Journal of Marine Technology and Environment 2021 Vol. 2

  • A TOOL FOR THE ASSESSMENT OF THERMAL EFFICIENCY OF IDEAL DIESEL CYCLES, PROVIDED TO FUTURE MARINE ENGINEERS

    Ionela TICU; Elena GOGU
    10/1/2021
    10.53464/JMTE.02.2021.11
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    Diesel engines are a type of internal combustion engine widely spread in the maritime sector. In a world depending on fossil fuels, the challenge faced by scientists and professionals consists in the efficient use of this kind of fuels. The future of these engines strongly depends on the efficiency enhancement. Future mechanical engineers have to be trained in order to gain engineering judgement and enterprising attitude. In this respect, this paper deals with a theoretical study focused on the improvement of the efficiency of the ideal Diesel cycle. This type of study was recently introduced in Constanta Maritime University, within Thermodynamics seminar activities, delivered to future marine engineers, enrolled in their third semester. This study will reveal the fact that the efficiency of Diesel cycles is affected by the variation of compression ratio, cut off ratio and specific heats ratio. The results obtained will show that, for the ranges taken into discussion, thermal efficiency might be enhanced by the rise of compression ratio and specific heat ratio values and by lowering cut off ratio values. The study is a predecessor of expensive and time costing experiences and it is also a guidance in the hand of future professionals – able to train them for real solutions.
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  • THE IMPORTANCE OF ECO-CLUSTERS IN THE CONSTANTA COUNTY

    Mirela Iuliana SUNDRI
    10/1/2021
    10.53464/JMTE.02.2021.10
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    Economic theory and international practice confirm the role of clusters as catalysts for competitiveness based on innovation and internationalization. Europe is facing the challenge of becoming a fair and prosperous society based on a modern, competitive and resource-efficient economy. Mobilizing industrial actors towards a clean and circular economy through in-depth cooperation along value chains as well as the use of new technologies, sustainable solutions and disruptive innovation are critical to achieving this goal. Clusters play an important role in operationalizing smart specialization strategies. Eco-clusters aim to increase the competitiveness of enterprises included in "cluster" structures in sectors of economic relevance, by concentrating resources and developing the production of innovative goods such as technologies, products, services, with the greatest possible reduction of waste. Constanta County, through its strategic positioning, through the concentration of economic activities, education and research is an area of maximum interest for the development of eco-innovation and eco-clusters. This study highlights the premises for the establishment of eco-clusters in the Constanta area, given their role as a driver in greening economic policies in the region and developing partnerships in order to obtain clean products. Through eco-clusters, there are also developments in the process of eco-innovation and implementation of sustainable development strategies in the Constanta area, as a means for a long-term socio-ecological transition.
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  • ANALYSIS OF THE ENGINE STRUCTURAL AND THERMAL STRESS

    Liviu Constantin STAN
    10/1/2021
    10.53464/JMTE.02.2021.09
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    The paper aims to analyse the demands of four-stroke naval pistons. To begin with, a brief analysis of the evolution of shipbuilding was made. Mechanical requests are produced by the gas pressure force and inertial force of the alternate moving masses. Under its action the piston suffers an axial deformation. The thermal demands appearing in the engine are all the more important as the engine power is higher. The possibility of calculating them is more difficult due to the complexity of the thermogazodynamic phenomena in the engine cylinder. Thus, in the piston head, which comes in contact with both the hot gases and the fresh (much cooler) load, a non-stationary heat flow is installed which leads to a certain thermal regime of the engine. Considering the demands outlined in the last chapter, they lead to the final conclusion that although the most unfavourable loading situation was considered as the maximum pressure during the processes and even exaggerated in establishing the working conditions, the piston is still close to the elastic limit. This demonstrates that the way of calculating the dimensions of the piston is correct and safe, as long as its constructive dimensions are not oversized.
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  • WASTE MANAGEMENT ON BOARD SEAGOING SHIPS

