V. Lazarov 4
I. Renewable energy sources and environment protection
II. Biofuels and biotechnologies
III. Energy efficiency and environment protection
INTEGRATION OF DISTRIBUTED ENERGY STORAGE AND SMALL
GENERATORS INTO AN ISLANDED MICROGRID
WITH RENEWABLE SOURCE
Thang Vu, Xavier Le
Pivert, Christian Schaeffer
Abstract: The purpose is to study how best to integrate distributed energy storage and small thermal generators in a Microgrid mainly powered by renewable sources. Optimal placing and capacity sharing of distributed energy storage helps to reduce Joule losses and voltage drops. Small generators give same advantages at optimal location. Optimal capacity sharing of Distributed energy storage is based on Droop mode control of specific inverter. Storage units are guided to behave homogenously to have the same evolution of State of Charge, so the same life cycle. By minimizing the Joule losses, the decentralization of storage allows to reduce the conductor section or the size of renewable power sources at design phase. For existed grid, it could delay distribution grid’s upgrade investment. It should be therefore financially interesting.
Keywords: Distributed Energy Storage, Optimal placing, Droop mode
TRANSFORMATION OF HORIZONTAL GLOBAL SOLAR DATA INTO TILTED IRRADIATION AT HOURLY SCALE: COMPARISON OF VARIOUS METHODOLOGIES
Gilles Notton, Christophe Paoli, Siyana Vasileva, Lilyana Ivanova, Marie Laure Nivet and Ludmil Stoyanov(PDF 1778k)
Abstract: Global irradiation on tilted planes is required in all engineering calculations for solar systems. Various methodologies are compared in view to obtain these data from measured horizontal global solar irradiation using empirical or semi-physical models and Artificial Neural Network (ANN).
Keywords: Solar radiation estimation, ANN method, conventional method.
ON SOLAR ABSORPTION REFRIGERATOR'S PERFORMANCES
Emna Berrich, Ali Fellah, Ammar Ben Brahim, Fethi Aloui, Michel Feidt(PDF 113k)
Abstract: Solar absorption refrigerator's performances are analysed by a conceptual optimization. The simulation is based on hierarchical decomposition, on the principles of the endoreversibility, respectively of the exoreversibility of the solar absorption refrigerators. Optimization is carried out by adopting the method of Lagrange multipliers. This methodology was been applied to absorption cycle composed of a solar concentrator (hot source), a thermal solar converter (thermal engine 1), an intermediate source, a cold source and four main elements: a generator, an absorber, a condenser and an evaporator. The generator and the absorber constitute a thermal engine ET2 and the whole condenser evaporator forms the thermal receptor RT. The parameterization of the installation comprises fluxes and powers and the temperatures that reign in the thermal machine compartments. This made it possible to get out two equation systems which guarantee the coupling of general optimal performance characteristics of a simple effect solar absorption cycle. The functional and conceptual characteristics are studied. In particular, the effect of the external sources temperatures on the performances is discussed. These results are interesting in absorption machine’s conception viewpoint. They encourage studies in an irreversible way.
Keywords: Absorption refrigerator, Solar energy, Optimization, Hierarchical decomposition, Endoreversibility, Exoreversibility.
FEASIBILITY STUDY OF HYBRIDATION OF MINI DIESEL POWER STATIONS WITH PHOTOVOLTAIC ENERGY SYSTEMSSaid Diaf and Gilles Notton
Abstract:. Nowadays, the majority of diesel
power stations located in the southern part of Algeria
operate under difficult conditions and their diesel
generators don't operate at nominal regime. The hybridation
of micro diesel power stations with photovoltaic(PV) energy
system permits to reduce the operation time of diesel
generators and consequently reduces the fuel consumption.
This paper presents a technical economic of hybrid
photovoltaic–diesel–battery system. The objective of this
work consists on developing a decision-making tool that
allows the opportunity evaluation for combining micro diesel
power stations with PV energy system.
This decision making tool is based on
• establishing of technical and economic models of the system’s components
• optimization of system sizing
The simulation results related to this study will be presented and analyzed in this paper.
Keywords: hybrid system, diesel generator, optimum system sizing, loss of power load probability, levelized cost of energy
EXPERIMENTAL STUDY OF LOSSES IN DOUBLY-FED INDUCTION GENERATOR
Vladimir Lazarov, Zahari Zarkov and Ludmil Stoyanov(PDF 1560k)
Abstract: This paper presents an experimental study of the losses doubly-fed induction generator (DFIG) for wind energy conversion system. The experiments were performed on a laboratory test bench. The losses in the components of the system - electronic converters, transformer and induction machine - are determined by measuring the power in different system points and by making the appropriate calculations. Quanti¬tative assess¬ment of the distribution of losses and of the overall system efficiency is also carried out. The results can serve to validate the theoretical models and assumptions. Although the study is designed for a small power machine, it makes it possible to outline certain trends and connections between the losses and the energy flows in sys¬tems with DFIG.
