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Heating value is an important indicator for assessment of the coal quality. Machine learning models are powerful computational tools that allow for the analysis of various heat and mass transfer phenomena in energy systems. In this paper, Random forest model for determining the lower heating values of coal from the thermal power plant “Kolubara A” is developed based on proximate and ultimate fuel analysis. A database of the proximate and ultimate fuel analysis values and lower heating value of coal was created by experimental measurements in the accredited test laboratory of the Department of Thermal Engineering and Energy (“VINČA” Institute of Nuclear Sciences). The developed Random forest models, applied to a relatively small database, showed acceptable predictions for the lower heating value based on both the proximate analysis (RMSE = 0.22 MJ/kg and MAPE = 2.26%) and the ultimate analysis (RMSE = 0.64 MJ/kg and MAPE = 6.12%), with better accuracy achieved by the model whose input data consisted of the values of technical fuel analysis. Power Plants 2023 : Elektrane 2023; November 8-10, 2023, Zlatibor, Serbia

Coal is the main energy source in Serbia. One of the problems associated with the production of energy from coal is the so-called “energy waste”, such as fly-ash and slag (bottomash), which are incombustible and unburt residue from combustion of coal. Fly-ash and slag are TENORM (Technically Enhanced Naturally Occurring Radioactive Material), and if they are released into the environment an increase and/or redistribution of natural radionuclide content can occur. To determine the potential impact of “energy waste” on the environment, samples of coal, fly-ash, and slag from thermal power plant “Nikola Tesla” and “Kolubara” were analyzed. The measured concentrations of natural radionuclides (uranium and thorium series and 40K) in samples of coal as well as in slag and fly-ash produced by combustion of coal are presented in this paper. Sealed samples were measured with a semiconductor HPGe spectrometer (37% relative efficiency) after the radioactive equilibrium was reached. Spectra were recorded and analyzed using software package GENIE 2K, with additional analysis performed by ANGES software. The obtained values of specific activity do not differ significantly compared to the values available in the literature. All the results were further statistically analyzed in order to determine the possible correlation. Ugalj predstavlja glavni izvor energije u Srbiji. Jedan od problema koji prati proizvodnju energije iz uglja je problem tzv. “energetskog otpada”, kao što su leteći pepeo i šljaka, koji predstavljaju nesagorivi i nesagoreli ostatak pri sagorevanju uglja. Leteći pepeo i šljaka predstavljaju TENORM (Technically Enhanced Naturally Occurring Radioactive Material), a u slučaju kada se odlažu u životnu sredinu mogu dovesti do uvećanja i/ili promene raspodele sadržaja prirodnih radionuklida. Da bi se odredio eventualni uticaj “energetskog otpada” na životnu sredinu analizirani su uzorci uglja, pepela i šljake iz termoelektrana “Nikola Tesla” i “Kolubara”. U radu su prikazani rezultati koncentracije prirodnih radionuklida (uranovog i torijumovog niza, kao i 40K) u uzorcima uglja, kao i šljake i pepela nastalih sagorevanjem uglja. Zatopljeni uzorci su mereni nakon uspostavljanja radioaktivne ravnoteže na poluprovodničkom HPGe spektrometru (37% relativne efikasnosti). Spektri uzoraka su snimljeni i analizirani pomoću programskog paketa GENIE 2K, uz dodatnu analizu korišćenjem programa ANGES. Dobijene vrednosti specifičnih aktivnosti ne odstupaju značajno u odnosu na vrednosti dostupne u literaturi. Svi dobijeni rezultati su dodatno statistički obrađeni u cilju određivanje mogućih korelacija. Power Plants 2014 : Elektrane 2014; Oktober 28-30, Zlatibor, 2014.

Korišćenje energije vetra jedan je od predmeta vizuelizacije u delima koja se mogu videti u muzejskim i značajnim privatnim kolekcijama. U ovom radu u fokusu istraživanja je način vizuelizacije i prezentacije korišćenja energije vetra u kontekstu tehnološko-kulturološkog fenomena vetrenjača, koji uz korišćenje blockchain tehnologije može proširiti znanja o tehnološkom mišljenju. Studija slučaja inspirisana je Zlatnom erom holandskog slikarstva. The use of wind energy is one of the subjects of visualization in acts that can be seen in museum and important private collections. In this paper, the focus of research is the way of the visualization and presentation of wind energy in the context of the technological-cultural phenomenon, which with the use of blockchain technology can expand the knowledge of technological opinion. Case study is inspired of Dutch Golden Age painting.

This chapter aims to evaluate energy flows in the life cycle of biogas utilization (i.e., production of thermal energy, cogeneration, traffic, and production of hydrogen), starting from feedstock and anaerobic digestion, up to the digestate as fertilizer for agricultural production. The analysis is based on the out-turn of a biogas plant on the dairy farm Mirotin Vrbas, Republic of Serbia. Life Cycle Energy Assessment (LCEA), presented in this chapter, has demonstrated that three scenarios – biogas for heat production, biogas in cogeneration, and biomethane in transportation have positive energy balances, which indicate that in terms of replacement of fossil fuel consumption, these energy systems are promising alternatives. In the fourth scenario, where biogas is used for hydrogen production, the energy balance is negative, therefore socio-economical factors should be considered for overall consideration to ensure sustainability.

