Stock management strategy

    Science. Business. Society., Vol. 9 (2024), Issue 1, pg(s) 11-13

    The set of methods and rules in the process of providing raw materials can be considered a strategy for stock management. Each strategy is associated with specific and expected costs. Still, optimally, we can call that strategy that, under the given conditions, leads to minimal expenses related to the material provision of the studied system. Part of the stock management process is establishing the timing of the deliveries, the necessary volumes and the distribution of the incoming lots to the various warehouses and units. The search for optimal strategies is subject to the theory of optimal stock management. This makes it possible to release significant funds frozen in the form of stocks, which leads to increased efficiency of the material resources used. The optimal inventory management strategy and flexibility also lead to improved production processes and reduced and excluded possible interruptions caused by lack or shortage of materials. The stock management process influences the planning, forecasting, and fulfilment of production needs and orders.
    The elements of the business system described so far, in which raw materials, materials and their stocks have a significant impact, show the importance of the stock management strategy of each economic unit. That the chosen and functioning system is optimal is a substantial part of the overall success in any enterprise or other form of business process implementation.


    Development of Modular Flue Gas Waste Heat Exchanger for ORC (Organic Rankine Cycle) Systems

    Mechanization in agriculture & Conserving of the resources, Vol. 67 (2023), Issue 6, pg(s) 172-174

    The escalating global demand for sustainable and efficient energy solutions has spurred increased exploration into waste heat recovery technologies. Among these, the integration of Organic Rankine Cycle (ORC) systems with diverse industrial processes stands out as a promising avenue for effectively harnessing low-grade waste heat. This integration not only holds the potential to significantly improve overall energy efficiency but also plays a crucial role in mitigating the environmental impact associated with industrial operations.
    Recognizing this potential, the primary focus of this research lies in the meticulous design, optimization, and performance evaluation of a modular Flue Gas Waste Heat Exchanger (FGWHE). This modular FGWHE is strategically crafted to seamlessly integrate with ORC systems across a spectrum of applications, offering versatility and adaptability to varying industrial settings. This paper further extends the exploration of this research through a comprehensive presentation of Computational Fluid Dynamics (CFD) simulations. These simulations delve into the intricacies of a specifically designed modular FGWHE tailored for Organic Rankine Cycle systems. Through detailed CFD analyses, the performance characteristics, heat transfer efficiencies, and fluid dynamics within the modular FGWHE are rigorously examined. The simulation outcomes provide valuable insights into the thermal behavior and overall effectiveness of the modular FGWHE under various operating conditions.


    The influence of steam extractions operation dynamics on the turbine efficiencies and losses

    Machines. Technologies. Materials., Vol. 17 (2023), Issue 1, pg(s) 3-6

    In this paper are presented results of a low-pressure steam turbine energy and exergy analysis during turbine extractions opening/closing. All possible combinations of extractions opening/closing are observed. The highest mechanical power which can be produced by this turbine (when all steam extractions are closed) is 28017.48 kW in real and 31988.20 kW in an ideal situation. For all observed steam extractions opening/closing combinations is obtained that energy efficiency and energy losses range is relatively small (from 87.56% to 87.94% for energy efficiency and from 3360.46 kW to 3970.72 kW for energy losses). Trends in energy and exergy losses (destructions) are identical for all observed extractions opening/closing combinations. Analyzed turbine efficiencies (both energy and exergy) will decrease for a maximum 1% during the steam extractions closing. Turbine steam extractions closing decrease turbine efficiencies and increases turbine losses (destructions), what is valid from both energy and exergy aspects.


    Analysis of planetary gear trains applied in vehicles

    Trans Motauto World, Vol. 8 (2023), Issue 1, pg(s) 5-8

    The paper presents a theoretical analysis in the field of the application of planetary gear trains in vehicles. The following main areas have been considered: design features of planetary gear trains, specific aspects of the application use of planetary gears in vehicles and possibilities of increasing the efficiency coefficient of these drives. An analysis of the option for investigating these gear sets has been implemented as well. Special attention is dedicated to the options of minimizing energy consumption, taking into account the relevant limitations and operating conditions of planetary gear trains. Conclusions have been deduces. Ideas for future scientific work are presented


    Energy audit analysis in private residential apartment in Tirana city

    Industry 4.0, Vol. 7 (2022), Issue 2, pg(s) 79-82

    Recently, Albania as a developing country is focusing on the energy efficiency in residential and industry sector. Residential sector has very high contribution energy consumption in Albania due to many construction buildings without energy efficiency standards implementation. Most of the contribute city is Tirana where energy consumption in residential sector is very high in comparison to the other cities in Albania. Our research work will be focused on analysis of the energy audit on a private residence apartment which is located in the area of Tirana. The purpose of this paper is based on the relevant standards and norms to give appropriate recommendations for the implementation of energy efficiency which would increase the energy performance of this building.


