Research Interests:
This paper aims to design an adaptive fuzzy logic voltage controller for a residential MG including PV-array and flywheel/battery hybrid energy storage implemented in a DC bus configuration. Specifically, the controller is developed for... more
This paper aims to design an adaptive fuzzy logic voltage controller for a residential MG including PV-array and flywheel/battery hybrid energy storage implemented in a DC bus configuration. Specifically, the controller is developed for the MG islanded operation. The most relevant simulation scenario is considered the maximum load, defined based on load power profiles and correlated PV generation profiles. Considering the DC bus voltage error and the battery state of charge as inputs, the fuzzy controller elaborates a power correction to be applied to the regular power assignments determined by the normal operation power management. Simulation results prove that the controller achieves very good performances in supplying the critical load during islanding, while maintaining adequate levels of voltage and frequency towards the critical load.
Research Interests:
Research Interests:
The paper objectives answer to European Commission requires which decided for transport sector a 90% reduction of pollutants emissions till the year 2050. Alternative fuels like animal fats can represent a viable solution for diesel... more
The paper objectives answer to European Commission requires which decided for transport sector a 90% reduction of pollutants emissions till the year 2050. Alternative fuels like animal fats can represent a viable solution for diesel engines due to their good combustion properties, pollution reduction, and the possibility of raw state use in blends with diesel fuel or as biodiesel. A D2156 truck diesel engine is fueled with preheated raw animal fats, blend with diesel fuel in 5% and 10%. At the 55% engine load and 1450 rpm engine speed, for 10% animal fats-diesel fuel blend, the pollutant emissions levels decrease with 21% for NOx, with 50% for HC, with 66% for CO, with 30% for smoke due to the decrease of carbon content and increase of oxygen content. The CO2 emission level decrease by 14%. An important novelty aspect is a good correlation between engine running regime, diesel fuel, and animal fats cyclic dose, pollutants emissions level and exhaust gases temperature. The use of ani...
Research Interests:
Research Interests:
The experimental investigations carried out within the present research focus on a simple gasification technology dedicated to biofuels conversion according to the Lurgi procedure. Specifically, an installation with a fixed grill and a... more
The experimental investigations carried out within the present research focus on a simple gasification technology dedicated to biofuels conversion according to the Lurgi procedure. Specifically, an installation with a fixed grill and a homogeneous distribution of the air inlet over the combustion space are considered. In order to provide a thorough background for the experimental research, this paper presents first the challenges related to the air distribution. If for coal gasification the difficulty of the homogeneous penetration of the air inlet within the whole combustion volume is balanced by the possibility of the direct emission of CO valorization, for biomass gasification this factor becomes fundamental. The original contribution of the technology introduced in this paper assumes an improved combustion process for Lurgi-type gas generators. The experimental installation employed has a particular design, enabling a homogeneous distribution of the air inlet over the entire com...
Research Interests:
The thermal treatment of chicken manure is an ecological alternative of neutralizing this kind of waste with energy recovery. In this regard, a two-stage pyrolysis process was chosen, the first stage having the purpose of preheating and... more
The thermal treatment of chicken manure is an ecological alternative of neutralizing this kind of waste with energy recovery. In this regard, a two-stage pyrolysis process was chosen, the first stage having the purpose of preheating and moisture elimination. The drying process up to the starting point of volatile matter release, about 200-250°C was taken into consideration. As a result of the moisture elimination in the first step of the pyrolysis process, a gas fuel riched in CO, CH4, H2 will be obtained. The experimental determinations consisted in the proximate and ultimate analysis of the initial residue and tests of the pyrolysis process in a pilot plant that allows the pyrolysis of a quantity of waste in range of 40-200g. A sample of a 140 g was subjected to the pyrolysis process at 500°C and the char (an organic, solid, consistent and odourless product) was obtained. The carbon (C), nitrogen (N), hydrogen (H) and sulphur (S) contents of the final product of pyrolysis were det...
