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Sökning: WFRF:(Genrup Magnus)

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1.
  • Fast, Magnus, et al. (författare)
  • A Novel Approach For Gas Turbine Condition Monitoring Combining Cusum Technique And Artificial Neural Network
  • 2009
  • Ingår i: Proceedings Of The Asme Turbo Expo 2009, Vol 1. - 9780791848821 ; , s. 567-574
  • Konferensbidrag (refereegranskat)abstract
    • Investigation of a novel condition monitoring approach, combining artificial neural network (ANN) with a sequential analysis technique, has been reported in this paper. For this purpose operational data from a Siemens SGT600 gas turbine has been employed for the training of an ANN model. This ANN model is subsequently used for the prediction of performance parameters of the gas turbine. Simulated anomalies are introduced on two different sets of operational data, acquired one year apart, whereupon this data is compared with corresponding ANN predictions. The cumulative sum (CUSUM) technique is used to improve and facilitate the detection of such anomalies in the gas turbine's performance. The results are promising, displaying fast detection of small changes and detection of changes even for a degraded gas turbine.
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2.
  • Ahlgren, Fredrik, 1980-, et al. (författare)
  • Energy integration of organic rankine cycle, exhaust gas recirculation and scrubber
  • 2018
  • Ingår i: Trends and challenges in maritime energy management. - Cham, Switzerland : Springer. - 9783319745756 - 9783319745763 ; , s. 157-168
  • Bokkapitel (refereegranskat)abstract
    • The vast majority of ships trafficking the oceans are fuelled by residual oil with high content of sulphur, which produces sulphur oxides (SOx) when combusted. Additionally, the high pressures and temperatures in modern diesel engines also produce nitrogen oxides (NOx). These emissions are both a hazard to health and the local environment, and regulations enforced by the International Maritime Organization (IMO) are driving the maritime sector towards the use of either distillate fuels containing less sulphur, or the use of exhaust gas cleaning devices.TwocommontechniquesforremovingSOx andlimitingNOx aretheopen loop wet scrubber and exhaust gas recirculation (EGR). A scrubber and EGR installation reduces the overall efficiency of the system as it needs significant pumping power, which means that the exhaust gases are cleaner but at the expense of higher CO2 emissions. In this paper we propose a method to integrate an exhaust gas cleaning device for both NOx and SOx with an organic Rankine cycle for waste heat recovery, thereby enhancing the system efficiency. We investigate three ORC configurations, integrated with the energy flows from both an existing state-of-the-art EGR system and an additional open loop wet scrubber.
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3.
  • Ahlgren, Fredrik, 1980-, et al. (författare)
  • Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle : A Case Study
  • 2015
  • Ingår i: ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. - : ASME Press. - 9780791856673 ; , s. 43392-43416
  • Konferensbidrag (refereegranskat)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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4.
  • Ahlgren, Fredrik, 1980-, et al. (författare)
  • Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle : A Case Study
  • 2016
  • Ingår i: Journal of engineering for gas turbines and power. - : ASME Press. - 0742-4795 .- 1528-8919. ; 138:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Maritime transportation is a significant contributor to SOx,NOx, and particle matter (PM) emissions, and to a lesser extent, of CO2. Recently, new regulations are being enforced in special geographical areas to limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry toward the improvement of the energy efficiency of ships. Although more sophisticated and complex engine designs can improve significantly of the energy systems on ships, waste heat recovery arises as the most effective technique for the reduction of the energy consump- tion. In this sense, it is estimated that around 50% of the total energy from the fuel con- sumed in a ship is wasted and rejected through liquid and gas streams. The primary heat sources for waste heat recovery are the engine exhaust and 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 (AE) exhaust heat. Experimental data from the engines on the cruise ship M/S Birka Stockholm were logged during a port-to- port cruise from Stockholm to Mariehamn, over a period of 4 weeks. The ship has four main engines (ME) W€artsil€ a 5850kW for propulsion, and four AE 2760kW which areused for electrical generation. Six engine load conditions were identified depending on the ship’s speed. The speed range from 12 to 14 kn was considered as the design condi- tion for the ORC, 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 as working fluid 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 elec- tricity consumption on board. These data confirmed the ORC as a feasible and promisingtechnology for the reduction of fuel consumption and CO2 emissions of existing ships.
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5.
  • Ali Motamed, Mohammad, et al. (författare)
  • Part-load thermal efficiency enhancement in gas turbine combined cycles by exhaust gas recirculation
  • 2024
  • Ingår i: Applied Thermal Engineering. - 1359-4311. ; 244
  • Tidskriftsartikel (refereegranskat)abstract
    • Gas turbine power plants are popular for offshore power generation due to high power density and their reliability. However, growing usage of renewable energies put gas turbines in a load following backup operation. These power plants suffer part-load efficiency losses when operating at less than full capacity, resulting in higher carbon dioxide (CO2) emission from natural gas combined cycles or higher consumption of carbon-free fuels in decarbonized gas turbines. In this article, a solution is proposed for enhancement of power plant part-load thermal efficiency based on exhaust gas recirculation in the gas turbine cycle. Recirculating exhaust gas into the gas turbine have been studied by several researchers and engineers due to its benefit for carbon-free combustion and carbon capture mechanisms. The proposed operation strategy is evaluated for single-spool and two-spool gas turbines operating jointly with a steam bottoming cycle harvesting the waste heat for further power production. In the suggested strategy, eliminating the necessity to cool down the recirculated gas resulted in less equipment footprint for the power plant which makes it more favorable for offshore applications. An in-house design and simulation tool is developed for evaluating gas turbines with modern gas recirculating systems and a flexibility in operation with carbon-free fuel mixtures. The enhancement in efficiency boost, emission reduction, and fuel consumption is quantified demonstrating the improvements with the proposed solution.
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6.
  • Anton, Nicholas, et al. (författare)
  • AXIAL TURBINE DESIGN FOR A TWIN-TURBINE HEAVY-DUTY TURBOCHARGER CONCEPT
  • 2018
  • Ingår i: PROCEEDINGS OF THE ASME TURBO EXPO. - : ASME Press. - 9780791851005
  • Konferensbidrag (refereegranskat)abstract
    • In the process of evaluating a parallel twin-turbine pulse-turbocharged concept, the results considering the turbine operation clearly pointed towards an axial type of turbine. The radial turbine design first analyzed was seen to suffer from sub-optimum values of flow coefficient, stage loading and blade speed-ratio. Modifying the radial turbine by both assessing the influence of "trim" and inlet tip diameter all concluded that this type of turbine is limited for the concept. Mainly, the turbine stage was experiencing high values of flow coefficient, requiring a more high flowing type of turbine. Therefore, an axial turbine stage could be feasible as this type of turbine can handle significantly higher flow rates very efficiently. Also, the design spectrum is broader as the shape of the turbine blades is not restricted by a radially fibred geometry as in the radial turbine case. In this paper, a single stage axial turbine design is presented. As most turbocharger concepts for automotive and heavy-duty applications are dominated by radial turbines, the axial turbine is an interesting option to be evaluated for pulse charged concepts. Values of crank-angle-resolved turbine and flow parameters from engine simulations are used as input to the design and subsequent analysis. The data provides a valuable insight into the fluctuating turbine operating conditions and is a necessity for matching a pulse-turbocharged system. Starting on a 1D-basis, the design process is followed through, resulting in a fully defined 3D-geometry. The 3D-design is evaluated both with respect to FEA and CFD as to confirm high performance and durability. Turbine maps were used as input to the engine simulation in order to assess this design with respect to "on-engine" conditions and to engine performance. The axial design shows clear advantages with regards to turbine parameters, efficiency and tip speed levels compared to a reference radial design. Improvement in turbine efficiency enhanced the engine performance significantly. The study concludes that the proposed single stage axial turbine stage design is viable for a pulse-turbocharged six cylinder heavy-duty engine. Taking into account both turbine performance and durability aspects, validation in engine simulations, a highly efficient engine with a practical and realizable turbocharger concept resulted.
