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Greenhouse gases emission as well as total energy consumption in buildings of public importance, such as schools, municipal buildings, health care centers, can be significantly reduced by increasing buildings' energy efficiency. Buildings' energy consumption adds up to 37% of total energy consumption in the EU countries. In the Republic of Serbia this amount is significantly higher, about 50%. School buildings are considered as one of the most diverse structures from the point of energy-efficient design and construction. The main aim of this paper is to determine the most appropriate settings for possible improvements in energy efficiency and temperature comfort inside a typical primary school classroom in Serbia. The energy efficiency analysis was performed during the heating season for the naturally ventilated primary school classroom located in the eastern Serbia region. The analysis was performed using novel CFD model, suggested in this paper. The suggested model was used to solve two hypothetical scenarios. The first scenario simulates the temperature field in classroom with current energy characteristic envelope of the school building. The calculated numerical data from the first scenario were compared with in-situ measurements values of temperature and wall heat fluxes and showed satisfying accuracy. The second scenario was simulated to indicate possible improvements, which would allow energy consumption decrease and thermal quality enhancement. The analyzed results, calculated using the suggested numerical model under the second scenario conditions, showed that using appropriate set of measures, it is possible to obtain desired temperature comfort levels without need for increase in the building energy consumption. [ABSTRACT FROM AUTHOR]

Kindergartens are probably the very first public buildings we actively use in our lives. Therefore, they can be considered as the physical structures that are providing for the very important educational and social function. Additionally, they can also be considered as the specific learning tool for future generations where they can encounter the ideas of green and energy-efficient buildings. One of the results of the research project "Energy efficiency in public buildings" has been formulated through the development of Serbian National Typology of Kindergartens which was conceived as a specific tool that can be used for improving this portion of building stock. The paper presents the methodology for identification of typical kindergarten buildings, covering various construction periods, building sizes and illustrates the type of analysis performed for model representatives. The potential for energy upgrades covering physical structure, installed technological systems, as well as expected impact on energy performance, has been estimated. The study presents results based on the analysis of the data derived from the National Typology, stressing out that energy retrofits of large and medium-sized kindergartens built during the 1970s and 1980s should be the primary focus of refurbishment activities. Accounting for almost 60% of total buildings and 69.59% of heated area, they are responsible for 75.97% of energy demands. Estimated energy savings of more than 60% indicate the effectiveness of their retrofit. The paper also presents the potential uses of National Typology as a retrofit tool on various scales, from single-building considerations to a strategic approach at the national level. [ABSTRACT FROM AUTHOR]

This paper analyzes the effects of intercity bus suspension system oscillatory parameters on driver’s ride comfort and road damage. The analysis has been carried out through simulation by means of validated in-plane bus model with six degrees of freedom ex-cited by real road roughness signal. Low root-mean-square values of the weighted vertical acceleration (less than 0.315 m/s²) have been achieved by shock-absorbers with lower damping coefficient and softer suspension system springs. Low values of dynamic load coefficient provide low shock-absorber damping and softer springs. However, low crest factor values for both axles are accomplished for high shock-absorber damping and softer springs in bus suspension system. Results from this analysis could be used as reference for selecting proper oscillatory parameter values when designing road-friendly bus suspension system which in turn would increase vehicle energy efficiency. Presented methods, results and analyzes are the part of wider methodology for assessing the impact of bus suspension system on fuel consumption and CO2 emission. [ABSTRACT FROM AUTHOR]