Research Interests:
Solid biomass combustion is characterized by two main issues: fuel high moisture weight (that generates some ignition failures) and the high rate of carbon monoxide from flue-gasses (that diminishes the efficiency of the burner an... more
Solid biomass combustion is characterized by two main issues: fuel high moisture weight (that generates some ignition failures) and the high rate of carbon monoxide from flue-gasses (that diminishes the efficiency of the burner an increases the pollution). Hydrogen injection (with a higher combustion velocity) disables the disadvantages mentioned above, allowing the design and operation of more efficient and less pollutant biomass boilers. The paper enhances the theoretical and experimental issues related to the hydrogen use during solid biomass combustion.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
In the context of carbon dioxide emissions reduction, hybrid energy systems including both classical and renewable power plants require additional technologies to achieve depollution targets. Power-to-methane concept gains a lot of... more
In the context of carbon dioxide emissions reduction, hybrid energy systems including both classical and renewable power plants require additional technologies to achieve depollution targets. Power-to-methane concept gains a lot of popularity, enabling both carbon dioxide utilization and renewable energy surplus management on long term time frames. This paper investigates the potential of power-to-methane technologies to contribute to renewable energy penetration augmentation and more reliable load supply. Moreover, the trends of renewable energy share in each sector are presented and discussed, in the perspective of cross-sectoral integration.
Research Interests:
This paper presents a comparative analysis of different battery charging strategies for off-grid solar PV systems. The strategies evaluated include constant voltage charging, constant current charging, PWM charging, and hybrid charging.... more
This paper presents a comparative analysis of different battery charging strategies for off-grid solar PV systems. The strategies evaluated include constant voltage charging, constant current charging, PWM charging, and hybrid charging. The performance of each strategy is evaluated based on factors such as battery capacity, cycle life, DOD, and charging efficiency, as well as the impact of environmental conditions such as temperature and sunlight. The results show that each charging strategy has its advantages and limitations, and the optimal approach will depend on the specific requirements and limitations of the off-grid solar PV system. This study provides valuable insights into the performance and effectiveness of different battery charging strategies, which can be used to inform the design and operation of off-grid solar PV systems. This paper concludes that the choice of charging strategy depends on the specific requirements and limitations of the off-grid solar PV system and ...
Research Interests:
The analysis aims to determine the most efficient and cost-effective way of providing power to a remote site. The two primary sources of power being considered are photovoltaics and small wind turbines, while the two potential storage... more
The analysis aims to determine the most efficient and cost-effective way of providing power to a remote site. The two primary sources of power being considered are photovoltaics and small wind turbines, while the two potential storage media are a battery bank and a hydrogen storage fuel cell system. Subsequently, the hydrogen is stored within a reservoir and employed as required by the fuel cell. This strategy offers a solution for retaining surplus power generated during peak production phases, subsequently utilizing it during periods when the renewable power sources are generating less power. To evaluate the performance of the hydrogen storage system, the analysis included a sensitivity analysis of the wind speed and the cost of the hydrogen subsystem. In this analysis, the capital and replacement costs of the electrolyzer and hydrogen storage tank were linked to the fuel cell capital cost. As the fuel cell cost decreases, the cost of the electrolyzer and hydrogen tank also decrea...
Research Interests:
The paper explores the possibility to create a general data management system based on doubly connected circular lists. This system would be very useful for the rapid development of the computer based models in engineering. The basic... more
The paper explores the possibility to create a general data management system based on doubly connected circular lists. This system would be very useful for the rapid development of the computer based models in engineering. The basic element of the list must have a general structure because it is the basic ‘building block’ in the concept development. Several solutions were studies, two of them being finally considered for extensive tests. The first solution is based on the ‘union’ data type which is simple and robust, but it has a series of inconveniencies. The second solution includes the declaration of a pointer to a random location in memory, at that address being found a given data type. The declaration is general, but the handling of a given data type requires particular declarations and functions. This latest solution is the most general one and it may be used to develop software for the most common data types, which will be useful for the rapid development of the upper level of complexity software applications. So far, the testing of the solutions and of their variants is still in progress in order to have a more accurate insight.
