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  • 1. Agren, N. D.
    et al.
    Westermark, Mats O.
    Bartlett, M. A.
    Lindquist, T.
    First experiments on an evaporative gas turbine pilot power plant: Water circuit chemistry and humidification evaluation2002Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 124, nr 1, s. 96-102Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The evaporative gas turbine (EvGT), also known as the humid air turbine (HAT) cycle, is a novel advanced gas turbine cycle that has attracted considerable interest for the last decade. This high-efficiency cycle shows the potential to be competitive with Diesel engines or combined cycles in small and intermediate scale plants for power production and/or cogeneration. A 0.6 MW natural gas-fired EvGT pilot plant has been constructed by a Swedish national research group in cooperation between universities and industry. The plant is located at the Lund Institute of Technology, Lund, Sweden. The pilot plant uses a humidification tower with metallic packing in which heated water from the flue gas economizer is brought into direct counter current contact with the pressurized air from the compressor This gives an efficient heat recovery and thereby a thermodynamically sound cycle. As the hot sections in high-temperature gas turbines are sensitive to particles and alkali compounds, water quality issues need to be carefully considered. As such, apart from evaluating the thermodynamic and part-load performance characteristics of the plant, and verifying the operation of the high-pressure humidifier, much attention is focused on the water chemistry issues associated with the recovery and reuse of condensate water from the flue gas. A water treatment system has been designed and integrated into the pilot plant. This paper presents the first water quality results from the plant. The experimental results show that the condensate contains low levels of alkali and calcium, around 2 mg/l Sigma(K,Na,Ca), probably originating from the unfiltered compressor intake, About 14 mg/l NO2- +NO3- comes from condensate absorption of flue gas NOx. Some Cu is noted, 16 mg/l, which originates from copper corrosion of the condenser tubes. After CO2 stripping, condensate filtration and a mixed bed ion exchanger the condensate is of suitable quality for reuse as humidification water The need,for large quantities of demineralized water has by manY authors been identified as a drawback for the evaporative cycle. However, by cooling the humid flue gas, the recovery, of condensed water cuts the need of water feed. A self-supporting water circuit can be achieved, with no need for any net addition of water to the system. In the pilot plant, this was achieved by cooling the flue gas to around 35degreesC.

  • 2. Agren, N. D.
    et al.
    Westermark, Mats O. J.
    Design study of part-flow evaporative gas turbine cycles: Performance and equipment sizing - Part I: Aeroderivative core2003Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 125, nr 1, s. 201-215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The evaporative gas turbine cycle is a new high-efficiency power cycle that has reached the pilot testing stage. This paper presents calculation results of a new humidification strategy based on part flow humidification. This strategy involves using only a fraction of the compressed air for humidification. Thermodynamically, it can be shown that not all the air needs to be passed through the humidification system to attain the intrinsic good flue gas heat recovery of an EvGT cycle. The system presented also includes live steam production and superheating by heat from the hottest flue gas region. The humidifier only uses the lower temperature levels flue gas heat, where it is best suited. The analyzed system is based on data for the aeroderivative Rolls Royce Trent as a gas turbine core. Part 11 of this two-part paper presents the results based on data for the industrial gas turbine ABB GTX100. Simulation results include electric efficiency and other process datas as functions of degree of part Tow. A detailed model of the humidifier is also used and described, which produces sizing results both for column height and diameter. Full flow humidification generates an electric efficiency of 51.5% (simple cycle 41%). The efficiency increases when the humidification airflow is reduced, to reach a maximum of 52.9% when airflow to the humidification amounts to around 12% of the intake air to the compressor. At the same time, total heat exchanger area is reduced by 50% and humidifier volume by 36% compared to full flow humidification. This calls for a recommendation not to use all the compressed air for humidification.

  • 3. Agren, N. D.
    et al.
    Westermark, Mats O. J.
    Design study of part-flow evaporative gas turbine cycles: Performance and equipment sizing - Part II: Industrial core2003Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 125, nr 1, s. 216-227Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This is Part II of a two-part paper and presents calculation results of a part-flow EvGT cycle based on gas turbine data for the ABB GTX100 (modified for intercooling). The evaporative gas turbine cycle is a new high-efficiency cycle that has reached the pilot testing stage. This paper presents calculation results of a new humidification strategy based on part-flow humidification. This strategy involves using only a fraction of the compressed air for humidification. Thermodynamically, it can be shown that not all the air needs to be passed through the humidification system to attain the intrinsic good flue gas heat recovery of an EvGT cycle. The presented system also includes live steam production and superheating, by heat from the hottest flue gas region, for injection. The humidifier then only uses the lower temperature levels, where it is best suited. The analyzed system is based on data for the ABB GTX100.gas turbine in intercooled mode. Part 1 of this two-part paper presents the results based on data for the aeroderovative Rolls Royce Trent. Simulation results include electric efficiency and other process data as function of degree of part flow. A detailed model of the humidifier is used, which produces sizing results both for column height and diameter. Paper 1 includes detailed description of the modeling. For the GTXI00 system, full flow humidification generates an electric efficiency of 52.6% (simple cycle 36.2%). The efficiency is virtually unaffected if the air portion to humidification is cut to 60% of accessible compressor air (represents 48% of compressor intake). If 30% of air from the compressor after cooling bleed (24% of intake) is led to the humidifier, the efficiency is reduced to 52.2%. On the other hand is the total heat exchanger area reduced by 20% and column volume by 50%. This calls for a recommendation not to use all the compressed air for humidification. It is recommended to use 15-30% of compressor intake air. The exact economic optimum depends on local fuel prices, CO2 taxes, interest rates, etc.