Climate changes which we are experiencing at the moment are affecting the entire globe. Serbia, as a developing country, is in the process of defining its own energy strategy and priorities when it comes to the problem of increased energy consumption in its building stock. Research shows that residential sector consumes the largest quantity of energy. The CO2 emissions present another big problem which is in a direct correlation with energy consumption. Green roofs have multiple positive effects on buildings and their surroundings which make them a desirable option for retrofitting roofs. The aim of this paper is to investigate thermal properties of chosen green roof system and its potential to positively influence energy consumption for heating buildings and therefore CO2 emissions trough refurbishing existing old flat roofs. The municipality of New Belgrade was chosen for this research for its unique urban characteristics - existence of large number of similar or identical buildings, which have same structural characteristics and similar surroundings. For the purpose of this paper, blocks 45 and 70 were chosen. Results of this research are applicable on all of the 132 buildings found at this location, which have total roof area of 90.990 m². By calculating energy quantity needed for heating the building with the existing roof and two hypothetical models, which have green roof, it was possible to quantify energy savings, which are in a direct correlation with CO2 emissions. A control roof was introduced in order to examine if the proposed green roof possesses better characteristics than a traditional solution, most commonly used in Serbia. Apart from energy savings, overall impact of the green roof on the CO2 reduction per building was calculated. By multiplying these results, we drew the conclusion that a project such as greening roofs of existing residential buildings in blocks 45 and 70 would have a noticeable effect on both the energy savings and CO2 emissions. [ABSTRACT FROM AUTHOR]

There is a global consensus relevant to consequences of inactivity on the mitigation of negative effects of the climate change. Clear tasks with measurable results that should be implemented in the specified time are also well known. The preparation of an energy policy is faced with strict constraints that require innovative approach throughout the whole cycle of policy making process, whereas particular attention has to be given to its implementation. Globally observed, energy efficiency is the best and the fastest way to reduce GHG emissions in the medium term. Energy efficiency should be observed as the means for curbing the exploitation of natural resources. The increase of energy efficiency towards the point of theoretical maximum requires new technical improvements and the establishment of economic environments that stimulate such a trend. In this paper, technical and economic potentials of energy efficiency are evaluated. Also, activities for the correction of energy policies are specified in order to achieve faster and better effects on lowering exhaustion of natural resources and reducing GHG emissions. [ABSTRACT FROM AUTHOR]

The impact of geometric parameters of teeth and lubricating oils to the efficiency of involute internal spur gears, when the transverse contact ratio is 2 < εα ≤ 3, has been analyzed in this paper. The mathematical model and computer program for determining the current and the effective value of the efficiency have been developed. The influence of the character of load distribution and energy losses due to heating effects during the meshing period is included in the factor of load distribution. The results of computer simulation are given in the form of a diagram of the current values of the efficiency during the meshing period. Also, the values of effective efficiency for the considered cylindrical gear pairs have been calculated. [ABSTRACT FROM AUTHOR]

The Urgent Care Center of the Clinical Center of Vojvodina in city of Novi Sad, Republic od Serbia, as a specific medical facility with very demanding conditions of work and functioning, has an extensive and constant energy demands. The building is new, set into operation in 2010. The state-of-the-art concept and the equipment installed create conditions for using advanced solutions in the framework of supervisory and control systems, increasing energy efficiency and reducing operating costs in the Urgent Center. The aim of this paper is the assessment of additional possibilities for increasing energy efficiency in the building using a number of control techniques available today. According to a source of energy, the most utilized is the electric power, which is consumed for air conditioning, compressed air, and lighting. Thermal energy is used for space heating in winter and the preparation of hot water. The first step in increasing energy efficiency was the continuous monitoring and recording of consumption. The next step was the analysis of the energy consumption and the discovery of critical areas of consumption. The final step was related to the plans and algorithms for the energy reduction. To this goal, the energy consumption in the period March 2014-February 2016 was measured and recorded. According to that measuring and data analysis, an expert system based on the methods of computational intelligence that combines all the developed actions and algorithms for increasing energy efficiency in one unit was implemented. [ABSTRACT FROM AUTHOR]

Accurate models for heat load prediction are essential to the operation and planning of a utility company. Load prediction helps a heat utility to make important and advanced decisions in district heating systems. As a popular data driven method, artificial neural networks are often used for prediction. The main idea is to achieve quality prediction for a short period in order to reduce the consumption of heat energy production and increased coefficient of exploitation of equipment. To improve the short term prediction accuracy, this paper presents a kind of improved artificial neural network model for 1 to 7 days ahead prediction of heat consumption of energy produced in small district heating system. Historical data set of one small district heating system from city of Nis, Serbia, was used. Particle swarm optimization is applied to adjust artificial neural network weights and threshold values. In this paper, application of feed forward artificial neural network for short-term prediction for period of 1, 3, and 7 days, of small district heating system, is presented. Two test data sets were considered with different interruption non-stationary performances. Comparison of prediction accuracy between regular and improved artificial neural network model was done. The comparison results reveal that improved artificial neural network model have better accuracy than that of artificial neural network ones. [ABSTRACT FROM AUTHOR]

