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22001177

18th Symposium on Thermal Science and Engineering of Serbia

under title:

“Energy – Ecology – Efficiency”

is organized by:

University of Niš, Faculty of Mechanical Engineering in Niš and

Society of Thermal Engineers of Serbia

Under patronage of the GOVERNMENT OF THE REPUBLIC OF SERBIA

MINISTRY OF EDUCATION, SCIENCE AND TECHNOLOGICAL DEVELOPMENT CITY OF NIŠ

and supported by:

Donors and Sponsors

POWER-B.N.M ELECTRIC POWER INDUSTRY OF SERBIA

ENERGOPROJEKT ENTEL VIA OCEL

OTP BANKA

WILO GO CRVENI KRST NIŠ FAZI NIŠ OVEX XELLA SERBIA D.O.O.-YTONG MD TRADE HERZ NIGOS ELEKTRONIK IVS Gmbh-SERBIA TERMONET RADING KRALJEVO

Влада Републике Србије

Министарство просвете, науке

и технолошког развоја Министарство рударства и

енергетиke

Град НИШ

Градска Општина

Црвени Крст

Design

Engineering

Project Management

Consulting

Commissioning

International Scientific Committee

Prof dr Agis Papadopulos [GR] Prof dr Petar Gvero [BH] Prof dr Gligor Kanevče [MK] Prof dr Maria Ichim [RO]

Prof dr Ljubica Kanevče [MK] Prof dr Vesna Barišić [FI] Prof dr Zvonko Guzović [HR] Prof dr Darko Knežević [BA] Prof dr Igor Vušanović [MN] Prof dr Gyula Grof [HU]

Prof dr Konstantinos Papakostas [GR] Prof dr Risto Filkoski [MK] Prof dr Sophia Natalia Boemi [GR] Prof dr Anna Stoppato [IT]

Prof dr Peter Novak [SI] Prof dr Vladimir Mijakovski [MK] Prof dr Jordan Hristov [BG] Prof dr Tetyana Morozyuk [GR]

Prof dr Ilija Ilijev [BG] Prof dr Friedrich Dinkelacker [GR] Prof dr Dušan Golubović [BA] Prof dr Zlatan Car [HR]

Prof dr Dečan Ivanović [ME] Prof dr Breda Kegl [SI] Prof dr Zdravko Milanović [BA] Prof dr Tuponogov V. Gennadevich [RU]

Program Committee

Prof dr Mladen Stojiljković, University of Niš, Faculty of Mechanical Engineering in Niš Prof dr Milan Radovanović, University of Belgrade, Faculty of Mechanical Engineering

Prof dr Simeon Oka, University of Belgrade, Vinča Institute of Nuclear Sciences Prof dr Dragoslava Stojiljković, University of Belgrade, Faculty of Mechanical Engineering

Prof dr Predrag Stefanović, University of Belgrade, Vinča Institute of Nuclear Sciences Prof dr Miloš Banjac University of Belgrade, Faculty of Mechanical Engineering

Prof dr Miodrag Mesarović, Energoprojekt ENTEL, Belgrade Prof dr Dušan Gvozdenac, University of Novi Sad, Faculty of Technical Sciences

Prof dr Milun Babić, University of Kragujevac, Faculty of Engineering Prof dr Vladan Karamarković, University of Kragujevac, Faculty of Mechanical and Civil Eng. in Kraljevo

Prof dr Maja Todorović, University of Belgrade, Faculty of Mechanical Engineering Prof dr Bratislav Blagojević, University of Niš, Faculty of Mechanical Engineering in Niš Prof dr Dragoljub Živković, University of Niš, Faculty of Mechanical Engineering in Niš

Prof dr Velimir Strefanović, University of Niš, Faculty of Mechanical Engineering in Niš Prof dr Borislav Grubor University of Belgrade, Vinča Institute of Nuclear Sciences

Prof dr Valentinno Stojkovski University “Ss. Cyril and Methodius”, Faculty of Mechanical Engineering Skopje

Prof dr Maja Đurović Petrović Innovation Center, Belgrade Prof dr Predrag Rašković University of Niš, Faculty of Technology in Leskovac

Prof dr Dragan Živković University of Belgrade, Vinča Institute of Nuclear Sciences

Honoured Committee

Prof. dr Nenad T. Pavlović, Prof. dr Vlastimir Nikolić,

Prof. dr Kosta Maglić Prof. dr Dimitrije Voronjec Prof. dr Slobodan Laković

Prof. dr Nenad Radojković Prof. dr Gradimir Ilić

Prof. dr Zoran Boričić

Organizing Committee

Prof. dr Mirjana Laković-Paunović,

University of Niš, Faculty of Mechanical Engineering in Niš

Prof. dr Mića Vukić, University of Niš, Faculty of Mechanical Engineering in Niš Prof. dr Dejan Mitrović, University of Niš, Faculty of Mechanical Engineering in Niš

Milica Jović University of Niš, Faculty of Mechanical Engineering in Niš Marko Ignjatović, University of Niš, Faculty of Mechanical Engineering in Niš

Doc. Predrag Živković, University of Niš, Faculty of Mechanical Engineering in Niš Prof. dr Jelena Janevski, University of Niš, Faculty of Mechanical Engineering in Niš

Prof. dr Branislav Stojanović, University of Niš, Faculty of Mechanical Engineering in Niš Doc. dr Goran Vučković, University of Niš, Faculty of Mechanical Engineering in Niš

Doc. dr Mirko Stojiljković, University of Niš, Faculty of Mechanical Engineering in Niš dr Ivan Pavlović University of Niš, Faculty of Mechanical Engineering in Niš dr Saša Pavlović University of Niš, Faculty of Mechanical Engineering in Niš

Marko Mančić University of Niš, Faculty of Mechanical Engineering in Niš Marko Ilić University of Niš, Faculty of Mechanical Engineering in Niš

Prof. dr Mileta Janjić University of Montenegro, Faculty of Mechanical Engineering in Podgorica

Danijela Stanisavljević University of Niš, Faculty of Mechanical Engineering in Niš

Disclaimer

The contents of the papers presented in this publication are the sole responsibility of their authors and can in no way be taken to reflect the views of the Organizer.