  • 4.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 135, nr 11, s. 113001-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts, the combined pressure drop of the recuperator and receiver is more important. In terms of both electricity costs and carbon emissions, the internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20–35%.

  • 5.
    Bartlett, Michael A.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Westermark, Mats O.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    A study of humidified gas turbines for short-term realization in midsized power generation - Part I: Nonintercooled cycle analysis2005Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 127, nr 1, s. 91-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Humidified Gas Turbine (HGT) cycles are a group of advanced gas turbine cycles that use water-air mixtures as the working media. In this article, three known HGT configurations are examined in the context of short-term realization for small to midsized power generation: the Steam Injected Gas Turbine, the Full-flow Evaporative Gas Turbine, and the Part-flow Evaporative Gas Turbine. The heat recovery characteristics and performance potential of these three cycles are assessed, with and without intercooling, and a preliminary economic analysis is carried out for the most promising cycles.

  • 6.
    Bartlett, Michael
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Westermark, Mats O.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    A study of humidified gas turbines for short-term realization in midsized power generation - Part II: Intercooled cycle analysis and final economic evaluation2005Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 127, nr 1, s. 100-108Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Humidified gas turbine (HGT) cycles are a group of advanced gas turbine cycles that use water-air mixtures as the working media. In this article, three known HGT configurations are examined in the context of short-term realization for small to mid-sized power generation: the steam injected gas turbine, the full-flow evaporative gas turbine, and the part-flow evaporative gas turbine. The heat recovery characteristics and performance potential of these three cycles are assessed, with and without intercooling, and a preliminary economic analysis is carried out for the most promising cycles.

  • 7.
    Fransson, Torsten H.
    et al.
    KTH, Tidigare Institutioner                               , Energiteknik.
    Hillion, F. X.
    Klein, E.
    An international electronic and interactive teaching and life-long learning platform for gas turbine technology in the 21st century2001Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 123, nr 3, s. 595-603Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An interactive learning platform which sets a new standard for electronic learning of gas turbine technology in a global life-long learning perspective is presented (Fig. I). The platform contains a theoretical section in the Sonn of several pages for each chapter available, with a significant number of related interactive simulations, movies, animations, virtual laboratory exercises, virtual study visits and realistic case studies. A significant background information related to historical development in the field, a display of existing components, nomenclature, multi-lingual dictionary and keywords, as well as questions for self-assessment and exams, an electronic communication group and a database of the user's ''successes and failures,'' enhance the learning process in a significant way. The program is intended as a platform for an international collaboration on learning heat and power technology. It can be used both in the classroom as well as for self-studies and is as such well adapted for both university and post-university learning, both on and off campus. Tools to facilitate the introduction of new material exist. It is thus hoped that teachers at different universities can join forces and in a noncompetitive way introduce material which can be shared, instead of developing similar simulations with somewhat different interfaces. The long-term goal of the learning platform is of course that users worldwide will have the possibility to access the best teaching material available from any specialist, and that this material will contain supplementary pedagogical information which will enhance the learning both at a university and a post-university level.

  • 8.
    Gutierrez, Mauricio
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Petrie-Repar, Paul
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Kielb, Robert E.
    Duke Univ, Dept Mech Engn, Durham, NC 27708 USA..
    Key, Nicole L.
    Purdue Univ, Sch Mech Engn, Zucrow Labs, Purdue, IN 47907 USA..
    A Mistuned Forced Response Analysis of an Embedded Compressor Blisk Using a Reduced-Order Model2019Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 141, nr 3, artikkel-id 032505Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Accuracy when assessing mistuned forced response analyses is still a major concern. Since a fully coupled analysis is still very computational expensive, several simplifications and reduced-order models (ROMs) are carried out. The use of a reduction method, the assumptions and simplifications, generate different uncertainties that challenge the accuracy of the results. Experimental data are needed for validation and also to understand the propagation of these uncertainties. This paper shows a detailed mistuned forced response analysis of a compressor blisk. The blisk belongs to the Purdue Three-Stage (P3S) Compressor Research Facility. Two different stator-rotor-stator configurations of 38 and 44 upstream stator vanes are taken into consideration. Several loading conditions are analyzed at three different speed lines. A ROM known as subset nominal mode (SNM), has been used for all the analyses. This reduction takes as a basis a set of modes within a selected frequency spectrum. It can consider a complete family of modes to study the disk-blade modal interaction. A detailed comparison between the predicted and measured results has been performed, showing a good agreement for the high loading (HL) conditions.

