FBE- Deniz Ulaştırma Mühendisliği Lisansüstü Programı - Doktora
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Yazar "Dere, Çağlar" ile FBE- Deniz Ulaştırma Mühendisliği Lisansüstü Programı - Doktora'a göz atma
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ÖgeEnergy efficiency oriented model based investigation of marine diesel engine and auxiliary systems(Lisansüstü Eğitim Enstitüsü, 2021) Dere, Çağlar ; Deniz, Cengiz ; 671339 ; Deniz Ulaştırma MühendisliğiThe fact that transportation of goods by seaways is the most efficient method in international transportation and the increasing trend in world trade leads to an increment in the volume of sea trade and raises the number of merchant ships. There is a directly proportional relationship between industrial production and transportation of goods. As a result of growth in production, the transportation of goods has been increasing with the share of carbon emission volume of shipping in total global anthropogenic emissions. Since the merchant fleet propulsion is heavily depended diesel engines, carbon-contained fuels are in use, particularly Heavy Fuel Oil (HFO) with 79% dominancy. Carbon emissions, the combustion product, as a greenhouse gas, has severe effects on environment, like climate change. Marine Environment Protection Committee (MEPC) as a sub-committee of International Maritime Organisation (IMO) has agreed on putting forward efficiency measures to decrease carbon emissions from shipping. Efficiency Design Index (EEDI) and Ship Energy Efficiency Management Plan (SEEMP) are two main mandatory regulations. Additionally, Energy Efficiency Operational Indicator (EEOI) was proposed to standardize the calculation method for ships' energy efficiency during operation; however, the type of calculation method will be superseded by Carbon Intensity Indicator (CII) as a new standard. With the new standard, not only the annual fuel consumption data "Annual Efficiency Ratio" (AER) will be asked but also the efficiency plans for the next three years for the ships will be required. Furthermore, the ships which cannot meet the minimum efficiency requirements, must re-new the SEEMP plans, with a procedure how will they achieve, their measuring, self-evaluation and improvement methods. IMO GHG Strategy aims to mitigate carbon intensity of international shipping by 40% until 2030 and at least 50% up to 70% abatement by the year 2050. The reference line was determined according to the year 2008, emission levels. In the short term it can be achieved by less fuel consumption, which results in mitigation of carbon emissions. For the upcoming mid-term solutions that reducing the fuel consumption of ships by reducing energy consumption and increasing main engine efficiency. These all studies are called energy efficiency studies in maritime sector and the efficiency issue has been becoming a decisive challenge for the future shipping industry. Although, alternative fuels without carbon are just initiated to integrate to the shipping sector, transformation of the primary power fuels to the not carbon-contained fuel will take a long time for shipping sector. A significant amount of emission reduction was achieved after 2008 to 2015 because of slow steaming operations, the average engine loads of the ships decreased significantly because of global volume trade, efficiency regulations. However, the significant reduction comes from intrinsic relation between ship hull and speed. There is a cubic relationship between the ship speed and required power for propulsion. Ships are designed for optimized range of operational speed. Their propeller and main engine are chosen according to planned rpm and propulsion power in the range of operational load. However, while in the slow steaming operation ships are not operated in their designated operational range. Although, operating out of the optimized operational range leads to loss of efficiency, reduced drag force with reduced speed enables lesser fuel oil consumption for per nautical mile. Nevertheless, the solution to be questioned is how long speed reduction will be a solution considering lowering speed is limited. After 2015 the efficiency increment trend has slowed down, because the ships had not reduced their speeds anymore, slightly increase and decrease can be observed at the trends. In the light of operational trends in recent years, a brief summary was prepared for the state of the art developing technologies to reduce both fuel consumption and emission, search on the new approaches to increase the efficiency of the engines, combined with engine room equipment. It can be seen that the most type of measures were developed for reduced loads, particularly. There are some methods applied on the shipping operations such as using limited engine power via slow steaming, fitting the ship with energy recovering installations, exchanging some equipment with more energy-efficient ones, using alternative fuels and optimisation of trim, ballast or voyage course etc. The study of the thesis aims to decrease energy consumption used by auxiliary systems or reduce the consumption of the fuel by main engine of the ship through the implementation of efficiency enhancement methods proved by model-based approach. The approach was applied on container ship. The container ships tankers and bulk carriers represent the 65% of world fleet. Due to the relatively higher speed of container ships, slow steaming is much more