Contents

1. Plenary Session 1

Energy system of/for tomorrow-role of exergy

2 Peter Novak

Evidential Reasoning Approach as a Tool for Use in Thermal Engineering Research

13 Miodrag Mesarović

2. Energy Efficiency and Rational Energy Usage 30

Technical Monitoring Results after Energy Efficiency Investment for University of Food Technologies

31 G. I. Valtchev, V. D. Rasheva, N. G. Kalojanov, М. S. Мinchev, S. Tz. Tasheva

Urban and architectural character of thermal ambient influences in operation of photovoltaic panels on buildings

39

Mihailo Mitković, Jelena Đekić, Petar Mitković, Milica Igić, Milena Dinić Branković, Ivana Bogdanović Protić, Milica Ljubenović

Techno-Economic Optimization of Configuration and Capacity of a Polygeneration System for the Energy Demands of a Public Swimming Pool Building 47

Marko Mančić, Dragoljub Živković, Milan Đorđević, Milena Jovanović, Milena Rajić, Dejan Mitrović

Improving Thermal Stability and Reduction of Energy Consumption in Serbia by Implementing Trombe Wall Construction 59

Miomir Vasov, Dušan Ranđelović, Veliborka Bogdanović, Marko Ignjatović, Jelena Stevanović

Energy efficient refurbishment of educational buildings: Case study Niš 69 Danica Stanković, Sanja Spasić Đorđević, Aleksandra Kostić, Hristina Krstić

Analysis of the Impact of Orientation and Building Envelope Characteristics on Energy Consumption of Office Building 78

Miomir Vasov, Jelena Stevanović, Veliborka Bogdanović, Marko Ignjatović, Dušan Ranđelović

The Impact of the Wall Structure on Its Dynamic Characteristics 87 Milica B. Ljubenović, Marko G. Ignjatović, Jelena N. Janevski, Branislav V. Stojanović

The physical model of the window and its influence on the thermodynamic characteristics of the window 95

Saša M. Kalinović, Milica M. Jović, Dejan I. Tanikić, Jelena M. Djoković

Ventilated facade - visual symbol of energy efficiency 104 Janja Brankovića, Dragana Dimitrijević Jovanović, Predrag Živković

Sustainability measurement of building energy system by two multi-criteria methods 113 Biljana Vučićević, Valentina Turanjanin, Marina Jovanović, Predrag Škobalj, Vukman Bakić

3. Technologies and Plants 119

Influence of the Characteristics of Biogas Generated in the Leather Industry on Combustion Quality

120 Lucian Mihăescu, Gheorghe Lăzăroiu, Gabriel P. Negreanu, Ionel Pîșă

Determination of the Surface Zone Emissivities within Hottel Zonal Model of Radiation in a Pulverized Coal-Fired Furnace

128

Nenad Crnomarković, Srđan Belošević, Stevan Nemoda, Ivan Tomanović, Aleksandar Milićević

Drying Intensity Influence on Quality of Dried Food 138 Filip Mojsovski, Predrag Živković

Prospects for Pump Storage HPP in Macedonia 144 Vlatko Čingoski, Ilija Andonov-Chento, Igor Nikolov

Comparison of CFD Simulation of Liquid Fuel Combustion in Bubbling Fluidized Bed with Experimental Results 154

Stevan Nemoda, Milica Mladenović, Milijana Paprika, Aleksandar Erić, Goran Živković

Technical and Economic Feasibility of Replacing Boilers Using Heavy Fuel with Biomass Boilers for Heating Purposes 166

Branislav Repić, Dragoljub Dakić, Milijana Paprika, Borislav Grubor

Energy Efficiency Increasing of Dryers for Wood with Heat Recovery 177 Jelena Janevski, Branislav Stojanović, Dejan Mitrović, Mladen Stojiljković

Most Suitable Sound Modulation of the Turbulent Axisymmetric Air Jet for Industrial Application 183

Dejan Cvetinović, Rastko Jovanović, Jiří Vejražka, Jaroslav Tihon, Kazuyoshi Nakabe, Kazuya Tatsumi

A method for determination of averaged axisymmetric flow surfaces in centrifugal pumps based on numerical simulation results 194

Jasmina Bogdanović-Jovanović, Dragica Milenković, Živojin Stamenović, Živan Spasić

Optimization of K-300-240 (LMZ) Steam Turbine Functioning under Changeable Operating Conditions within Republika Srpska Electric Power System 207

Zdravko Milovanović, Mirjana Laković-Paunović, Aleksandar Milasinović, Darko Knežević, Jovan Škundrić

Analysis and Modeling of the Effects of Process Parameters on Specific Cutting Energy in Abrasive Water Jet Cutting 221

Predrag Janković, Miloš Madić, Dušan Petković, Miroslav Radovanović

The Influence of Temperature on the Adsorption of Cationic Surfactants on Muscovite Mica 231

Jelena Manojlović

Construction Optimization of Hot Water Fire-Tube Boiler Using Thermomechanical FEA 243 Milena Rajić, Milan Banić, Dragoljub Živković, Miša Tomić, Marko Mančić

Stress and Deformation State in Furnace Tube, Smoke Tubes and Tube Plate of Reversal Chamber of the Hot Water Boiler 252

Dragan B. Jovanović, Milena N. Rajić, Dragoljub S. Živković

Assessment of Thermal Processing Behaviour of Corn Cob, Vine Rod and Sunflower 262 Simona Domazetovska, Vladimir Strezov, Risto V. Filkoski, Tao Kan

Investigation of Drying Kinetics of Corn in Function of Air Velocity 272 Mića Vukić, Predrag Živković, Mladen Tomić, Jelena Janevski

Exergy and Exergoeconomic Analysis of a 1000 t ph Lignite-Fired Steam Boiler 281 Dejan M. Mitrović, Branislav V. Stojanović, Jelena N. Janevski, Marko G. Ignjatović