  • 9.
    Gutierrez Salas, Mauricio
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Bladh, Ronnie
    Martensson, Hans
    Petrie-Repar, Paul
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Vogt, Damian M.
    Forced Response Analysis of a Mistuned, Compressor Blisk Comparing Three Different Reduced Order Model Approaches2017Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 139, nr 6, artikkel-id 062501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Accurate structural modeling of blisk mistuning is critical for the analysis of forced response in turbomachinery. Apart from intentional mistuning, mistuning can be due to the manufacturing tolerances, corrosion, foreign object damage, and in-service wear in general. It has been shown in past studies that mistuning can increase the risk of blade failure due to energy localization. For weak blade to blade coupling, this localization has been shown to be critical and higher amplitudes of vibration are expected in few blades. This paper presents a comparison of three reduced order models (ROMs) for the structural modeling of blisks. Two of the models assume cyclic symmetry, while the third model is free of this assumption. The performance of the reduced order models for cases with small and large amount of mistuning will be examined. The benefits and drawbacks of each reduction method will be discussed.

  • 10.
    Guédez, Rafael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Enhancing the Economic Competitiveness of Concentrating Solar Power Plants Through an Innovative Integrated Solar-Combined Cycle With Thermal Energy Storage2015Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, nr 4, artikkel-id 041701Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present work deals with the thermo-economic analysis of an innovative combined power cycle consisting of a molten-salt solar tower power plant with storage supported by additional heat provided from the exhaust of a topping gas-turbine unit. A detailed dynamic model has been elaborated using an in house simulation tool that simultaneously encompasses meteorological, demand and price data. A wide range of possible designs are evaluated in order to show the trade-offs between the objectives of achieving sustainable and economically competitive designs. Results show that optimal designs of the novel concept are a promising cost-effective hybrid option that can successfully fulfill both the roles of a gas peaker plant and a baseload solar power plant in a more effective manner. Moreover, designs are also compared against conventional combined cycle gas turbine (CCGT) power plants and it is shown that, under specific peaking operating strategies (P-OSs), the innovative concept cannot only perform better from an environmental standpoint but also economically.

  • 11. Johansson, E. M.
    et al.
    Danielsson, K. M. J.
    Ersson, A. G.
    Järås, Sven G.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Development of hexaaluminate catalysts for combustion of gasified biomass in gas turbines2002Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 124, nr 2, s. 235-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is an increasing interest in Catalytic combustors fuelled by low-heating value (LHV) gases, with a LHV of 5-7 MJ/Nm(3). This is because catalytic combustion could be advantageous compared to flame combustion with respect to stable combustion of LHV-gases and low conversions of fuel-N (mainly NH3) to NOX. In the present project, funded by the EU Joule Program, catalytic combustion of gasified wood for gas turbine applications is studied. A synthetic gas mixture of H-2, CO, CO2, H2O, CH4, N-2, and NH3, that resembles the output from a fluidized bed gasifier using biomass as raw material, is used. The gas mixture is mixed with air at atmospheric pressure and combusted over wash-coated cordierite monoliths in a bench-scale laboratory quartz-reactor. The objectives of the work described here are twofold. To begin with, improvement of the thermal stability of hexaaluminate washcoats by substitutions of rare earth or transition metal compounds is being studied. Secondly, catalytic combustion of gasified biomass over these washcoats has been studied in a bench-scale unit. In. this on-going project, obtained result show that it is possible to improve the surface area of hexaaluminate compounds up to 17 m(2)/g after careful synthesis and calcination up to 1400degreesC for four hours. The selectivity of NH3-conversion to N-2 is at present at 60 percent, but varies strongly with temperature. Fuel components such as H-2, CO, C2H4, and NH3 ignite at temperatures close to compressor outlet temperatures. This means that a pilot-flame may not be needed for ignition of the fuel. A comparison between a Pd-impregnated lanthanum hexaaluminate and a Mn-substituted lanthanum hexaaluminate showed that the ignition temperature and the NOX-formation varied strongly over the two different catalysts.

