| 1. |
- Baldi, Francesco, 1986, et al.
(författare)
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Optimal load allocation of complex ship power plants
- 2016
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 124, s. 344-356
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Tidskriftsartikel (refereegranskat)abstract
- In a world with increased pressure on reducing fuel consumption and carbon dioxide emissions, thecruise industry is growing in size and impact. In this context, further effort is required for improvingthe energy efficiency of cruise ship energy systems.In this paper, we propose a generic method for modelling the power plant of an isolated system withmechanical, electric and thermal power demands and for the optimal load allocation of the different componentsthat are able to fulfil the demand.The optimisation problem is presented in the form of a mixed integer linear programming (MINLP)problem, where the number of engines and/or boilers running is represented by the integer variables,while their respective load is represented by the non-integer variables. The individual components aremodelled using a combination of first-principle models and polynomial regressions, thus making thesystem nonlinear.The proposed method is applied to the load-allocation problem of a cruise ship sailing in the Baltic Sea,and used to compare the existing power plant with a hybrid propulsion plant. The results show thebenefits brought by using the proposing method, which allow estimating the performance of the hybridsystem (for which the load allocation is a non-trivial problem) while also including the contribution ofthe heat demand. This allows showing that, based on a reference round voyage, up to 3% savings couldbe achieved by installing the proposed system, compared to the existing one, and that a NPV of11 kUSD could be achieved already 5 years after the installation of the system.
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| 2. |
- Ancona, M. A., et al.
(författare)
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Efficiency improvement on a cruise ship: Load allocation optimization
- 2018
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 164, s. 42-58
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Tidskriftsartikel (refereegranskat)abstract
- Last years have been characterized by a worldwide increasing attention towards the reduction of fuel consumption and carbon dioxide emissions. Several industrial fields, as well as the civil and residential sector, have introduced innovative approaches for the design and the operation of energy systems. These actions are aimed to reach higher values of energy conversion efficiency, also including an increase in the use of renewable resources. In this context, especially in the sector of cruise ships, further efforts are required to improve the energy efficiency of the employed energy systems. The aim of this paper is to propose an optimization framework based on genetic algorithms in order to maximize the energy efficiency and minimize both the fuel consumption and the thermal energy dissipation, by optimizing the load allocation of the ship energy systems. To this purpose, different strategies for the energy systems on board of an existing cruise ship are proposed and analyzed. In particular, two main engines configurations have been defined: standard (current logic of operation maintained) and hybrid configuration. For each proposed strategy – being the ship a particular and interesting application of isolated energy grid (i.e. a grid without connections with electric and fuel national grids) – an in-house-developed software has been adapted and applied to optimize the load allocation of the various energy systems. Furthermore, an economic and environmental analysis has been carried out, in order to point out the benefits – or the eventual limits – related to the proposed solutions. The considered approach is based on the concept of introducing economically and structurally suitable modifications to the current cruise energy systems configuration, in order to reach the goal of increasing the energy efficiency. The carried out analysis shows that the hybrid strategies allow to reach the best results in terms of energy (fuel consumption and heat dissipation reduction), economic and environmental points of view.
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| 3. |
- Andersson, Karin, 1952, et al.
(författare)
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Shipping and the environment
- 2016
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Ingår i: Shipping and the Environment: Improving Environmental Performance in Marine Transportation. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783662490457 ; , s. 3-27
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Humans have always had a close relationship with the aquatic environment, including the early use of the sea for food harvesting and communication. Today, the sea is an important component of the transportation system, with large amounts of cargo and passengers. This chapter provides a short introduction to ships and shipping, focussing primarily on commercial ships; nonetheless, many of the emissions, impacts and measures discussed throughout this book are common to other sectors, such as leisure, research and fishing. This chapter also introduces the environmental impacts related to ship operations. Ship transportation has increased tremendously since the industrial revolution, which has resulted in increased emissions due to shipping and increased stresses on the environment. However, this trend is not only related to shipping. Currently, there are several warning signs that we are not taking care of the Earth and its ecosystem in a sustainable manner, that the Earth's ecosystems are degrading and that natural capital is being exploited, e.g., by the burning of fossil fuels. The marine industry is a component of our society; similar to all industry sectors, it contributes to unsustainable patterns in our society. Although the marine industry is a contributor to these problems, it can also be part of the solution, yet several challenges must be addressed. Sustainability and related concepts, such as ecosystem services, planetary boundaries and resilience thinking, could be used as guidance in addressing these challenges. Humans have always had a close relationship with the aquatic environment. Indeed, a scientific discussion debates whether the first humans evolved in a dry land environment, on the savannah, or in shallow water environments (as the "water man" or "aquatic ape") [1]. With respect to environmental awareness, the sea has come into focus relatively late compared with other natural areas. Independent of this observation, the sea has served as an important transportation route and a source of food and recreation throughout history. In a world where more than 70 % of the surface is covered by oceans, our interaction with and dependence on the sea in numerous aspects is obvious.