Research Interests:
The efficiency of the direct methanation of the flue gases from the energy installations is influenced both by the relatively low participation of the CO2 component and by the presence of water vapor and oxygen from the excess air. The... more
The efficiency of the direct methanation of the flue gases from the energy installations is influenced both by the relatively low participation of the CO2 component and by the presence of water vapor and oxygen from the excess air. The water vapor content reduces the efficiency of the methanation process by a small percentage. The excess air has been analysed in the paper in more detail to determine whether it can lead to the process of self-ignition (explosion) of hydrogen in the phase of its admission to the methanizer. Thus, an analytical calculation was performed for the composition of the flue gases from an energy installation that uses liquid fuel, the excess air being 1.3. At the end of the paper, the objectives of the experimental tests to be performed were presented, and details regarding the complex experimental installation and the already achieved methanizer were provided.
Research Interests:
Research Interests:
The purpose of this paper is to contribute to the enhancement of a hydroelectric plant protection by coordinating protection measures / existing security and introducing new measures under a risk management process. In addition, plan... more
The purpose of this paper is to contribute to the enhancement of a hydroelectric plant protection by coordinating protection measures / existing security and introducing new measures under a risk management process. In addition, plan identifies key critical elements of a hydroelectric plant, from its level vulnerabilities and threats it is subjected to in order to achieve the necessary protection measures to reduce the level of risk.
Research Interests:
In the worlds need for renewable energies environmental friendly solution, biogas production and usage has become one major interest topic which needs adjustments and research for every application domain. The tests carried out in a... more
In the worlds need for renewable energies environmental friendly solution, biogas production and usage has become one major interest topic which needs adjustments and research for every application domain. The tests carried out in a digester with anaerobic fermentation of animal protein revealed a gas which mainly contains CH4 and CO2. After an initial research of the biogas combustion using a burner with automatic drawing in air, which yielded good results, a burner using diffusion technology was also tested. Due to the fact that this is a feature of medium and large flows, switching to this technology also lead to a theoretical study of the combustion, in order to bring out the constructive solutions for burners and improve their settings. This paper highlights the strong connection between the biogas obtained by anaerobic digestion of the animal protein coming from leather industry and the main characteristics of the combustion process behavior.
Research Interests:
Abstract:In the development process of Romania, the energy sector for 2030 contributes essentially through its influence on the quality of life, the environment, the competitiveness of the economy, as well as the climate [1]. Thus, the... more
Abstract:In the development process of Romania, the energy sector for 2030 contributes essentially through its influence on the quality of life, the environment, the competitiveness of the economy, as well as the climate [1]. Thus, the energy sector from Romania must become more economically efficient, less polluting, and more technologically advanced.This paper presents the analysis of innovative methanation decarbonation technologies, the following aspects were pursued: methanisation, the reactions involved and the importance of the methanisation process, methanisation technologies and methane use, decarbonisation through methanisation, the importance of catalysts in methanation processes, decarbonisation with Carbon Capture Storage (CCS), catalyst enabled processes. Behind modern methanation decarbonization technologies is a history of over 100 years based on research and development [2]. At present, methanization is in the attention of scientists, industry, and energy companies,...