    Liliana Viorica POPA
    10/1/2021
    10.53464/JMTE.02.2021.08
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    The reality remains uncomfortable, the climate crisis is coming with extreme phenomena more and more devastating around the globe and more and more people and more and more parts of ecosystems are suffering from the greed of large companies and lack of constructive action and coherent decision-makers. There are various types of waste generated during operation, and to be able to implement a waste management system, it is necessary to identify and quantify the different types of waste on board. The purpose of this paper is to examine the responsibilities, management, handling and disposal of ship-generated waste and the requirements for the preparation of an on-board waste management plan.
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  • THE EIS OPTIONS AT MONITORING THE SPREAD OF POLLUTION IN THE STREAM

    Jana PAŘÍLKOVÁ; Zbyněk ZACHOVAL; Jan JANDORA; Šimon POŠPÍŠILÍK; Jan MIKULKA; Jan DUŠEK; David JUŘIČKA; Boriss GJUNSBURGS; Algirdas RADZEVIČIUS; Rytis SKOMINAS
    10/1/2021
    10.53464/JMTE.02.2021.07
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    Water pollution is one of the most significant problems in the world today and is a global problem. Surface water pollution in streams and reservoirs is reflected in the deterioration of the quality of aquatic ecosystems, including those that occur in their vicinity or follow them. Lack of quality drinking water is one of the main causes of various diseases, which can lead to death, especially in developing countries. Therefore, it is important to detect water pollution in time and anticipate how it could develop and be transported in the stream. Measurements on a physical model are time-consuming and economically demanding, but for a given locality it can provide comprehensive information, including the proposal of possible measures and their verification. It is also a suitable approach for calibration and verification of mathematical models. One of the main tasks in the physical modelling of the spread of pollution in the stream was to find a suitable substance that would simulate the pollution without being aggressive towards the water pumping circuit. The method of electrical impedance spectrometry was chosen for its detection in the stream.
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  • ENERGY EFFICIENCY IN CONSTANTA HARBOR - A THEORETICAL ASSESSMENT OF THE PERFORMANCE OF A HEAT PUMP FOR HEATING NEEDS, FOR A LESS POLLUTANT ADMINISTRATION OFFICE

    Feiza MEMET
    10/1/2021
    10.53464/JMTE.02.2021.06
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    In accordance with the present energetic exigencies, the energy consumption in port buildings is of a vital importance. From this perspective, heat pumps are less pollutant and more energy efficient options than the traditional heating technologies. This study focuses on an air source heat pump (ASHP), operating in an administration office located in Constanta harbor, Romania, in order to supply heated water during December of 2020. Electrically driven heat pumps are seen as a successful alternative to classical expensive heating means, such as electrical heating or the one based on fossil fuels combustion. Within this research, are investigated influences of the heated water temperatures and exterior air temperatures on the theoretical Coefficient of Performance, the compression ratio and the discharge temperature. The cycle is working with R134a, with 50C superheating and sub cooling. It will be considered that the heated water is supplied in the range (40-50) 0C, while the outdoor air temperature varies in the range (0-10) 0C. Obtained results show that the highest efficiency of the ASHP is obtained for the lowest value of the heated water temperature and for the highest value of the outdoor air temperature. This situation corresponds also to the good working of the compressor of the refrigeration plant, since are seen lowest values of the compression rate and the discharge temperature, as well. This means that the compressor do not consume high amounts of energy and the oil is not damaged because of high temperatures of the refrigerant vapors.
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  • THE ENERGY POTENTIAL OF BLACK SEA IN ROMANIAN SEASIDE AREA

    Valentina JALAN; Dumitru DINU; Raluca RĂDULESCU
    10/1/2021
    10.53464/JMTE.02.2021.05
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    The Black Sea is considered a relatively calm sea, the optimal choice for the capture process is influenced by the wave regime and its peculiarities. This sea is characterized by winds that blow towards land with greater intensity in January causing the sea to be more agitated and with less power in May, June and July, when the sea was the calmest of the year. It should be noted that the frequency of strong winds is 38%, and of those of low speed of 1m/s of only 1.5%. For the collection of oceanographic and meteorological information, data provided by the Gloria platform located in front of Romania’s coast were is used, as well as records from the three offshore buoys anchored in the Romanian seaside area and which are part of the EMSO EUXINUS research infrastructure managed by National Institute for Research and Development on Marine Geology and Geoecology - GeoEcoMar. In addition, free data such as those provided by the site of the research institute Grigore Antipa were easily accessed. Presently there are three fixed platforms in the Black Sea. Wave energy is underexploited, both worldwide and in the Black Sea. The potential of this type of energy is huge, and the environmental impact is low compared to other renewable energy technologies.
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  • STABILIZING THE PERIODIC ORBITS IN A CHAOTIC MAPPING DESCRIBING THE DISCRETE HEALTH SYSTEMS VIA PREDICTION-BASED CONTROL

