The laws and regulations regarding the radiated noise and the on-board noise of the ship are expected to be stricter in the future. There is a big concern in this field, especially for the underwater noise. The radiated noise from the ship is harming the life of the underwater mammals while the on-board noise is threatening the health of the on-board crew. One of the main contributors to the noise generated by a vessel is the propulsion system. It is true that the noise reduction can be achieved by doing the corrective action in the later design stage, such as installing mounting and noise absorption material. Nevertheless, the decision in early-design stage often gives the highest impact on the noise generated by the propulsion system where the level of uncertainty is high. This thesis has two main goals; to determine the design choices of propulsion systems which affect the noise excitation, and to develop an evaluation methodology to assess a certain power configuration from the perspective of generated noise.
First, the aspects of the propulsion system that affect its noise are determined. Those are transmission types, number of engines, number of shafts and number of compartments. The loading point is also included as one of the parameters. Although it is not a design choice, it has a significant role in the noise generated by the propulsion system. Second, the selection of the significant noise source in the propulsion system needs to be done. There is much equipment inside a propulsion plant, but not all of them give sufficient contribution to the overall noise level. Based on the literature review, the equipment that is considered as the main noise sources are the diesel engine, the diesel generator set, the reduction gear and the electric motor.
A noise model from SNAME is implemented in this project to predict the airborne and structure-borne noise source levels of the equipment and the transmission losses to the receiver location. An engine room-sizing model is developed in this project since the transmission loss is a function of the compartment dimensions. Furthermore, the room dimensions depend on the equipment dimensions. Therefore, it is necessary to develop a model to predict the size of the equipment too. Afterwards, the evaluation methodology is established to quantify the effect of a certain design choice towards the noise of a propulsion system.
The effects of varying ship requirements are also investigated to see the behaviour of the model with a different input. These requirements are the ship installed power, the ship propulsion power and the ship auxiliary power
This project provides a general guideline for the marine engineer to evaluate the propulsion system based on the noise considerations in the early design phase. The evaluation methodology proves to be applicable to a wide range of propulsion plant type. It is possible to extend the application of this method for a ship with prime mover other than the diesel engine and the electric motor.
... Read more

Carbon dioxide emission into the earth’s atmosphere by maritime activities are a concern for the people within and outside the industry. This is because of the environmental impacts that are caused by these greenhouse gas emissions which changes the very chemistry of this planet. These impacts can be mitigated by reducing the CO2 emissions which can be achieved by several design and/or operational means. Waste heat recovery (WHR) technology is one such means that is capable of reducing emissions. This is achieved by improving the overall fuel efficiency of marine engines which reduces the fuel consumption of the vessel. This improvement is realised by harnessing the heat energy that is expelled by the engine through waste heat sources such as exhaust gas, etc.
 Organic Rankine cycle (ORC) is one of many WHR technologies that is capable of harnessing that waste heat energy from the fuel which cannot be utilised by the engine operation alone. ORC as a WHR system (WHRS) is widely implemented in land based applications due to its fluid choice flexibility, plant simplicity and net efficiency. However, it is rather new to the maritime industry because WHRS on-board ships are predominantly based on steam Rankine cycle or turbo-compounding. These systems have their own advantages but ORC-WHRS may outweigh them in certain applications on-board ships. This is especially for electrical power generation from low and medium temperature waste heat sources. However, ORC in marine application encounters challenges unlike seen in land based applications. These challenges are caused by the physical & geometrical constraints, operational profile of the vessel or uncertainties caused at sea.
 In this thesis, the implementation of ORC-WHRS to marine engines for exhaust gas is investigated and studied to understand how such an application can be beneficial. Unlike steam Rankine cycle, an ORC system has flexibility in choosing an organic fluid that is suitable based on the application. This flexibility in fluid choices are confronted by the above mentioned maritime related challenges. Hence, a screening methodology is devised in this thesis that finds a suitable fluid based on the waste heat source profile and selection parameters. These selection parameters are necessary to filter out functioning organic fluids that can be limited due to the mentioned challenges. In this thesis, the power density of the ORC plant is the selection parameter used.As mentioned earlier, the ORC-WHRS may often be subjected to off-design conditions due to the operational profile of the vessel or by uncertainties at sea. Hence, off-design performance is analysed to study the ORC system when designed at several discrete engine load points. These analysis are carried out in plant models modified from an existing steam based dynamic model and developed into a simple-ORC and a recuperative-ORC dynamic plant models. Sensitivity analysis of these models are also performed to understand uncertainties in the model output corresponding to uncertainties in model input parameter. This analysis is followed by analysis of the dynamic behaviour of the ORC plant model to varying load step functions and step duration for plants designed at discrete engine load points.
 This thesis can be extended, not only to study how ORC can be used to meet future regulations on CO2 emissions, but also on operability limitations imposed on ships. The fluid screening approach used here can also be modified based on parameters, such as toxicity, flammability, cost, specific power etc. This can present a realistic approach to an end product that can be safely and economically operated on board. ... Read more

The aging behaviour of lithium-ion batteries is studied to develop an aging prediction model for the capacity loss of batteries in full electric ships. This model is used to investigate the effects of battery aging on the battery size and operational strategies of two case studies, a full electric ferry and a full electric tug. ... Read more