    Energy evaluation of a steam turbine from solar-based combined cycle power plant

    Machines. Technologies. Materials., Vol. 16 (2022), Issue 3, pg(s) 86-89

    In this paper is performed energy evaluation of steam turbine from the solar-based combined cycle power plant which includes analysis of each cylinder and the whole turbine. Steam turbine has three cylinders – high, intermediate and low pressure cylinders (HPC, IPC and LPC). Observed turbine is interesting because it possesses steam cooling before its expansion through the last cylinder (LPC). Due to unknown steam mass flow rates through each cylinder, for the evaluation are used specific variables. The highest specific work is obtained in LPC, while the lowest specific work is obtained in IPC. The highest loss of a specific work is obtained in LPC (29.8 kJ/kg), followed by HPC (24.5 kJ/kg), while the lowest loss of a specific work is obtained for the IPC (19.5 kJ/kg). Regardless of higher loss in specific work, HPC has higher energy efficiency in comparison to IPC (95.08% in comparison to 95.02%), while the lowest energy efficiency of all cylinders has LPC (94.92%). For the whole observed steam turbine loss of a specific work is equal to 73.8 kJ/kg, while the energy efficiency of the whole turbine is 95.00%.


    Exergy analysis of a complex four-cylinder steam turbine

    Machines. Technologies. Materials., Vol. 16 (2022), Issue 1, pg(s) 3-7

    This paper presents an exergy analysis of a complex four-cylinder steam turbine, which operate in a coal-fired power plant. Analyzed steam turbine consists of high pressure single flow cylinder (HPC), intermediate pressure dual flow cylinder (IPC) and two low pressure dual flow cylinders (LPC1 and LPC2). The highest part of cumulative mechanical power (787.87 MW) is developed in IPC (389.85 MW) and HPC (254.67 MW), while both low pressure cylinders develop a small part of cumulative mechanical power (70.29 MW in LPC1 and 73.06 MW in LPC2). Cylinder exergy destruction (cylinder exergy power loss) continuously increases as the steam expands through the turbine. The lowest exergy destruction has HPC (13.07 MW), followed by the IPC (20.95 MW), while the highest exergy destructions are noted in low pressure cylinders (24.37 MW in LPC1 and 27.17 MW in LPC2). Cylinder exergy efficiency continuously decreases as the steam expands through the turbine. The highest exergy efficiency has HPC (95.12%), followed by the IPC (94.90%) and LPC1 (74.25%), while the lowest exergy efficiency of all cylinders is obtained in LPC2 (72.89%). Exergy efficiencies of LPC1 and LPC2 are much lower in comparison to other low pressure dual flow cylinders from comparable steam power plants. The whole observed steam turbine has exergy
    efficiency equal to 90.20%.


    Coupled two-carrier planetary gearboxes for two-speed drives

    Machines. Technologies. Materials., Vol. 15 (2021), Issue 6, pg(s) 212-218

    The following paper reviews all the possible cases of coupled two-carrier planetary gears with four external shafts. An emphasis is made on the work of these gears with one degree of freedom, one input and one output shaft and brakes on the other two shafts . When switching over the gears, the speed ratio of the gear is changed, thus allowing the use in two-speed mechanical transmissions of technological lifting and other machines. Some relations are deduced for determining the speed ratios and the efficiency of all structural schemes.
    Recommendations for the selection of the most appropriate structural scheme according to the current necessities can be made. A 3D model of the S13V3 two-speed, two-carrier gearbox was created to demonstrate the process of determining the viability of a particular gearbox layout.