Within the Climate and Energy Directive, the European Commission has set three main targets: reduction of GHG emissions, increase a share of renewable resources, and improvements in energy efficiency. This paper introduces needs and solutions for capacity building in cross-border regions of Slovenia-Croatia-Hungary in order to better implement energy efficiency and renewable resources potentials. It was identified that a lack of knowledge by the stakeholders represents a main obstacle for implementing more environmental and economic acceptable energy solutions on a local and regional levels. To address the competences gaps by the stakeholders, online training modules were designed and implemented. The results of trainings revealed the best evaluation scores, and consequently improved knowledge and competencies in Hungary, followed by Croatia and Slovenia. [ABSTRACT FROM AUTHOR]

A uniquely constructed technical solution of a solar energy collector is presented in this paper. It presents a great breakthrough in the field of energy efficiency and successful exploitation of renewable energy sources. The principle of this high-temperature energy storage enables the energy accumulated from the sun to be yielded when necessary and continuously, 24 hours a day and 365 days a year. Furthermore, this paper contains a modeling of Sun irradiance, generated energy intensity for flat solar panel and for a newly developed concentrator. The modeling is made with genetic programming which is found to be a suitable method for modeling energy intensity. It offers the results which are within the acceptable tolerances while maintaining the ease of use and short computational time. Genetic programming yielded the results of 12.97, 14.6 and 9.25% average percent error for the irradiance, the flat solar panel and the novel solar concentrator, respectively. [ABSTRACT FROM AUTHOR]

The introduction of the Energy Management System into the industrial sector of the Republic of Serbia, as one of the sectors within the System, formally started on March 15, 2013, when the National Assembly of the Republic of Serbia adopted the Law on Efficient Use of Energy. This indigenous and legally established system of organized management of energy flows, from the processes of production through the processes of transmission, distribution, and ways of consumption of energy, for the purpose of optimization and rationalization of this processes, includes a wide range of regulatory, organizational, incentive, technical, and other measures and activities that within the scope of their powers are determined and implemented by the subjects of this system: the Government of the Republic of Serbia, the Ministry of Mining and Energy, designated organizations, energy managers, and authorized energy advisors. For the purpose informing the industrial sector, as one of legal obligors of the Energy Management System, the achieved results, next steps and future plans for the development of this System are present in this paper. [ABSTRACT FROM AUTHOR]

By harmonizing national legislation to European codes concerning energy efficiency in building sector, Serbia took commitment to improve energy efficiency of national government buildings. Following the Directive 2012/27/EU principles, refurbishment of this part of building stock is recognized as a leading example in long-term process of applying energy efficiency regulations at national level. Initial steps in implementation of adopted energy efficiency principles were made in Serbia during 2015, when first energy certificates for three most valuable buildings of national authorities (Government building, The National Assembly, and the Palace of Serbia) were issued. This paper will present results obtained during energy-assessment and energy-certification process of this particular buildings, showing at the same time their specificity, that pretty much traces possible category and range of proposed energy refurbishment scenarios. [ABSTRACT FROM AUTHOR]

Balanced Scorecards represent powerful management tool for describing, explaining, representing and implementing different business strategies. Being in use for more than two decades, this tool proved its applicability in public, private and non-profit enterprises, which makes it suitable for applying in local development plans. The municipality of Savski Venac applied balanced scorecards as decision-making tools to structure its objectives and articulate them into the strategy. However, the energy efficiency, although perceived as a national priority, was not included in the developed municipality strategy map. This paper investigates the possibilities to integrate the energy efficiency objectives and the municipality strategic objectives, in order to identify and apply proper key performance indicators, targets and measures to improve energy efficiency in different sectors. The ultimate goal is to propose proper GHG mitigation measures to enhance energy efficiency that will fit within the local development strategy of the municipality of Savski Venac, to align the energy efficiency measures with its energy policy, to improve the selection process of the energy efficiency measures and to adjust it to the municipality needs. [ABSTRACT FROM AUTHOR]

