| 1. |
- Guedez, Rafael, et al.
(författare)
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Techno-economic comparative analysis of innovative combined cycle power plant layouts integrated with heat pumps and thermal energy storage
- 2019
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Ingår i: Proceedings of the ASME Turbo Expo. - : ASME Press. - 9780791858608
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Konferensbidrag (refereegranskat)abstract
- In the pursuit of increasing their profitability, the design and operation of combined cycle power plants needs to be optimized for new liberalized markets with large penetration of renewables. A clear consequence of such renewable integration is the need for these plants for being more flexible in terms of ramping-up periods and higher part-load efficiencies. Flexibility becomes an even clearer need for combined heat and power plants to be more competitive, particularly when simultaneously following the market hourly price dynamics and varying demands for both the heat and the electricity markets. In this paper, three new plant layouts have been investigated by integrating different storage concepts and heat-pump units in key sections of a traditional plant layout. The study analyses the influence that market has on determining the optimum layouts for maximizing profits in energy-only markets (in terms of plant configuration, sizing and operation strategies). The study is performed for a given location nearby Turin, Italy, for which hourly electricity and heat prices, as well as meteorological data, have been gathered. A multi parameter modeling approach was followed using KTH's in house teclmo-economic modeling tool, which uses time dependent market data, e.g. price and weather, to determine the trade-off curves between minimizing investment and maximizing profits when varying critical size-related power plant parameters e.g. installed power capacities and storage size, for pre-defined layouts and operating strategies. A comparative analysis between the best configurations found for each of the proposed layouts and the reference plant is presented in the discussion section of the results. For the specific case study set in northern Italy, it is shown that the integration of a pre-cooling loop into baseload-like power-oriented combined cycle plants is not justified, calling for investigating new markets and different operating strategies. Only the integration of a heat pump alone was shown to improve the profitability, but within the margin of error of the study. Alternatively, a layout where district heating supply water is preheated with a combination of a heat pump with hot thermal tank was able to increase the internal rate of return of the plant by up to 0.5%, absolute, yet within the error margin and thus not justifying the added complexity in operation and in investment costs. All in all, the analysis shows that even when considering energy-only market revenue streams (i.e. heat and electricity sells) the integration of heat pump and storage units could increase the profitability of plants by making them more flexible in terms of power output levels and load variations. The latter is shown true even when excluding other flexibilityrelated revenue streams. It is therefore conclusively suggested to further investigate the proposed layouts in markets with larger heat and power price variations, as well as to investigate the impact of additional control logics and dispatch strategies.
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| 2. |
- Kavvalos, Mavroudis, et al.
(författare)
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Compressor Characteristics for Transient and Part-load Performance Simulation
- 2019
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Ingår i: Proceedings of the ASME Turbo Expo, American Society of Mechanical Engineers (ASME), 2019. - : American Society of Mechanical Engineers (ASME). - 9780791858608
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Konferensbidrag (refereegranskat)abstract
- Compressor performance tests are mainly focused on the typical range of operation, resulting in limited knowledge of compressor behavior in the low-speed region. The main target of this work comprises the generation of compressor characteristics at low part-load by giving particular insight into the physical aspect of this operating condition. It is necessary for running transient and part-load performance simulation and can be considered as the first crucial step toward an optimal engine starting schedule. Modelling the low part-load operating regime requires accurate component performance maps extended to the low-speed area, where engine starting and altitude relight occur. In this work, a robust methodology for generating compressor maps in the low part-load operating regime is developed. Compressor geometry and typical operation range compressor map are required as inputs. Two different modelling processes are incorporated within this methodology. Extrapolation based on the principle of similarity laws with modified law exponents constitutes the first modelling process, which seems inaccurate when predicting compressor performance at fixed-rotor conditions. Interpolation based on the fixed-rotor characteristic constitutes the second modelling process, which can be either linear or adaptive. The adaptive interpolation scheme was developed by the authors and generates low-speed characteristics using the same allocation trend as the one obtained from given performance data. It is observed that performance data points of each β-line follow an exponential trend in mass flow differences while increasing rotational speed, with a calculated average relativized Root Mean Square (RMS) error of less than 5%. Adapting the same trend in mass flow to the low-speed region, a compressor performance map with continuous exponential trend in all characteristics (for part- and full-load conditions) can be achieved. Implementing the developed methodology on the High Pressure Compressor (HPC) of the Energy Efficient Engine (E3) project is also presented, showcasing its applicability and the merit of it being incorporated into any conventional performance prediction tool. Furthermore, a sensitivity analysis for input variables, namely compressor exit effective area and pressure loss model coefficients is carried out, demonstrating the significant impact of the former on the shape of the low part-load characteristics. Generation of compressor characteristics at low-speeds with this methodology can be viewed as an enabler for running credible transient starting simulation and transient diagnostics, thereby defining an optimal starting schedule, applicable to both power generation and aerospace industry.