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7.
  • Anton, Nicholas (författare)
  • Engine Optimized Turbine Design
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The focus on our environment has never been as great as it is today. The impact of global warming and emissions from combustion processes become increasingly more evident with growing concerns among the world’s inhabitants. The consequences of extreme weather events, rising sea levels, urban air quality, etc. create a desperate need for immediate action. A major contributor to the cause of these effects is the transportation sector, a sector that relies heavily on the internal combustion engine and fossil fuels. The heavy-duty segment of the transportation sector is a major consumer of oil and is responsible for a large proportion of emissions.The global community has agreed on multiple levels to reduce the effect of man-made emissions into the atmosphere. Legislation for future reductions and, ultimately, a totally fossil-free society is on the agenda for many industrialized countries and an increasing number of emerging economies.Improvements of the internal combustion engine will be of importance in order to effectively reduce emissions from the transportation sector both presently and in the future. The primary focus of these improvements is undoubtedly in the field of engine efficiency. The gas exchange system is of major importance in this respect. The inlet and exhaust flows as the cylinder is emptied and filled will significantly influence the pumping work of the engine. At the center of the gas exchange system is the turbocharger. The turbine stage of the turbocharger can utilize the energy in the exhaust flow by expanding the exhaust gases in order to power the compressor stage of the turbocharger.If turbocharger components can operate at high efficiency, it is possible to achieve high engine efficiency and low fuel consumption. Low exhaust pressure during the exhaust stroke combined with high pressure at the induction stroke results in favorable pumping work. For the process to work, a systems-based approach is required as the turbocharger is only one component of the engine and gas exchange system.In this thesis, the implications of turbocharger turbine stage design with regards to exhaust energy utilization have been extensively studied. Emphasis has been placed on the turbine stage in a systems context with regards to engine performance and the influence of exhaust system components.The most commonly used turbine stage in turbochargers, the radial turbine, is associated with inherent limitations in the context of exhaust energy utilization. Primarily, turbine stage design constraints result in low efficiency in the pulsating exhaust flow, which impairs the gas exchange process. Gas stand and numerical evaluation of the common twin scroll radial turbine stage highlighted low efficiency levels at high loadings. For a pulse-turbocharged engine with low exhaust manifold volume, the majority of extracted work by the turbine will occur at high loadings, far from the optimum efficiency point for radial turbines. In order for the relevant conditions to be assessed with regards to turbine operation, the entire exhaust pulse must be considered in detail. Averaged conditions will not capture the variability in energy content of the exhaust pulse important for exhaust energy utilization.Modification of the radial turbine stage design in order to improve performance is very difficult to achieve. Typical re-sizing with modifying tip diameter and trim are not adequate for altering turbine operation into high efficiency regions at the energetic exhaust pulse peak.The axial turbine type is an alternative as a turbocharger turbine stage for a pulse-turbocharged engine. The axial turbine stage design can allow for high utilization of exhaust energy with minimal pressure interference in the gas exchange process; a combination which has been shown to result in engine efficiency improvements compared to state-of-the-art radial turbine stages.
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8.
  • Anton, Nicholas, et al. (författare)
  • Exhaust volume dependency of turbocharger turbine design for a heavy duty otto cycle engine
  • 2017
  • Ingår i: Proceedings of the ASME Turbo Expo. - : ASME Press. - 9780791850800
  • Konferensbidrag (refereegranskat)abstract
    • This study is considering turbocharger turbine performance at "on-engine" conditions with respect to turbine design variables and exhaust manifold volume. The highly unsteady nature of the internal combustion engine will result in a very wide range of turbine operation, far from steady flow conditions. As most turbomachinery design work is conducted at steady state, the influence of the chosen turbine design variables on the crank-angle-resolved turbine performance will be of prime interest. In order to achieve high turbocharger efficiency with the greatest benefits for the engine, the turbine will need high efficiency at the energetic exhaust pressure pulse peak. The starting point for this paper is a target full load power curve for a heavy duty Otto-cycle engine, which will dictate an initial compressor and turbine match. Three radial turbine designs are investigated, differing with respect to efficiency characteristics, using a common compressor stage. The influence of the chosen turbine design variables considering a main contributor to unsteadiness, exhaust manifold volume, is evaluated using 1D engine simulation software. A discussion is held in conjunction with this regarding the efficiency potential of each turbine design and limitations of turbine types.
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9.
  • Anton, Nicholas, et al. (författare)
  • ON THE CHOICE OF TURBINE TYPE FOR A TWIN-TURBINE HEAVY-DUTY TURBOCHARGER CONCEPT
  • 2018
  • Ingår i: PROCEEDINGS OF THE ASME TURBO EXPO. - : AMER SOC MECHANICAL ENGINEERS. ; 8
  • Konferensbidrag (refereegranskat)abstract
    • In this study, a fundamental approach to the choice of turbocharger turbine for a pulse-charged heavy-duty diesel engine is presented. A standard six-cylinder engine build with a production exhaust manifold and a Twin-scroll turbocharger is used as a baseline case. The engine exhaust configuration is redesigned and evaluated in engine simulations for a pulse-charged concept consisting of a parallel twin-turbine layout. This concept will allow for pulse separation with minimized exhaust pulse interference and low exhaust manifold volume. This turbocharger concept is uncommon, as most previous studies have considered two stage systems, various multiple entry turbine stages etc. Even more rare is the fundamental aspect regarding the choice of turbine type as most manufacturers tend to focus on radial turbines, which by far dominate the turbochargers of automotive and heavy-duty applications. By characterizing the turbine operation with regards to turbine parameters for optimum performance found in literature a better understanding of the limitations of turbine types can be achieved. A compact and low volume exhaust manifold design is constructed for the turbocharger concept and the reference radial turbine map is scaled in engine simulations to a pre-set AFR-target at a low engine RPM. By obtaining crank-angle-resolved data from engine simulations, key turbine parameters are studied with regard to the engine exhaust pulse-train. At the energetic exhaust pressure pulse peak, the reference radial turbine is seen to operate with suboptimum values of Blade-Speed-Ratio, Stage Loading and Flow Coefficient. The study concludes that in order to achieve high turbine efficiency for this pulse-charged turbocharger concept, a turbine with efficiency optimum towards low Blade-Speed Ratios, high Stage Loading and high Flow Coefficient is required. An axial turbine of low degree of reaction-design could be viable in this respect.
