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The paper presents a study for implementing a brake sequence for a small wind generator for regimes that exceeds the rated values. Considering data from a real wind generator, two scenarios are presented: first, during a strong wind gust both the electrical and the mechanical brakes are coupled and, for the second case, a fault in the permanent magnet synchronous generator (PMSG) is caused. This study...
We civilized citizens are accustomed to hot tap water, comfortable temperature in rooms and cooled food at home. These things are part of our everyday life and organic components of our lifestyle. We do not recognize this modern luxury really until they are lost. The issue with our current lifestyle is the growth in consumption which comes with increasing energy prices and growing environmental pollution...
This paper analyzes the coefficient of performance separately for the heat pump and separately for the heating system-cooling heat pump. Stationary mathematical model with concentrated state parameters has been created. The analysis was done with the mathematical models of coefficient of performance for heat pumps and separately for the heating-cooling system with heat pump. For the analysis, graph-analytical...
Power quality is the set of regulations of electrical properties that allows electrical systems to function without significant loss of performance or aging. The term is used to describe electric power that drives an electrical load and the load's ability to operate properly with that electric power. Without the proper power, an electrical device (or load) may malfunction, fail prematurely or not...
The solution of accumulating and keeping the heat in the walls is through insulating from the outside, a common method used in Europe although it hadn't been confirmed on the physical basis, in regards with the conditions of continental climate, may it be in winter or in summer. In effect, during summer season part of the heat gets inside despite the insulations in the walls and over the night the...
This paper analyzes energy efficiency in Serbia. Regardless of constant attempts to improve and increase energy efficiency and to expand utilization of renewable energy sources, it seems that accomplished results are still very modest. The analysis of several energy indicators and their changes in the midterm period, confirms this statement. The paper also provides views for necessary actions which...
This article deals with theory and practice of solar collectors for thermal applications. In the first part the theoretical fundamentals are introduced. The second part is about development of a prototype solar collector. The third part introduces testing and test results of a built prototype.
Hungary begins an intensive development. At present, geothermal heat consumption is about 4.5 PJ a year. This very small energy quantity can be raised to more than 60 PJ a year on the basis of the available energy basis data. Nowadays, geothermal heat has a tiny share in district heat supply in Hungary. In addition to the official district heating, also other utilization in building heating is to...
The amount of renewable energy sources constantly increased during recent years requiring detailed analysis about their impact on system security and operation. Because of the variability of these sources, which is the main aspect that affects the operating conditions of the power system, new tools of analysis are necessary. This paper presents the analysis of large wind farm integration in nowadays...
Taking into account the directives of the European Union concerning the increasing role of renewable power sources for supplying loads and reduction of CO2 emission, this paper presents details of the technical and economic characteristics for a hybrid solution generation power system. The goal of this micro power system is to supply residential electrical load that consist in 60 consumers of 5 kW...
The present paper refers to some examples that use the finite element method (FEM) in the process of analysis, design and optimization of the electrical machines used in wind energy conversion systems. The 2D-FEM program Opera 13 of Vector Fields is used in the analyzed examples. These examples refer to two types of synchronous generators with permanent magnets. Some possibilities and advantages of...
The following topics are dealt with: zero energy buildings; geothermal and biomass-based heating plants; sun collectors; biogas production; Stirling engines; thermoelectric generators; energy efficiency; wind energy conversion systems; hybrid wind-photovoltaic generation systems; power quality monitoring and; hydrogenerators refurbishment.
The paper contains a brief overview of development of the Stirling engine with basic functioning and structure of the division. The second part explains the detailed operation of resonant Stirling engine, with a demonstration of examples of use in practice. The last part refers to the view Lamina Flow Stirling Engine.
As an introduction to the current approaches to building's greening and sustainability this paper outlines the intrinsic harmony of the traditional village houses encompassing efficiency and balanced use of renewable materials and energy sources. Further paper reviews technical advances in integrating energy efficiency, solar and other renewable energy sources in new and existing buildings, to approach...
The paper reviews the main multi-input converter and systems topologies for power flow control in renewable energy systems, with more than one energy generation unit. The multi-input converters/systems are synthesized from two or more single input converters, which have only one output filter and one control system, coordinated by a common energy management unit. The circuits configurations and theoretical...
The author introduces and analyses the two-phase pressure drop correlation for refrigerant R134a in the condenser of a heat pump heating-cooling system. The following correlation will be included: the Lockhart and Martinelli, Friedel, Chrishom, Tran et al, Wang et al. and the Wilson et al. The previously mentioned correlations were analyzed numerically depending on mass velocity and vapor quality...
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