The considerable thicknesses of common insulation systems, applied to the internal or external building envelope, can be inappropriate in the Mediterranean climates for improving buildings' energy efficiency and their internal comfort at the same time; in fact, the high thicknesses of insulating material provided by legislation standards can be cause of environments' over-heating and formation of condensation. In this framework, the S-MUnSTa system is an innovative dynamic ventilated insulation system able to overcome condensation and overheating phenomena, also exploiting Internet of Things technologies; the main characteristic of the proposed smart insulation is that the ventilated external layer is equipped with dynamic valves of insulating material, for opening and closing the air channel, with the aim to optimize the thermal performance. In order to guarantee the expected performance of the system, as it has been patented, in this paper an innovative fixing system to install the insulating panels is presented. This new method allows a rapid and easy installation, without any specialization required and with low maintenance costs. [ABSTRACT FROM AUTHOR]

Integrated fleet maintenance management represents implementation of measures, actions and decision making with the aim of decreasing total maintenance costs and increasing energy efficiency fulfilling requirements of three interdependent components: transport, maintenance and their environment. Therefore, a methodology for integrated fleet maintenance management is developed and presented in this paper. The purpose of the methodology is to contribute in increasing fleet s energy efficiency and evaluate managers ' fleet maintenance management efficiency. The methodology was implemented in the company with own light and medium goods vehicle fleet. According to realized values of defined indicators, the maintenance management has become more efficient in the observed period. It contributed to specific fuel consumption reduction per transport volume, thereby increasing fleet's energy efficiency. Further, the fleet size was reduced, which affected the rational realization of the given transport volume in the observed period. [ABSTRACT FROM AUTHOR]

This article focuses on the usage of geothermic energy in greenhouses, its energy-, economic efficiency- and sustainability-related questions. The most notable cost greenhouses produce during operation is the usage of heat energy, which is why when planning a system for this purpose, the energetic analysis of the solution to be used is one of the most important factors. The presented analyses suggest that of the energy resources currently available and usable, geothermic energy has the lowest unit cost. In the case of greenhouse heating, this method turned out to be the most cost-effective among all solutions using any of the energy resources. Regarding the environmental aspect, the CO2 emission rates of the various heating methods have been examined as well. Using the thermal water of the greenhouses before reinjection is an efficient way of energy utilization. Even though the firewood and pellet boilers look the most efficient forms for the first time, past experiences proved them to be the most expensive ones as well. Therefore, it can be stated that the utilization of geothermal energy is the best solution for greenhouse heating, from the perspectives of economic and environmental aspects as well. Based on the previous observations in terms of environmental and economic efficiency this paper aims to discover the opportunities for high-scale thermal utilization in Hungary in order to meet its future renewable targets. [ABSTRACT FROM AUTHOR]

This paper focuses on elements of transport policies affecting energy efficiency of road haulage. The purpose is to present a tool developed to support decision making during the policy making process, at the stage of formulating the elements of transport policies. The paper describes a model developed to assess the impact of policy instruments on fleet energy efficiency by multi-criteria ranking applying the Analytical Network Process. The paper describes the possibilities to employ the defined model giving the example of international road haulage in the Republic of Serbia. The application led to a proposal for policy instruments which could have the highest impact on the increase of energy efficiency in this sector and which will be considered further in detail during the policy formulation process. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to present the advantages of using Cost-Benefit analysis in energy efficiency projects implemented in public buildings, and to prove the hypothesis that Cost-Benefit analysis boosts the effectiveness and efficiency of the said type of projects. The paper offers theoretical and practical explanation of the implementation of Cost-Benefit analysis in the relevant area. Since energy efficiency projects in public buildings usually represent a part of a broader portfolio of similar projects and their implementation demands allocation of substantial financial resources, communities are often be interested in achieving maximal economic and non-economic benefits. This paper aims to demonstrate that Cost-Benefit analysis can represent an excellent contribution when attempting to select the projects for implementation within a broader portfolio of energy efficiency projects in public buildings. This hypothesis was demonstrated by putting a greater emphasis on non-economic benefits and the costs arising from implementation of the aforementioned types of projects. In addition, a practical test of this hypothesis was performed through the implementation of an energy efficiency portfolio in public buildings, worth several tens of millions of dollars - the Serbian Energy Efficiency Project. The paper concludes that the use of Cost-Benefit analysis can help us to effectively evaluate and manage projects of this type aimed at achieving maximum benefits for the community in question. [ABSTRACT FROM AUTHOR]