Research Interests:
The rotating half-bridge of a settling tank is employed to sweep the sludge from the wastewater and to vacuum and sent it to the central collector. It has a complex geometry but the main beam may be considered a slender bar loaded by the... more
The rotating half-bridge of a settling tank is employed to sweep the sludge from the wastewater and to vacuum and sent it to the central collector. It has a complex geometry but the main beam may be considered a slender bar loaded by the following category of forces: concentrated forces produced by the weight of the scrapping system of blades, suction pipes, local sludge collecting chamber, plus the sludge in the horizontal sludge transporting pipes; forces produced by the access bridge; buoyant forces produced by the floating barrels according to Archimedes' principle; distributed forces produced by the weight of the main bridge; hydrodynamic forces. In order to evaluate the hydrodynamic loads we have conceived a numerical model based on the finite volume method, using the ANSYS-Fluent software. To model the flow we used the equations of Reynolds Averaged Navier-Stokes (RANS) for liquids together with Volume of Fluid model (VOF) for multiphase flows. For turbulent model k-epsilon we used the equation for turbulent kinetic energy k and dissipation epsilon. These results will be used to increase the accuracy of the loads' sub-model in the theoretical models, e. the finite element model and the analytical model.
Research Interests:
Research Interests:
This paper presents the main steps for the synchronous interconnection of Ukrainian and Moldovan power systems to the Continental European ENTSO-E power system and the feasibility study recently accomplished. The first step in this... more
This paper presents the main steps for the synchronous interconnection of Ukrainian and Moldovan power systems to the Continental European ENTSO-E power system and the feasibility study recently accomplished. The first step in this process was the feasibility study. The overall objective of this study was to identify the main elements needed to make possible the synchronous interconnection and to recommend the main measures to be taken in order to overcome the main technical, organizational and legal possible obstacles.
Research Interests:
Developing offshore wind farms are becoming a more attractive solution nowadays. For preventing the changes of the climate, the world leaders have set some environmental goals, which will be difficult to reach out without RES production... more
Developing offshore wind farms are becoming a more attractive solution nowadays. For preventing the changes of the climate, the world leaders have set some environmental goals, which will be difficult to reach out without RES production and the removal of production units with very high emissions. In this paper has been analyzed the possibility to install an offshore wind farm under two constructive options (HVAC and HVDC) considering also the operational reliability of some items specific to the offshore wind platforms. The main purpose of this paper is to provide the most comprehensive synthesis on the offshore wind sources and based on the results of the simulations performed to offer solutions for their interconnected operation with an even lower impact of the Wind Power Plants to the environment. Following the simulations performed, it has been defined that whether an alternative current connection solution is chosen, the wind power plant condition, in case of outage, is reflected by the wind turbine operation. In case of the direct current connection, the wind turbines are disconnected from the network and thus the wind power plant (WPP) behavior is dictated by the convertors condition.
Research Interests:
Research Interests:
Research Interests:
The general objective of the research is analyzes of the preheated gas oil-animal fat blends use at the experimental diesel engine, type CFR- IT9-3M, adequate instrumentation. The engine was fuelled firstly with diesel fuel then with... more
The general objective of the research is analyzes of the preheated gas oil-animal fat blends use at the experimental diesel engine, type CFR- IT9-3M, adequate instrumentation. The engine was fuelled firstly with diesel fuel then with different diesel fuel-animal fats blends (5%, 10%, 15% animal fats content in mixture with diesel fuel). The main animal fat advantages - cetane number and calorific value close to diesel fuel, higher oxygen content it recommend a good alternative fuel for diesel engines. But, the high viscosity and poor vaporization characteristics of animal fats need prior their heating. The results of experimental investigations show the animal fats effects on auto ignition delay, on the combustion parameters and on the pollutants emissions level. Thus, at the animal fats content increase in mixture with diesel fuel, for same engine adjustments, were obtained the follow results: auto ignition delay increases with ~20%; maximum gas pressure decreases with 10%; gas temperature decreases with 8%; indicate efficiency decreases with 10%; NOx emissions level decreases with 30%; CO emission level increases with 28%; HC emissions level increases with 58%; CO2 emission level decreases with 3.5% and smoke emissions decreases with 65%. Was established the animal fats effects on the fuel auto ignition and combustion. Animal fats can be considered a good alternative fuel for diesel engine, assuring the replace of the fossil fuels and resolving the major problem of animal wastes.