  • 12. Korakianitis, T
    et al.
    Grantström, J
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Wässingbo, Peter
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Massardo, A F
    Parametric performance of combined-cogeneration power plants with various power and efficiency enhancements2005Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 127, nr 1, s. 65-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The design-point performance characteristics of a wide variety of combined-cogeneration power plants, with different amounts of supplementary firing (or no supplementary firing), different amounts of steam injection (or no steam injection), different amounts of exhaust gas condensation, etc., without limiting these parameters to present-day limits are investigated. A representative power plant with appropriate components for these plant enhancements is developed. A computer program,is used to evaluate the performance of various power plants using standard inputs for component efficiencies, and the design-point performance of these plants is computed. The results are presented as thermal efficiency, specific power, effectiveness, and specific rate of energy in district heating. The performance of the simple-cycle gas turbine dominates the overall plant performance; the plant efficiency and power are mainly determined by turbine inlet temperature and compressor pressure ratio; increasing amounts of steam injection in the gas turbine increases the efficiency and power; increasing amounts of supplementary firing decreases the efficiency but increases the power; with sufficient amounts of supplementary team injection the exhaust-gas condensate is sufficient to make up for water lost in steam injection; and the steam-turbine power is a fraction (0.1 to 0.5) of the gas-turbine power output. Regions of "optimum" parameters for the power plant based oil design-point power hot-water demand, and efficiency are shown. A method,for fuel-cost allocation between electricity and hot water is recommended.

  • 13.
    Lim, Shyang Maw
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Centra, Competence Center for Gas Exchange (CCGEx). KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Dahlkild, Anders
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Mihaescu, Mihai
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för industriell teknik och management (ITM), Centra, Competence Center for Gas Exchange (CCGEx).
    Influence of Upstream Exhaust Manifold on Pulsatile Turbocharger Turbine Performance2019Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 141, nr 6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This research was primary motivated by limited efforts to understand the effects of secondary flow and flow unsteadiness on the heat transfer and the performance of a turbocharger turbine subjected to pulsatile flow. In this study, we aimed to investigate the influence of exhaust manifold on the flow physics and the performance of its downstream components, including the effects on heat transfer, under engine-like pulsatile flow conditions. Based on the predicted results by detached eddy simulation (DES), qualitative and quantitative flow fields analyses in the scroll and the rotor's inlet were performed, in addition to the quantification of turbine performance by using the flow exergy methodology. With the specified geometry configuration and exhaust valve strategy, our study showed that (1) the exhaust manifold influences the flow field and the heat transfer in the scroll significantly and (2) although the exhaust gas blow-down disturbs the relative flow angle at rotor inlet, the consequence on the turbine power is relatively small.

  • 14.
    Lucio, Monaco
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Bergmans, John
    Vogt, Damian
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    A Remotely Operated Aeroelastically Unstable Low Pressure Turbine Cascade for Turbomachinery Aeromechanics Education and Training-Remote Flutter Lab2015Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, nr 3, artikkel-id 032507Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of advanced pedagogical methodologies in connection with advanced use of modern information technology for delivery enables new ways of communicating, of exchanging knowledge, and of learning that are gaining increasing relevance in our society. Remote laboratory exercises offer the possibility to enhance learning for students in different technical areas, especially to the ones not having physical access to laboratory facilities and thus spreading knowledge in a world-wide perspective. A new "Remote Flutter Laboratory" has been developed to introduce aeromechanics engineering students and professionals to aeroelastic phenomena in turbomachinery. The laboratory is world-wide unique in the sense that it allows global access for learners anywhere and anytime to a facility dedicated to what is both a complex and relevant area for gas turbine design and operation. The core of the system consists of an aeroelastically unstable turbine blade row that exhibits self-excited and self-sustained flutter at specific operating conditions. Steady and unsteady blade loading and motion data are simultaneously acquired on five neighboring suspended blades and the whole system allows for a distant-based operation and monitoring of the rig as well as for automatic data retrieval. This paper focuses on the development of the Remote Flutter Laboratory exercise as a hands-on learning platform for online and distant-based education and training in turbomachinery aeromechanics enabling familiarization with the concept of critical reduced frequency and of flutter phenomena. This laboratory setup can easily be used "as is" directly by any turbomachinery teacher in the world, free of charge and independent upon time and location with the intended learning outcomes as specified in the lab, but it can also very easily be adapted to other intended learning outcomes that a teacher might want to highlight in a specific course. As such it is also a base for a turbomachinery repository of advanced remote laboratories of global uniqueness and access. The present work documents also the pioneer implementation of the LabSocket System for the remote operation of a wind tunnel test facility from any Internet-enabled computer, tablet or smartphone with no end-user software or plug-in installation.

  • 15.
    Lupo, Giandomenico
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Duwig, Christophe
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    A Numerical Study of Ethanol-Water Droplet Evaporation2018Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 140, nr 2, artikkel-id 021401Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present effort focuses on detailed numerical modeling of the evaporation of an ethanol-water droplet. The model intends to capture all relevant details of the process: it includes species and heat transport in the liquid and gas phases, and detailed thermophysical and transport properties, varying with both temperature and composition. Special attention is reserved to the composition range near and below the ethanol/water azeotrope point at ambient pressure. For this case, a significant fraction of the droplet lifetime exhibits evaporation dynamics similar to those of a pure droplet. The results are analyzed, and model simplifications are examined. In particular, the assumptions of constant liquid properties, homogeneous liquid phase composition and no differential volatility may not be valid depending on the initial droplet temperature.

