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- Ahlgren, Fredrik, 1980-, et al.
(author)
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Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle : A Case Study
- 2015
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In: ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. - : ASME Press. - 9780791856673 ; , s. 43392-43416
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Conference paper (peer-reviewed)abstract
- Maritime transportation is a significant contributor to SOx, NOx and particle matter emissions, even though it has a quite low CO2 impact. New regulations are being enforced in special areas that limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry towards the improvement of the energy efficiency of current ship engines and the reduction of their energy demand. Although more sophisticated and complex engine designs can improve significantly the efficiency of the energy systems in ships, waste heat recovery arises as the most influent technique for the reduction of the energy consumption. In this sense, it is estimated that around 50% of the total energy from the fuel consumed in a ship is wasted and rejected in fluid and exhaust gas streams. The primary heat sources for waste heat recovery are the engine exhaust and the engine coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines exhaust heat. Experimental data from the operating conditions of the engines on the M/S Birka Stockholm cruise ship were logged during a port-to-port cruise from Stockholm to Mariehamn over a period of time close to one month. The ship has four main engines Wärtsilä 5850 kW for propulsion, and four auxiliary engines 2760 kW used for electrical consumers. A number of six load conditions were identified depending on the vessel speed. The speed range from 12–14 knots was considered as the design condition, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total electricity consumption on board. These data confirmed the ORC as a feasible and promising technology for the reduction of fuel consumption and CO2 emissions of existing ships.
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| 2. |
- Samuelsson, Sebastian, 1987, et al.
(author)
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Consistent Conceptual Design and Performance Modelling of Aero Engines
- 2015
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In: Proceedings of the ASME Turbo Expo. - 9780791856673 ; , s. V003T06A017-
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Conference paper (peer-reviewed)abstract
- During the conceptual design process of an engine, a thermodynamic cycle is initially defined. This is done to ensure that all aircraft requirements, defined in a number of discrete operating points, can be met. Critical component requirements can then be screened off from these operating points underpinning the conceptual design process. As an example, this has traditionally meant that aerodynamic sizing for low specific thrust turbofan engines occurs at top-of-climb and mechanical and temperature constraints are set at take-off.By providing additional parameters indicating the level of technology assumed, such as diffusion factors and stage loadings, a basic geometric representation of the engine can be mapped out as part of the conceptual design process. However, by choosing the parameters representing the component technology levels explicitly, the ability to trade efficiency for weight, or efficiency for cost, becomes less potent. In general, an explicit parameter choice will mean that a suboptimal solution is found.Hence, it makes sense to develop methods that allow including these technology parameters into the conceptual design and performance modeling process in a consistent way. If, for instance, component efficiency is modeled based on turbomachinery stage loading, including the stage loading parameters into the optimization means that the efficiency must be updated based on the stage loading variation. In general, a consistent method requires that conceptual design input is collected in a number of performance operating points, transferred into the conceptual design process and that output from the conceptual design process is returned to the optimizer.To illustrate the consistent conceptual design and performance modeling process, turbomachinery component models are included in the paper, interrelating polytropic efficiency, Reynolds number, size effects and component entry into service. These equations are solved consistently in the conceptual design and performance modeling to establish an optimum year 2020 engine. The method is then further illustrated by comparing the year 2020 engine with two year 2030 engines. The first year 2030 engine is established by an optimization assuming fixed polytropic turbomachinery efficiencies. The other case is defined by assuming the same engine architecture, i.e., the same number of turbomachinery stages as the year 2020 engine. In this case, the efficiency modeling is done using a consistent conceptual design optimization. The consistent optimization produced a more efficient engine despite the fact that the stage numbers were limited to the year 2020 configuration. The benefit is obtained by more thoroughly exploring the pressure ratio distribution between the engine components, as a result of the consistent optimization methodology.
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| 3. |
- Spelling, James, et al.
(author)
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Thermoeconomic Evaluation of a Novel Utility-Scale Hybrid Solar Dish Micro Gas-Turbine Power Plant
- 2015
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In: Proceedings of the ASME Turbo Expo 2015. Montreal, Canada. June 15-19. - : ASME Press. - 9780791856673
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Conference paper (peer-reviewed)abstract
- A novel solar power plant concept is presented, based on the use of a coupled network of hybrid solar-dish micro gas-turbines, driving a centralized heat recovery steam generator and steam-cycle, thereby seeking to combine the high collector efficiency of the solar dish with the high conversion efficiency of a combined-cycle power block. To explore the potential of the concept, its performance has been compared against a more conventional solar dish farm based on recuperated micro gas-turbines. Multi-objective optimization has been used to identify Pareto-optimal designs and examine the trade-offs between minimizing capital costs and maximizing performance. The micro gas-turbine combined-cycle layout has been shown to be promising for utility-scale applications, reducing electricity costs by 5–10%, depending on the degree of solar integration; this novel power plant layout also reduces emissions through increased conversion efficiency of the power block. However, at smaller plant sizes (outputs below 18 MWe), more traditional recuperated solar dish farms remain the most viable option.
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