| 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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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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- Baldi, Francesco, 1986, et al.
(författare)
-
Energy and exergy analysis of ship energy systems - the case study of a chemical tanker
- 2014
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Ingår i: 27th ECOS, International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. - 9781634391344
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Konferensbidrag (refereegranskat)abstract
- Shipping is already a relevant contributor to global carbon dioxide 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 how ship energy consumption is generated, through a detailed analysis of its energy systems. In this paper, a method for the analysis of ship energy systems is proposed and applied on one year of operations of a chemical tanker, for which both measurements and mechanistic knowledge of ship systems were available. Energy analysis applied to the case-study vessel allowed comparing 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. This last information was then processed in order to estimate the potential for waste energy recovery under different conditions. 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 waste heat recovery is relevant, especially in the exhaust gas, which contains an exergy flow sized 18% of engine power output.
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| 8. |
- 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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| 9. |
- Baldi, Francesco, 1986, et al.
(författare)
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From Energy Flows to Monetary Flows - An Innovative Way of Assessing Ship Performances Through Thermo-Economic Analysis
- 2012
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Ingår i: International Association of Maritime Economists Conference (IAME 2012 Taipei)..
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Konferensbidrag (refereegranskat)abstract
- Recent events concerning world economy, environmental policies and resources depletion have grown a large interest in the matter of reducing energy consumption. Unfortunately, even if several cost-effective measures could bring to sensible reductions in fuel consumption, shipping industry is often much reluctant to act in this direction. It is in the opinion of the authors, based on recent studies on the subject (Johnson, 2012),(Johnson, 2011), that a primary reason for this behavior lays in the lack of clear and effective tools for including these matters in the decision making processes. Therefore, the aim of this paper is to propose a new and innovative methodology for improving communication between technical and management departments of a shipping company when dealing with ship fuel consumption analysis. This will be done by making use of Sankey diagrams as graphical support and by converting energy flows to monetary flows, thus showing how energy is being used by different components or wasted to the environment in a much tangible manner. A case study will be presented in order to support the analysis with numerical values.
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| 10. |
- 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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