Faculty of Mechanical Engineering
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Item type:Publication, Drying conditions for paddy processing in mixed-flow high-capacity plant(Faculty of Mechanical Engineering, Ss. Cyril and Methodius University in Skopje, Republic of North Macedonia, 2019)A research was conducted to obtain information on needed procedures for transforming one universal cereal dryer in special equipment for paddy. Harvested paddy was dried under controlled air conditions in continuous-flow high-capacity grain dryer. The realization of the planned study was carried out in three steps: 1) correction of dryer construction, 2) insertion of intermittent drying process, and 3) selection of correct drying conditions. Intermittent drying process was studied by tempering paddy during its processing. In a drying section two zones system was exploited, zone 1 with air temperatures up to 45oC, and zone 2 with air temperatures up to 40 oC. In a cooling section air temperatures up to 26 oC were used. Variations in moisture content, between the grains from two successive horizontal elements of the dryer, were in the range of near one percentage points. In the first horizontal elements of heating section, the variation of moisture content wet basis was two times higher than in the rest horizontal elements of drying section. Correct drying conditions, for local paddy varieties, were selected and are reported. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Influence of Stable Data Location on Wind Energy Prediction(University of Niš, Faculty of Mechanical Engineering in Niš, 2019-10); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Analysis of values from the climatic curve and heat load on the water losses in TPP „Bitola“(Faculty of Mechanical Engineering, University of Banja Luka, 2019-05); Lutovska, MonikaHeat transfer is conducted through latent heat transfer and is proportional to the change in absolute humidity. Since the input temperature of the dry air thermometer or the relative humidity affect the latent/sensible heat ratio, they also affect the amount of evaporated - lost water. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermal capability of hyperbolic cooling tower(Faculty of Mechanical Engineering, University of Banja Luka, 2019-05); Mijakovski, VladimirOperating flexibility of hyperbolic cooling tower, used for large power installation, is examined at various loads and weather conditions. Existing cooling tower theory can’t be sufficient for predicting, planning and improving the cooling tower thermal capability. With the actual research, a procedure for evaluation of thermal capability of hyperbolic cooling tower is offered. The analysis is performed in four phases: 1. design of cooling tower, 2. building of unit, 3. field acceptance test, and 4. long term exploitation. Tested cooling towers are used in the field of electric power generation and correspond to thermal power units of 100 and 200 MW. Performance curves, based on long term operation experience, are proposed. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Apple quality preservation with the use of intermittent drying process(Balkan Environmental Association (B.EN.A.), 2018); During the fruit drying, the processes of heat transfer and mass transfer occur simultaneously in the dried product. To preserve the fresh fruit quality or even to improve some of its nutrition characteristics, discontinuous heat input is used in the proposed intermittent drying process. The pause, in the heat supply, provides enough time for moisture diffusion within the material. Existing food drying theory can not be sufficient for specifying the intermittent drying regime. In the industrial environment, in which this research is conducted, true intermittent drying process is searched through tests at relevant drying conditions. Intermittent drying process is studied by tempering apple rings during air drying. The investigation was performed using a three-level industrial type dryer. Multi-thermal zone convective drying process is applied, with different intermittent regimes, on three identical continuous flow dryers. The influence of air state (temperatures 35-85oC, velocities 2-5 m/s) and drying intensity (5-10 h per cycle) on dried product quality is evaluated through field work tests at three simultaneously operating plants. Correct drying conditions are reached. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Drying Intensity Influence on Quality of Dried Food(University of Niš, Faculty of Mechanical Engineering in Niš, 2017-10); Živković, PredragFood is dried to needed moisture content. Drying intensity results from interrelationships among the characteristics of dried product, drying medium and dryer. This dependence is investigated by tests at one laboratory and three industrial type dryers. The attention is concentrated on rice and apple drying because of their significance for actual local agriculture. Paddy thin layer drying is examined at temperatures up to 42 oC and final moisture content wet basis of 10 %. Apple rings are dried at temperatures up to 80 oC and final moisture content wet basis of 24 %. For the both drying products, process of drying in more periods with intermittent tempering is evaluated. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Impact of indoor air quality on health effects(Faculty of Mechanical Engineering, University of Banja Luka, 2017-05); In modern industrial society man spends the greater part of his life indoors. A large proportion of the population, over 90%, spends more than 20 hours a day in an artificial environment: at home, at the workplace, at shops, at variety of recreation places, cafes, theaters, cinemas, galleries, etc), during transportation etc. Since we spend most of our time indoors the character of the Indoor Environment Quality (IEQ) is of great significance for how we feel, for our health, wellbeing and productivity. Indoor environment quality has a special role as health determinant, and management of indoor air requires different approaches than outdoor air. To achieve indoor environment quality is determined by many factors, but the designers are focused on four different perspectives such as: Indoor Air Quality (IAQ), Thermal Comfort (TC), Visual Comfort (VC) and Acoustical Comfort (AC). The concept of Indoor Air Quality (IAQ) is used as a general denomination for the cleanliness of indoor air. The requirements of the occupants for the indoor air quality in a space are first that the health risk of breathing the air should be negligible and second that the air should be perceived to be fresh and pleasant rather than stale, stuffy and irritating. Indoor air quality may be controlled by a combination of pollutant source control and ventilation. Indoor air quality is vital to human health because most human activities take place in the indoor environment. Therefore the indoor air quality have become priority a for federal, provincial and regional health authorities. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Solar drying of raspberry(Faculty of Mechanical Engineering, Ss. Cyril and Methodius University in Skopje, Republic of Macedonia, 2016)Drying conditions for solar drying of fruits were estimated by field conducted experiments. Solar driers without auxiliary heat source were under investigation. Water-filled vessels and a bed of rocks were used as heat accumulators. Air state or psychrometric zones in the drying room of the dryer, flow rates of air, product thickness and the time of drying are proposed for red raspberry solar drying. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Performance evaluation of micro orc systems for power generation in nearly zero energy buildings (NZEB)(Faculty of mechanical engineering, University of Banja Luka, 2019-05); ; According the Energy Performance of Buildings Directive it is required all new buildings to be nearly zero-energy by the end of 2020. Micro cogeneration systems are considered as one of the system solutions with the highest potential to enable nearly zero energy buildings (nZEB). In this paper is assessed the potential for application of Micro-Organic Rankine Cycle system for power generation in nZEB, where as a heat source is considered solar energy (solar thermal collectors) biomass (pellet boiler), which are also integrated part of the heating system and DHW. Analysis is performed in order to select optimal ORC working fluid for highest thermal efficiency. The solar thermal system, building, heating/cooling and DHW systems are modeled with Transient System Simulation Tool (TRNSYS) and for the meteorological data is used Typical Meteorological Year for Macedonia. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Review of Major Greenhouse gas emissions in Skopje(Faculty of Mechanical Engineering in Nis, 2019-10); Climate change is a serious threat to the environment and people’s health, wellbeing and quality of life, reducing access to natural resources and harming the economy and infrastructure. Greenhouse gases, as the most significant driver of observed climate change are attributable primarily to human activities. Worldwide, net emissions of greenhouse gases increased by 35% in the last three decades. The comparison between emissions of different gases based on a global warming potential concept is made with climate change indicators that characterize emissions of the gases, their concentrations in the atmosphere and the change over time. Like most urban centers, the majority of greenhouse gas emissions in Skopje result from electricity generation, transportation and other forms of energy production. The main problems originate mainly from the sector of stationary energy accounted for about 75% of the total gas emissions ranging from 4948 kt CO2-eq in 2008 to 5343kt CO2-eq in 2012. As the most dominant greenhouse gas carbon dioxide, CO2 accounted for 93% of the total emissions. Significant measures to reduce its emissions in the sectors of energy supply, buildings and transportation are proposed. They are expected to achieve 22%, or more ambitious 32% reduction in emissions by 2020.