New Library Ship Energy Systems

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New Library Ship Energy Systems

  1. 1. 4 Power Generation New Library Ship Energy Systems Malte Freund FutureShip, Hamburg, Germany Alex Magdanz and Tim Jungnickel ITI, Dresden, Germany Kurzfassung Die Entwicklung der neuen Bibliothek Ship Energy Systems ist abgeschlossen. Das Ziel der Bibliothek ist es ein Tool bereitzustellen, das das System rund um die Schiffsmotoren optimieren kann. Der Fokus liegt auf der Umwandlung elektrischer zu mechanischer Energie, sowie der Darstellung der Hilfssysteme, die Kühlwasser und Frischluft bereitstellen. Die Bibliothek vereinfacht die Durchführung von Variantenrechnungen, ist in der Lage reale Betriebsprofile darzustellen und zeigt monetäre Einsparpotentiale auf. Es wurde im Folgenden ein Beispielmodell von einer typischen Schiffsmotorenanlage für ein mittelgroßes Frachtschiff erstellt. Abstract Development of the new library Ship Energy Systems is finished. The purpose of this library is to provide a tool to the ship building industry for the optimization of ship machinery. The focus lies on the conversion of electrical and mechanical energy as well as related auxiliary systems for providing cooling water and air. The library enables a user to optimize the machinery through variant analysis by means of an actual operational profile of the vessel and quantification of saving potentials. An example model considering a typical machinery arrangement of a medium sized freight vessel is presented. Background For decades, ships have been designed for much lower fuel costs. Increasing fuel prices and IMO regulations to curb CO2 (carbon-dioxide) emissions has put pressure on ship owners to obtain more fuel efficient ships. As a result, we have seen a multitude of proposals to reduce fuel consumption in ships. Overviews of available options in resistance, propulsion, machinery and operation can be found e.g. in Buhaug et al. (2009) and OCIMF (2011). The majority of a ship’s fuel consumption is used for propulsion. The share may range from 55% (cruise vessels) to 90% (bulk carriers). Correspondingly, there has been large focus on measures to improve the hydrodynamics of ships, e.g. Bertram (2011). However, there is wide consensus that significant savings can also be made in machinery and operation. Energy flow simulation methods for ship machinery operation 138
  2. 2. New Library Ship Energy Systems have seen a very rapid development worldwide in recent years, Freund et al. (2009), Freund and Hansen (2010), Vugt and Marlen (2010), Dimopoulos and Kakalis (2010), Coraddu et al. (2013). Oil Price 1997 - 2012 140 700 120 600 100 500 80 400 60 300 40 200 20 US $ per Barrel Crude Oil 800 100 US $ per Metric Ton HFO 160 0 0 01/2012 01/2011 01/2010 01/2009 01/2008 01/2007 01/2006 01/2005 01/2004 01/2003 01/2002 01/2001 01/2000 01/1999 01/1998 01/1997 Figure 1: Crude oil prices (continuous line, left axis) and fuel oil prices (dots, right axis) from 1997 to 2013 Library Optimization of ship energy efficiency for realistic operation profiles is a key topic in the shipbuilding industry. Until now, there have only been tools for specific, limited issues in testing and designing the increasingly complex systems on board ships. Only typical operation points could be calculated, using standard spreadsheet tools. There was no comprehensive tool for ship energy management. Together with ITI, FutureShip has developed a simulation library for designing and testing the energy efficiency of a ship using the software SimulationX. This library, called Ship Energy Systems, advances the state of the art in ship energy calculations significantly: •• all auxiliary systems of a ship can be modeled and calculated simultaneously, •• the entire dynamic operation profile of the ship can be entered including ambient air pressure and temperature, seawater temperature, and individual operation profiles of each engine. Ship Energy Systems facilitates obtaining results from variant calculations, making the library ideal for design offices and shipyards. In addition, component suppliers may use the library to provide evidence and supporting documents of the functionality and energy savings of their components. 139