Keywords: DFIG, losses, wind generator
ON THE WAY TO IMPROVE BIO-ETHANOL PRODUCTION FROM WOODEN BIOMASS AS APPROPRIATE ALTERNATIVE FUEL FOR SPARK IGNITION ENGINES
Laurentiu Fara, Alexandru-Cristian Racovitză and Gheorghe Niculae(PDF 239k)
Abstract: Bio-ethanol has been proved to be a better alternative fuel to SI Engines for reasons concerning classic fuel economy, lower emissions’ levels and promising industrial obtaining methods by using chemical and biological means. Bio-ethanol is the main product to be achieved through the fermentation of the sugar-compounds that are themselves obtained from wooden biomass. The primary biomass source comes from a special poplar clones harvested from three different zones of Romania in order to offer a comparison basis in terms of biomass production efficiency. Among all the known industrial fermentation methods of the sweet compounds extracted from biomass, this paper reveals a new and more efficient process given by the enzymatic fermentation.
Keywords: Bio-ethanol, wooden biomass, enzymatic fermentation, efficiency, low emissions.
CONTRIBUTION OF SECOND GENERATION BIOETHANOL TO
SUSTAINABLE ENERGY INDEPENDENCE
Kantcho Lahtchev(PDF 495k)
Abstract. In this review the basic
approaches for development and improvement of bioethanol
industry, its perspectives and problems encounter are
summarized. Bioethanol produced from plant biomass
by biochemical method (second generation bioethanol) is
object of special attention. The perspectives and
quality of this biofuel are compared with those of
bioethanol produced from starch feedstock (first
generation bioethanol). The advantages as well as
problems concerning manufacturing and commercialization
of second generation bioethanol are discussed also. It
is pointed on the necessity of global approach to
develop and stimulate such industry. The initial steps
of commercialization of second generation bioethanol as
well as future impacts of such industry on
sustainability and environmental are presented also.
Key words: bioethanol, commercialization, sustainability, environment
REVIEW OF GASIFICATION BIOMASS TECHNOLOGIES, THEIR
APPLICATION AND POTENTIAL RISK REGARDING
THE SAFETY AND ENVIRONMENT
Petar Kaleychev, Kostadin Belev, Ivan Ivanov(PDF 79k)
Abstract: Biomass gasification as technology for energy production has recently significant development and perspectives for further increasingly application. A number of institutes in the EU work towards establishing a unified approach to the risk assessment of technology for gasification of biomass. The report takes a variant of how this approach can be applied to research of concrete installations. Covers all possible aspects and serves as an addition to the existing information. The report presents initial results up by research into installations for the gasification of biomass, which are intended to show their position on the safety and impact on the environment. They are a basis for future research focused on the formation of recommendations and proposals on specific aspects of the operation of these facilities.
Keywords: gasification, biomass, risk assessment, safety, environment
NEARLY-ZERO-ENERGY BUILDING: STUDY CASE ON A
BLOCK OF FLATS
Emilia-Cerna Mladin, Alexandru Dobrovicescu, Tudor Prisecaru(PDF 179k)
The study is
focused on a multi-family building block of flats type
and includes an energy analysis on its construction and
installations elements. Results conclude with energy
performance indicators and recommendations for
additional energy efficiency measures. Different
packages of measures were analyzed for economical
efficiency and appropriate conclusions are drawn. It is
thus shown how a building can approach conditions
compatible with “nearly zero” energy consumption from
classical sources, with reasonable costs for owners.
Keywords: nearly-zero energy, energy efficiency, energy performance, energy efficient buildings
INFLUENCE OF THE COATINGS ON THE THERMAL
PERFORMANCE OF INSULATING GLASS UNITS
Nina Penkova(PDF 304k)
Abstract: A mathematical model of 3D
conjugated heat transfer at insulating glass units (IGU)
is composed and applied for numerical calculations by
computational fluid dynamic technique with ANSYS.
Temperature field in glass panes and temperature,
pressure and velocity fields in gas space are calculated
for several variants of flat double glazed IGU: uncoated
glass panes; low emissivity coating on inner pane and
uncoated outer glass pane, and solar control coating on
outer pane and uncoated inner glass pane. The numerical
calculations are made for winter and spring conditions
in order to validate the models and to analyze the
coatings influence on thermal behaviour of IGU.
Keywords: IGU, coatings, CFD calculations, heat transfer, free convection
COMPUTATION OF PERFORMANCE AND EFFICIENCY OF
THE WATER OXYGENATION PROCESS IN NON-STATIONARY CONDITIONS
Nicolae Băran, Alexandru Sorin Pătulea and Ionela Mihaela Căluşaru(PDF 342k)
presents a method for computing the performance and
efficiency of the water oxygenation process. The method
can be used when the concentration of dissolved oxygen
increases in function of the duration of the process of
introducing in the water. The theoretical results are
verified by experimental researches.
Keywords: oxygen dissolved in water, oxygenation efficiency.