Due to more stringent legislation regarding ship emissions and higher fuel prices, ships owners and naval architects have lately been focusing more on energy efficiency. Traditionally, ship design process has been concentrating on optimizing the ship in one design point, where the ship is the most efficient in. However, ships are not always operating near design points, and thus, the optimization to a single design point does not lead to holistic optimization of ship energy efficiency. Therefore, ship designers require a tool that takes into account varying operation conditions and ship parameters.This thesis introduces a simulation tool for handysize bulk carrier for utilization in concept design phase. The tool is based on multi-domain energy flow method. This tool covers all the main machinery components such as main engine, diesel generators, exhaust gas and oil fired-boilers and cooling circuits. The dynamic results acquired from the tool include fuel and energy consumption for main- and auxiliary engines, steam energy produced from the exhaust gas and oil-fired boilers, sea water pump mass flow and evaporator energy consumption.Simulation tool was applied to two different case studies. First, a steam system was modified by lowering steam pressure produced by the exhaust gas boiler. Secondly, cooling circuit components were optimized for obtaining lower total fuel consumption. In the first case, the energy recovered from the exhaust gas was higher and thus oil fired boiler was less utilized, as was expected. This also leads to lower fuel consumption and maintenance costs. In the second case, the results were also as expected. The variable speed drive sea water pump decreases the total fuel consumption and maintenance costs of auxiliary engines due to less electrical energy utilized.The validation of results was excluded from the thesis, and thus, the results are just guide values rather than absolute truth. Therefore, the simulation tool is suitable for quick analysis to be utilized in concept phase and is usable by any designer, without an extensive background of ship machinery.
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