More than half of the world's electricity is produced by burning large amounts of coal in thermal power plants and at the same time producing huge quantities of coal ash. Hydraulic transportation of coal ash from coal fired thermal power plants to ash ponds, using high concentration slurry disposal systems (HCSD) is safe, reliable, economical and attractive method due to its low maintenance costs, round the year availability and being environmentally friendly. Present study reports simulated pressure drop for the flow of high concentration fly ash slurries (in the range of 50 70 % by weight) through sudden and conical pipe contractions at various flow velocities using available experimentally obtained rheological parameters. For calculations the finite volume method is applied, which is the most commonly used and gives very good results in the analysis of problems in fluid mechanics and heat transfer. The method in this paper is adapted for simulation of flow of viscoplastic materials whose behavior is described by viscoplastic (Bingham) model. The simulation results are compared with corresponding analytical solutions and experimental data and good agreement between the results is shown.

In this paper analyses of the current state of the thermal insulation of walls without styrofoam and existing windows of Alipasino polje buildings in Sarajevo, Bosnia and Herzegovina, which is powered boiler K-5 through its substations, and current fuel consumption is performed. Research results lead to the conclusion that it is worth to consider insulation of buildings, i.e., simulation of adding styrofoam and new windows on the existing structure in order to reduce heat losses and thus reduce fuel consumption and gas emissions. Savings obtained by this simulation are over 30%. Surface area of buildings subject to the installation of the insulation is obtained on the basis of projects from the district heating system Toplane Sarajevo. Styrofoam thickness is determined by optimizing reduction of the payback period. Prediction of fuel consumption was evaluated for the existing and projected future depending on outside temperature. © 2014 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of DAAAM International Vienna.

This paper presents the analysis of the infl uence of conventional hot (CH) and high frequency (HF) gluing on relevant physical and mechanical properties of Laminated Veneer Lumber (LVL) made from beech peeled veneer with the thickness of 2.1 mm. Student’s T-test was applied to determine the signifi cance of differences between mean values of results obtained for the two different treatments. A signifi cant difference has been determined for the thickness loss, density, moisture and bending strength, while no statistically signifi cant difference has been established for the modulus of elasticity and shear strength of gluing between the means of the tested samples.

U ovom radu danje tehnicki opis sustava za ciscenje cjevovoda, koji služi za hidraulicki transport pepela i sljake u termoelektrani Nikola Tesla B u Obrenovcu. Ovaj sustav realizirala je tvrtka Energoinvest d.d. Sarajevo. Trasa magistralnog cjevovoda je položena od ventilske stanice smjestene pored silosa pepela, pa sve do odlagalista, ukljucujuci i distributivni i istakacki cjevovod. Predviđene su tri linije magistralnog cjevovoda. Dvije transportne linije magistralnog cjevovoda su radne, a treca je rezervna. Zbog relativno visokog pritiska, za sve tri linije magistralnog cjevovoda, izabrane su celicne cijevi St 37.4, na dionici od silosa pepela do ulaza na odlagaliste. Distributivni i istakacki cjevovodi, od PEHD materijala, ce se ugraditi u palicama dužine 12 m sa prirubnickim tuljkom i prirubnicama na krajevima. Nagib distributivnog cjevovoda ce omoguciti ispustanje hidromjesavine na odlagaliste. U svrhu redovnog ciscenja cjevovoda predviđen je odgovarajuci „PIG“ sustav. Lansirna rampa se nalazi u ventilskoj stanici, a prijemna rampa na kraju magistralnog celicnog cjevovoda. Prijemna rampa podrazumjeva u stvari montažnu/demontažnu PEHD cijev dužine cca 50m, koja bi se spojila sa krajem magistralnog celicnog cjevovoda. Detaljniji opis ovog sustava prikazan je u drugom dijelu rada.

New technology of hydraulic transport is based on the dense slurry in the mass ratio (fly ash: water - 1:1). The basic characteristic of this technology is that the water mixes with fly ash and bottom ash in the ratio in the form of dense slurry transporting by high pressure pumps and by pipeline to disposal area. Transport of fly ash and bottom ash slurry is carried out by three transport lines, two are operational and one is reserve. Each transport line starts from conditioner and consists of composite centrifugal slurry pumps, long distance steel pipelines and pipeline distributions around the depot. Hydraulic calculation refers to nominal transport capacity, maximum length of pipelines and maximum elevation head of unloading. By this calculation 4 pumps connected in line have been selected, according to high requirements of system performances. In this paper the description of system of fly ash and bottom ash transport from thermal power plant Nikola Tesla B in Obrenovac which is realized by company Energoinvest d.d. Sarajevo is given.

Increase of the emission of CO2, which is mostly the result of the combusted fossil fuels into the atmosphere, exponentially increases. Through increased energy efficiency there is lower CO2 emission. There is a tendency to reduce exhaust gases temperatures down from their original value referred to as “acid dew point”, 115-160°C. A result is vapor condensation of wet flue in chimney. Condensation occurs when the surface temperature is below the dew point of the vapor-gas mixture. Therefore, Vapor-Liquid Equilibrium models are required in order to determine the dew point of the mixture. Wet flue gas is simulated with vapor-air mixture. A numerical model was presented to calculate the velocity and thermal field of turbulent vapor-air mixture flow trough a chimney. The momentum and temperature field were calculated via a finite-volume CFD code, using the k – e turbulence model. The validation of this calculation was conducted employing an experimental set for heat and mass transfer in vertical upward vapor-air mixture. Measurements were done using a stainless steel tube of 13.2 mm I.D. (internal diameter) and 70 I.D. lengths. Flow rates of steam and air were varied as the experimental parameters. The experiment involves two-phase, two-component, heat and mass transfer. Comparisons of wall temperature and condensate rate were made and the model was shown to give an acceptable results.

SUMMARY Infl uences of conventional hot (CH) and high frequency (HF) gluing on some relevant physical and mechanical characteristics, and creep at constant load and high humidity have been researched for LVL made from beach peeled veneer. Th e Standard linear and fourparameter viscoelasticity Burger model were considered. Unknown model parameters were determined according to the experimental creep results and the method of the least squares. Obtained results for diff erent gluing procedures were showed and discussed.

ABSTRACT This article presents a development of the finite-volume method for solving linear thermoviscoelastic deformation problems. Hereditary continuum problems represented by spatially elliptic second-order partial differential equations with memory are considered. This is motivated by the need to develop numerical algorithms for the solution of thermoviscoelastic stress analysis problems, although it is expected that results presented will generalize to other Volterra problems. Assuming that the hydrostatic and deviatoric responses are uncoupled, and using the temperature–time equivalence hypothesis, the constitutive equations are expressed in an incremental form. Procedures for analyzing linear viscoelastic deformation are described, and numerical examples are given to demonstrate the effectiveness of the model and the numerical algorithms. The accuracy of the method is demonstrated through comparison with analytical and experimental results as well as with numerical solutions obtained elsewhere.

Although the population of the Western Balkans has been connected to the power grid at a high level, there are still regions in which there is no electricity network or the network capacity is insufficient. Often those areas include regions of special care of the state (underdeveloped, impaired in war, depopulated), islands, and mountainous area. But, in the same time, those regions are areas with good renewable energy potential. The decentralised energy generation based on RES (primarily solar, wind, biomass and hydro) could be used to provide electricity for users located in remote, often isolated, rural areas (off-grid applications). Those applications will be primarily tourist related, covering mountainous, rural and coastal tourism. Also, wood, agriculture and food processing industries will be users of DEG based on biomass (most probably with cogeneration plants, connected on- grid).