Buildings consume a significant amount of energy today and are expected to consume even more in the future. This consumption necessitates the use of fossil fuels such as coal and natural gas, both of which have significant environmental impacts. While renewable energy sources remain promising, the most of the energy supply will still use conventional fuels in the near term. Therefore, improving the energy efficiency in buildings is critical, and one of the central visions of “smart buildings” is to reduce their energy use while maintaining the same level of service and comfort. However, to make the buildings meaningfully “smart”, their envelopes must first be made compliant with the current energy efficiency standards. In this paper, we first examine how the public awareness of energy efficiency was risen in Serbia through different demonstration projects, funded by the state budget and through implementation of the energy efficiency measures in public buildings, funded by municipal funds and soft loans from the banks. Then, we describe how the energy efficiency in buildings might further be increased by the use of new technologies and smart networks for control of the energy consumption. We finally, argue that these controls should take into account the personal variables (activity, clothing) along with environmental variables (air temperature, velocity, and humidity) for an optimum thermal comfort to be achieved in public and residential buildings. [ABSTRACT FROM AUTHOR]

In this paper, presented is the state-of-the-art of energy Efficiency of residential buildings in Serbia. Special attention is paid to energy efficiency in already existing buildings. The average energy consumption in residential buildings in Serbia is over 150 kWhm-2 per year, while in developed European countries it is about 50 kWm-2 per year. In this paper examined is the contribution of ventilation losses, through the windows of low quality, regardless whether they are poorly made, or made from bad materials, or with no adequate glass. Besides ventilation losses, which are of major importance in our buildings, special attention is paid to transmission losses, which are consequence of the quality and energy efficiency of the facade. All of the above statements are proved by measurements obtained on a representative building of the Block 34 in New Belgrade, built in the eighties of the last century. In addition to measurements performed the calculation of energy consumption for heating during winter has been made. The results of two different methods of calculation of energy consumption for heating are compared with the values obtained by measuring. [ABSTRACT FROM AUTHOR]

This paper presents a methodology development and the results achieved in the process of establishing energy management system in the city of Kragujevac (Serbia) and in its public services. The paper is an overview of influential factors in the field of energy management, analyzing their impact on raising the energy efficiency of individual utility service and the city of Kragujevac, as a whole. The paper also presents the most interesting scientific and research projects realized in the co-operation of several actors which were co-ordinated by Regional Euro Energy Efficiency Center Kragujevac. The municipal companies together with the city administration are the direct beneficiaries of the results realized in the following areas: - Development of energy management in municipalities and the establishment of energy planning at the local level; - Improvement of municipal services by applying energy efficiency measures in public enterprises: "Energetika" (heating), "Cistoca" (communal waste management), and "Vodovod i kanalizacija" (water and waste water management). [ABSTRACT FROM AUTHOR]

This paper presents practical experiences of savings within compressed air systems with special attention to the compressed air end uses, particularly in pneumatic control systems. Firstly, the systematic approach to energy savings is presented. Secondly, various energy-saving measures, encompassing system analysis and harmonization of production and consumption, minimisation of losses (leak prevention strategy, identification and quantification of leakages), possibilities for reducing pressure drop on filters, and three methods for optimization of pneumatic control: by-pass control, PWM control, and usage of exhaust air have been reviewed. Finally, energy conservation of a complex robotic cell with installed electric and pneumatic devices is shown. [ABSTRACT FROM AUTHOR]