  • 16. Maunsbach, K.
    et al.
    Isaksson, A.
    Yan, Jinyue
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Svedberg, G.
    Eidensten, L.
    Integration of advanced gas turbines in pulp and paper mills for increased power generation2001Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 123, nr 4, s. 734-740Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The pulp and paper industry handles large amounts of energy and today produces the steam needed for the process and some of the required electricity. Several studies have shown that black liquor gasification and combined cycles increase the power production significantly compared to the traditional processes used today. It is of interest to investigate the performance when advanced gas turbines are integrated with next-generation pulp and paper mills. The present study focused on comparing the combined cycle with the integration of advanced gas turbines such as steam injected gas turbine (STIG) and evaporative gas turbine (EvGT) in pulp and paper mills. Two categories of simulations have been performed: (1) comparison of gasification of both black liquor and biomass connected to either a combined cycle or steam injected gas turbine with a heat recovery steam generator: (2) externally fired gas turbine in combination with the traditional recovery boiler The energy demand of the pulp and paper mills is satisfied in all cases and the possibility to deliver a power surplus for external use is verified. The study investigates new system combinations of applications for advanced gas turbines.

  • 17. Moyroud, F.
    et al.
    Fransson, Torsten H.
    KTH, Tidigare Institutioner                               , Energiteknik.
    Jacquet-Richardet, G.
    A comparison of two finite element reduction techniques for mistuned bladed disks2002Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 124, nr 4, s. 942-952Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The high performance bladed disks used in today's turbomachines must meet strict standards in terms of aeroelastic stability and resonant response level. One structural characteristic that can significantly impact on both these areas is that of bladed disk mistuning. To predict the effects of mistuning, computational efficient methods are much needed to make free-vibration and forced-response analyses of full assembly finite element (FE) models feasible in both research and industrial environments. Due to the size and complexity of typical industrial bladed disk models, one must resort to robust and systematic reduction techniques to produce reduced-order models of sufficient accuracy. The objective of this paper is to compare two prevalent reduction methods on representative test rotors, including a modern design industrial shrouded bladed disk, in terms of accuracy (for frequencies and mode shapes), reduction order computational efficiency, sensitivity to intersector elastic coupling, and ability to capture the phenomenon of mode localization. The first reduction technique employs a modal reduction approach with a modal basis consisting of mode shapes of the tuned bladed disk which can be obtained from a classical cyclic symmetric modal analysis. The second reduction technique uses Craig and Bampton substructure modes. The results show a perfect agreement between the two reduced-order models and the nonreduced finite element model. It is found that the phenomena of mode localization is equally well predicted by the two reduction models. In terms of computational cost, reductions from one to two orders of magnitude are obtained for the industrial bladed disk, with the modal reduction method being the most computationally efficient approach.

  • 18.
    Mörtberg, Magnus
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasaik, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Gupta, A.K.
    Experimental Investigation of Flow Phenomena of a Single Fuel Jet in Cross-Flow during Highly Preheated Air Combustion Conditions2007Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 129, nr 2, s. 556-564Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Particle image velocimetry and a spectroscopy technique has been used to obtain information on the flow dynamics and flame thermal signatures of a fuel jet injected into a cross-flow of normal temperature and very high-temperature combustion air Flame fluctuations were obtained using a high-speed camera and then performing fast Fourier transform on the signal. High-temperature air combustion has been demonstrated to provide significant energy savings, higher heat flux, and reduction of pollution and equipment size of industrial furnaces. The dynamics of flow associated with high temperature combustion air conditions (for mean velocity, axial strain rate and vorticity) has been obtained in two-dimensional using propane and methane as the fuels. The data have been compared with normal temperature combustion air case, including the nonburning case. A specially designed experimental test furnace facility was used to provide well-controlled conditions and allowed air preheats to 1100 degrees C using regenerative burners. Four different experimental cases have been examined. The momentum flux ratio between the burning and nonburning conditions was kept constant to provide comparison between cases. The results provide the role of high-temperature combustion air on the dynamics of the flow, turbulence, and mixing under nonburning and combustion conditions. The data provide the direct role of combustion on flow dynamics, turbulence, and flame fluctuations. High-temperature combustion air at low-oxygen concentration showed larger flame volume with less fluctuation than normal or high-temperature normal air cases. High-temperature combustion air technology prolongs mixing in the combustion zone to enhance the flame volume, reduce flame fluctuations, and to provide uniform flow and thermal characteristics. This information assists in model validation and model development for new applications and technology development using high-temperature air combustion principles.

