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Naval engineering and ship control special edition editorial
No full textEditorial Special Issue: Naval Engineering and Ship Control IIGreen Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Ship Design, Production and Operation
Autonomous control for adaptive ships: with hybrid propulsion and power generation
No full textShipping plays a crucial role in modern society, but has to reduce its impact on the environment. The commercial availability of power electronic converters and lithium-ion batteries provides an opportunity to improve performance of ships energy systems while reducing their environmental impact. However, the degrees of freedom in control for hybrid propulsion and power generation require advanced control strategies to autonomously achieve the best trade-off between fuel consumption, emissions, radiated noise, propulsion availability, manoeuvrability and maintainability. This PhD thesis proposes dynamic simulation models, benchmark manoeuvres and measures of performance (MOP) to quantify energy system performance. These simulation models and MOPs are used to quantify the improvements with three novel control strategies: adaptive pitch control, parallel adaptive pitch control and energy management for hybrid propulsion and power generation. Finally, a layered control strategy is proposed that can autonomously adapt to changing ship functions, using the proposed control strategies. The proposed energy systems and control strategies can thus significantly reduce the impact of shipping on the environment, while more autonomously achieving its increasingly diverse missions at seaShip Design, Production and Operation
Optimization study of a hybrid powertrain: Optimization of the system components and energy management of a zero-emission hydrogen powered boat
No full textThe company H2 Marine Solutions has designed a zero-emission hydrogen powered boat. This boat is compared to its fossil fuel counterpart more than twice as heavy. The reason for this is that the system components that are used in the hybrid powertrain of the hydrogen powered boat are heavier. The main question of this research is: How can we establish the optimal energy and power of the system components of a hybrid power system with optimal energy management for a zero-emission hydrogen powered boat for different operational profiles? This results in a sizing and control optimization problem. Because these two problems are coupled this is a multi-objective double-layer optimization problem. The most popular strategy to solve this problem is with the control problem nested in the sizing problem \cite{Hybrid-ship}. The most popular algorithms to solve these problems are evolutionary algorithms.Unfortunately due to the complexity of these algorithms and due to lack of time the sizing and control problems are solved separately in this research. First, the system components of the plant are described and modeled. The components that are modeled are the battery, the fuel cells, and the DC/DC converter. To find the optimal energy management strategy an online optimization strategy is used. This is done because the problem is solved in real-time than and could be used in a real application. The strategy that is chosen to solve the control problem is the Equivalent Consumption Minimization Strategy (ECMS). This strategy translates the electrical energy from the battery into equivalent hydrogen consumption. For every timestep, the equivalent consumption is minimized by the ECMS. Because there are different variants of ECMS three of these variants are discussed and compared in the research. Also, two rule-based energy management strategies are compared. The sizing problem is described by linear equality and inequality constraints. The problem is solved by the Linprog function in Matlab. The objective of the sizing problem is to minimize the weight of the system components. The input in the sizing problem is the energy and power demand of the most energy intensive operational profile. After solving the sizing and control problem the results are combined and the different operational profiles are used as input to show the robustness of the optimization.The three different energy management strategies all minimize the instantaneous equivalent consumption but show different behaviors when controlling the system components. The optimal energy management strategy is the Smooth Adaptive Penalty (SAP)-ECMS. With this controller, the fuel cells work on a steady operating point and ramp up and down the output power smoothly when necessary. Due to this behavior, the average efficiency of the fuel cell is the highest, and the hydrogen consumption is the lowest compared to the other controllers. The results of the sizing problem show that the weight will decrease when a bigger fuel cell is used in combination with a smaller battery. The consideration between a bigger fuel cell and a smaller battery is a consideration between lower weight and more hydrogen consumption. When a bigger fuel cell is used it is recommended to implement an optimal energy management strategy such as the SAP-ECMS to control the output power of the system components. This is preferable above a rule-based controller which can not find the optimal operating point at all timesteps. Even better energy management strategies may exist or could be made by combining different ECMS's. When the sizing and control problem are solved in a nested strategy more accurate results could be achieved.Electrical Engineering | Sustainable Energy Technolog
Adaptive pitch control for ships with diesel mechanical and hybrid propulsion