4. New and Renewable Energy Sources 290

Exergy Efficiency of Solar Components and Systems 291 Lana Jaramaz, Miloš Banjac

Review of Wind Energy Potential and Experiences from Operation of the First Wind Park in Republic of Macedonia

300

Vladimir Mijakovski, Monika Lutovska, Zoran Trajkovski, Tale Geramitčioski, Vangelče Mitrevski

Techno-economic Analysis of a Grid Connected PV and PV/Battery Power Systems Considering an Unreliable Electric Grid in Serbia 309

Saša Stojković

Geothermal Energy from Deep Boreholes 320 Velimir Stefanović, Bojan Drobnjaković, Sasa Pavlović

Small-Scale Biodiesel Production – Attractive simplicity vs. rigorous quality standards, is there a solution? 332

Pavle Hadžić, Vladimir Jovanović, Nebojša Manić, Dragoslava Stojiljković

Use of renewable energy sources for smart village model 341 Milica Igić, Petar Mitković, Milena Dinić-Branković, Jelena Đekić, Mihailo Mitković

Equipment for Obtaining Thermal Energy by Using Biomass 351 Gabriela Matache, Ioan Pavel, Gheorghe Sovaiala. Mihai Alexandru Hristea

Chemical Kinetics and Numerical Simulation of the Process in the Experimental Chamber for Denitrification of Flue Gases 359

Milica Mladenović, Stevan Nemoda, Ana Marinković, Milijana Paprika

Wind Energy Potentials Temporal Changes 370 Predrag Živković, Mladen Tomić, Dragana Dimitrijević, Ivana Kecman, Mirko Dobrnjac

Dry Extrusion Processing of Soybean Seeds for Their Superior Capitalization in Animal Feed 378

Anişoara Pǎun, Carmen Brăcăcescu, Dumitru Milea, Alexandru Zaica

Solar Energy Measurement in Čačak, Central Serbia 384 Snežana Dragićević, Milan Marjanović, Vojislav Vujučić, Ivan Milićević, Marko Popović

Underground Waters of the South of Western Siberia (Russia) as a Source of Renewable Energy 392

Olga V. Shiganova, Yuriy Yu. Marchenko, Alexandr A. Shevchenko

Benefits of solid recovery fuel implementation for energy utilization purposes 397 Marina Jovanović, Biljana Vučićević, Valentina Turanjanin, Vuk Spasojvić, Vukman Bakić

5. Flow, Heat and Mass Transfer, Combustion 402

Entropy Generation of Zirconia-Water Nanofluid Flow through Rectangular Microchannel 403 Cuneyt Uysal, Kamil Arslan, Huseyin Kurt

Capillary-Porous Heat Exchangers for Cooling of Melting Units

413

Alexander A. Genbach, Nellya O. Jamankulova, Vukman V. Bakić

Study of Thermal Stability and Degradation of Microcrystalline Nitrocellulose Isolated from Wood Fiber During its Ageing Using Different Isothermal Kinetic Models 420

Mohammed Amin Dali, Damir Jerkovic, Narimane Rezgui

Flow-Thermal Calculation of the Condenser H-1217 in the Process of Extractive Distillation Butadiene in FSK Elemir 436

Matilda Lazić, Duško Salemović, Aleksandar Dedić, Dragan Halas

Application of “Two-Fluid” Model for Vertical Flow in Evaporator Tube Drift Analysis 443

Ivana Kecman, Mirko Dobrnjac, Predrag Živković, Jovan Škundrić, Vladimir Stevanović, Milan Lečić

The Effect of Volume Fraction of SiO2 Nanoparticle on Flow and Heat Transfer

Characteristics in a Duct with Corrugated Backward-Facing Step 450 Recep Ekiciler, Emre Aydeniz, Kamil Arslan

Influence of electrical-conductivity of walls on MHD flow and heat transfer of micropolar

fluid 463 Miloš Kocić, Živojin Stamenković, Jelena Petrović, Milica Nikodijević

The Impact of the Ventilation System in Fire in Road Tunnels 475 Milica Jović, Dragoljub Živković, Mirjana Laković

Two-Phase Gas-Solid Flow in Horizontal Channels with a Quadratic Cross-Section

Considering Secondary Flow 486 Saša Milanović, Miloš Jovanović, Boban Nikolić, Vladislav Blagojević

The Exergy Destruction Splitting in Heat Transfer Engineering Devices 496 Pavel Trubaev, Goran Vučković, Egor Zaytcev

Flow and Heat Transfer of Three Immiscible Fluids in the Presence of Electric and Inclined Magnetic Field 507

Živojin Stamenković, Miloš Kocić, Jelena Petrović, Milica Nikodijević

6. Examination of Operating Plants and Experimental Examination of Processes 520

Equilibrium Moisture Content of Red Beetroot 521 I. A. Kiryakov, M. G. Georgieva, A. I. Tashev, I. R. Tashev

Experimental Investigation on the Convective Heat Transfer in a Spirally Coiled

Corrugated Tube with Radiant Heating

526 Milan Đorđević, Velimir Stefanović, Mića Vukić, Marko Mančić

Repair of Damaged Surfaces of Components of Turbine and Hydromechanical Equipment through the use of Cold Metallization 536

Miodrag Arsić, Srđan Bošnjak, Vencislav Grabulov, Bojan Međo, Mladen Mladenović, Zoran Savić

The Influence of Wind Turbine Generators on Power Systems Dynamic Behavior 541 Dana-Alexandra Ciupăgeanu, Gheorghe Lăzăroiu, Oana Zachia

Results of the Reconstruction and Modernization of theElectrostatic Precipitators at Unit

B1 of the TPP Kostolac B 552

Milić Erić, Predrag Stefanović, Zoran Marković, Vuk Spasojević, Ivan Lazović,Dragan Živić, Željko Ilić

Experimental and Analytical Study of the Radiation Heat Transfer of a Burning Car 564 Angel Terziev, Svetlin Antonov, Ivan Antonov, Kamen Grozdanov, Velimir Stefanović

Optimization of Cutting Temperature in End Milling Aluminum 6082-T6 Using Taguchi

