar symmetry where there are two possible positions of the auxiliary electrodes. Using the proposed mathematical model can be highlighted the influence of different constructive factors on the discharge evolution. The practice experience in implementation of the GlidArc type reactors with auxiliary electrodes is fully confirmed by the results offered by the mathematical model proposed in this paper.

Availability model of wind and solution to immunize the generators against short time perturbations

Following a previously presented availability model of wind considered as a self-repairable system, the authors developed a new one based on over two years of continuously wind state monitoring in a given location. The new aspects are related to short time wind perturbations defined by its speed variations outside the generic useful speed limits, to establish the correspondent availability model and to bring out how to immunize a wind aggregate to some kind of wind perturbations based on the mechanical time constant and on the similar methods used to immunize the electrical drives against voltage dips. A case study is also presented with a parametrical analysis and numerical results. The research was done using the facilities offered by new laboratory, LACARP - Laboratory for Applied Research and Prototype Design of the Power Engineering Department.

Availability assessment for grid-connected photovoltaic systems with energy storage

The availability indices of a grid-connected photovoltaic system, with and without backup energy storage, have been quantitative and qualitative analyzed in this paper. The analyses allow identification of photovoltaic system components whose reliability should be improved in the operational stage. In order to evaluate availability indices, the LACARP PV system structure has been considered in this study.

Zirconium and titanium surface treatment using non-thermal plasma for dentistry applications

The cold plasma reactors are more often used in the last decades in surface treatment and bio-decontamination. The aim of this paper is to present the GlidArc plasma effects on the material surfaces used in dentistry (zirconium and titanium plates). For the conducted tests two GlidArc reactors were used: the first one having two electrodes, producing a planar electrical discharge and the second one with three electrodes and volumic discharge. Keeping the treatment time constant (60 seconds) the nature of the blowing gas used (humid and dry air) and the distance between the plasma and the treating samples was modified. The surfaces were analyzed performing atomic force microscopy (AFM) in air at room temperature. Both topographical and adhesion force measurements were considered as parameters used for characterizing the morphological modifications of the surfaces induced by the plasma treatment.

Electrical modeling of a double spark at atmospheric pressure

Since the spark produced by the classic spark plug does not always ensure a complete and efficient combustion, various other types of spark plugs have been proposed for internal combustion engines (ICE). Among these different technical solutions have been found to be effective: pulsed LASER ignition, [1], system with multi ignition points, [2], electrical Corona or GlidArc discharges, [3], [4], multi - electrodes plug, developed by Bosch, [5], pulse jet combustor etc. We propose an ignition system with a double spark, achieved by placing between the high voltage electrode and the ground one, of a third unpowered electrode, having floating potential, with the shape of a washer. The validation of this type of plug by the chemical results corresponding to a better combustion, involves optimizing its construction in terms of breakdown of the double spark, using the optimal positioning of the auxiliary electrode. In order to achieve the optimization the equivalent electric capacity of the double spark plug is calculated, before the spark ignition. The parametric value of the capacity is introduced into an electrical schema similar to the classic spark ignition model. The schema has been simulated by using MULTISIM software, [6]. The simulated voltage characteristic was compared to the real voltage waveform. The perturbation values associated with working of the double spark plug in air were checked by measuring electromagnetic radiation perturbations near the ignition system with a spectrum analyzer. In the case of the double spark ignition into a combustion chamber, at different high pressure values, electromagnetic radiation perturbation is very low, so the described method could not be used for optimization of double spark construction. For this reason, all the experimental analyses such the voltage and electromagnetic radiation perturbation measurements have been realized for the discharge produced in air, at atmospheric pressure and humidity.

A review over the cold plasma reactors and their applications

The cold plasma reactors are more often used in the last decades for diverse activities such as: the pollutant treatment from air or from solutions, plastic or metallic surfaces treatment, improvement of the combustion or treatments which involves biological applications. The requirements imposed to these multiple applications of the cold plasma are very different, so we have proposed to realize an appreciation of these requirements to be able to identify the “preferences” for each type of the cold plasma reactor from the multitude of the constructive variants which can be founded in the specialized laboratories today. Thereby, for surfaces treatment or for implant materials treatment to ensure the bio-compatibility with the human tissue, can be used reactors with Corona discharges, DBD or especially GlidArc. In the case of treatments of the living tissues (human tissue), targeting the blood coagulation or wound healing, the most important problem is to how the avoid the electrocution - which means that the plasma power supply parameters have to be conveniently chosen, especially the working frequency, but also the constructive type of the reactor. The preferred one would be the reactor that works with a floating potential electrode.

The influence of the dispersion flux on the connection transient regime for DC electromagnets

The aim of the present paper is to analyze the behavior of the direct current electromagnets with null starting flux (when the initial position of the mobile armature does not meet the mechanical equilibrium) in dynamic regime. The electromagnets are considered as electromechanical energy conversion systems with two degrees of freedom, one electric (magnetic) and another mechanic [1]. The behavior of these electromagnetic devices is described by using typical mathematical systems of differential equations which can be solve with the finite difference method and iterative calculation of the characteristic parameters. The papers discuss about the influence of the dispersion magnetic flux from the connection process that can be translated into a decrease of the useful flux found at the electromagnet air gap, which also leads to a decrease of the electromagnetic force of the device. All this factors contribute at the increase of the connection time. By using modern methods for calculation, monitor of the parameters evolution with appropriate software (Mathcad 15) for a U-I electromagnet type supplied by a direct current power supply, was developed an algorithm which can determine the parameters values in the connection process. (displacement of the armature, total magnetic flux, dispersion magnetic flux etc.).

A New Spark Plug to Improve the Performances of Combustion Engines: Study and Analysis of Unburned Exhaust Gases

The ignition sparks provided by the conventional spark plug do not always ensure a fast and complete combustion of the hydrocarbon-air mixture. For this reason, we offer a new type of plug with a double spark using two simultaneous discharges generated by a pulsed high voltage-power supply. This work presents the comparison of two spark plugs, a classical one and a double spark plug, by analyzing the unburned hydrocarbon gases from the exhaust pipe of the engine. For a first gasoline engine, we measure the oxygen concentration in the exhaust gases with a lambda probe and the unburned hydrocarbon by the use of GC–MS coupled with SPME extraction technique. We can observe a clear decrease of total unburned hydrocarbon (THC). For a second motor test bench, powered with propane, we complete measures in function of air/fuel ratio of the THC, NOx, CO2 and CO. These results confirm that we obtained a better combustion especially for leaner mixtures.

Voltage dips analysis for grid connections of dispatchable photovoltaic systems

This paper focuses on an analysis on compatibility between power grid quality voltage and dispatchable photovoltaic plant integration. In this order, based on a simulation, voltage dips have been calculated on the bus bars of a test system (IEEE-RTS). The method for voltage dip estimation used in this paper provides the frequency of voltage dips, due to symmetrical and unsymmetrical faults in the grid.