| 1. |
- Baldi, Francesco, 1986, et al.
(författare)
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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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| 2. |
- Baldi, Francesco, 1986, et al.
(författare)
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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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| 3. |
- Baldi, Francesco, 1986, et al.
(författare)
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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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| 4. |
- Baldi, Francesco, 1986, et al.
(författare)
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Energy and exergy analysis of a cruise ship
- 2015
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Ingår i: Proceedings of ECOS 2015 - the 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. - Pau : Pau University. - 9782955553909
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Konferensbidrag (refereegranskat)abstract
- The shipping sector is today facing numerous challenges. Fuel prices are expected to increase in the medium-long term, and a sharp turn in environmental regulations will require several companies to switch to more expensive distillate fuels. In this context, passenger ships represent a small but increasing share of the industry. The complexity of the energy system of a ship where the energy required by propulsion is no longer the trivial main contributor to the whole energy use thus makes this kind of ship of particular interest for the analysis of how energy is converted from its original form to its final use on board.To illustrate this, we performed an analysis of the energy and exergy flow rates of a cruise ship sailing in the Baltic Sea based on a combination of available measurements from ship operations and of mechanistic knowledge of the system. The energy analysis allows identifying propulsion as the main energy user (41% of the total) followed by heat (34%) and electric power (25%) generation; the exergy analysis allowed instead identifying the main inefficiencies of the system: exergy is primarily destroyed in all processes involving combustion (88% of the exergy destruction is generated in the Diesel engines and in the oil-fired boilers) and in the sea water cooler (5.4%); the main exergy losses happen instead in the exhaust gas, mostly from the main engines (67% of total losses) and particularly from those not equipped with heat recovery devices.The improved understanding which derives from the results of the energy and exergy analysis can be used as a guidance to identify where improvements of the systems should be directed.
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| 5. |
- Baldi, Francesco, 1986, et al.
(författare)
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Energy and exergy analysis of ship energy systems - The case study of a chemical tanker
- 2015
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Ingår i: International Journal of Applied Thermodynamics. - : International Centre for Applied Thermodynamics (ICAT). - 1301-9724 .- 2146-1511. ; 18:2, s. 82-93
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Tidskriftsartikel (refereegranskat)abstract
- Shipping contributes today to 2.1% of global anthropogenic greenhouse gas emissions and its share is expected to grow together with global trade in the coming years. At the same time, bunker prices are increasing and companies start to feel the pressure of growing fuel bills in their balance sheet. In order to address both challenges, it is important to improve the understanding of the energy consumption trends on ships through a detailed analysis of their energy systems. In this paper, energy and exergy analysis are applied to the energy system of a chemical tanker, for which both measurements and technic knowledge of ship systems were available. The application of energy analysis to the case-study vessel allowed for the comparison of different energy flows and therefore identifying system components and interactions critical for ship energy consumption. Exergy analysis allowed instead identifying main inefficiencies and evaluating waste flows. Results showed that propulsion is the main contributor to ship energy consumption (70%), but that also auxiliary heat (16.5%) and power (13.5%) needs are relevant sources of energy consumption. The potential for recovering waste heat is relevant, especially from the exhaust gases, as their exergetic value represents 18% of the engine power output.
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| 6. |
- 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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| 7. |
- Salo, Kent, 1967, et al.
(författare)
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Emissions to the air
- 2016
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Ingår i: Shipping and the Environment: Improving Environmental Performance in Marine Transportation. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783662490457 ; , s. 169-227
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Seeing the black smoke coming out of the funnel of a manoeuvring ship makes it easy to understand that the ship's propulsion contributes to the emission of air pollutants. However, there is more than meets the eye going up in smoke. A vast majority of ships use fossil fuels, increasing a positive net contribution of carbon dioxide to the atmosphere when they are combusted. Because the fuels that are used are often of low quality and possess a high sulphur content, a number of other air pollutants are also emitted. Emissions to the air from ships include greenhouse gases (such as carbon dioxide, methane and nitrous oxide), sulphur and nitrogen oxides, with both acidifying and eutrophication effects, and different forms of particles, with impacts on health and climate. However, not all emissions to the atmosphere from ships originate from the combustion of fuels for propulsion and energy production. The handling of crude oil as cargo and compounds used in refrigeration systems cause emissions of volatile organic compounds and ozone-depleting substances. The sources of the most important emissions and relevant regulations are described in this chapter.
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| 8. |
- Wilewska-Bien, Magda, 1977, et al.
(författare)
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Measures to reduce discharges and emissions
- 2016
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Ingår i: Shipping and the Environment: Improving Environmental Performance in Marine Transportation. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783662490457 ; , s. 341-396
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Discharges and émissions from shipping can be reduced through different technical measures, many of which apply similar principies, e.g., filtration or absorption. Ballast water treatment systems can be used to limit the spread of invasive species. Selective catalytic reduction units and exhaust gas recirculation can be used to reduce nitrogen oxide emissions, and scrubbers and diesel particulate filters can be used to reduce sulphur dioxide and particle emissions. The restoration or remediation of natural environments may also be required after large oil spills. Possible remediation methods include booms, mechanical techniques and dispersant chemicals. These and several additional technical measures to reduce discharges and emissions are described in this chapter, including measures to reduce the impact of the infrastructure related to the shipping industry.
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