Method 572 Jelena Stanojković, Miroslav Radovanović

The Thermal Imaging in Maintenance 578 Saša Petrović, Pedja Milosavljević, Jasmina Lozanović Sajić

Effect of Hood Design at Howell Bunger Valve Refer to Cavitations 584 Valentino Stojkovski, Zvonimir Kostikj, Filip Stojkovski

Experimental testing the Characteristics of Hot-Water Calorifier 592 Dejan Mitrović, Branislav Stojanović, Jelena Janevski, Mladen Stojiljković

Results of the Temperature Variation in Experimental Researchof the Kolubara Lignite Drying Process in Packed Bed 597

Milić Erić, Rastko Jovanović, Zoran Marković, Nikola Živković, Predrag Škobalj

7. Mathematical modeling and Numerical Simulation 608

Numerical Modeling of the Operation of a Two-Phase Thermosyphon with Heat Carrier Desalinated Water

609

Veselka Kamburova, Ahmed Ahmedov, Iliya K. Iliev, Ivan Beloev, Mirjana Laković-Paunović

Numerical Simulation of Water Hammer in Penstock of the Hydropower Plant Bistrica

622

Jovana Spasić, Živojin Stamenković, Dragica Milenković

Numerical Investigation of the Influence of the Shape of the Straight Profile on the Reversible Axial Fan Performance 631

Živan Spasić, Jasmina Bogdanović-Jovanović, Saša Milanović, Vladislav Blagojević, Veljko Begović

Thermal and Exergetic Investigation of an Innovative Solar Dish Concentrator with Spiral

Cavity Receiver 641 S. Pavlovic, E.Bellos, V. Stefanovic, M. Djordjevic, D. Vasiljevic

Numerical Optimization of Pulverized Coal Furnace Sorbent Injection under Various Operating Conditions 651

Ivan Tomanović, Srđan Belošević, Aleksandar Milićević, Nenad Crnomarković, Dragan Tucaković

Mathematical Model of Pulverized Coal Devolatilization and Combustion in a Swirl Burner– Development and Validation 658

Aleksandar R. Milićević, Srđan V. Belošević, Ivan D. Tomanović, Nenad Đ. Crnomarković, Dragan R. Tucaković

Influential Parameters in the Investigation of Pressure Pulsations in a Pump-Turbine Draft

Tube 667 Zoran Markov, Viktor Iliev, Predrag Popovski, Aleksandar Gajić

Optimization of theMeteorogical Guyed Mast 678 Milada Pezo, Vukman Bakić, Lato Pezo

Ignition Timing Map Calibration Based on Nonlinear Dynamic System Identification using

NARX Neural Network 685 Predrag Mrđa, Nenad Miljić, Slobodan Popović, Marko Kitanović

Determination and Prediction of Electricity Consumption Using Monte Carlo Simulation Method 694

Mirjana Laković, Ivan Pavlović, Miloš Banjac, Milica Jović

Modeling for pyrolysis of wood particles 700 Biljana Miljković

Numerical Simulation of Hybrid Nanofluid Flow in a Square Cross-Sectioned Horizontal Duct 707 Mutlu Tekir, Recep Ekiciler, Kamil Arslan

CFD Analyses to the Impact of the Pipe Connectors on the Flow Distribution in Parallel

Short Pipelines 716 Filip Stojkovski, Valentino Stojkovski, Aleksandar Nospal

8. Environmental Protection, Water, Air and Soil Quality Management 725

Particulate Emission (PM10 and PM2.5) from Residential Wood Combustion in Bitola 726 Zoran Trajkovski, Sanja Popovska – Vasilevska, Vladimir Mijakovski, Cvete Dimitrieska

Computer-Aided Modeling and Simulation of Cement Production Plant 735 John Pius John, Tatiana Morosuk, George Tsatsaronis, Predrag Rašković

Modelling of PM10 Immision from Individual Furnaces and City Boiler Rooms in Pljevlja 750 Vladan Ivanović, Esad Tombarević

Risk of Thermal Pollution of the Danube Passing Through Serbia Due to Thermal Power

Plants 758 Mirjana Laković, Miloš Banjac, Jasmina Bogdanović-Jovanović, Milica Jović

Fire Safety and Fire Standards for Green Living Roofs 771 Dragana Dimitrijević Jovanović, Predrag Živković, Dragoljub Živković, Žana Stevanović

Modelling of Thermophysical Properties of Potential Solvents for Regenerative Flue Gas

Desulfurisation Processes 780 Andrej Stanimirović, Nikola Živković, Emila Živković, Divna Majstorović, Mirjana Kijevčanin

Regenerative Process Operating Parameters for Sulfur Dioxide Physical Absorption from

Flue Gases 787

Nikola Živković, Mirjana Kijevčanin, Emila Živković, Predrag Stefanović, Vuk Spasojević, Milić Erić

The Optimization of Organic Waste Fractions Ratio for the Maximum Biogas Yield 796

Ana Momčilović, Predrag Rajković, Nenad Stojković, Biljana Milutinović, Milica Ivanović, Gordana Stefanović

Evaluation of Kostolac Lignite Carbon Emission Characteristics 803

Vuk Spasojević, Predrag Stefanović, Nikola Živković, Ana Marinković-Radojević, Milić Erić, Zoran Marković

Anaerobic Co Digestion of Sewage Sludge and Organic Fraction of Municipal Waste: A

Case Study City of Niš 810 Milica Ivanović, Gordana Stefanović, Ana Momčilović, Biljana Milutinović

Numerical Research of the Swirl Velocity on the Origin Of Cavitations 817 Aleksandar Levkoski, Valentino Stojkovski

9. Automatization and Control of Processes 824

Overview of Application of Electrostatic Measurement Method for Supervision of Pneumatic Transport of Pulverized Coal 825

B. Jurjevčič, I. Kuštrin, A. Senegačnik

Application of Digital Sliding Modes to Synchronization of the Work of Several Pneumatic Semi Rotary Drives 831

Vladislav Blagojević, Saša Milanović, Živan Spasić, Miloš Jovanović

Machine Learning Based Computationally Intelligent District Heating System Gas Consumption and Heat Load Forecasting 837