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| 4. |
- Baldi, Francesco, 1986, et al.
(författare)
-
A feasibility analysis of waste heat recovery systems for marine applications
- 2015
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Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 80, s. 654-665
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Tidskriftsartikel (refereegranskat)abstract
- The shipping sector is today facing challenges which require a larger focus on energy efficiency and fuel consumption. In this article, a methodology for performing a feasibility analysis of the installation of a WHR (waste heat recovery) system on a vessel is described and applied to a case study vessel. The method proposes to calculate the amount of energy and exergy available for the WHR systems and to compare it with the propulsion and auxiliary power needs based on available data for ship operational profile. The expected exergy efficiency of the WHR system is used as an independent variable, thus allowing estimating the expected fuel savings when a detailed design of the WHR system is not yet available. The use of the proposed method can guide in the choice of the installation depending on the requirements of the owner in terms of payback time and capital investment. The results of the application of this method to the case study ship suggest that fuel savings of 5%–15% can realistically be expected, depending on the sources of waste heat used and on the expected efficiency of the WHR system.
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| 5. |
- Baldi, Francesco, 1986, et al.
(författare)
-
A preliminary study on the application of thermal storage to merchant ships
- 2015
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 75, s. 2169-2174
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Konferensbidrag (refereegranskat)abstract
- The shipping industry is focusing more and more on reducing fuel consumption and greenhouse gas emissions. Anon-negligible amount of fuel is consumed while ships are in port, waiting for loading or unloading, for heating upaccommodation spaces and fuel tanks, while when at sea waste heat from engines exhaust is under-used because oflow demand. In this paper we propose the use of thermal energy storage as a solution for the mismatch between heat availability and demand. A simplified system is proposed and the influence of design parameters (storage size, heat exchangers surface, secondary fluid mass flow rate, storage temperature) on the performance of the system is analyzed. The results of the application of a thermal energy storage system to a case study ship show that the installation of a storage tank of 1000 m3 could reduce the fuel consumption from the boilers by 80%, which would lead to yearly savings of 268,000 USD. This preliminary analysis shows that there is potential of both economic and environmental benefits from the application of thermal energy storage to merchant vessels.
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| 6. |
- Baldi, Francesco, 1986, et al.
(författare)
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Analysis of the influence of the engine, propeller and auxiliary generation interaction on the energy efficiency of controllable pitch propeller ships
- 2014
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Ingår i: International Conference of Maritime Technology.
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Konferensbidrag (refereegranskat)abstract
- In a context of increasing requirements for energy efficiency, this paper aims at improving theunderstanding on the interaction between engine, propeller, and auxiliary heat and power generation in theparticular case of controllable pitch propeller (CPP) ships. The case study of a CPP propelled chemical tankeris used to analyze the application of the proposed approach. The performance of the ship’s standardarrangement using a shaft generator for the fulfillment of auxiliary power demand is compared to theoperational alternative of using auxiliary engines, and with the possibilities for retrofitting with frequencyconverters and waste heat recovery systems. The influence of control systems parameters and of sea state arealso analyzed and compared. The results show a large possibility for improvements, both via operationaloptimization (up to 8.3% increased energy efficiency) and via different types of retrofitting (with increasedefficiencies of up to 11.4% for frequency converters, and 16.5% for WHR systems). The influence of a broadoperational envelope brings even larger improvements to the efficiency of the energy system at low speeds. Theresults of the paper provide useful information about the influence of different technologies for auxiliary powergeneration on the efficiency of CPP propelled vessels.
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| 7. |
- Baldi, Francesco, 1986, et al.