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12.
  • Bahrami, Saeed, et al. (författare)
  • Performance Comparison between Steam Injected Gas Turbine and Combined Cycle during Frequency Drops
  • 2015
  • Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 8:8, s. 7582-7592
  • Tidskriftsartikel (refereegranskat)abstract
    • Single-shaft gas turbine and its cycles are sensitive to frequency drops and, therefore, sudden change loads or large frequency dips might affect their stability. This phenomenon is related to the reduction of the air mass flow passing through the machine during the frequency dips, which might lead to an interaction between governor and temperature control loop. In this paper, the performance of the combined cycle and steam-injected gas turbine are studied during frequency dips and transient maneuvers. For this purpose, two similar units are developed based on these cycles and their performances are studied in different scenarios. The simulation results show that the steam injected gas turbine has a better performance during frequency drops and it can handle relatively larger change loads.
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13.
  • Dahlquist, Adrian, et al. (författare)
  • Aerodynamic turbine design for an oxy-fuel combined cycle
  • 2016
  • Ingår i: Turbomachinery. - 9780791849705 ; 2B-2016
  • Konferensbidrag (refereegranskat)abstract
    • The oxy-fuel combined cycle (OCC) is one of several carbon capture and sequestration (CCS) technologies being developed to reduce CO2 emissions from thermal power plants. The OCC consists of a semi-closed topping Bryton cycle, and a traditional bottoming Rankine cycle. The topping cycle operates with a working medium mixture of mainly CO2 and H2O. This CO2-rich working fluid has significantly different gas properties compared to a conventional open gas turbine cycle, which thereby affects the aerodynamic turbine design for the gas turbine units. The aerodynamic turbine design for oxyfuel gas turbines is an unexplored research field. The topic of this study was therefore to investigate the aerodynamic turbine design of turbines operating with a CO2-rich working fluid. The investigation was performed through a typical turbine aerodesign loop, which covered the 1D mid-span, 2D through-flow, 3D blade profiling design and the steady-state 3D analysis. The design was performed through the use of conventional design methods and criteria in order to investigate if any significant departures from conventional turbine design methods were required. The survey revealed some minor deviations in design considerations, yet it showed that the design is feasible with today's state-of-the-art technology by using conventional design practice and methods. The performance of the oxy-fuel combined cycle was revised based on the performance figures from the components design. The expected total performance figures for the oxy-fuel combined cycle were calculated to be a net electrical power of 119.9 MW and a net thermal efficiency of 48.2%. These figures include the parasitic consumption for the oxygen production required for the combustion and the CO2 compression of the CO2 bleed stream.
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14.
  • Dahlquist, Adrian, et al. (författare)
  • The influence from the working medium on the profile loss in compressor and turbine airfoils
  • 2014
  • Ingår i: Proceedings of the ASME Turbo Expo: Turbine Technical Conference And Exposition, 2014, Vol 2C. ; , s. 02-38
  • Konferensbidrag (refereegranskat)abstract
    • A number of CCS-technologies are currently being developed for the reduction of CO2 emissions from thermal power stations. One such technology is the oxyfuel process, in which a mixture of CO2 and steam is used as the working medium. The semi-closed oxyfuel combustion combined cycle (SCOC-CC) is an oxyfuel cycle where the working medium mainly consists of CO2 (85-95%). Current practice is to design turbomachinery using 1D and 2D flow tools, which primarily rely on loss models derived from experiments with air. For the oxyfuel case, the losses are hence extrapolated from air to a CO2/steam mixture, which can have adverse effects on the accuracy of the loss model. Therefore, the applicability and accuracy in using profile loss correlations derived with air when changing the working medium to the oxyfuel like environment of pure CO2 was investigated. The reason that 100% CO2 was chosen as the working medium and not a CO2/H2O mixture is that the water content present is relatively low and varies from case-to-case. Hence, a general water content could not be specified that was relevant for all cases. The study was done with typical compressor and turbine airfoils using a steady-state Navier-Stokes' 3D flow solver. This solver type can resolve the boundary layer (y(+) of about unity) rather than relying upon a boundary layer equation, - hence eliminating the latter as a source of error. The hypothesis was that the profile loss depended on the viscosity, and that amendments to the viscosity would affect the profile loss. This trend was observed, e.g. when changing the working medium from air to CO2, the profile loss coefficient (Y-p) for the compressor was reduced with 25% and for the turbine with 6%, respectively. A slight difference in profile loss for an individual cascade was found when changing the working medium from air to CO2. Theoretically, this difference leads to an increased mismatch of the stages downstream even at design point, and thus increases the losses and reduces the stability. However, the difference in profile loss is relatively small at the design point, and thus it is the authors' opinion that the practical effect will be quite small. Therefore, it is considered safe to use loss correlations derived from air for design point calculations even when the working medium is CO2. However, there is a certain risk involved that air- based loss models are not capable of predicting the behavior over the full operating range, as the boundary layers risk to behave in a different manner. Another aspect that was considered is how the wet surface area (physical size) of a turbomachine performing the same work (mho) will change between the two gases. This is important as the total profile loss in a whole compressor or turbine is directly proportional to this change. The conclusion was that the total wet area would increase by some 20% for CO2 compared to air.
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15.
  • Deshpande, Srikanth, et al. (författare)
  • Effect of spanwise variation of chord on the performance of a turbine cascade
  • 2017
  • Ingår i: Turbomachinery. - 9780791850787 ; 2A-2017
  • Konferensbidrag (refereegranskat)abstract
    • This paper compares the aerodynamic performance of two cascade designs, viz.: -constant-chord and varying-chord. The varying-chord design is typical of industrial gas turbines and steam turbine stators in order to reduce manufacturing costs. The present study aims to increase the understanding of the implications of this manufacturing constraint on the aerodynamics of the stator. Experiments are carried out in a linear cascade wind tunnel. Numerical simulations are performed using commercial code CFX. The profile losses and secondary losses in the two designs are compared. The overall total pressure losses indicate better aerodynamic performance of a turbine cascade with constant chord as compared to a turbine cascade of varying-chord design
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16.