Marina Stoiljković, Žarko Ćojbašić, Vlastimir Nikolić, Miloš Simonović, Nemanja Marković

Advanced Infrared Camera Based System for Pedestrian Detection on Railway Crossings 845

Milan Pavlović, Ivan Ćirić, Vlastimir Nikolić, Miloš Simonović, Emina Petrović, Milica Ćirić, Milan Banić

Radiator Heating System Modelling, Simulation and Advanced Control 852 Ristanović Milan, Ćojbašić Žarko, Maja Todorović, Goran Petrović

Principles of Automatic Control and Monitoring Systems of an Industrial Biomass Boiler 863 Milijana Paprikaa, Branislav Repić, Dragoljub Dakić, Milica Mladenović, Aleksandar Erić

10. Energy Management in Industry and Buildings 873

Convergence between Cost-Optimality and Nearly Zero-Energy Buildings 874 Marko Serafimov, Filip Mojsovski, Igor Shesho

Challenges While Implementing an Energy Management System in a Refractory Industry 891 Ana M. Lazarevska, Zlatko Gjurchinoski, Atanasko Tuneski

Different Approaches for Prediction an Energy Production from the Run-of-River Small Hydro Power Plant 904

Valentino Stojkovski, Dame Korunoski, Zoran Markov

Managing and Implementation of Projects for Construction of Hydropower Plants 913 Duško Dimitrovski, Valentino Stojkovski

Optimisation of Heating Structure in Urban Areas Igor K. Shesho, Risto V. Filkoski, Done J. Tashevski, Dame M. Dimitrovski 921

Energy Performance Certification and CFD Simulations of Thermal Comfort in Non-Residential Building 931

T.S. Bajc, D.D. Dostić, M.N. Todorović

11. Energy and Environmental aspects of transport 938

Development of Fuel Feed and Electronic Control Systems for High-Speed and Medium-Speed Gas Diesel Engines 939

Mikhail G. Shatrov, Vladimir V. Sinyavski, Ivan G. Shishlov, Andrey V. Vakulenko

A Control Method of Fuel Distribution by Combustion Chamber Zones and Its Dependence on Injection Conditions 947

Mikhail G. Shatrov, Valery I. Malchuk, Andrey U. Dunin, Ivan G. Shishlov

The Road Transportation Effects on Climate Change for Ankara Province of Turkey 955 Ali Can

Electric Energy Consumption and Recuperation on E-bus in Different Exploitation Condition 961

Slobodan Mišanović, Jasna Glišović, Dragan Taranović, Radivoje Pešić

Load Analysis of Crankshaft Drive with the Use Computer Simulation 977 Luka Vujičić, Jovan Dorić, Nebojša Nikolić

Simulation of Working Process in New I.C. Engine 983 Jovan Dorić, Nebojša Nikolić, Luka Vujičić

Dynamic Programming Study of a Hybrid Electric Powertrain System for a Transit Bus 988 Marko N. Kitanović, Slobodan J. Popović, Nenad L. Miljić, Predrag D. Mrđa

Application of Refrigeration Simulation Tools in Study of Automotive Air-Conditioner 998 Dragan A. Ružić, Vladimir M. Sovilj

Effect of Biodiesel on Diesel Engine Emissions 1005 B. Nikolić, B. Kegl, S. Milanović, M. Jovanović, M. Milošević

Energy Efficient Refurbishment of Educational Buildings: Case Study

Niš

Danica Stanković a, Sanja Spasić Đorđevićb, Aleksandra Kostić c, Hristina Krstićd

a Faculty of Civil Engineering and Architecture, Nis, Serbia, danica.stankovic@gaf.ni.ac.rs b Faculty of Civil Engineering and Architecture, Nis, Serbia, sanjaspasic@ymail.com

c Faculty of Civil Engineering and Architecture, Nis, Serbia, aleksandrakostic85@gmail.com d Faculty of Civil Engineering and Architecture, Nis, Serbia, hristina.krstic@gaf.ni.ac.rs

Abstract: Extremely affected by the need for energy efficiency improvements, this research directs to help reduce energy consumption by applying successful energy actions. Improvements in a building's energy efficiency has the largest potential in terms of saving energy. In this work, we analyzed 23 elementary schools and 21 kindergartens, which are located in the city of Niš. Through the case study we will indicate the deficiencies that were identified in the school facilities and also give a proposal for the improvement of energy efficiency. The aim of this engineering analysis is to affect some relevant future conclusions concerning the organized refurbishment and improvement of the existing educational buildings in order to continuously reduce energy consumption. Instead of dispossessing the users anywise, energy saving benefits the competitiveness of the facility, comfort and quality of the environment.

Keywords: educational buildings, energy efficiency, kindergartens, improvement, Niš, schools

1. Introduction The increasing need for protection, promotion and preservation of natural resources, based on the fact that overpopulation, and urban concentration negatively affected the changes that have occurred in nature. Efficient use of electric energy became a priority in terms of natural environment protection. The building sector is one of the most important consumers of energy, there is about 50% of the total energy produced is spent in facilities, on what conditions need to propose measures for improving energy efficiency [1]. The task of modern society is to manage natural resources today rational, and to predict and avoid negative consequences of human impact in the future. For that reason, the subject of analyses in this paper are primary schools and kindergartens which located in city of Niš ( Republic of Serbia). Beside significant savings in energy consumption, by implementing the principles of efficient energy consumption in school facilities, we are investing in future generations which are going to benefit all advantages which will come as a result of these actions. Kindergartens and primary schools account for 11% of the total energy used by institutional/commercial sector and are the second largest energy consumers in this sector. More than half of preschool buildings in Serbia are in urgent need of energy efficiency improvements, as they are wasting expensive energy (approximately 2500 nurseries and kindergartens) [2]. Beside of future school facilities which are going to be built according to principles of efficient energy consumption, there is a need to revitalize already built objects in way to become more comfortable, healthy and ecological place for children stay. The opportunities for energy efficiency in existing building are vary widely, depending on [3]:

• the climate-zone where the building is located, • the age of the building and the type of construction and • the requirements and incentives involved

As all analysed objects are placed on territory of the city of Nis, we are going to analyse its current states and to find solution how to influence the energy savings in these facilities. We will try to determine whether the year of construction of the facilities had an impact on the state of the facilities for the youngest, but also how much it is possible to improve their energy efficiency in the use of solar panels.