popular among in container ships. With high power demand of the ships, and the increment in the sizes of the ships results in increment in installed main engine power. Increment in both capacity and main engine power, the auxiliary power demand of the ships increases. Therefore, not only the fuel consumption of the main engine but also energy demand of the auxiliary systems must be analysed. The study is carried out by three main studies, which are published articles, stated in chapters 2-3-4. In the thesis, the energy management methods, which are applied to main engine and auxiliary systems, will be introduced with their quantitative results section by section. Chapter one issues the main engine operational efficiency under different operational loads. The model-based approach was carried out with together with the combination of mean value engine model approach and zero dimensional model. Mechanical and thermodynamic principles are utilized to represent engine load-rpm relation and determination of in-cylinder and after processes, including, combustion, cooling, turbocharging. With the help of the developed engine model, cooling phenomenon is studied in order to calculate the potential of energy efficiency improvement in a container vessel. The effect of cooling on in-cylinder processes is discussed under variable engine loads, reduced loads, particularly. The outputs of the model is in-cylinder pressure and temperature diagram in a crank angle domain, Scavenge pressure, Exhaust pressure and temperature, turbocharging power, cooling losses, injection timing. All engine conditions are evaluated at steady state conditions. The simulation results showed that with elevated liner temperatures, as in the range of maximum continuous rating temperatures, at reduced loads, has favourable effects on generated power. If the power generated by the engine fixed with constant rpm for the ship brake specific fuel oil consumption reduces with lesser heat loss to the cylinder walls. As a consequence of keeping some part of the heat in the cylinder, increased pressure in the cylinder can be converted to mechanical energy through piston head and piston rod and that energy can be transferred to the motion of the propeller shaft via crank shaft rotation. However, not all the power can be transferred to a mechanical power, around 30% of the unrejected heat could be utilized as shaft power. Chapter two treats the operational case of seawater and freshwater cooling system in the engine room. As can be calculated in case study one, the main engine liner cooling demand reduces significantly in reduced loads. The goal of the study is to minimize electrical power consumption during slow steaming operation, hence equivalent fuel consumption and emissions could be decreased. A computational study was carried out in order to clarify potential savings with respect to main engine load. An optimized operation of auxiliary machinery load is proposed to increase the energy efficiency aspect of the main diesel engine operation. The study quantifies the energy savings in main engine cooling system which has significant potential to reduce electrical power consumption in slow steaming operations. The values obtained from the simulator were verified using the technical manual of a diesel engine, which have similar output power range. The results of calculations show that there is great potential to improve energy efficiency when variable pumps are used. Based on the results, from the main engine cooling system, 60% of electrical power demand reduction can be achieved. The power reduction saved by pumps, decreases considerable amount of marine diesel oil as 296.2 tons used by diesel generators or oil fired boiler which corresponds 924 tons of CO2 emission reduction and $207,300 cost saving. The Chapter three issues the compressed air system used as a vital sub-system for the operation of main engine and its components. The compressed air is a valuable energy source in operational manner, by the reason of intrinsic lack of efficiency in pressurization process. Operational pressure and leakage rate are the major variables which affect operational efficiency of the system. This study aims to reveal potential energy saving for the compressed air system. To this end, several pressure ranges, 29-30 bars to 14-18 bars, and different leakage rates 2.4% to 45% are evaluated. After the data was obtained from ships, thermodynamic calculations had been carried out. Optimization of pressure saves 47.3% in daily power requirement, 58,2% in compressed air unit cost, 18.4 and 57.4 tons of reduction in fuel consumption and CO2 emissions in a year respectively. High leakage rates can cause 2.7 times more power and fuel consumption. Finally, operating load, as an important indicator of compressor, makes imperfections identifiable. A detailed graphical evaluation of achieved improvement at electrical consumption need by suggested design pressure ranges was presented from both economic and environmental concept. In the conclusion, evaluation of energy management methods in the past to present and relation with the current studies are discussed with model based approaches. Further studies can be proposed by modelling method by integrated the models, developed in this studies. Model-based approach will be a prominent solution for near future shipping to prepare more realistic and accurate SEEMP plan and observing the future obstacles for subject ship.