(författare)
-
Comparison of different procedures for the optimisation of a combined Diesel engine and organic Rankine cycle system based on ship operational profile
- 2015
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Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 110:Part B, s. 85-93
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Tidskriftsartikel (refereegranskat)abstract
- At a time of strong challenges for shipping in relation to economic and environmental performance, the potential of waste heat recovery has been identified as among the most important technologies to lower fuel consumption. This paper presents the comparison of four different procedures for the optimisation of a combined Diesel and organic Rankine cycle system with increasing attention to the ship operational profile and to the inclusion of engine control variables in the optimisation procedure. Measured data from two years of operations of a chemical tanker are used to test the application of the different procedures. The results indicate that for the investigated case study the application of an optimisation procedure which takes the operational profile into account can increase the savings of the installation of an organic Rankine cycle from 7.3% to 11.4% of the original yearly fuel consumption. The results of this study further show that (i) simulating the part-load behavior of the ORC is important to ensure its correct operations at low engine load and (ii) allowing the engine control strategy to be part of the optimisation procedure leads to significantly larger fuel savings than the optimisation of the waste recovery system alone.
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| 8. |
- Baldi, Francesco, 1986, et al.
(författare)
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Development of a combined mean value-zero dimensional model and application for a large marine four-stroke Diesel engine simulation
- 2015
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Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 154, s. 402-415
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a combined mean value–zero dimensional model is developed using a modular approach in the computational environment of Matlab/Simulink. According to that, only the closed cycle of one engine cylinder is modelled by following the zero-dimensional approach, whereas the cylinder open cycle as well as the other engine components are modelled according to the mean value concept. The proposed model combines the advantages of the mean value and zero-dimensional models allowing for the calculation of engine performance parameters including the in-cylinder ones in relatively short execution time and therefore, it can be used in cases where the mean value model exceeds its limitations. A large marine four-stroke Diesel engine steady state operation at constant speed was simulated and the results were validated against the engine shop trials data. The model provided results comparable to the respective ones obtained by using a mean value model. Then, a number of simulation runs were performed, so that the mapping of the brake specific fuel consumption for the whole operating envelope was derived. In addition, runs with varying turbocharger turbine geometric area were carried out and the influence of variable turbine geometry on the engine performance was evaluated. Finally, the developed model was used to investigated the propulsion system behaviour of a handymax size product carrier for constant and variable engine speed operation. The results are presented and discussed enlightening the most efficient strategies for the ship operation and quantifying the expected fuel savings.
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| 9. |
- Baldi, Francesco, 1986, et al.
(författare)
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Dynamic modelling and analysis of the potential for waste heat recovery on Diesel engine driven applications with a cyclical operational profile
- 2015
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Ingår i: Proceedings of ECOS 2015 - The 28th international conference on efficiency, cost, optimisation, simulation and environmental impact of energy systems. - 9782955553909
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Konferensbidrag (refereegranskat)abstract
- As the world faces the challenge of the need for decreasing the anthropogenic carbon footprint, thecontinuous economic growth puts additional stress on the need for increased energy systems efficiency. In this context, waste heat recovery is identified as one of the most viable solutions for reducing the fuel consumption of existing systems in transportation.In this paper, we present an analysis of the potential of a waste heat recovery system applied to Diesel engine-driven systems where the operational cycle is dynamic but reducible to a limited number of operational modes. The analysis is applied to a case study for which this operational pattern is of particular relevance: a machine for sugar beet harvesting. The existence of periodical low-load periods forces to bypass the waste heat recovery turbine to avoid water condensation during the expansion. Hence, we propose the use of a thermal inertia to keep the required level of steam superheating during low-loadperiods.The results of the study showed an improvement of 27% in the recoverable exergy of the flow at the heat exchanger cold outlet when the heat exchanger wall thickness was increased from 0.5 mm to 2.5 mm. The results also show that a limited amount of the overall heat exchange inertia contributes to such improvement.
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| 10. |
- Baldi, Francesco, 1986, et al.
(författare)
-
Energy analysis of a ship - the case study of a chemical tanker
- 2014
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 61, s. 1732-1735
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Konferensbidrag (refereegranskat)abstract
- Improved understanding of ship energy use can be a crucial part of the process of increasing ship energy efficiency. In this paper, the methodology of energy analysis is applied to ship energy systems in order to showcase the benefits of such methodology. Data from one year of operations of a case study ship were used, together with mechanistic knowledge of ship systems, in order to evaluate the different energy flows. The identification of main producers, consumers and waste flows, allowed by the application of the method, leads to the suggestion of a number of possible improvements guided by the improved knowledge of the ship's energy system.
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