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| 3. |
- Richter, Sandra, et al.
(författare)
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An investigation of combustion properties of a gasoline primary reference fuel surrogate blended with butanol
- 2019
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Ingår i: Coal, Biomass, Hydrogen, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems. - 9780791858608 ; 3
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Konferensbidrag (refereegranskat)abstract
- Currently, many research studies are exploring opportunities for the use of novel fuels and of their blends with conventional, i.e. petroleum-based fuels. To pave the way for their acceptance and implementation in the existing energy market, a comprehensive knowledge about their combustion properties is inevitable, among others. Within this context, alcohols, with butanol in particular, are considered as attractive candidates for the needed de-fossilization of the energy sector. In this work, we report on the oxidation of mixtures of n-heptane/i-octane (PRF90, primary reference fuel, a gasoline surrogat e) and addition of n-butanol, 20% and 40%, respectively, in a combined experimental and modeling effort. The focus was set on two fundamental combustion properties: (i) Ignition delay times measured in a shock tube, at ambient and elevated pressures, for stoichiometric mixtures, and (ii) Laminar burning velocities, at ambient and elevated pressures. Moreover, two detailed chemical kinetic reaction mechanisms, with an in-house model among them, have been used for investigating and analyzing the combustion of these mixtures. In general, the experimental data agree well with the model predictions of the in-house reaction model, for the temperatures, pressures, and fuel-air ratios studied. Room for improvements is seen for PRF90. The results achieved were also compared to those of n-butanol reported recently; the findings demonstrated clearly the effect of the n-butanol sub model on binary fuel-air mixtures consisting of PRF and n-butanol. From the present work it can be concluded that the addition of n-butanol to gasoline appears to be an attractive alternative fuel for most types of heat engines.
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| 4. |
- Sahoo, Smruti, et al.
(författare)
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Performance assessment of an integrated parallel hybrid-electric propulsion system aircraft
- 2019
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Ingår i: Proceedings of the ASME Turbo Expo. - : American Society of Mechanical Engineers (ASME). - 9780791858608
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Konferensbidrag (refereegranskat)abstract
- Hybrid-electric propulsion system promises avenues for a greener aviation sector. Ground research work was performed in the past for the feasibility assessment, at the system level, for such novel concepts and the results showed were promising. Such designs, however, possess unique challenges from an operational point of view, and for sizing of the sub-system components; necessitating further design space exploration for associating with an optimal operational strategy. In light of the above, the paper aims at presenting an operational analysis and performance assessment study, for a conceptualised parallel hybrid design of an advanced geared turbofan engine, based on 2035 timeframe technology level. It is identified that the hybrid power operation of the engine is constrained with respect to the requirement of maintaining an adequate surge margin for the low pressure side components; however, a core re-optimised engine design with consideration of electrical power add-in for the design condition, relieves such limit. Therefore such a design, makes it suitable for implementation of higher degree of hybridisation. Furthermore, performance assessment is made both at engine and engine-aircraft integrated level for both scenarios of hybrid operation and the benefits are established relative to the baseline engine. The performance at engine level engine specific fuel consumption (SFC), thrust specific power consumption (TSPC), and overall efficiency, shows improvement in both hybridised scenarios. Improvement in SFC is achieved due to supply of the electrical power, whereas, the boost in TSPC, and overall efficiency is attributed to the use of higher efficiency electrical drive system. Furthermore, it is observed that while the hybridised scenario performs better at engine level, the core re-optimised design exhibits a better saving for block fuel/energy consumption, due to the considerable weight savings in the core components.