No full textShipping urgently needs to reduce its impact on the environment, both due to CO2, NOx and particulate matter (PM) emissions and due to underwater noise. On the other hand, multifunction ships such as offshore support vessels, anchor handling and towing vessels, naval vessels and wind farm construction and support vessels require fast and accurate manoeuvring and need highly reliable systems to support reduced or no crew. Diesel mechanical propulsion with controllable pitch propellers provides high efficiency and low CO2 emissions, but has traditionally been poor in manoeuvrability, can suffer from thermal overloading due to manoeuvring and requires significant measures to meet NOx and PM emission regulations. The control strategy of diesel mechanical propulsion with fixed combinator curves is one of the causes of the poor manoeuvrability, thermal overloading and cavitation noise during manoeuvring, such as slam start and intermediate acceleration manoeuvres. This paper proposes an adaptive pitch control strategy with slow integrating speed control that reduces fuel consumption, CO2, NOx and PM emissions and underwater noise, improves acceleration performance, limits engine loading and prevents engine under- and overspeed. A simulation study with a validated model of a case study Holland class Patrol Vessel demonstrates 5–15% reduction in fuel consumption and CO2 emissions, compared to the baseline transit control mode in the ship speed range from 6 to 15 kts, during constant speed sailing. Moreover, the adaptive pitch control strategy reduces acceleration time from 0 to 15 kts with the slam start procedure by 32% compared to the baseline manoeuvre control mode and by 84% for an intermediate acceleration from 10 to 15 kts, while preventing thermal overloading of the engine, during straight line manoeuvres. Combining this control strategy with hybrid propulsion, running an electric drive in parallel with the propulsion diesel engine, can potentially further reduce fuel consumption at low speeds while also improving acceleration performance even more. Therefore, hybrid propulsion plants with controllable pitch propellers and adaptive pitch control can provide a significant contribution to the urgent reduction of environmental impact of shipping and to the need for more autonomous and reliable ship systems.Ship Design, Production and OperationsTransport Engineering and Logistic
Operational data-driven energy performance assessment of ships: the case study of a naval vessel with hybrid propulsion
No full textShip designers hardly ever receive feedback from the actual operation of their designs apart from sea acceptance trials. Similarly, crews operating the vessels do not receive a clear picture of the energy performance and environmental footprint of different options. This paper proposes a methodology based on operational data from continuous monitoring, and applies it to an ocean patrol vessel of the Royal Netherlands Navy in order to identify the impact of diverse operational conditions on energy performance over the whole operating range, but also to examine the decision to equip the vessel with hybrid propulsion. Specifically, it introduces mean energy effectiveness indicator and mean total energy efficiency over discretised vessel speed, as the main tool in quantifying the energy gains and losses to assist in making better-advised design and operational decisions. Moreover, it demonstrates a dataset enrichment procedure, using manufacturers' information, in case not all needed sensors are available. Results suggest that electrical propulsion was 15–25% less efficient than the best mechanical propulsion mode, and on the overall energy performance of the vessel, increasing speed by 1 knot caused a 7% and 14% increase over the minimum (Formula presented.) /mile emissions between 8 and 14, and above 14 knots respectively.Ship Design, Production and Operation
Energy transition for the replacement Air Defense and Command Frigate
No full textProgressing targets on Greenhouse Gas (GHG) emission reduction urge the Netherlands Ministry of Defense (NL MoD) to reduce GHG emissions, without sacrificing striking power. The Royal Netherlands Navy (RNLN) is investigating the replacement of the Air Defense and Command Frigate (LCF) between 2030 and 2040 by a Large Surface Combatant. As it will be impossible to achieve substantial reduction of GHG emissions through energy-saving technologies, sustainable fuels need to be implemented in the design. In this paper, a literature review is presented to establish possible directions for the strategy to migrate future naval combatants from current fossil fuels to future sustainable fuels. We examined the effect of short- and long-carbon chain sustainable fuels, sustainable methanol and sustainable diesel, respectively, on the replacement Large Surface Combatant; specifically their advantages, disadvantages, production routes, future production cost estimates and availability to give an understanding which pathways can help the NL MoD to achieve their stated GHG emissions reduction goals. Moreover, we present three different design concepts with respect to fuel composition and propulsion configuration on which the impact of the established fuels is qualitatively examined. Firstly, operating on methanol has a significant impact on the design of a large surface combatant: the endurance of the ship is more than halved or the tank capacity has to be increased by 700 to 900 m3 ; the ship might need a longer machinery space to allow for more propulsion engines to compensate for the increased power requirement and unavailability of gas turbines on methanol; and required auxiliary and safety systems add further volume area to the engine room. Secondly, sustainable diesel is a drop-in fuel, which makes blending of sustainable diesel with fossil diesel possible in the existing infrastructure allowing a gradual transfer from fossil diesel to sustainable diesel. However, the production is less efficient in a well-to-wake approach and the cost of Bio-diesel and E-diesel is 5% to 30% more expensive with a mean estimated additional cost of 6 C/GJ compared to methanol. Finally, navies could consider a two-fuel strategy: sail on methanol during operations with limited autonomy, typically in peace time, and operate on diesel during operations with high autonomy, during war time operations. In this case the design needs to include both diesel and methanol fuel systems and additional space for methanol safety measures. In order to more exactly quantify the impact of methanol on the design, a concept design iteration is required, which is identified as research for future work.Ship Design, Production and Operation