  • 19.
    Rafidi, Nabil
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Blasiak, Wlodzimierz
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Gupta, Ashwani K.
    High-temperature air combustion phenomena and its thermodynamics2008Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 130, nr 2, s. 023001-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The fundamentals and thermodynamic analysis of high-temperature air combustion (HiTAC) technology is presented. The HiTAC is characterized by high temperature of combustion air having low oxygen concentration. This study provides a theoretical analysis of HiTA C process from the thermodynamic point of view. The results demonstrate the possibilities of reducing thermodynamic irreversibility of combustion by considering an oxygen-deficient combustion process that utilizes both gas and heat recirculations. HiTA C conditions reduce irreversibility. Furthermore, combustion with the use of oxygen (in place of air) is also analyzed. The results showed that a system, which utilizes oxygen as an oxidizer results in higher first and second law efficiencies as compared to the case with air as the oxidizer. The entropy generation for an adiabatic combustion process is reduced by more than 60% due to the effect of either preheating or oxygen enrichment. This study is aimed at providing technical guidance to further improve efficiency of a combustion process, which shows very small temperature increases due to mild chemical reactions.

  • 20.
    Rahman, Moksadur
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Malmquist, Anders
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Modeling and Simulation of an Externally Fired Micro-Gas Turbine for Standalone Polygeneration Application2016Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, nr 11, artikkel-id 112301Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Small-scale distributed generation systems are expected to play a vital role in future energy supplies. Subsequently, power generation using micro-gas turbine (MGT) is getting more and more attention. In particular, externally fired micro-gas turbine (EFMGT) is preferred among small-scale distributed generators, mainly due to high fuel flexibility, high overall efficiency, environmental benefits, and low maintenance requirement. The goal of this work is to evaluate the performance of an EFMGT-based standalone polygeneration system with the help of computational simulation studies. The main focus of this work is to develop a dynamic model for an EFMGT. The dynamic model is accomplished by merging a thermodynamic model with a mechanical model of the rotor and a transfer function based control system model. The developed model is suitable for analyzing system performance particularly from thermodynamic and control point of view. Simple models for other components of the polygeneration systems, electrical and thermal loads, membrane distillation unit, and electrical and thermal storage, are also developed and integrated with the EFMGT model. The modeling of the entire polygeneration system is implemented and simulated in MATLAB/SIMULINK environment. Available operating data from test runs of both the laboratory setups are used in this work for further analysis and validation of the developed model.

  • 21. Salewski, Mirko
    et al.
    Stankovic, Dragan
    Fuchs, Laszlo
    A comparison of single and multiphase jets in a crossflow using large eddy simulations2007Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 129, nr 1, s. 61-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Large eddy simulations (LES) are performed for single and multiphase jets in crossflow (JICF). The multiphase JICF are compared to the single-phase case for the same momentum and mass flow, ratios but with droplets of different sizes. Multiphase JICF have stronger counterrotating vortex pairs (CVPs) than a corresponding single-phase JICF. Moreover their trajectories are higher and their induced waves weaker. The smaller the Stokes number of the droplets, the more the solution approaches the solution for single-phase flow. The computed results show the formation of a CVP and horseshoe vortices, which are convected downstream. LES also reveals the intermittent formation of upright wake vortices from the horseshoe vortices oil the ground toward the CVP. The dispersion of polydisperse spray droplets is computed using the stochastic parcel method. Atomization and droplet breakup are modeled by a combination of the breakup model by Reitz and the Taylor analogy breakup model (see Caraeni, D., Bergstrom, C., and Fuchs, L., 2000, Flow, Turbid. Combust., 65(2), pp. 223-244). Evaporation and droplet collision are also modeled. The flow solver uses two-way coupling. Averages of the velocity and gaseous fuel mass fraction are computed. The single-phase JICF is validated against experimental data obtained by PIV. Additionally, the PDFs and frequency spectra are presented.

  • 22.
    Salomon Popa, Marianne
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fridh, Jens
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Kessar, Alexandros
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Gas Turbine Simulations in the Computerized Educational Program CompEduHPT: Three Case Studies2005Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919Artikkel i tidsskrift (Fagfellevurdert)
  • 23.
    Sandoz, Raphael
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Air-Based Bottoming-Cycles for Water-Free Hybrid Solar Gas-Turbine Power Plants2013Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 135, nr 10, s. 101701-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A thermoeconomic model of a novel hybrid solar gas-turbine power plant with an air-based bottoming cycle has been developed, allowing its thermodynamic, economic, and environmental performance to be analyzed. Multi-objective optimization has been performed to identify the trade-offs between two conflicting objectives: minimum capital cost and minimum specific CO2 emissions. In-depth thermoeconomic analysis reveals that the additional bottoming cycle significantly reduces both the levelized cost of electricity and the environmental impact of the power plant (in terms of CO2 emissions and water consumption) when compared to a simple gas-turbine power plant without bottoming cycle. Overall, the novel concept appears to be a promising solution for sustainable power generation, especially in water-scarce areas.