In this paper, vulcanization, a process widely used in the rubber industry, is analysed in terms of its flexibility to reduce energy consumption and environmental impact. In the observed case of the study - production of rubber hoses for car engine cooling systems, the main goal was to identify interactions between equipment design and energy sources (hot water and water vapour) to avoid unnecessary process modifications and inefficient reductions. The water reuse system was modelled and calculations were performed based on case data. The results show that the implementations are viable, and they will be used as input for further simulations and optimization studies based on the proposed model.

One of the most important key factors for the development of non-urban areas is infrastructure, and energy generation is one of the fundamental infrastructure elements. This paper provides a new solution for energy generation based on wood chips which has a multi-sector effect because the authors offer to combine planning of forest cleaning cutting with bioenergy generation in one complex project, which will have socio-economic and ecological effects. The situation with forest fires makes the authors’ idea more attractive because after forest fires the problem of cleaning cutting in forest becomes very important and urgent by ecological and economical points: after cleaning cutting there are a lot of low quality wood which can be recycled into chips for the production bioenergy by the authors’ idea. This enriched methodology has successfully been applied into the regional strategical planning in the field of bioenergy and forestry of the Ural region of Russia; however, it is suitable for applications in regional development in any non-urban forested region of the world. © 2017, Editura Universitatii din Bucuresti. All rights reserved.

Belgrade City authorities have commissioned a team of researchers from Faculty of Architecture, University of Belgrade to investigate energy performance of residential buildings and explore potentials for energy improvements and related savings in heating costs. The paper presents the methodology for structuring, investigation and improvement of residential building stock in Belgrade, developed for the purpose of this project. Typology of buildings has been generated based upon building stock periodization, applied building technology and architectural qualities (features which should remain undisturbed). These aspects define typology matrix which was further investigated and analyzed in detail. Totally, 30 multifamily and 2 family buildings were analyzed. In-situ thermographic imaging was used as an investigation means for technical detection of main energy losses through building facades. These data, compared to the original detail drawings obtained through insight into archive technical documentation provide valuable findings regarding actual quality of facade structures and their improvement strategies. At the same time, it also reveals faults which occurred through construction process and as a consequence of poor detailing. Defined improvement strategies vary significantly based on complexity of improvement measures application. Theoretical calculations based upon available technical documentation and measurements were conducted for every building, resulting in data about overall energy reduction, energy reduction costs, improvement measures payback period, improvement investment per m2 and improvement investment per flat. The paper presents the summary results highlighting the most interesting building types regarding each analyzed criteria.

The paper presents the World Bank's risk assessment for Serbia. Based on these scenarios and forecasts, investment risk factors for the Serbian region in agriculture are formed. The results for the period from 2020 to 2039 are shown for the following indicators: risk categorization, population in accordance with temperature rise, display of complex risk on the map. Rad prikazuje procenu rizika Svetske banke za Srbiju. Na osnovu ovih scenarija i prognoza formiraju se faktori rizika ulaganja za oblast Srbije u poljoprivredi. Prikazani su rezultati za period 2020 do 2039 za sledece pokazatelje: категоризацију ризика, популацију у складиса порастом температуре, приказ сложеног ризика на карти.

The interdisciplinary research conducted in this paper covers all processes from the moment of production of photovoltaic panels, through the processes of transformation of solar energy into electricity, to the decomposition of all used materials, or parts, in the context of circular economy. The goal was to use all materials or parts that remain as excess in the process of producing electricity from solar, as a resource in another process at the right time, and to reuse them to the level of zero waste. In this way, new, increased costs of electricity production from solar panels are achieved. The author calculated and named them as environmental protection costs and sustainability costs. The costs are expressed in €c/kWh. Environmental protection cost and sustainability cost should be added to technology costs in all optimizing analysis. Environmental protection costs include all costs arising from all mitigation measures of direct environmental impact in the process of electricity production from solar energy. What is called sustainable costs in this paper includes all the additional costs of decomposing all used materials and reusing them to the level of zero wastes. The electric power system of Serbia was a case study to which the previous principles were tested and calculated, giving a comparison of technology, environmental and sustainability cost.

Numerous numerical investigations of isolated horizontal-axis wind turbine rotor consisting of three blades have been performed in ANSYS FLUENT 16.2. These flows are three-dimensional, complex, unsteady, turbulent and vortical with several interesting flow phenomena, such as flow separation and dynamic stalling, appearing. Flow field is modeled by Reynolds Averaged Navier-Stokes (RANS) equations. Two different turbulent models are tried: Spalart- Allmaras and k-ω SST. For resolving the rotational motion of the blades both Moving frame of reference (MFR) and Sliding mesh (SM) approaches were employed. Both computational approaches are briefly explained. Obtained numerical results are compared to available experimental data. Presented results include fluid flow visualizations in the form of pressure and velocity contours, sectional pressure distributions and values of power and thrust force coefficients for a range of operational regimes. Although obtained numerical results vary in accuracy, all presented numerical settings seem to slightly underestimate the global wind turbine parameters (power and thrust force coefficients). Turbulence can greatly affect the wind turbine aerodynamics and should be modeled with care.