  3. 3. 4 Power Generation Library Scope The library was developed to include the main components of a vessels’ machinery, with focus on cooling, conversion of mechanical and electrical energy and related auxiliary systems. These are the largest consumers on board. Most components were parameterized with characteristic curves and a physical description of the component behavior. The intent was to create models with data available to the user, not proprietary design parameters. A simulation model shall calculate the required energy supply for given demand characteristics. The operation profiles of engines and electrical consumers are the starting points of the calculation. In each component of the modeled system, the losses resulting from energy transfer or conversion are considered. The end result is a fuel consumption rate and total fuel consumption which can be viewed in terms of volume or cost. Components Engines are central components to the Ship Energy Systems library. The engines are modeled from an energy-based, not a mechanical point of view. Based on the requested mechanical power, the heat flow to the cooling system and engine room is defined via curves. The following properties are calculated for the engine: •• •• •• •• Heat transfer to engine room Heat transfer to cooling water Exhaust gas properties Fuel consumption The engine cooling circuits can be modeled using components such as pumps, heat exchangers, throttles, fluid volumes, pressure vessels, and three-way valves. Fluid data for both water and seawater is available. Heat is emitted through convection and radiation from the engines to the engine room. One or more engine rooms may be present in a simulation model, and each engine is assigned to a particular room using an identifying number. In turn, each engine room is cooled by a fan. The electrical power required by the fans can be supplied using the generator model. Based on the efficiency curve and electrical power demand, the generator calculates the necessary mechanical power. If the requested electrical power exceeds the capa140
  4. 4. New Library Ship Energy Systems city of one generator, the component power splitter can split the requested electrical power to various other power sources. The fuel tank component calculates fuel costs resulting from fuel consumption in order to analyze possible savings made by improved system design or operation. The fuel costs may be used to calculate payback time or return on investment for system variations. Variant Analysis In a simulation, operating conditions and profiles for engines and electrical power demand can be described using curves and the changing energy demand for system variations analyzed. The library design aims for minimal effort in calculating variant analyses of energy efficiency. The SimulationX Variant Wizard allows the user to automate the process of testing system variations by selecting parameters of interest and setting corresponding ranges via a simple menu. Results from each variation can be saved and plotted. Model Extensions The Ship Energy Systems library comes with a complete set of parameterized components. The hierarchical library allows users to save commonly used parameter sets for a component for reuse in new models. For instance, if a ship builder uses a particular type of heat exchanger in the cooling circuits, and knows the parameters for 141
  5. 5. 4 Power Generation that component (nominal temperatures, load, etc.), a new heat exchanger model can be created by making an extension of the original heat exchanger and saving those parameters as default. The changes can be made using the SimulationX TypeDesigner, which helps a user to make the changes step by step. Users can simply drag in their specialized component to a new simulation model, rather than parameterizing the original component each time. Example Model A simplified engine room is modeled. The model represents a typical configuration of a medium-size freight vessel with a two-stroke main engine and three auxiliary for electrical power. The auxiliary systems are implemented with the fresh-water cooling circuit for the engines and the seawater cooling circuit, which cools the fresh-water circuit in the central cooler. Additionally, the heat influx into the engine room is modeled by a fan providing cooling air from the environment. Figure 2: Example model of a medium-size freight vessel Fig. 2 gives an overview of the example model. Its parts are described below. In Fig. 2, the main engine is located on the bottom right and the auxiliary engines and generators to its left. The fresh-water cooling circuit surrounds the engines, with the central cooler and the pump close to the generators. Throttles are used for controlling the cooling water flow in the different branches of the cooling water system. The seawater cooling circuit is connected to the central cooler on the bottom left of Fig. 2; the engine room with its fan for cooling air can be found in the upper left. In the upper 142