  • Deshpande, Srikanth, et al. (författare)
  • Efficiency improvements in an industrial steam turbine stage - Part 1
  • 2016
  • Ingår i: Turbomachinery. - 9780791849705 ; 2B-2016
  • Konferensbidrag (refereegranskat)abstract
    • The present work approaches the idea of increasing the efficiency of an industrial steam turbine stage. For this endeavor, an industrial steam turbine stage comprising of prismatic stator and rotor is considered. With the velocity triangles as input, airfoil design is carried out. Firstly, the rotor is redesigned to take care of any incidence issues in the baseline case. In rotor blades, the peak Mach number is reduced in blade to blade flow passage and hence, efficiency of stage is increased. Rotor is made front loaded. After finalizing the rotor, the stator is redesigned. Stator is made more aft-loaded when compared to the baseline case. By making the stator aft-loaded, the efficiency increased by reducing profile losses. This design modification also showed advantage in secondary losses. The total pressure loss in the stator was reduced by a delta of 0.15. When creating an airfoil for stator or rotor, MISES was used in order to evaluate profile losses. The design verification for the stage was numerically done using commercial CFD software ANSYS CFX. Steady state RANS simulations were carried out. The stator and the rotor still being prismatic, only by virtue of airfoil design, the total to total stage efficiency improvement of 0.33% was predicted.
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17.
  • Deshpande, Srikanth, et al. (författare)
  • Efficiency improvements in an industrial steam turbine stage - Part 2
  • 2016
  • Ingår i: Turbomachinery. - 9780791849705 ; 2B-2016
  • Konferensbidrag (refereegranskat)abstract
    • Improvement in isentropic total to total efficiency of a low reaction turbine stage by airfoil redesign was considered in first part of the paper. Further, modifications in the flow path of the baseline stage is considered in second part of the paper. Flow path of the baseline stage incorporates axisymmetric meridional endwall contour(commonly called Russian kink). For a stage comprising of high aspect ratio blades, assessment of performance with endwall contour is performed. Alternatives, if required for endwall contour had to be explored and numerically verified. Endeavor in the present paper is in this direction. Static pressure distribution at the stator exit is considered as the main objective. Along with flow path modification, stator modifications like vortexing and lean are attempted to obtain stator exit static pressure distribution similar to baseline case. Straight lean on stator provides good results in terms of reducing stator exit pressure gradient as well as reducing gradient of rotor inlet swirl. Since the pressure distribution at stator exit also drives the tip leakage flow, effect of flowpath and stator modifications on tip leakage flow is studied. Performance numbers are reported for cases with and without tip shroud.
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18.
  • Deshpande, Srikanth, et al. (författare)
  • Influence of compound lean on an industrial steam turbine stage
  • 2015
  • Ingår i: ASME 2015 Gas Turbine India Conference, GTINDIA 2015. - 9780791857311
  • Konferensbidrag (refereegranskat)abstract
    • Compound lean implemented on stator of an industrial steam turbine stage in order to reduce secondary losses are discussed. Baseline stator is a prismatic vane with aspect ratio of unity. Compound lean stator blade is designed by shearing the airfoil sections in tangential direction. Modifications are analyzed numerically using commercial code CFX. Three blade rows i.e. one complete stage with a downstream stator are analyzed. Steady state Reynolds averaged Navier Stokes equations are solved. Total pressure loss (TPL) is used as objective function to monitor reduction in secondary losses. Rotor is retained the same for baseline as well as compound leaned stator. Results show reduction in total pressure loss of stator in excess of 5%. Also, computations of coefficient of secondary kinetic energy shows significant reduction in secondary losses in excess of 30% in stator. Efficiency gained by implementation of compound lean are discussed.
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19.
  • Deshpande, Srikanth, et al. (författare)
  • Reduction in Secondary Losses in Turbine Cascade Using Contoured Boundary Layer Fence
  • 2014
  • Ingår i: Proceedings of the ASME 2014 Gas Turbine India Conference. - 9780791849644 ; , s. 2014-8175
  • Konferensbidrag (refereegranskat)abstract
    • Present work deals with reducing secondary losses in turbine cascade by using boundary layer fences in two ways. Firstly, to reduce the strength of vortex which is incident at the leading edge of airfoil and hence reduce the strength of horse shoe vortex, and secondly, to reduce the pressure gradient between the pressure side and the suction side in the flow passage region between airfoils. In previous works, the boundary layer fence followed the profile of airfoil. In this publication, boundary layer fence does not follow the profile of airfoil i.e stagger and camber of boundary fence is different when compared to airfoil. A profiled boundary layer fence is proposed in the present work which reduces the incident voracity and also reduces pressure gradient from pressure side to suction side. Such boundary layer fence was checked on T106 test cascade which is available as open literature. Numerical work is carried out using commercial software Ansys CFX. Viscous RANS simulations are carried out using k-omega SST turbulence model with yplus value around unity on all walls. Coefficient of secondary kinetic energy (CSKE) and Secondary Kinetic energy helicity (SKEH) are used as target functions. Total pressure loss is also monitored. All the three functions show a reduction in secondary loss. The strength of horse shoe vortex is reduced by the fence protruding in front of leading edge. The converging flow passage created by the fence near the pressure side of airfoil reduces the pressure gradient from pressure side to suction side. The total pressure loss was reduced by 1.5 % and CSKE was improved by 36 % when the boundary layer fence was adopted.
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20.
  • Deshpande, Srikanth, et al. (författare)
  • Vortexing methods to reduce secondary losses in a low reaction industrial turbine
  • 2015
  • Ingår i: Turbomachinery. - 9780791856635 ; 2A
  • Konferensbidrag (refereegranskat)abstract
    • Vortexing methods implemented on an industrial steam turbine vane in order to reduce secondary losses are discussed. Three vortexing methods presented are prismatic blade design, inverse vortex and parabolic forced vortex. Baseline industrial vane considered for study is a prismatic blade design. Modifications are analysed numerically using commercial code CFX. Modified vanes along with baseline rotor as a complete stage is considered for analysis. Steady state Reynolds averaged Navier Stokes equations are solved. Total pressure loss (TPL) is used as target functions to monitor reduction in secondary losses. Rotor considered for the study is the baseline industrial rotor for all design modifications of vane.
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21.
  • Engdar, Ulf, et al. (författare)
  • Investigation of the two-phase flow field of the GTX100 compressor inlet during off-line washing
  • 2004
  • Ingår i: ASME Turbo Expo 2004: Power for Land, Sea, and Air. - 0791841693 ; 4, s. 509-518
  • Konferensbidrag (refereegranskat)abstract
    • A modern gas turbine compressor, with its highly aerodynamically loaded blades, is sensitive to changes in profile shape and to surface roughness. Fouling is inevitable, despite highly efficient filtration systems. The remedy to this problem is washing. There are two different approaches, online or off-line washing. The off-line wash is the most effective one, whilst on-line washing only prolongs the interval between off-line washes. Most findings in this field are highly empirical, being based on some 50 years of industrial gas turbine operation. This paper is an investigation of the two-phase flow in the bellmouth of the compressor during off-line washing conditions. The unit under study was the GTX100 turbo-set. Computational fluid dynamics (CFD) is used in this paper to perform a detailed study of the flow field. The main emphasis has been on studying the characteristics of the injected spray used for cleaning of the compressor. The benefit of heating this fluid is of special interest, since if this heating can be avoided, the outage time for the off-line compressor wash can be shortened. To provide the CFD computations with accurate boundary conditions for the spray, laser-based measurements of a spray, originating from an authentic wash nozzle, have been conducted. The commercial CFD program Star-Cd has been used for all computations. The computations show that the water injected, regardless of its inlet temperature, is cooled down to ambient air temperature well before the spray reaches the inlet guide vanes. This indicates that heating of the wash fluid can be abolished. The airflow seems not to be to influenced by the injected fluid to any great extend.