In this paper comparison of experimentally obtained results of energy efficiency of photovoltaic solar plant of 2.08 kWp installed on the roof of the ASARS in Banja Luka in the real climate conditions in 2013 and 2014 are given. It was found that energy efficiency of photovoltaic solar plant from April till November 2013 was 12.28%, and in same period in 2014 was 13.03%. Also, it was found that the increase in the ambient temperature by 1 °C, photovoltaic solar plant efficiency decreases by 0.43% from April till November 2013, and by 0.27% in the same period in 2014. [ABSTRACT FROM AUTHOR]

Research in this paper comprised experimental determination of energy efficiency of different bus subsystems (diesel bus, trolleybus and fully electric bus) on chosen public transport route in Belgrade, Serbia. Experimental measuring of energy efficiency of each bus type has been done based on the analysis of parameters of vehicle driving cycles between stops. Results of this analysis were basis for development of theoretical simulation model of energy efficiency. The model was latter compared with the results of simulation done by "Solaris Bus & Coach" company for the chosen electric bus route. Based on demonstrated simulation, characteristics of electric bus batteries were defined, the method and dynamic of their re-charge was suggested, as well as choice for other aggregates for drive system and technical characteristics for the electric buses were suggested. [ABSTRACT FROM AUTHOR]

The buildings are among major energy consumers, whose energy efficiency is rather low. Clerestory windows are responsible for a large portion of energy losses from the buildings. The energy efficiency of buildings can greatly be improved by upgrading clerestory and other windows. This paper focuses on the theoretical and experimental investigations on how this can be performed in an old school building in the town of Bor in eastern part of Serbia. For that purpose a modern measuring technique has been applied to identify the existing status, and to compare theoretical and actual conditions. [ABSTRACT FROM AUTHOR]

The present paper aims at analysing the performances of organic Rankine cycles adopted for the exploitation of the biomass resulting from the pruning residues in a 3000 hectares district in Southern Italy. A parametric energy analysis has been carried out to define the influence of the main plant operating conditions. To this purpose, both subcritical and transcritical power plants have been examined and saturated and superheated conditions at the turbine inlet have been imposed. Moreover, the effect of the working fluid, condensation temperature, and internal regeneration on system performances has been investigated. The results show that the organic Rankine cycle plants represent an interesting and sustainable solution for decentralised and small-scale power production. Furthermore, the analysis highlights the significant impact of the maximum temperature and the noticeable effect of internal regeneration on the performances of the biomass power plants. [ABSTRACT FROM AUTHOR]

The aim of this paper is to analyze and explore the most suitable energy policy instruments for energy efficiency improvement in Serbia. The analysis has been carried out with a focus on energy indicators for Serbia and EU27. It encompasses a period of twenty-two years and is directed towards the consideration of amendments that need to be made in the National Energy Efficiency Policy. Despite 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 comparative analysis of the situation in the area of energy efficiency in Serbia and in the EU takes into consideration deficiencies in the energy policy in Serbia and proposed measures for overcoming them. The Multiple Criteria Decision Analysis method is used for analyzing the extent of key influences on success in the implementation of energy efficiency policy in Serbia and also for the interpretation of results. The analysis shows that identified energy policy instruments are such that the success in their implementation will depend on a reformed institutional approach. This method can be applied in any other country. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to evaluate the thermal properties of existing residential buildings built in industrial manner in Novi Sad, Serbia, from 1960 to 1990 based on building typology. Each of three analyzed building types has its characteristic façade, with thermal performances divided into periods according to the development of domestic thermal protection building codes. The necessary layer of subsequent insulation is determined by calculations in order to comply with European standards, also applied in Serbia from 2012. The proposed method of periodization simplifies the process of thermal performance assessment and it was checked through the case studies. Evaluation of energy consumption rationalization has been done through comparative analysis of energy losses. Based on the most common energy rehabilitation measures applied in Serbia, it was estimated that it was possible to reduce the energy losses in heating up to 60%. [ABSTRACT FROM AUTHOR]