Injection and Evaporation of 100% methanol: Experimental and simulation-based research into the injection and evaporation of 100% methanol for use in a port-injected spark-ignited ICE
No full textThe maritime sector faces major challenges to reduce its impact on global warming. The use of methanol as a fuel alternative is considered one of the more promising options to be implemented in a relatively short to medium time frame; based on the potential availability, emission reduction, energy density, potential to be synthetically produced, scalability of production, and its implementation on board ships (both new build and retrofitted).This report investigates potential improvements of the injection system, to achieve complete evaporation in the air inlet of a port-fuel injection engine to avoid wall-wetting of the scavenger air receiver and inlet valve. As a result, the methanol-air mixture in the cylinder would become more homogeneous and able to provide 100% of the rated engine power. Earlier research indicated that the wall-wetting fuel film and its evaporation rate directly affect the air-fuel ratio of the in-cylinder mixture, stability of the combustion process, and overall engine performance. The study includes the development of an injection model simulating low-pressure port-fuel injection, similar to the system fitted on our Caterpillar test engine, and the development of a single-droplet evaporation model to gain inside into the evaporation process of 100% methanol.Based on the performed experimental research, we conclude the average droplet size ranges between 100 and 120 μm. The average droplet speed was determined at ±35 m/s and the spray angle at 20°. At room temperature and pressure, the injection spray ended against the back-glass of the evaporation chamber, indicating almost none of the ethanol evaporates under these conditions. The injection length exceeds at least ±40 cm at atmospheric temperature and pressure, which is in line with the results of the single-droplet evaporation model.MENENSMarine Technology | Marine Engineerin
Charge air configurations for propulsion diesel engines aboard fast naval combatants: a simulation study on efficiency and performance
No full textThe time a naval combatant can be deployed for a mission is limited by its dependency on supplies. At a certain point the ship needs to leave the area of operations to be replenished in a harbour or by a support ship. Moreover, the Royal Netherlands Navy has a societal obligation to reduce its environmental impact, in particular on global warming. Therefore, the Royal Netherlands Navy (RNLN) wants to reduce the fossil fuel dependency of its fleet significantly [50]. One of the methods to reduce fossil fuel dependency of ships is to reduce their energy requirement. The operational profile of fast naval combatants for the RNLN requires that the ships operate on the diesel engines for 90 percent of the time, often in part load. In part load, the turbocharger cannot supply the engine with the right amount of charge air. This results in a limited operating envelope for the diesel engine, and a decreased efficiency in part load. This is caused by the matching of a turbocharger, which is a compromise between high efficiency in the design point, and off design performance. However, in part load, advanced charge air configurations can potentially resolve this and improve the results as shown by Grimmelius et al. [15] and Zhang et al. [56]This study investigates the effect of advanced charge air configurations on the efficiency and acceleration performance of diesel engines in hybrid configurations aboard fast naval combatants. First, two mean value first principle diesel engine models based on the work of Geertsma et al. [12] were used to model the diesel engine. Next, the models were partly validated with ship data. We found that an approach using compressor maps and a motion based turbocharger model was most accurate. Then, a parallel-sequential turbocharger and a hybrid electric turbocharger were incorporated into the model. A hybrid turbocharger is a turbocharger with an electric machine coupled to the turbocharger shaft. The electric machine can increase the turbocharger speed to boost the charge air pressure in motor mode. Also, in generator mode excessive power from the turbocharger shaft can be taken out and utilized elsewhere. It was concluded that the application of advanced charge air configurations can significantly improve the engine efficiency in part load. For example, in a diesel hybrid propulsion configuration with power take-off this can lead to an efficiency increase of almost 10% at 20% load in comparison with a single charged engine. Furthermore, hybrid turbocharging enables extending the operating envelope of a parallel-sequential turbocharged engine with up to 25% at 60% engine speed. This enables the engine to deliver constant torque from 600 to 1000 rpm. With these concepts therefore, both improved efficiency and improved acceleration performance can be achieved.Marine Technology | Ship Design, Production and Operation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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