  • 24.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Jöcker, Markus
    Martin, Andrew
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Thermal Modeling of a Solar Steam Turbine With a Focus on Start-Up Time Reduction2012Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 134, nr 1, s. 013001-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Steam turbines in solar thermal power plants experience a much greater number of starts than those operating in baseload plants. In order to preserve the lifetime of the turbine while still allowing fast starts, it is of great interest to find ways to maintain the turbine temperature during idle periods. A dynamic model of a solar steam turbine has been elaborated, simulating both the heat conduction within the body and the heat exchange with the gland steam, main steam and the environment, allowing prediction of the temperatures within the turbine during off-design operation and standby. The model has been validated against 96 h of measured data from the Andasol 1 power plant, giving an average error of 1.2% for key temperature measurements. The validated model was then used to evaluate a number of modifications that can be made to maintain the turbine temperature during idle periods. Heat blankets were shown to be the most effective measure for keeping the turbine casing warm, whereas increasing the gland steam temperature was most effective in maintaining the temperature of the rotor. By applying a combination of these measures the dispatchability of the turbine can be improved significantly: electrical output can be increased by up to 9.5% after a long cooldown and up to 9.8% after a short cooldown.

  • 25.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Thermo-economic evaluation of solar thermal and photovoltaic hybridization options for combined-cycle power plants2015Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, nr 3, s. 031801-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hybridization of combined-cycle power plants with solar energy is an attractive means of reducing carbon dioxide (CO2) emissions from gas-based power generation. However, the construction of the first generation of commercial hybrid power plants will present the designer with a large number of choices. To assist decision making, a thermo-economic study has been performed for three different hybrid power plant configurations, including both solar thermal and photovoltaic hybridization options. Solar photovoltaic combined-cycle (SPVCC) power plants were shown to be able to integrate up to 63% solar energy on an annual basis, whereas hybrid gas turbine combined-cycle (HGTCC) systems provide the lowest cost of solar electricity, with costs only 2.1% higher than a reference, unmodified combined-cycle power plant. The integrated solar combined-cycle (ISCC) configuration has been shown to be economically unattractive.

  • 26.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    A Comparative Thermoeconomic Study of Hybrid Solar Gas-Turbine Power Plants2014Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 136, nr 1, s. 011801-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The construction of the first generation of commercial hybrid solar gas-turbine power plants will present the designer with a large number of choices. To assist decision making, a thermoeconomic study has been performed for three different power plant configurations, namely, simple-and combined-cycles along with a simple-cycle with the addition of thermal energy storage. Multi-objective optimization has been used to identify Pareto-optimal designs and highlight the trade-offs between minimizing investment costs and minimizing specific CO2 emissions. The solar hybrid combined-cycle power plant provides a 60% reduction in electricity cost compared to parabolic trough power plants at annual solar shares up to 20%. The storage integrated designs can achieve much higher solar shares and provide a 7-13% reduction in electricity costs at annual solar shares up to 90%. At the same time, the water consumption of the solar gas-turbine systems is significantly lower than conventional steam-cycle based solar power plants.

  • 27.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Optimal Gas-Turbine Design for Hybrid Solar Power Plant Operation2012Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 134, nr 9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dynamic simulation model of a hybrid solar gas-turbine power plant has been developed, allowing determination of its thermodynamic and economic performance. In order to examine optimum gas-turbine designs for hybrid solar power plants, multi-objective thermoeconomic analysis has been performed, with two conflicting objectives: minimum levelized electricity costs and minimum specific CO2 emissions. Optimum cycle conditions: pressure-ratio, receiver temperature, turbine inlet temperature and flow rate, have been identified for a 15 MWe gas-turbine under different degrees of solarization. At moderate solar shares, the hybrid solar gas-turbine concept was shown to provide significant water and CO2 savings with only a minor increase in the levelized electricity cost.

  • 28.
    Topel, Monika
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Genrup, Magnus
    Lund University.
    Jöcker, Markus
    Siemens Industrial Turbomachinery.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Operational Improvements for Startup Time Reduction in Solar Steam Turbines2015Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, nr 4, artikkel-id 042604Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solar steam turbines are subject to high thermal stresses as a result of temperature gradients during transient operation, which occurs more frequently due to the variability of the solar resource. In order to increase the flexibility of the turbines while preserving lifting requirements, several operational modifications for maintaining turbine temperatures during offline periods are proposed and investigated. The modifications were implemented in a dynamic thermal turbine model and the potential improvements were quantified. The modifications studied included: increasing the gland steam pressure injected to the end-seals, increasing the back pressure and increasing the barring speed. These last two take advantage of the ventilation and friction work. The effects of the modifications were studied both individually as well as in different combinations. The temperatures obtained when applying the combined modifications were compared to regular turbine cool-down (CD) temperatures and showed significant improvements on the startup times of the turbine.

