The Experts below are selected from a list of 45522 Experts worldwide ranked by ideXlab platform
Elysia J Sheu - One of the best experts on this subject based on the ideXlab platform.
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redox reforming based integrated solar natural gas plants reforming and thermodynamic Cycle efficiency
International Journal of Hydrogen Energy, 2014Co-Authors: Elysia J Sheu, Ahmed F GhoniemAbstract:Abstract As demand for energy continues to rise, the concern over the increase in emissions grows, prompting much interest in using renewable energy resources such as solar energy. However, there are numerous issues with using solar energy including intermittency and the need for storage. A potential solution is the concept of Hybrid solar-fossil fuel power generation. Previous work has shown that utilizing solar reforming in conventional power Cycles has higher performance compared to other integration methods. Most previous studies have focused on steam or dry reforming and on specific component analysis rather than a systems level analysis. In this article, a system analysis of a Hybrid Cycle utilizing redox reforming is presented. Important Cycle design and operation parameters such as the oxidation temperature and reformer operating pressure are identified and their effect on both the reformer and Cycle performance is discussed. Simulation results show that increasing oxidation temperature can improve reformer and Cycle efficiency. Also shown is that increasing the amount of reforming water leads to a higher reformer efficiency, but can be detrimental to Cycle efficiency depending on how the reforming water is utilized.
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optimization of a Hybrid solar fossil fuel plant solar steam reforming of methane in a combined Cycle
Energy, 2013Co-Authors: Elysia J Sheu, Alexander MitsosAbstract:In this article, an analysis of solar reforming as the solar integration method for a Hybrid solar-fossil fuel Cycle is presented. The solar reformer is integrated with a solar tower and steam reforming of methane is studied. The tower reformer system is integrated with a standard combined Cycle, and the design and operation of the Hybrid Cycle are optimized for highest annual work output for a fixed fuel input and solar collector area. A heuristic two step procedure is used for the optimization: first, both the design and operation of the plant is optimized for every hour and then in the second step, the design is fixed at the average value determined by the first step and the operation of the plant is again optimized for every hour. The optimization results indicate that the tower reforming integration method is a promising integration option in that this type of Hybrid Cycle yields high incremental solar efficiencies compared to alternatives. Moreover, the analyzed Hybrid Cycle has a higher efficiency for a fixed CO2 emissions compared to a linear combination of solar only and fossil fuel only Cycles of comparable complexity.
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a review of Hybrid solar fossil fuel power generation systems and performance metrics
Journal of Solar Energy Engineering-transactions of The Asme, 2012Co-Authors: Elysia J Sheu, Alexander Mitsos, Ahmad A Eter, Esmail M A Mokheimer, Mohamed A Habib, Amro M AlqutubAbstract:A literature review of Hybrid solar―fossil fuel power generation is given with an emphasis on system integration and evaluation. Hybrid systems are defined as those which use solar energy and fuel simultaneously, thus excluding the viable alternative of solar thermal plants which use fossil fuels as backup. The review is divided into three main sections: performance metrics, the different concentrated solar receiver technologies and their operating conditions, and the different Hybridization schemes. In addition, a new linear combination metric for analysis of Hybrid systems, which considers trade-off of different metrics at the fleet level, is presented. This metric is also compared to alternative metrics from multi-objective optimization. Some previous work only evaluates the Hybrid Cycle at a certain point in time, which can be misleading as this evaluation would not take into account certain aspects of Hybrid Cycle, such as fluctuating solar supply. Furthermore, almost all previous work designs the Hybrid solar―fossil fuel systems for a certain point in time and then evaluates the performance of the system for an entire year. By not taking into account fluctuating solar supply and selling price of electricity in the design of the system, the best possible annual performance of the Hybrid Cycle may not be reached.
Scott G Samuelsen - One of the best experts on this subject based on the ideXlab platform.
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analysis and optimization of a solid oxide fuel cell and intercooled gas turbine sofc icgt Hybrid Cycle
Journal of Power Sources, 2004Co-Authors: Ashok Rao, Jacob Brouwer, Scott G SamuelsenAbstract:Abstract The power generation community faces a major challenge: to protect the environment while producing a plentiful supply of clean low-cost energy. “21st Century Energy Plants” (Vision 21 Plants) have been proposed and conceptualized to meet the energy and environmental challenges. The solid oxide fuel cell and intercooled gas turbine (SOFC–ICGT) Hybrid Cycle introduced in this work is one example of a Vision 21 Plant. The system includes an internal-reforming tubular-SOFC, an intercooled gas turbine, a humidifier, and other auxiliary components. A recently developed thermodynamic analysis computer code entitled advanced power systems analyses tools (APSAT) was applied to analyze the system performance of the SOFC–ICGT Cycle. Sensitivity analyses of several major system parameters were studied to identify the key development needs and design and operating improvements for this Hybrid Cycle. A novel optimization strategy including a design of experiments (DOEx) approach is proposed and applied to the Hybrid system. Using this optimization strategy, a system electrical efficiency higher than 75% (net ac/lower heating value (LHV)) could be achieved when the system was designed to operate under a high operating pressure (50 bara) and with a low percent excess air (EA) (55%) in the SOFC.
François Maréchal - One of the best experts on this subject based on the ideXlab platform.