The paper presents the results of researches regarding the equipments protection against the corrosion using a new application procedure of the volatile inhibitors. The method consists in the "storage" of volatile inhibitor on... more
The paper presents the results of researches regarding the equipments protection against the corrosion using a new application procedure of the volatile inhibitors. The method consists in the "storage" of volatile inhibitor on the porous carrying agents, thus creating a high reserve of inhibitors in small amounts of adsorbents volumes. In this way, the experiment productivity is increased, thus existing the possibility to adjust the inhibitor's losing speed in the bearer agent, implicitly adjusting its concentration in a closed space.
Research Interests:
Under environmental legislation, biomass is seen as a zero emitter of carbon dioxide emissions releasing only recently fixed carbon following combustion. Simultaneous combustion of biomass with coal is such an alternative energy with... more
Under environmental legislation, biomass is seen as a zero emitter of carbon dioxide emissions releasing only recently fixed carbon following combustion. Simultaneous combustion of biomass with coal is such an alternative energy with economic potential. Among the many stages that occur during combustion of biomass, combustion of coke (the final solid phase) is most relevant to the issue of alkali metals. The paper analyses the potential corrosion and the formation of adherent deposits in the coal-straws co-combustion process at the pilot installations. The straw (in the form of cylindrical briquettes) burning experiments carried out on 2 MW thermal pilot plant. The results of chemical analysis of ash were presented, compared with those obtained from the singular burning of straws in the burning experimental thermal plant of 55 kW.
Research Interests:
In the paper authors present the experimental results on the combustion efficiency of composite fuel briquettes and on the polluting emissions level. The use of composite combustibles using pitcoal and sawdust represents a high... more
In the paper authors present the experimental results on the combustion efficiency of composite fuel briquettes and on the polluting emissions level. The use of composite combustibles using pitcoal and sawdust represents a high perspective. A special care is given to the determination of boiler efficiency and to the establishment of exploiting economic conditions, like the supply, cleaning, etc. The research of the combustion of pitcoal-wood biomass briquettes is conducted on a 55-kW boiler. The numerical modelling of the combustion processes realised in FLUENT software the boiler allowed a critical comparison between the experimental and numerical data.
Classical constructions of boilers for burning straw briquettes had encountered problems particularly due to the ash melting in the furnace. The boiler being developed is a flame tube construction (the temperature at the end of the... more
Classical constructions of boilers for burning straw briquettes had encountered problems particularly due to the ash melting in the furnace. The boiler being developed is a flame tube construction (the temperature at the end of the furnace reaches 650 0 C to 850 0 C). With respect to the technology, the boiler construction is more complicated especially for rolling part of the casing and of the tube. Another difficulty is introduced by some difficulties to reach the welding cordons. The burning is realized on a mechanical grate having water cooled fixed steps and controlled by a fuel pushing device. Above the boiler casing a convective heat exchanger is placed, with vertical fume tubes, in order to allow the ash exhaust during operation by mean of a mechanical system
The constructive solution of the boiler is that of a flame tube in order to achieve an intensified cooling of the flue gases at the end of the furnace. Thus, the ash slagging is prevented, which, in the classical boiler solutions requires... more
The constructive solution of the boiler is that of a flame tube in order to achieve an intensified cooling of the flue gases at the end of the furnace. Thus, the ash slagging is prevented, which, in the classical boiler solutions requires frequent stops for cleaning. The convective heat exchanger tubes are positioned vertically, so that the cleaned ash evacuation is enabled during the boiler operation. Each tube cleaning is performed by means of a helical system, which is driven either by a translation movement or by a rotation movement. These solutions enable the lengthening of operating time between consecutive stops for boiler cleaning, to about 2 to 3 months.