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22.
  • Eriksson, Pontus, et al. (författare)
  • Off-design performance investigation of a low calorific gas fired two-shaft gas turbine
  • 2009
  • Ingår i: Proceedings of the ASME Turbo Expo 2009 : Power for Land, Sea and Air - Power for Land, Sea and Air. - 9780791848852 ; 4, s. 21-32
  • Konferensbidrag (refereegranskat)abstract
    • Gas turbine systems are predominantly designed to be fuelled with gaseous fuels within a limited Wobbe index range (typically HHV=45-55 MJ/Nm3 or 1200-1480 Btu/scf). When low calorific fuel gases are fired, the engine will be forced to operate outside its design envelope. The added mass flow will typically raise the cycle pressure ratio and in two-shaft designs also raise the gas generator shaft speed. Typical constraints to be considered due to the altered fuel composition are pressure loads, shaft torques, shaft overspeeds, centrifugal overloading of disks and blades, combustor flameout, surge and flutter limits for the turbomachinery. This poses limitations to usable fuel choices. In this study, the response of a natural gas fired simple cycle two-shaft gas turbine is investigated. A lean premixed combustor is also included in the model. Emphasis has been put on predicting the turbomachinery and combustor behavior as different amounts of N2 or CO2 are added to the fuel path. These two inerts are typically found in large quantities in medium and low calorific fuels. The fuels lower heating value is thus gradually changed from 50 MJ/kg (21.5 kBtu/lb) to 5MJ/kg (2.15 kBtu/lb). A model, based on the Volvo Aero Corp. VT4400 gas turbine (originally Dresser Rand DR990) characterized by one compressor and two expander maps is considered. The free turbine is operated at fixed physical speed. The operating point is plotted in the compressor map and the turbine maps at three distinct firing temperatures representing turndown from full load to bleed opening point. Gas generator speed and shaft power are shown. Surge margin and power turbine power is plotted. Overall efficiency is computed. The behavior of the Volvo lean premixed combustor is also discussed. Air split, primary zone equivalence ratio and temperature is plotted. Combustor loading, combustion intensity and pressure drop is graphed. Results are, as far as possible, given as non-dimensional parameter groups for easy comparison with other machines.
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23.
  • Eriksson, Pontus, et al. (författare)
  • Re-sizing of a natural gas fired two-shaft gas turbine for low calorific gas operation
  • 2009
  • Ingår i: Proceedings of the ASME Turbo Expo 2009 : Power for Land, Sea and Air - Power for Land, Sea and Air. - 9780791848852 ; 4, s. 539-550
  • Konferensbidrag (refereegranskat)abstract
    • Gas turbine systems are predominantly designed to be fuelled with gaseous fuels within a limited Wobbe index range (typically HHV=45-55 MJ/Nm3 or 1200-1480 Btu/scf). When low calorific fuel gases are fired, the engine will be forced to operate outside its design envelope. The added mass flow will typically raise the cycle pressure ratio and in two-shaft designs also raise the gas generator shaft speed. In this study, the response of a natural gas fired simple cycle two-shaft gas turbine operating at full firing temperature is investigated. A model based on the Volvo Aero Corp. VT4400 gas turbine (originally Dresser Rand DR990) characterized by one compressor and two expander maps is considered. The free turbine is operated at fixed physical speed. Different amounts of N2 or CO2 are added to the fuel path. These two inerts are typically found in large quantities in medium and low calorific fuels. The fuels lower heating value is thus gradually changed from 50 MJ/kg (21.5 kBtu/lb) to 5MJ/kg (2.15 kBtu/lb). Emphasis has been put on predicting the compressor behavior in different resizing scenarios. The full 'firing temperature' operating point in the compressor map is tracked as the compressor size is reduced up to 7.5%, high pressure turbine size is increased up to 20%, low pressure turbine size is changed ±7.5% or up to 10% of steam (c.f. design point compressor air mass flow) is injected between the turbines. Different re-matching schemes are discussed where one turbomachinery component size is fixed and the two other component sizes are changed such that the compressor design point is restored. Finally a re-optimized turbine flow path is computed in a fixed compressor size scenario. Results are, as far as possible, given as non-dimensional parameter groups for easy comparison with other machines.
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24.
  • Fredriksson Möller, Björn, et al. (författare)
  • On the off-design of a natural gas-fired combined cycle with CO2 capture
  • 2007
  • Ingår i: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 32:4, s. 353-359
  • Tidskriftsartikel (refereegranskat)abstract
    • During the last 15 years cycles with CO, capture have been in focus, due to the growing concern over our climate. Often, a natural gas fired combined cycle with a chemical absorption plant for CO, capture from the flue gases have been used as a reference in comparisons between cycles. Neither the integration of the steam production for regeneration of amines in the combined cycle nor the off-design behaviour of such a plant has been extensively Studied before. In this paper, the integration of steam production for regeneration of the amines is modelled at design load and studied in off-design conditions for a combined cycle. Different ambient conditions and part-load strategies and their influence on the cycle performance are also examined. Of particular interest is a novel strategy with the possibility of longer life of gas turbine blading, with marginal loss in efficiency. The off-design performance of the combined cycle is modelled in a rigorous Way using a gas turbine performance deck, while the boiler is calculated using simplified correlations for oft-design heat transfer and pressure drop. The steam turbine calculation is based on verified models for the flow-pressure-efficiency relations, whilst the steam condenser is based oil the HEI method.
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25.
  • Fredriksson Möller, Björn, et al. (författare)
  • On the off-design of a natural gas-fired combined cycle with CO2 capture
  • 2005
  • Ingår i: Proceedings of Ecos 2005, Vols 1-3 - Shaping our future energy systems. - 8251920418 ; , s. 811-818
  • Konferensbidrag (refereegranskat)abstract
    • During the last 15 years cycles with CO2 capture have been in focus, due to the growing concern over our climate. Often a natural-gas fired combined cycle with a chemical absorption plant for CO2 capture from the flue gases have been used as a reference in comparisons between cycles. The integration of the steam production in the cycle to minimise the drop in efficiency have not been extensively studied. Neither have there been any studies on the off-design behaviour of such a plant if it should be built. In this paper the integration of steam production for regeneration of the amines is modelled at design load and studied in off-design conditions for a combined cycle. Different ambient conditions and part-load strategies and their influence on the cycle performance are also examined. Of particular interest is a novel strategy with the possibility of longer life of gas turbine blading, with marginal loss in efficiency. The off-design performance of the combined cycle is modelled in a rigorous way, using a gas turbine performance deck to calculate the performance of the gas turbine. The boiler is calculated using simplified correlations for off-design heat transfer and pressure drop. The steam turbine calculation is based on verified models for the flow - pressure - efficiency relations, whilst the steam condenser is based on the HEI (Heat Exchange Institute) method.