18th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 17–20, 2017

Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš

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The aim is to point out the defects in terms of energy consumption and to give guidelines for their improvement and increase the comfort of the facilities. Also, in the state of kindergartens and primary schools in Nis on mistakes that could be prevented and avoided in the construction of future buildings intended for children.

2. Review of the current state of educational objects Modern principles of projecting objects have a big emphasize at importance of the sustainable architecture, use of natural resources and modern technologic innovations. Using these principles whether in building of the new objects or through reconstructing of already built ones, it ensures significantly healthier living, and also the significant savings.

In which way is it possible to implement new principles of energy efficiency in existing school objects on territory of the city of Nis, and what result would such intervention bring, we are going to answer in the following chapters. Through an analysis of the current state, we will observe the condition of the facilities today, and what steps should be taken in order to raise the energy balance in these buildings. A total of 44 buildings have been analyzed, of which 21 were kindergartens (yellow) and 23 were primary schools (blue) (Figure 1). A large number of facilities are located in urban city areas, while a small number of only 14% are located in peripheral town settlements (Branko Bjegović, Medoševac, Brzi Brod..).

Figure 1: The location of the analyzed objects in the city of Nis

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The period of greatest development of the city of Niš has undergone during the 70s (Table 1) of the last century, when it came to rapid urbanization, construction and settlement. During this period, the largest number of facilities for education were built, and the existing ones were renovated during that period. Since that period, little has been invested in them. Most of the works included painting the walls and repairs of the roof, while nothing was done in terms of energy efficiency.[4] The Law on Energy Efficiency was adopted in 2012 and clearly sets out the goals that buildings need to realize, so they are the main reasons for reconstruction [2]:

• The building’s conditions are technical reasons for reconstruction. There are overheat energy losses trough the walls, the windows, doors and roof of the school or kindergarten building;

• Socio-economics reasons for reconstruction refer to the increased energy consumption in the building and unsatisfactory conditions in kindergartens.

Some of the measures that are undertaken in order to reduce energy loss and increase energy efficiency are the isolation of buildings, the replacement of worn-out joinery, and the implementation of solar systems.

2.1. Analysis of schools and kindergartens in nis from the aspect of energy efficiency

Table 1: Data on analyzed schools and kindergartens in Nis

Kinder gartens

Year of const

Number of floors

Type of the roof

Elementary school

Year of const

Number of floors

Type of the roof

Bajka 1977 P+1 pitched Dositej Obradović 1962 P+1 flat+pitched Lane 2012

P+0 pitched Učitelj Tasa 1935 P+3 pitched

Crvenkapa 1976 P+1 pitched Radoje

1932 P+1 pitched Neven 1976 P+1 flat Ratko Vukićević 1958 P+3 pitched Maslačak 1976 Po+P+1+Pk flat Sveti Sava 1980 P+1 pitched Pinokio 1979 P+1 pitched Car Konstantin 1962 P+1 pitched Slavuj 1970 Po+P+1 pitched Dušan Radović 1987 P+1 pitched Palčić 1963 Po+P+1 pitched Zoran Đinđić 1963 P+1 pitched Bambi 1978 P+1 flat Vožd Karađorđe 1889 P+1 pitched Cvrčak 1983 P+1 pitched Ćele Kula 1966 P+1 pitched Zvončić 1992 P+1 pitched Branko Miljković 1965 P+1 pitched Petar Pan 2005 P+1 pitched Kole Rašić 1977 P+1 pitched Leptirić 1978 P+1 flat Bubanjski heroji 1972 P+1 pitched Biser 2010 Po+P+1 pitched Ivo Andrić 1974 P+1 pitched Pepeljuga 1980 P+1 pitched Vuk Karadžić 1960 P+1 pitched Kolibri 1977 Po+P+1 pitched Milan Rakić 1964 P+1 pitched Vilin grad 2000 P+1 pitched Stefan Nemanja 1973 P+2 pitched Bubamara 1963 P+0 pitched Miroslav Antić 1983 P+1 flat+pitched Svitac 2002 P+1 pitched Ivan Goran

1963 P+1 pitched

Cvetić

2012 P+1+Pk pitched Kralj Petar Prvi

1933 P+2 pitched Plavi

1983 P+1 pitched Sreten

1982 P+1 pitched

Njegoš 1955 P+1 pitched Čegar 1959 P+1 pitched

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The use of solar energy is one of the basic strategies in modern sustainable architectural design. Solar energy can be used through two systems: passive and active solar systems. There are two approaches of using solar energy in architecture [5]: • Active systems - which places emphasis on installation equipment; • Passive systems - which translate energy phenomena in the architectural concept where the house becomes a receiver that covers and protects most of the sun's energy. The active systems include primarily the use of solar collectors that cover the requirements of the hot water facility, and photovoltaic panels that influence the rationalization of the use of electricity. Photovoltaic panels produce electricity directly due to the effects of sunlight, panels are easily implemented in existing buildings and are environmentally acceptable. In order for collectors to be cost effective, they need to be placed in places that have enough sunlight. According to the Ministry of Energetic of Serbia, the number of sunny hours in Serbia for one year is greater than 2000h. This is more than in the most European countries, but solar potential is completely unused. The average annual value of global radiation for the horizontal surface in the north of the country is 1294 kWh / m2, and in the south 1578 kWh / m2, specifically for Niš 1531,40 kWh / m2. [9] For this reason, we consider analysis of the possibility of installing photovoltaic panels in educational facilities on the territory of the city of Niš as justified. The panels are usually installed on rooftops because they are large free surfaces that are not used for other purposes, but also represent the highest point of buildings and thus receive the most sunlight. "Photovoltaic systems can be installed on all types of roofs, but the difference between flat, glass and sloping roofs must be made" [6]. Analyzed schools and kindergartens are in very high level P + 1 and there are no glass roofs. The most common is the sloping roof in as much as 88% of the buildings, while in only 4 buildings there are only flat roofs. Miroslav Antić and Dositej Obradović schools have a combination of both roof levels. The following table shows the ratio of flat, hip and gable roofs to schools and kindergartens (Figure2).