    Structure of the Model of Hybrid Electric Vehicle Energy Efficiency

    Trans Motauto World, Vol. 6 (2021), Issue 3, pg(s) 76-79

    The hybrid electric vehicles (HEV) are promising vehicles with low exhaust emissions and increased autonomy of movement including internal combustion engine (ICE) and electric motor (EM) which is powered by the battery (B) . The main advantage of HEV over classic cars is the reduced fuel consumption, especially in urban traffic [1]. This is a prerequisite for good energy efficiency of HEV, which is determined by the fuel consumption and consumption, respectively the regeneration of electricity of HEV. These values depend on many factors such as speed, mileage, acceleration, mass, drag, climatic conditions and more. The modelling of the energy efficiency of HEV is related to the study and structuring of the factors that determine the fuel consumption and electricity consumption and the dependencies between them and their connection and construction in a model. The model of energy efficiency of HEV gives a quantitative assessment of the fuel consumption and the consumption (regeneration) of electricity of HEV, according to the main influencing parameters. In addition, the HEV energy efficiency model indicates the influencing parameters and their analytical or experimental determination. The correct modelling of energy efficiency is related to the correct determination of energy parameters and their logical connection in a selected model. The optimal model of energy efficiency of HEV is built from these factors that can be directly measured or calculated, which increases the accuracy and reliability of the results. This article discusses building an energy efficiency model of a hybrid electric vehicle.


    Study of the psychophysiological state of adolescents using the method of gas-discharge visualization

    Science. Business. Society., Vol. 6 (2021), Issue 1, pg(s) 27-33

    The article presents the results of development and research of methods and adjustment of modes of operation of the device for gas-discharge visualization for the most accurate and prompt determination of the psychophysiological state of human health in th e field of his professional activity. Determining the ability of a teenager to cope with certain intellectual tasks, both at the beginning of the educational task and at the end of the working day, is necessary for the rational use of human labor and to ensure the quality and efficiency of the educational institution as a whole. Factors influencing the quality of the process of obtaining and accuracy of processing in formation about the psychophysiological state of man with a device for gas-discharge visualization,among which the greatest influence are external factors such as human (correct preparation and conduct of the experiment), climatic (humidity, ambient temperature) , guidance of ele ctromagnetic fields from power-operated devices nearby), elimination, or at least minimization of which allows to increase accuracy (by 8-12%), reliability (by 3-5%) and reproducibility (more than 1.8 times) of results diagnosing a device for gas discharge visualization. The daily dependences of the psychophysiological state of the adolescent on mental load were obtained, which showed the following: the best indicators of the psychophysiological state observed in the morning (period from 10-00 to 12-00) in the absence of other physical and intellectual morning load. At the same time it is established that active rest for 40-60 minutes or change of mental exercises by physical (within 60-90 minutes) after mental loading, restores the previous psychophysiological condition of the teenager by 85-90% whereas passive rest within 120-150 minutes, allows you to restore the previous psychophysiological state of the adolescent by only 35-45%.


    Impedance matching analysis of magnetic resonance coupled power transfer system

    Industry 4.0, Vol. 6 (2021), Issue 2, pg(s) 46-49

    Remote Electric Vehicles (EV) charging could become a viable alternative to cable systems. This paper is dedicated to the ana lysis of the Strongly Coupled Magnetic Resonance (SCMR) serial-to-serial topology aimed at establishing the impedance matching and obtains the maximum efficiency and power transfer coefficient. The research was done by using a model of equivalent circuits, experimental investigation and finite-element modeling of the mutual inductance. Upon generalizing the results obtained from the analytical and experimental research as well as 3D modelling of magnetic fields using Comsol Multiphysics, the interrelationships between internal resistance of voltage source and load resistance, characteristic and loss resistances as well as the distance between coils (the strength of magnetic coupling) necessary to ensure maximum efficiency and power transfer coefficient were established. The results of exp erimental research and modelling of the active power transfer coeff icient were presented.


    Gaz diesel engine operating modes and environmental efficiency analysis

    Trans Motauto World, Vol. 6 (2021), Issue 1, pg(s) 30-31

    The article discusses the benefits of converting diesel to gaseous fuels, such as reducing the toxicity of engine exhaust gases, fuel costs and noise. It is also noted that the conversion of a gas diesel engine is technically simple and, if necessary, it is possible to operate on diesel fuel. The main focus is on improving the efficiency of the diesel engine by adjusting the fuel mixture so that the power of the gas-diesel engine and the diesel engine is the same under all load conditions. The influence of the explosive properties of fuel and its dosage on the characteristics of gasoline is estimated.