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26.
  • Genrup, Magnus, et al. (författare)
  • A reduced-order through-flow program for choked and cooled axial turbines
  • 2005
  • Ingår i: Proceedings of the ASME Turbo Expo. ; 6 PART B, s. 1161-1168
  • Konferensbidrag (refereegranskat)abstract
    • A reduced-order through-flow program has been developed at the Lund Institute of Technology. The goal of the work was to develop and verify a program suitable for scientific studies of coaxial turbines. The program has built-in capability for multiple choked stages, and turbine cooling, as well as flexible modules for state, losses, deviation, and blockage. The code uses Matlab [trademark] as a platform for numerics, pre- and post-processing. The turbine modules are available from the Institute free of charge for scientific use. Matlab is a commercially available mathematical package and is used as a numerical tool by many universities and companies. Today, several codes are available for turbine analysis at different levels. Most of the codes are proprietary and not available outside the companies that have developed them. There are, however, commercially available codes, but the user does not normally have accesses to the source code. This poses serious problems when such codes are used for scientific studies, and open easily modified code is indeed a desirable feature. The present paper describes in detail the calculation methods used to simulate performance of a cooled and choked turbine at off-design conditions. The algorithms necessary for finding the turbine choke point will, for example, be described in detail. The way in which the loss, deviation (including secondary and tip clearance), and blockage are included in a quasi 1-D calculation environment is also presented. The code is suitable for further development (e.g. streamline curvature through-flow), since it is based on modules for e.g. state, combustion, loss, deviation, diffuser, numerics, and in and output data processing. It is fairly easy to transform the Matlab program into e.g. Fortran. However, the use of the original platform simplifies plotting of turbine characteristics, velocity triangles, etc. The program is validated against test-rig data from an industrial two-stage power turbine. Copyright
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27.
  • Genrup, Magnus, et al. (författare)
  • A review of gas turbine flow path analysis - From paper calculation to artificial neural networks
  • 2002
  • Ingår i: American Society of Mechanical Engineers, International Gas Turbine Institute, Turbo Expo (Publication) IGTI. ; 2 A, s. 75-82
  • Konferensbidrag (refereegranskat)abstract
    • Today many methods are available for gas turbine flow path analysis. Some of them are very simple but yet very useful, since they give an indication of the compressor capacity with almost no calculation effort. The state of the art today is the heat and mass balance models (HMB), which are more sophisticated. This paper presents a general overview of these methods, including the most recent trend, Artificial Neural Networks (ANN). In the future, the ANN-based flow path analysis system will probably, to some extent, replace the HMB-based systems, or become a complementary tool for monitoring and performance analysis of power production units. This paper will give a comprehensive explanation of how to build a flow path analysis system in an equation-solving package (e.g. spreadsheet program), by using relationships presented here. This may give a system that is well within the capabilities of most commercially available systems, used and developed by consultant companies (third party companies).
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28.
  • Genrup, Magnus (författare)
  • On Degradation and Monitoring Tools for Gas and Steam Turbines
  • 2005
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The revenue from a power plant is strongly dependent on the life cycle cost. Today, when the market conditions for power-producing companies have shifted from a protected market to a deregulated market, the need for tools to monitor power plants has increased significantly. In this new competitive market, targeted revenues and operational economy drive the need for advanced monitoring tools. In this thesis, monitoring tools for both the gas turbine and the steam turbine are described. The thesis gives a thorough description of the state-of-the-art model-based gas turbine flow path analysis system. The underlying mechanisms for degradation are also described, together with some remedying actions. The main intention of the thesis is to provide guidance for the user of the plant on how a model-based system works. The information is presented in general terms, since it is impossible to cover all gas turbine based power plant configurations. The tools presented here have different levels of sophistication, from the most simple to state-of-the-art heat and mass balance programs. The level of sophistication that is achievable is dependent on the extent of knowledge about a specific engine type. The highest level of sophistication is reserved for systems delivered by the manufacturing companies (OEMs). This level of model-based monitoring system requires detailed propriety turbine data that are not available outside the OEM. A system delivered by an OEM is more costly in general, but the additional know-how is a very valuable commodity. When working with the operational aspects of a power plant, one needs to make quantitative estimations of the effects of deteriorated components. Usually, the software for more detailed analysis are not available to the users since they use in-house code developed by the manufacturers. Besides being proprietary, such code is normally neither user-friendly nor adapted for this type of analysis. However, there are commercially available software packages on the market, but these do not usually provide the required level of off-design prediction capability. Thus, it was decided to develop a flexible tool with open structure that would enable both general power plant simulation useful for the plant owners, and detailed component analysis that is of special interest for research purposes. This work resulted in three different tools, a gas turbine performance deck or off-design performance prediction tool, a steam cycle analysis tool, and a reduced-order through-flow program. The gas turbine performance deck is suitable for both gas turbine and complete combined cycle analysis. This tool has also been used to analyze the off-design behavior of advanced wet gas turbine based cycles. The steam cycle analysis tool was developed for general steam cycle studies, and is suitable for highly loaded turbine components such as control stages at partial load. This tool was calibrated against high-quality data measured from test code (DIN) performance tests, and the results are well within expectation. The steam cycle calculation tool has been used by the project partners as a tool for generating data for ANN training purposes and general power plant off-design performance studies. The first two calculation models presented are at the component level ? where the performance of a component is simulated ? rather than dealing with an individual stage in a compressor or a turbine. As a complement, the author developed a reduced-order through-flow program, where more detailed analysis at the stage level can be performed. This software can be used for an arbitrary number of cooled and choked turbine stages. The code was validated against data measured from a turbine test rig, and the results show that the accuracy is well within the figures expected. This program is available at the department's website as open source code in Matlab?. The theories behind these calculation programs are presented in this thesis in Chapters 5, 6 and 7. Knowing the underlying degradation mechanisms, and with the possibility of including these in a condition-monitoring system, the potential for improving the economics of operation is significant. The availability of a plant can be increased if early warnings can be obtained. Also, in the case of component breakdowns, the cost of secondary replacement parts can be avoided entirely.
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29.