Figure 2: Ratio of different roof structures in analyzed objects

The advantage of flat roofs is the possibility of placing panels at different angles, depending on the orientation of the building. With sloping roofs, there is a possibility of implementation in an already existing roof structure, which is aesthetically most acceptable. For solar panels, the southern orientation is ideal, because in this case it is the most exposed to sunlight. If they are installed to the east or west, the utilization is almost twice as low, so we will analyze the possibility of placing the panels exclusively on the south side. Facilities with flat roof are the kindergartens Leptirić, Bambi, Maslačak and Neven.

0

5

10

15

20

25

flat roof gable roof hip roof

Primary schools

Kindergartens

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At the kindergartens Bambi, Leptirić and Neven it is possible to install photovoltaic panels almost in the entire roof area. As it is a flat roof, the panels that are placed need to be turned to the south side in order to receive as much energy as possible and thus justify this intervention. Unlike these objects, where there are no objects that would put shadow on the object with their proximity, this is not the case in the Maslačak kindergarten. The building is located in the city center, where there is a high density of construction, so around the building there are residential buildings of higher floors that throw shadow on the analyzed object. Due to its position, the kindergarten Maslačak is mostly in the shade, and for this reason it is not profitable to use the panels at this facility. Among the analyzed objects, there is a case where flat and pitched roofs occur, in the case of school buildings Dositej Obradović and Miroslav Antić. In these schools it is possible to install roof panels on the part of a flat roof. The roof tile is not suitable for panel installation due to poor orientation. In the Dositej Obradović school, panels can be placed on the tract with classrooms, while at Miroslav Antić school it can be done on a part of the roof placed above the sports hall.

Figure 3: Analysis of possibilities for setting up photovoltaic panels on the roofs of kindergartens

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Figure 4: Analysis of possibilities for setting up photovoltaic panels on the roofs of primary schools

When we observe objects that have a gable roof, it is clear that we will plan panels towards the southern orientation. It is possible to plan panels at Maslačak and Plavi čuperak kindergartens, while at the Kolibri kindergarten this is not the case because of inadequate orientation of the building. School Ratko Vukićević, despite the fact that the area that is adequate for placement of panels does not have a purely southern orientation, we consider that the savings caused by such intervention would be significant. The non-typical number of floors of the building (P + 3) emphasizes this object as the highest in the surrounding envi ronment. For this reason, it is sunny for most of the day, so the planning of solar panels, despite the southeast orientation of the roof level, is justified, the same case occurs at the Učitelj Tasa School, which has a hip roof. In school buildings with hip roof panels we can plan on as many as 9 buildings. In schools Sveti Sava and Miroslav Antić, panels can be installed only on the roofs of sport hall, due to the orientation of school buildings. In school buildings with hip roof panels can be placed along entire areas in which classrooms are located. The good example would be situation of the Njegoš and Čegar school, which are designed with two classroom areas, and these areas are ideal for locating panels on such roofs. The savings in the installation of the panels would be large because of the large roof surfaces.

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The most common reasons why it is not possible to plan panels instalation on other objects is inadequate orientation (Zoran Đinđić, Ćele Kula, Miroslav Antić, Ivan Goran Kovačić and Kralj Petar Prvi) and surrounding of the buildings, which is made from high greenery and buildings (Bubanjski heroji and Car Konstantin). For kindergartens with hip roof, it is possible to place panels in four buildings: Zvončić, Petar Pan, Pepeljuga and Vilin grad on a small part of the roof surface. For other facilities for the youngest, the most common reason is the inadequate orientation of the buildings.

2.2.Discusion There are numerous reasons why there is a need to reconstruct the analyzed objects. One of the most important is that school and preschool facilities, as public institutions, are a good presenter of new technologies, thus they can serve as a good example for visitors and who can use it in their households as well. In addition, users of the analyzed objects are children, so if we could get used to using renewable sources at an early age, we could be sure that the future of our environment will be in good hands [4]. From the paper we can see that for the largest number of analyzed objects the reason why there is a need to reconstruct the analyzed objects is that the greatest number of objects is over 30 years old, and in that time the heat transfer coefficient according to the law was k=0,9 W/m²K, while today it is limited to the values of k=0.25-0.35 W/m²K. Consequently, the construction years play a major role in the construction of buildings in accordance with energy standards. According to the analysis of the current situation, we can see that the implementation of solar panels is possible in as many as 9 kindergartens and 16 elementary schools. In the given view we can see that the percentage of possible implantation is higher in schools than in kindergartens (Figure5). This is due to the fact that in schools, in most cases, it is planned that the tract with the classrooms be on the south side, as well as the possibility of placing panels on the roofs of the sports hall. The most common problems we have observed when planning photovoltaic panels are: • poor orientation of the object, or objects that do not have a roof surface that can be used for the south-facing installation. In the kindergarten, this is the case with the Pinokio, Cvrčak, Bubamara and Svitac objects, and for schools: the school building Sveti Sava (for sports hall there is a possibility), Zoran Đinđić, Ćele Kula, Miroslav Antić and Ivan Goran Kovačić. • The shelter of the building by higher buildings which are in the neighborhood or high greenery that casts shadows on the analyzed object: Lane kindergarten and schools Car Konstantin and Bubanjski heroji • Great dismounting of the roof surface or curved roof case (sports hall at the school Zoran Đinđić) and therefore a small roof surface where it is possible to plan panels installation. This relates to a hexagonal roof where there is no possibility of implementation because of the small surface on which panels can be installed. This case occurred in three kindergartens: Crvenkapa, Leptirić and Cvetić. According to the data collected for 45% of facilities, the energy consumption in the analyzed facilities is about 583.000 kWh / year [9], which means that the average consumption for 1m2 is 390.75 kWh. Such data indicate emergency intervention, as according to the analyzed data, the average consumption of electricity in public facilities for the EU is 286 kWh / m2 [7].