The paper presents a theoretical analysis of the cooling system of a 110 MW coal-fired power plant located in central Serbia, where eight evaporative towers cool down the plant. An updated research on the evaporative tower cooling system has been carried out to show the theoretical analysis of the tower heat and mass balance, taking into account the sensible and latent heat exchanged during the processes which occur inside these towers. Power plants which are using wet cooling towers for cooling condenser cooling water have higher design temperature of cooling water, thus the designed condensing pressure is higher compared to plants with a once-through cooling system. Daily and seasonal changes further deteriorate energy efficiency of these plants, so it can be concluded that these plants have up to 5% less efficiency compared to systems with once-through cooling. The whole analysis permitted to evaluate the optimal conditions, as far as the operation of the towers is concerned, and to suggest an improvement of the plant. Since plant energy efficiency improvement has become a quite common issue today, the evaluation of the cooling system operation was conducted under the hypothesis of an increase in the plant overall energy efficiency due to low cost improvement in cooling tower system. [ABSTRACT FROM AUTHOR]

Non-destructive testing methods are increasingly in use. With these methods it is possible to obtain the desired information about the system, without altering or damaging it in any way. This paper examines the possibilities of applying these methods in the quantification of losses incurred by leaking of compressed air from the system in the terms of increasing energy efficiency of the system. The emphasis is on the application of ultrasound detector and infrared thermographic camera. The potentials and limitations of these technologies are analyzed for leakage quantification on a steel pipe in compressed air systems, as well as the reliability and accuracy of the results thus obtained. [ABSTRACT FROM AUTHOR]

This paper presents a new approach in mathematical modeling of thermodynamic cycles and electric power of utility district-heating and co-generation steam turbines. The approach is based on the application of the dimensionless mass flows, which describe the thermodynamic cycle of a combined heat and power steam turbine. The mass flows are calculated relative to the mass flow to low pressure turbine. The procedure introduces the extraction mass flow load parameter ?h which clearly indicates the energy transformation process, as well as the co-generation turbine design features, but also its fitness for the electrical energy system requirements. The presented approach allows fast computations, as well as direct calculation of the selected energy efficiency indicators. The approach is exemplified with the calculation results of the district heat power to electric power ratio, as well as the cycle efficiency, vs. ?h. The influence of ?h on the conformity of a combined heat and power turbine to the grid requirements is also analyzed and discussed. [ABSTRACT FROM AUTHOR]

Non-destructive testing methods are increasingly in use. With these methods it is possible to obtain the desired information about the system, without altering or damaging it in any way. This paper examines the possibilities of applying these methods in the quantification of losses incurred by leaking of compressed air from the system in the terms of increasing energy efficiency of the system. The emphasis is on the application of ultrasound detector and infrared thermographic camera. The potentials and limitations of these technologies are analyzed for leakage quantification on a steel pipe in compressed air systems, as well as the reliability and accuracy of the results thus obtained. [ABSTRACT FROM AUTHOR]

The motivation for this study is the disagreement of statistical and literature data about potential quantities of biomass in Serbia. This difference is mainly caused by changed status in practice due to several reasons: changes in ownership caused by transition, different application of technologies in practices, organization of work and economic reasons. The main aim is to precisely establish sorts and amounts of organic biomass in Serbia that can be transformed into heat and electricity. So far, data about the quantities of biomass residues in agriculture, forestry and communal services have been collected and published. Data collection methods are different and generally based on statistical data. The paper explains in detail methods of data collection and processing of crop production, fruit growing and viticulture, livestock, forestry and communal services. On the basis of precise data collection, it has been established that there are 26.3 million tons of biomass residue in Serbia every year. The total amount of biomass is reduced by 20-30% in relation to the period of 10 and more years ago. On the basis of the situation in agriculture and forest production in Serbia, it is estimated that out of the total amount of biomass, some 30-40% can be used for the production of heat energy, electricity and biofuel. The remaining biomass can be used in order to increase soil fertility, as cattle spread, for vegetable production, means for polishing in metal industry, for insulation in civil engineering, in cosmetics industry, production of animal feed, and so on. [ABSTRACT FROM AUTHOR]