    Dumitru DELEANU
    10/1/2021
    10.53464/JMTE.02.2021.04
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    In the paper the problem of location and stabilization of unstable periodic orbits (UPOs) in discrete systems is investigated via the prediction-based control (PBC). It involves using the state of the free system one period ahead as reference for the control signal. Two types of control gains are tested, the first requiring the knowledge of the UPO to be stabilized and the second depending only on the actual state of the trajectory. The effectiveness of PBC is demonstrated on a chaotic mapping describing the malignant tumor growth. When the results obtained with the two control laws are compared with each other, it is found that the second variant is qualitatively superior, both in terms of convergence and the number of stabilized UPOs, especially for long-period orbits.
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  • RESEARCH ON OPTIMIZING THE OPERATION OF SHIPS IN CONTAINER TERMINALS

    Robert Alexandru DĂINEANU; Dumitru DINU; Mariana PANAITESCU; Fănel-Viorel PANAITESCU
    10/1/2021
    10.53464/JMTE.02.2021.03
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    The time allotted to a single ship at berth varies greatly depending on the characteristics of the ship, the volume of cargo and its specifications.. Taking into account the service time and the problem of terminals by overcrowding of waiting ships and available berths (which may vary in number, depending on the size of ships already berthed), the average waiting time is calculated and obtained. The operating process is usually sequential, ie each type of cargo is stacked separately from the other types. For this reason, the operating time was considered to consist of four other indicators, which correspond to the main types of cargo of Ro-Ro / Ro-Pax ships: complete trucks, semi-trailers, • passenger cars, vehicles as goods themselves. Also, the time of operation of the goods by the dockers can be formulated by two other different terms: the time related to the ship and the time in the terminal. In this context, we intend to analyze the capacity of the terminal in Constanța Port.. Two different scenarios are considered: a more "common" case for the studied terminal with 40 semi-trailers and 80 trucks to be unloaded and the same amount to be loaded and an "extreme" case in which all goods are composed of semi-trailers ( 160 plus 160 in total). By using simulation models, the values for the optimal quay time were obtained, in relation to the number of units for loading data in the specified scenarios. Using modeling algorithms, we obtain reports of situations that include tables and graphs that allow the optimization of terminal operation.
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  • ELECTRICAL DRIVE AND CONTROL OF AN ELECTRIC MOTOR STEP BY STEP BY STEP BIPOLAR

    Violeta-Vali CIUCUR
    10/1/2021
    10.53464/JMTE.02.2021.02
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    PWM, (Pulse Width Modulation) is the most effective way to control analog circuits using numerical outputs by changing the duration and frequency of the signal. The duration of each state t1 and t2, so the filling factor, where T = t1 + t2 = constant. If only one of the times (t1 or t2) varies, then the Tt period of a cycle varies, so the f = 1 / T frequency varies. The PWM signal is actually a modulated rectangular signal over the duration by modifying the duration of each period t1, t2 of the cycle as well as the change in frequency. The maximum benefit of a stepper motor can only be obtained if it is ordered correctly, this requiring a direct current source, an electronic switch and a controlled pulse generator (numerical information). The frequency of the CLOCK cycle is measured in Hz and the filling factor is measured in percentage (%). The amplitude of the output signal is constant even if the amplitude of signals producing the fill factor varies.
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  • Increasing the Efficiency Of Marine Energy Conversion

    Violeta-Vali CIUCUR
    10/1/2021
    10.53464/JMTE.02.2021.01
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes
    New approaches need to be taken into account in adopting the configuration of residual heat recovery systems, design, operation and control and to consider equipment and the energy conversion process in the perspective of integrated systems in order to increase measurable energy efficiency in existing marine energy systems as well as other new systems.
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