NO 30% YES

70%

0%

0% Schools

NO 57% YES

43%

0%

0% Kindergartens

Figure 5: Percentage of objects in which intervention can be made

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Most of the energy in school and preschool facilities is spent on heating and cooling the facility, which must meet the high standards, because the users of space are children. That is the reason why It is expected that the energy produced by photovoltaic panels will cover most of the total consumption.

Table 2: Review of possible energy saving for kindergarten Leptirić:

Surface of PV panels [m2]

Production of electric energy

per month

[kWh/month]

Production of electric energy

per year

[kWh/year]

Annual

consumption of electric

energy

[kWh/year]

Annual consumption

reduced by production of electric

energy

[kWh/year]

Percentage of energy savings

[%] Leptirić* 181 2402,50 28236 12883,32 -15352,68 219,17

* Data collected for monograph: D. Stanković, M. Tanić: Revitalization of prescool facilities in Niš: For research were used Premium S poly photovoltaic panels, with power output of 130W/m2. They were installed at 40.7° on flat roof of kindergarten Leptirić. Solar radiation energy of 3.3kWh/m2, characteristic for Serbia, was adopted. On the example of the kindergarten Leptirić [Table 2], by implementing a simple calculation we can see that it is possible that a part of the generated energy is distributed to the city electrical network. [9] This is another advantage of this treatment, depending on the surface on which the panels are placed, we can calculate savings for other objects in a similar way. From the previous analysis, we came to the conclusion that planning the panels would be profitable to a total of 25 facilities. In addition to the feasibility of photovoltaic panels implementation, large electricity consumption in school buildings and kindergartens in Nis is due to inadequate care of facilities, lack of investment and lack of motivation to reduce consumption. Additional measures that can be taken to achieve this goal are the following [3]: • Insulation of building envelopes; • heat recovery ventilation systems • optimization of engineering equipment operation; • installation of any types of meters and control of resource consumption. The plan of the reconstruction includes: to change the windows, to change the outside doors, to install heat reflecting barriers and to install radiator’s temperature regulators. As we know that there were no significant investments in the objects additionally after their construction, and in order to increase savings of these objects, significant investments must take their place.

3. Conclusion Based on the analysis we have done, we can conclude that intervention on buildings is possible on a large number of schools and kindergartens. As objects built during the period when construction laws were blazed, it is necessary to adapt them to new tendencies. In this paper, we have shown in which objects it is possible to install photovoltaic panels, and which steps could be applied in order to align the characteristics of the objects with the principles of energy efficiency. Also, through the discussion, we explained the problems we have noticed that hinder the installation of solar panels in some of the analyzed kindergartens and primary schools. Consequently, we blamed which mistakes should be taken when building future facilities for the education of children. By implementing the panels in existing and future facilities, in addition to achieving energy savings, the economic savings will be greatly influenced, as well as the healthier environment for the children who stay

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in them daily. It can be expected that the project of architectural building improvement (besides improving energy efficiency - improving internal conditions of benefits, contributing to a cleaner and healthier environment) will bring positive social changes by reducing social problems. [8]. The savings that the analyzed objects would have achieved would directly affect the cost of staying in kindergartens, but also the investment in activities that would make children staying at this buildings more comfortable and more interesting. From the analysis that is presented, it can be seen that none of the facilities currently do not meet the principles of energy efficiency. This points to the low awareness of the administration of schools and municipalities, but also of general citizens, about the impact of energy efficiency. For this reason, it is necessary to increase the interest of citizens, but also generally raise awareness of the advantages of photovoltaic panels and encourage the municipality to invest in the renovation of existing facilities. Particular emphasis should be placed on the economic aspect, as well as the impact on the preservation of the natural environment and the pleasant stay of children in schools and kindergartens. The presented case study method performed in a individual case where the schools and kindergartens analyzed in the city of Niš, have a greater significance, precisely because it is possible, with minor modifications, to adapt to other public buildings in the city of Niš and other cities. With this illustration we pointed out the possibility of implementing photovoltaic panels in school and kindergartens, and the importance that even when constructing future facilities, it is necessary to take into account the harmonization with the principles of energy efficiency. References Papers: [1] M. Pucar, M. Nenković-Riznić, N. Kažić: Aesthetic and energy consequences of airconditioning systems in

building design integration, Architectura and urbanisam, br 24/25. 2009, str. 96-111 [2] D. Stanković, M. Tanić, A. Kostić et al: Revitalization of Preschool Buildings: A Methodological Approach,

Procedia Engineering, Volume 117, 2015, Pages 723-736 [3] D. Stanković: Improvement of Energy Efficiency of Schools and Kindergartens, Matec Web of Conferences 53,

Number of work: 01018, 2016. [4] V. Nikolić, M. Tanić, D. Stanković et al: Implementation of solar energy systems and power efficiency increase

for preschool facilities in city of Niš (Republic of Serbia), Construction of Unique Buildings and Structures, No4 (19), 2014, 21-33

[5] S. Spasić: Application of Passive Solar Systems in Architecture, 16th Symposium on Thermal Science and Engineering of Serbia, Sokobanja, Serbia, October 22–25, 2013, 574-579

[6] M. Nedeljković: Fotonaponske ćelije kao deo krovne konstrukcije, Zbornik radova Građevinsko– arhitektonskog fakulteta Niš, broj 28/2013, Građevinsko – arhitektonski fakultet, Niš, 2013, pp.173 – 184

[7] B. Lapillonne, K. Pollier, N. Samci: Energy Efficiency Trends in Buildings in the EU, http://www.odyssee-mure.eu, 2015.

[8] M. Todorović, O. Ećim, I. Martinović: an approach to advance the energy efficiency and sustainability of masonry buildings, MATERIJALI I KONSTRUKCIJE 53, 2010

Monograph: [9] D. Stanković, M. Tanić: Revitalization of prescool facilities in Niš, Faculty of Civil engineering and architecture

University of Niš, 2014

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