  • 29.
    Topel, Monika
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Jöcker, M.
    Paul, S.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Differential Expansion Sensitivity Studies during Steam Turbine Startup2015Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, nr 6, artikkel-id GTP-15-1419Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to improve the startup flexibility of steam turbines, it becomes relevant to analyze their dynamic thermal behavior. In this work, the relative expansion between rotor and casing was studied during cold-start conditions. This is an important property to monitor during startup given that clearances between rotating and stationary components must be controlled in order to avoid rubbing. The investigation was performed using a turbine thermal simplified model from previous work by the authors. The first step during the investigation was to extend and refine the modeling tool in order to include thermomechanical properties. Then, the range of applicability of the model was validated by a twofold comparison with a higher order finite element (FE) numerical model and measured data of a cold start from an installed turbine. Finally, sensitivity studies were conducted with the aim of identifying the modeling assumptions that have the largest influence in capturing the correct thermal behavior of the turbine. It was found that the assumptions for the bearing oil and intercasing cavity temperatures have a large influence ranging between ±25% from the measured values. In addition, the sensitivity studies also involved increasing the initial temperature of the casing in order to reduce the peak of differential expansion. Improvements of up to 30% were accounted to this measure. The studies performed serve as a base toward further understanding the differential expansion during start and establishing future clearance control strategies during turbine transient operation.

  • 30.
    Topel, Monika
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Nilsson, Åsa
    Jöcker, Markus
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Investigation into the Thermal Limitations of Steam Turbines During Start-up Operation2017Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Liberalized electricity market conditions and concentrating solar power technologies call for increased power plant operational flexibility. Concerning the steam turbine component, one key aspect of its flexibility is the capability for fast starts. In current practice, turbine start-up limitations are set by consideration of thermal stress and low cycle fatigue. However, the pursuit of faster starts raises the question whether other thermal phenomena can become a limiting factor to the start-up process. Differential expansion is one of such thermal properties, especially since the design of axial clearances is not included as part of start-up schedule design and because its measurement during operation is often limited or not a possibility at all.The aim of this work is to understand differential expansion behavior with respect to transient operation and to quantify the effect that such operation would have in the design and operation of axial clearances. This was accomplished through the use of a validated thermo-mechanical model that was used to compare differential expansion behavior for different operating conditions of the machine. These comparisons showed that faster starts do not necessarily imply that wider axial clearances are needed, which means that the thermal flexibility of the studied turbine is not limited by differential expansion. However, for particular locations it was also obtained that axial rubbing can indeed become a limiting factor in direct relation to start-up operation. The resulting approach presented in this work serves to avoid over-conservative limitations in both design and operation concerning axial clearances.

  • 31.
    Vogt, Damian M.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Experimental investigation of mode shape sensitivity of an oscillating low-pressure turbine cascade at design and off-design conditions2007Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 129, nr 2, s. 530-541Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of negative incidence operation on mode shape sensitivity of an oscillating low-pressure turbine rotor blade row has been studied experimentally. An annular sector cascade has been employed in which the middle blade has been made oscillating in controlled three-dimensional rigid-body modes. Unsteady blade surface pressure data were acquired at midspan on the oscillating blade and two pairs of nonoscillating neighbor blades and reduced to aeroelastic stability data. The test program covered variations in reduced frequency, flow velocity, and inflow incidence; at each operating point, a set Of three orthogonal modes was tested such as to allow for generation of stability plots by mode recombination. At nominal incidence, it has been found that increasing reduced frequency has a stabilizing effect on all modes. The analysis of mode shape sensitivity yielded that the most stable modes are of bending type with axial to chordwise character whereas high sensitivity has been found for torsion-dominated modes. Negative incidence operation caused the flow to separate on the fore pressure side. This separation was found to have a destabilizing effect on bending modes of chordwise character, whereas an increase in stability could be noted for bending modes of edgewise character Variations of stability parameter with inflow incidence have hereby found being largely linear within the range of conditions tested. For torsion-dominated modes, the influence on aeroelastic stability was close to neutral.

  • 32. Wolf, J.
    et al.
    Barone, F.
    Yan, Jinyue
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Performance analysis of evaporative biomass air turbine cycle with gasification for topping combustion2002Inngår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 124, nr 4, s. 757-761Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper investigates the performance of a new power cycle, a so called evaporative biomass air turbine (EvGT-BAT) cycle with gasification for topping combustion. The process integrates an externally fired gas turbine (EFGT), an evaporative gas turbine (EvGT), and biomass gasification. Through such integration, the system may provide the potential for adapting features from different advanced solid-fuel-based power generation technologies, e.g., externally fired gas turbine, integrated gasification combined cycle (IGCC), and fluidized bed combustion, thus improving the system performance and reducing the technical difficulties. In the paper the features of the EvGT-BAT cycle have been addressed. The thermal efficiencies for different integrations of the gasification for topping combustion and the heat recovery have been analyzed. By drying the biomass feedstock, the thermal efficiency of the EvGT-BAT cycle can be increased by more than three percentage points. The impact of the outlet air temperature of the high-temperature heat exchanger has also been studied in the present system. Finally, the size of the gasifier for topping combustion has been compared with the one in IGCC, which illustrates that the gasifier of the studied system can be much smaller compared to IGCC The results of the study will be useful for the future engineering development of advanced solid fuel power generation technologies.

1 - 32 of 32
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