This paper analyzes energy efficiency in Serbia. The analysis has been done on the basis of energy intensity indicators for Serbia and neighboring countries, and some other countries and regions. It relates to the period of some ten years and it is directed to the consideration of required interventions regarding the change of the National Energy Efficiency Policy. 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. [ABSTRACT FROM AUTHOR]

This paper is a review of the state-of-the-art of biomass gasification and the future of using biomass in Serbia and it presents researches within the project "The Development of a CHP Plant with Biomass Gasification". The concept of downdraft demonstration unit coupled with gas engine is adopted. Downdraft fixed-bed gasification is generally favored for CHP, owing to the simple and reliable gasifiers and low content of tar and dust in produced gas. The composition and quantity of gas and the amount of air are defined by modeling biomass residues gasification process. The gas (290-400 m³/h for 0.5-0.7 MW biomass input) obtained by gasification at 800 °C with air at atmospheric pressure contains 14% H2, 27% CO, 9% CO2, 2% CH4, and 48% N2, and its net heating value is 4.8-6 MJ/Nm³. The expected gasifier efficiency is up to 80%. The review of the work on biomass gasification has shown that the development of technology has reached the mature stage. There are CHP plants with biomass gasification operating as demonstration plants and several gasification demonstration units are successfully oriented to biofuel production. No attempt has been made here to address the economic feasibility of the system. Economics will be the part of a later work as firmer data are acquired. [ABSTRACT FROM AUTHOR]

The aim of the paper is the analysis of the energetic performances of structured and pelletized aftertreatment systems in flow-through and reverse-flow designs (passive and active flow control, respectively) for Diesel internal combustion engines. To this purpose, the influence of the engine operating conditions on the system performances has been investigated adopting a one-dimensional transient model. Specifically, the thermal behaviour and the fuel saving capability of several arrangements have been characterized. The analysis has shown that the active emission control system with pelletized design guarantees higher heat reten-tion capability. Furthermore, the numerical model has revealed the significant influence of the solid and exhaust gas temperature on the energy efficiency of the aftertreatment systems and the large effect of exhaust mass flow rate and unburned hydrocarbons concentration. [ABSTRACT FROM AUTHOR]

The conventional steam power plant working under the Rankine Cycle and the steam condenser as a heat sink and the steam boiler as a heat source have the same importance for the power plant operating process. Energy efficiency of the coal fired power plant strongly depends on its turbine-condenser system operation mode. For the given thermal power plant configuration, cooling water temperature or/and flow rate change generate alterations in the condenser pressure. Those changes have great influence on the energy efficiency of the plant. This paper focuses on the influence of the cooling water temperature and flow rate on the condenser performance, and thus on the specific heat rate of the coal fired plant and its energy efficiency. Reference plant is working under turbine-follow mode with an open cycle cooling system. Analysis is done using thermodynamic theory, in order to define heat load dependence on the cooling water temperature and flow rate. Having these correlations, for given cooling water temperature it is possible to determine optimal flow rate of the cooling water in order to achieve an optimal condensing pressure, and thus, optimal energy efficiency of the plant. Obtained results could be used as useful guidelines in improving existing power plants performances and also in design of the new power plants. [ABSTRACT FROM AUTHOR]

Transport represents an industry sector with intense energy consumption, the road transport sector within is the dominant subsector. The objective of the research presented in this paper is in defining the activities which applied within road freight transport companies contribute to enhancing vehicles' energy efficiency. Vehicle fleet operation management process effects on fuel consumption decrease have been looked into. Operation parameters that influence vehicle fuel consumption were analysed. In this sense, a survey has been realised in order to evaluate the vehicle load factor impact on the specific fuel consumption. Measures for enhancing vehicle's logistics efficiency have been defined. As a tool for those measures' implementation an algorithm for vehicle fleet operation management was developed which represented a basis for a dedicated software package development for vehicle dispatching process decision support. A set of measures has been recommended and their effects in fuel savings were evaluated. [ABSTRACT FROM AUTHOR]