  6. 6. New Library Ship Energy Systems middle, the icons specifying the boundary conditions for the exhaust gas flow and the ambient conditions of the environment are located. Instead of a conventional by-pass control in the fresh-water cooling circuit, a frequency controlled seawater cooling pump is demonstrated to keep the feed water temperature at the desired temperature of 36 °C. This significantly reduces the amount of seawater pumped through the central cooler and thus the electrical power demand if the vessel’s main and auxiliary engines are operated with lower than design power or at non-tropical seawater temperatures. This is demonstrated in Fig. 4 for an exemplary voyage over 18 h. Here, the main engine load varies between 0% and Figure 3: Seawater cooling system 95% MCR and seawater temperature between with frequency control 25 °C and 30 °C. Instead of its nominal rotational speed, the pump is operated between 30% and 80% of the nominal speed. The varying pump speed is displayed in Fig. 4 (mid, swPump1.n) together with the main influence factors (main engine operation, seawater temperature, resulting temperature in the fresh-water cooling circuit). Figure 4: Operational profile of main engine (top), rotational speed of seawater cooling pump and resulting temperature in fresh-water cooling circuit (middle) and seawater temperature over the exemplary 18 h voyage 143
  7. 7. 4 Power Generation The electrical power demand is simulated using the demand from constant consumers (provided by ramp signals), in addition to the power demand from the engine room fan. The resulting power demand is distributed to the generators by the power splitter, i.e. only the necessary generator sets are running to cover the power demand. Figure 5: Power distribution to generators and attached auxiliary engines The heat from the individual engines and generators of the model is summed up and connected to the engine room component automatically. Cooling air is provided to the engine room by a speed controlled fan. The used air is specified by boundary conditions connected to the ambient conditions and then discharged back to the environment. The Figure 6: Engine room compartment with controlled control for the required amount of cooling air is based on the cooling air fan and ambient conditions temperature of the outflowing air as measured by the temperature sensor. The example model integrates key aspects for machinery analysis on a typical layout of a medium-size freight vessel. Variations in machinery can easily be integrated to quantify their operational performance and influence on the energy demand. Conclusion The new library Ship Energy Systems is developed for simulation of ship machinery with the focus on electrical and mechanical energy conversion and the auxiliary systems. Aim is to enable the users to easily establish a simulation of the ship machinery, incorporating the operational profile of vessel and individual machinery. Variant calculations for optimal configuration of machinery can be executed and saving potentials quantified. Compared to the development of simulation models for each project, the library reduces the required time for simulation of typical ship machinery significantly. The development effort lies then in the establishing of a model by drag and drop of the 144
  8. 8. New Library Ship Energy Systems components, their logical connection and their adaptation to the present project by parameterization, not in the challenge of the physical description of the required machinery. The users can integrate their adapted and pre-parameterized components in the library for a quick reuse in other models as well as integrate special components which are in the focus of their projects. References [1] BERTRAM, V. (2011), Practical Ship Hydrodynamics, 2nd Ed., Butterworth & Heinemann, Oxford [2] BUHAUG, Ø.; CORBETT, J.J.; ENDRESEN, Ø.; EYRING, V.; FABER, J.; HANAYAMA, S.; LEE, D.S.; LEE, D.; LINDSTAD, H.; MARKOWSKA, A.Z.; MJELDE, A.; NELISSEN, D.; NILSEN, J.; PÅLSSON, C.; WINEBRAKE, J.J.; WU, W.Q.; YOSHIDA, K. (2009), Second IMO GHG study 2009, International Maritime Organization (IMO), London [3] http://www.imo.org/blast/blastDataHelper.asp?data_id=27795&filename=GHGStudyFINAL.pdf [4] CORADDU, A.; FIGARI, M.; SAVIO, S. (2013), Ship energy assessment by numerical simulation, 5th Int. Conf. Computational Methods in Marine Engineering (MARINE), Hamburg, pp.530-540 [5] DIMOPOULOS, G.G.; KAKALIS, N.M.P. (2010), An integrated modelling framework for the design, operation and control of marine energy systems, 26th CIMAC World Congress, Bergen [6] FREUND, M.; WÜRSIG, G.M.; KABELAC, S. (2009), Simulation tool to evaluate fuel and energy consumption, 8th Conf. Computer and IT Applications in the Maritime Industries (COMPIT), Budapest, pp.364-373 [7] HANSEN, H.; FREUND, M. (2010), Assistance tools for operational fuel efficiency, 9th Conf. Computer and IT Applications in the Maritime Industries (COMPIT), Gubbio, pp.356-366 [8] OCIMF (2011), GHG emission-mitigating measures for oil tankers – Part A: Review of reduction potential, Oil Companies International Marine Forum, London. http://www.ocimf.com/library/information-papers [9] VUGT, J. van; MARLEN, B. van (2010), The use of a generic energy systems (GES) model for fishing vessels, 1st Int. Symp. Fishing Vessel Energy Efficiency (E-Fishing), Vigo 145

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