  • Genrup, Magnus, et al. (författare)
  • Trigeneration: Thermodynamic performance and cold expander aerodynamic design in humid air turbines
  • 2003
  • Ingår i: American Society of Mechanical Engineers, International Gas Turbine Institute, Turbo Expo (Publication) IGTI. ; 6 A, s. 1-8
  • Konferensbidrag (refereegranskat)abstract
    • Improving electrical efficiency has been proposed as the most convenient means of reducing, e.g. CO2 emission from power plants. Increasing fuel utilization through combined heat and power generation is another useful measure for emission reduction. Trigeneration technology for the production of heat, power and cooling is an interesting alternative for further improvement of fuel utilization. Previous studies at The Department of Heat and Power Engineering in Lund. Sweden, have shown that wet cycles are the best candidates, with a high potential to achieve fuel utilization higher than 100%, based on the fuel's lower heating value [1, 2, 8]. Apart from high fuel utilization, trigeneration technology can produce cooling without the use of harmful cooling agents. The basic principle of trigeneration is to interrupt the expansion at an elevated pressure level and extract heat from the working medium. The final expansion then takes place at low temperature admission levels resulting in a very low temperature at the turbine exhaust. In this paper results from both thermodynamic analysis of the humid air turbine concept in conjunction with trigeneration. and the expander design criterion required for realization of the last section of the expander are presented. The thermodynamic study gives the boundary conditions for the cold turbine design. Optimum conditions for the inlet to the cold expander are a pressure of 2 to 3 bar and a temperature of 47
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30.
  • Grönstedt, Tomas, 1970, et al. (författare)
  • Multidisciplinary assessment of a year 2035 turbofan propulsion system
  • 2022
  • Ingår i: 33rd Congress of the International Council of the Aeronautical Sciences, ICAS 2022. - : International Council of the Aeronautical Sciences. - 9781713871163 ; 7, s. 4981-4990
  • Konferensbidrag (refereegranskat)abstract
    • A conceptual design of a year 2035 turbofan is developed and integrated onto a year 2035 aircraft model. The mission performance is evaluated for CO2, noise and NOx and is compared with a notional XWB/A350-model. An OGV heat exchanger is then studied rejecting heat from an electric generator, and its top-level performance is evaluated. The fan, the booster and the low-pressure turbine of the propulsion system are subject to more detailed aero design based on using commercial design tools and CFD-optimization. Booster aerodynamic modelling output is introduced back into the performance model to study the integrated performance of the component. The top-level performance aircraft improvements are compared to top-level-trends and ICAO estimates of technology progress potential, attempting to evaluate whether there is some additional margin for efficiency improvement beyond the ICAO technology predictions for the same time frame.
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31.
  • Hildebrandt, Andre, et al. (författare)
  • Numerical investigation of the effect of different back sweep angle and exducer width on the impeller outlet flow pattern of a centrifugal compressor with vaneless diffuser
  • 2007
  • Ingår i: Journal of Turbomachinery - Transaction of the ASME. - : ASME International. - 0889-504X .- 1528-8900. ; 129:2, s. 421-433
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents a numerical investigation of the effect of different back sweep angles and exducer widths on the steady-state impeller outlet flow pattern of a centrifugal compressor with a vaneless diffuser. The investigations have been performed with commercial computational fluid dynamics (CFD) and in-house programmed one-dimensional (ID) codes. CFD calculations aim to investigate how flow pattern from the impeller is quantitatively influenced by compressor geometry parameters; thereby, the location of wake and its magnitude (flow angle and relative velocity magnitude) are analyzed. Results show that the increased back sweep impeller provides a more uniform flow pattern in terms of velocity and flow deviation angle distribution, and offers better potential for the diffusion process inside a vaneless (or vaned) diffuser Secondary flux fraction and flow deviation angle from CFD simulation are implemented into the ID two-zone program to improve ID prediction results.
  •  
32.
  • Hildebrandt, Andre, et al. (författare)
  • Numerical investigation of the effect of different back sweep angle and exducer width on the impeller outlet flow pattern of a centrifugal compressor with vaneless diffuser
  • 2006
  • Ingår i: Proceedings of the ASME Turbo Expo. - 079184241X ; 6 PART B, s. 1077-1086
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents a numerical investigation of the effect of different back sweep angles and exducer widths on the steady-state impeller outlet flow pattern of a centrifugal compressor with a vaneless diffuser. The investigations have been performed with commercial CFD and in-house programmed 1-D codes. CFD calculations aim to investigate how flow pattern from the impeller is quantitatively influenced by compressor geometry parameters; thereby, the location of wake and its magnitude (flow angle and relative velocity magnitude) are analyzed. Results show that the increased back sweep impeller provides a more uniform flow pattern in terms of velocity and flow deviation angle distribution, and offers better potential for the diffusion process inside a vaneless (or vaned) diffuser. Secondary flux fraction and flow deviation angle from CFD simulation arc implemented into the 1-D two-zone program to improve 1-D prediction results. Copyright
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33.
  • Hildebrandt, Andre, et al. (författare)
  • Steady-state and transient compressor surge behavior within a SOFC-GT-hybrid system
  • 2004
  • Ingår i: Proceedings of the ASME Turbo Expo 2004. ; 7, s. 541-550
  • Konferensbidrag (refereegranskat)abstract
    • Future pressurized Solid Oxide Fuel Cell- (SOFC) Gas Turbine Hybrid Systems (HS) promise high efficiency at both full-and part-load on account of the upper and lower SOFC temperature limit and the compressor surge line [1]. The compressor surge constraint is also evident in transient HS operation, caused by the slow transients of SOFC temperature imposed by large SOFC plenum, and fast turbo-machinery transients. This paper presents steady-state and unsteady-state HS modeling and calculation results with regard to surge. The transient compressor and SOFC models have been validated against literature. Calculation results of the coupled SOFC-GT-HS reveal a small operational window in case of unmatched turbine and the critical transient characteristics for HS shut-down.
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34.
  • Hu, Heng, et al. (författare)
  • NUMERICAL ANALYSIS OF AN AXIAL HIGH PRESSURE PARTIAL ADMISSION TURBINE
  • 2022
  • Ingår i: Turbomachinery - Axial Flow Turbine Aerodynamics; Deposition, Erosion, Fouling, and Icing; Radial Turbomachinery Aerodynamics. - 9780791886106 ; 10-B
  • Konferensbidrag (refereegranskat)abstract
    • The transformation of the energy systems will call for new turbomachinery designs for harvesting low-grade heat. The word “low-grade” has many definitions and ranges from levels where steam is the preferred selection to very low grades where specially adopted ORC technology is used. In this work, turbomachinery for cascading the steam cycle with a very low-temperature ORC technology is studied. The steam turbine being investigated here is, in principle, a highly-loaded small backpressure turbine. One indeed important feature is the trade-off between losses related to partial arc admission and losses due to having very short blades. This sets the overall architecture of the turbine and is one of the most prominent selections during the design. Due to the special working/boundary conditions, a supersonic axial turbine model and partial-arc admission were necessary. Previous open literature had shown better performance with one admitted arc. A full three-dimensional analysis of such a turbine model using CFD techniques is rather challenging. Due to the special character of the supersonic flow and the interaction of possible shocks with boundary layer flow, a fine grid is required for this application. On the other hand, due to the unsymmetrical feature of the geometry imposed by the existence of only one blocked arc, modeling of the full annulus of the turbine is unavoidable. Computations are done to assess the characteristics of the flow inside threedimensional supersonic turbine using commercial CFD codes. The unsteady loads of the rotor blades are analyzed both in time and frequency domains.