Under environmental legislation, biomass is seen as a zero emitter of carbon dioxide emissions releasing only recently fixed carbon following combustion. Combustion of biomass is such an alternative energy with economic potential. The... more
Under environmental legislation, biomass is seen as a zero emitter of carbon dioxide emissions releasing only recently fixed carbon following combustion. Combustion of biomass is such an alternative energy with economic potential. The paper presents some Romanian researches and achievements regarding wood and agricultural biomass energy conversion, specially for residential and district heating (boilers ≤ 1 MW t). Among the many stages that occur during combustion of biomass, combustion of coke (the final solid phase) is most relevant to the issue of alkali metals. It was quantified the influence of the biomass combustion, by corrosion, against the transfer heating surfaces.
For extending the use of biomass in electricity output, high thermal powers (over 1MW) are necessary. These thermal powers can be achieved by choosing the solution of suspension burning in equipments similar to pulverized coal burners and... more
For extending the use of biomass in electricity output, high thermal powers (over 1MW) are necessary. These thermal powers can be achieved by choosing the solution of suspension burning in equipments similar to pulverized coal burners and injection of gas enriched with hydrogen (HRG). In the present research we study the influence of HRG injection over the sawdust combustion process.
The paper deals with theoretical basis and experimental tests of mixed hydrogen diffusion in the dense system of biomass. Research regarding hydrogen diffusion in the porous system of biomass is part of wider research focusing on using... more
The paper deals with theoretical basis and experimental tests of mixed hydrogen diffusion in the dense system of biomass. Research regarding hydrogen diffusion in the porous system of biomass is part of wider research focusing on using hydrogen as an active medium for solid biomass combustion. In parallel with hydrogen diffusion in solid biomass, tests regarding biomass combustion previously subjected to a hydrogen flux will be carried out.
In energy valorization by burning solid biomass fuels, the achieved thermal power is relatively low, so that maximum electrical power is about 2 MW for agricultural waste and 5 MW for wood waste. Low power turbine construction involves... more
In energy valorization by burning solid biomass fuels, the achieved thermal power is relatively low, so that maximum electrical power is about 2 MW for agricultural waste and 5 MW for wood waste. Low power turbine construction involves solving a multitude of functional and structural problems. This paper examines different solutions for steam turbines up to 2 MW electrical power. The thermo-economic analysis is carried out for a 200 kW steam turbine used for valorizing energy willow, resulting from its harvesting experience in Romania. Keyword biomass valorization, steam turbines, thermo-economic analysis. Notations: m -mass flow rate [kg/s] ε -admission degree [-] c -absolute velocity of steam [m/s] u -peripheral velocity [m/s] d -mean diameter [m] l -height/length of nozzles/blades [m] v -specific volume [m 3 /kg] H -mass flow coefficient [-] t-section area factor [-] α -nozzle exit angle [rad] n -turbine speed [rpm] Indexes: 1 – exit from nozzles 2 – exit from blades a–nozzle p -...
The paper deals with mathematical model and experimental tests of hydrogen diffusion in the porous system of biomass. A mathematical model has been developed for gas diffusion in a porous system and based on it a numerical simulation for... more
The paper deals with mathematical model and experimental tests of hydrogen diffusion in the porous system of biomass. A mathematical model has been developed for gas diffusion in a porous system and based on it a numerical simulation for hydrogen absorption gas been carried out. The results are presented graphically and they point out that them concentration variation inside the pore decreases with the increases of pore length and increases with the increase of hydrogen flux. Also, the absorbed hydrogen quantity decreases with the increase of the pore length and for a given pore length the absorbed hydrogen quantity increases with the increases of hydrogen flux and internal pore surface. Research regarding hydrogen diffusion in the porous system of biomass is part of wider research focusing on using hydrogen as an active medium for solid biomass combustion. In parallel with hydrogen diffusion in solid biomass, tests regarding biomass combustion previously subjected to a hydrogen flu...