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design and optimization of an innovative solid oxide fuel cell gas turbine Hybrid Cycle for small scale distributed generation
Fuel Cells, 2014Co-Authors: Emanuele Facchinetti, Daniel Favrat, François MaréchalAbstract:An attractive way toward a more rational conversion of fuel and biofuel is the decentralized power generation and cogeneration. The fuel cell-gas turbine Hybrid Cycles are emerging as the most promising candidates to achieve in decentralized generation comparable or higher efficiency than in large scale power plants. The present contribution is devoted to the design and optimization of an innovative concept of small scale Solid Oxide Fuel Cell – Gas Turbine Hybrid Cycle for residential applications. A 5kW planar SOFC module, operating at atmospheric pressure, is integrated with a micro gas turbine unit, including two radial turbines and one radial compressor, based on an inverted Brayton Cycle. A thermodynamic optimization approach, coupled with system energy integration, is applied to evaluate several design options. The optimization results indicate the existence of realistic optimal designs achieving exergy efficiency higher than 66%. Sensitivity analyses on the more sensible parameters are carried out. The heat exchanger network definition is performed for an optimal configuration and a system layout is proposed. The cogeneration performance of the system and its integration in common residential buildings are discussed.
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Synthesis and thermo-economic design optimization of wood-gasifier-SOFC systems for small scale applications
2013Co-Authors: Morandin Matteo, François Maréchal, Giacomini StefanoAbstract:The conceptual design of a biomass integrated gasification fuel cell system for small scale applications (40 kg h−1 woody biomass input with 50% mass fraction water content) is discussed in this work. Two different biomass gasifiers (circulating fluidized bed and downdraft), two different reformers, a solid oxide fuel cell, a gas turbine and a heat recovery steam Cycle were investigated. A two-step optimization procedure was used to perform thermo-economic design optimizations of nine system configurations generated by combining different technologies. At the master level an evolutionary algorithm is used to optimize the system intensive parameters following the minimization of the system costs and the maximization of the net power production simultaneously (two-objective). At the inner level, system mass flow rates are optimized by linear programming subject to the thermal balance and to the heat transfer feasibility constraints which were formulated by means of Pinch Analysis techniques. The degree of system internal heat recovery was studied by including the minimum temperature difference between hot and cold streams as a decision variable at the master optimization level. Optimization results are shown by means of an optimal Pareto front for each configuration. The degree of system internal heat recovery of some specific solutions is discussed by means of Pinch Analysis composite curves. The study shows that very high system efficiencies can be obtained but only at the expense of really high system costs mainly because of the high costs of the fuel cell and of the gasifier especially at the small scale level considered here. Minimum specific plant costs of the most cost-effective configuration, based on a Hybrid Cycle, greater than 7000 $ kW−1 (2010 dollars) are found. The indirect circulating fluidized bed gasifier appears the most promising choice both in terms of cost and of system performance since it allows for better thermal integration at high temperatures and greater hydrogen yields. Auto-thermal reforming is a cheaper solution compared to steam reforming but does not benefit of the system internal heat recovery thus leading to comparably lower system efficiency. Steam reforming is particularly convenient when the system is pressurized and extra power can be recovered by gas expansion since a great amount of steam can be injected prior the reformer and vaporized by recovering the heat from exhaust gases
Fangqi Zhu - One of the best experts on this subject based on the ideXlab platform.
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a novel Hybrid solid sorption compression refrigeration technology for refrigerated transportation and storage
International Journal of Refrigeration-revue Internationale Du Froid, 2021Co-Authors: P Gao, L W Wang, Fangqi ZhuAbstract:Abstract The conventional solid sorption refrigeration system could hardly utilize hot water below 90 °C as the driving heat source, and obtain a refrigerating temperature below -10 °C at a condensing temperature above 35 °C, which severely restricts its scope of application. Additionally, for vapor-compression refrigeration systems, low evaporating temperatures inevitably result in high power consumption and low coefficient of performance (COP). To solve these problems, a novel Hybrid solid sorption-compression refrigeration Cycle is proposed, and a compressor is added between sorption bed and condenser to control desorption pressure, allowing sorbent to regenerate at a lower heat source temperature. At a condensing temperature of 35 °C, the Hybrid Cycle utilizing the working pair of SrCl2 NH3 can operate even at a heat source temperature of 60 °C, while for the conventional one, heat source temperature must exceed 98.6 °C. Its COP is almost independent of the evaporating temperature, mainly benefiting from the constant pressure ratio and compressor power consumption at a given heat source temperature. Furthermore, the Hybrid system can effectively recover the waste heat of engine jacket water, thereby providing refrigerating capacity for refrigerated trucks. Under the conditions of 50 °C condensing temperature and -25 °C evaporating temperature, its COP is up to 5.0, while the value of conventional system is only 1.3. Moreover, the Hybrid system can utilize 60–90 °C solar hot water to provide refrigerating capacity for refrigerated warehouses. Ultimately, the novel Hybrid Cycle not only effectively extends the application range of the solid sorption Cycle, but also features a higher COP compared to the vapor-compression one.
Piotr Cyklis - One of the best experts on this subject based on the ideXlab platform.
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two stage ecological Hybrid sorption compression refrigeration Cycle
International Journal of Refrigeration-revue Internationale Du Froid, 2014Co-Authors: Piotr CyklisAbstract:Abstract Low critical point of CO 2 results in transcritical refrigeration Cycles with low efficiency and high discharge pressure. H 2 O has a high triple point temperature that limits its application to temperatures above 0 °C. In this paper the two stage Hybrid Cycle is presented, where the Low Temperature (LT) stage is the compression Cycle with CO 2 and the High Temperature (HT) stage is the H 2 O sorption Cycle. The choice between absorption and adsorption technology depends on the application and most of all is related to the temperature available for the desorber. This paper presents the adsorption technology on the HT stage powered by solar thermal energy. The combined Hybrid Cycle has been tested for two years at the Politechnika Krakowska, and a summary of the results is shown in this paper. The experimental results have been compared with two-refrigerants, two stage Cycles and CO 2 - only Cycles.