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| 5. |
- Sielemann, M., et al.
(författare)
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Modelica and functional mock-up interface : Open standards for gas turbine simulation
- 2019
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Ingår i: Proceedings of the ASME Turbo Expo. - : American Society of Mechanical Engineers (ASME). - 9780791858608
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Konferensbidrag (refereegranskat)abstract
- This paper introduces two physical modeling standards in the gas turbine and cycle analysis context. Modelica is the defacto standard for physical system modeling and simulation. The Functional Mock-Up Interface is a domain-independent standard for model exchange (“engine decks”). The paper summarizes key language concepts and discusses important design patterns in the application of gas turbine simulation concepts to the acausal modeling language. To substantiate how open standards are applicable to gas turbine simulation, the paper closes with two application examples, a conventional unmixed turbofan thermodynamic cycle and weight analysis as well as an electrically boosted geared turbofan.
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| 6. |
- Sorce, Alessandro, et al.
(författare)
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Analysis of a combined cycle exploiting inlet conditioning technologies for power modulation
- 2019
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Ingår i: Proceedings of the ASME Turbo Expo. - : ASME Press. - 9780791858608
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Konferensbidrag (refereegranskat)abstract
- The high share of non-dispatchable renewable energy source generators in the electrical grid has increased the need for flexibility of Gas Turbine Combined Cycles (GTCC) already installed. To maximize not only the maximum power produced, via Power Augmentation Technologies (PATs), but also to reduce the Minimum Environmental Load (MEL), both OEMs and GTCC owners have adopted several technical solutions. This kind of flexibility has become, year-by-year, ever more crucial to guarantee GTCC economical sustainability. Amongst the solutions which can be adapted to guarantee GTCC flexibility, the Inlet Conditioning System is a particularly interesting technical solution, which can be installed without restrictions related to the different GT design. In this paper, an evaluation of the compressor inlet temperature effect over the Combined Cycle performance is presented, with a focus on the bottoming Cycle impact. Different Inlet Conditioning Strategies are then compared considering the energy, and the environmental impact on GTCC behavior. The performance of a layout including a Thermal Energy Storage (TES) and a Heat Pump (HP) is then evaluated and compared to other technical solutions.
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| 7. |
- Xin, Zhao, et al.
(författare)
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A framework for optimization of hybrid aircraft
- 2019
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Ingår i: Proceedings of the ASME Turbo Expo. - : American Society of Mechanical Engineers (ASME). - 9780791858608 ; 3
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Konferensbidrag (refereegranskat)abstract
- To achieve the goals of substantial improvements in efficiency and emissions set by Flightpath 2050, fundamentally different concepts are required. As one of the most promising solutions, electrification of the aircraft primary propulsion is currently a prime focus of research and development. Unconventional propulsion sub-systems, mainly the electrical power system, associated thermal management system and transmission system, provide a variety of options for integration in the existing propulsion systems. Different combinations of the gas turbine and the unconventional propulsion sub-systems introduce different configurations and operation control strategies. The trade-off between the use of the two energy sources, jet fuel and electrical energy, is primarily a result of the trade-offs between efficiencies and sizing characteristics of these sub-systems. The aircraft structure and performance are the final carrier of these trade-offs. Hence, full design space exploration of various hybrid derivatives requires global investigation of the entire aircraft considering these key propulsion sub-systems and the aircraft structure and performance, as well as their interactions. This paper presents a recent contribution of the development for a physics-based simulation and optimization platform for hybrid electric aircraft conceptual design. Modeling of each subsystem and the aircraft structure are described as well as the aircraft performance modeling and integration technique. With a focus on the key propulsion sub-systems, aircraft structure and performance that interfaces with existing conceptual design frameworks, this platform aims at full design space exploration of various hybrid concepts at a low TRL level.
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