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35.
  • Jonshagen, Klas, et al. (författare)
  • A Novel Approach of Retrofitting a Combined Cycle With Post Combustion CO2 Capture
  • 2011
  • Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 133:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Most state-of-the-art natural gas-fired combined cycle (NGCC) plants are triple-pressure reheat cycles with efficiencies close to 60%. However, with carbon capture and storage, the efficiency will be penalized by almost 10% units. To limit the energy consumption for a carbon capture NGCC plant, exhaust gas recirculation (EGR) is necessary. Utilizing EGR increases the CO2 content in the gas turbine exhaust while it reduces the flue gas flow to be treated in the capture plant. Nevertheless, due to EGR, the gas turbine will experience a different media with different properties compared with the design case. This study looks into how the turbomachinery reacts to EGR. The work also discusses the potential of further improvements by utilizing pressurized water rather than extraction steam as the heat source for the CO2 stripper. The results show that the required low-pressure level should be elevated to a point close to the intermediate-pressure to achieve optimum efficiency, hence, one pressure level can be omitted. The main tool used for this study is an in-house off-design model based on fully dimensionless groups programmed in the commercially available heat and mass balance program IPSEPRO. The model is based on a GE 109FB machine with a triple-pressure reheat steam cycle. [DOI: 10.1115/1.4001988]
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36.
  • Jonshagen, Klas, et al. (författare)
  • Improved load control for a steam cycle combined heat and power plant
  • 2010
  • Ingår i: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 35:4, s. 1694-1700
  • Tidskriftsartikel (refereegranskat)abstract
    • The problem of optimum load control of steam power plants has been dealt within many technical papers during the last decades. Deregulation of the power markets and close to the (bio-) fuel source thinking has lead to a trend of small scale combined heat and power plants. These plants are usually operated according to the heat demand and therefore they spend a significant time on partial load. The load control of such plants is in general done by partial arc control. This work applies a hybrid control strategy, which is a combination of partial arc control and sliding pressure control. The method achieves further improvement in performance at partial load. Hybrid control itself is not novel and has earlier been used on traditional coal-fired condensing plants. This has, to the author's knowledge, not earlier been applied on combined heat and power plants. The results show that there is a potential for improved electricity production at a significant part of the load range. (C) 2009 Elsevier Ltd. All rights reserved.
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37.
  • Jonshagen, Klas, et al. (författare)
  • Low-Calorific Fuel Mix In A Large Size Combined Cycle Plant
  • 2009
  • Ingår i: Proceedings Of The Asme Turbo Expo 2009, Vol 1. - 9780791848821 ; , s. 367-376
  • Konferensbidrag (refereegranskat)abstract
    • This paper will address the effects of mixing low-calorific fuel in to a natural gas fuelled large size combined cycle plant. Three different biofuels are tested namely; air blown gasification gas, indirect gasification gas and digestion gas. Simulations have been performed from 0-100% biofuel natural gas mixtures. The biofuel impacts on the full cycle performance are discussed. Some more in-depth discussion about turbo-machinery components will be introduced when needed for the discussion. The compressors pressure ratio will increase in order to push the inert ballast of the low calorific fuels trough the turbine. Despite the increased expansion ratio in the gas turbine, the exhaust temperature raises slightly which derives from changed gas properties. The work is based on an in-house advanced off-design model within the software package IPSEPro. Sweden's newest plant "Oresundsverket", which is a combined heat and power (CHP) plant, is used as a basis for the Investigation. The plant is based on a GE Frame-9 gas turbine and has a triple-pressure reheat steam cycle.
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38.
  • Jonshagen, Klas, et al. (författare)
  • Optimal Combined Cycle For Co2 Capture With EGR
  • 2010
  • Ingår i: Proceedings Of The ASME Turbo Expo 2010, Volume 3: Controls, Diagnostics and Instrumentation; Cycle Innovations; Marine. - 9780791843987 ; 3, s. 867-875
  • Konferensbidrag (refereegranskat)abstract
    • Most state-of-the-art natural gas fired combined cycle (NGCC) plants are triple-pressure reheat cycles with efficiencies close to 60 percent. However, with carbon capture and storage, the efficiency will be penalized by almost 10 percent units. To limit the energy consumption for a carbon capture NGCC plant, exhaust gas recirculation (EGR) is necessary. Utilizing EGR increases the CO2 content in the gas turbine exhaust while it reduces the flue gas flow to be treated in the capture plant. Nevertheless, due to EGR, the gas turbine will experience a different: media with different properties compared to the design case. This study looks into how the turbo machinery reacts to EGR. The work also discusses the potential of further improvements by utilizing pressurized water rather than extraction steam as the heat source for the CO2 stripper. The results show that the required low-pressure level should be elevated to a point close to the intermediate-pressure to achieve optimum efficiency; hence one pressure level can be omitted. The main tool used for this study is an in-house off-design model based on fully dimensionless groups programmed in the commercially-available heat and mass balance program IPSEpro. The model is based on a GE 109FB machine with a triple-pressure reheat steam cycle.
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39.
  • Jonshagen, Klas, et al. (författare)
  • Postcombustion CO2 Capture for Combined Cycles Utilizing Hot-Water Absorbent Regeneration
  • 2012
  • Ingår i: Journal of Engineering for Gas Turbines and Power. - : ASME International. - 1528-8919 .- 0742-4795. ; 134:1, s. 143-151
  • Tidskriftsartikel (refereegranskat)abstract
    • The partly hot-water driven CO2 capture plant offers a significant potential for improvement in performance when implemented in a combined-cycle power plant (CCPP). It is possible to achieve the same performance with a dual-pressure steam cycle as in a triple-pressure unit. Even a single-pressure plant can attain an efficiency competitive with that achievable with a triple-pressure plant without the hot-water reboiler. The underlying reasons are better heat utilization in the heat recovery unit and less steam extraction to the absorbent regenerating unit(s). In this paper, the design criteria for a combined cycle power plant utilizing hot-water absorbent regeneration will be examined and presented. The results show that the most suitable plant is one with two steam pressure levels. The low-pressure level should be much higher than in a conventional combined cycle in order to increase the amount of heat available in the economizer. The external heat required in the CO2 capture plant is partly supplied by the economizer, allowing temperature optimization in the unit. The maximum value of the low-pressure level is determined by the reboiler, as too great a temperature difference is unfavorable. This work evaluates the benefits of coupling the economizer and the reboiler in a specially designed CCPP. In the CO2 separation plant both monoethanolamine (MEA) and ammonia are evaluated as absorbents. Higher regeneration temperatures can be tolerated in ammonia-based plants than in MEA-based plants. When using a liquid heat carrier the reboiler temperature is not constant on the hot side, which results in greater temperature differences. The temperature difference can be greatly reduced by dividing the regeneration process into two units operating at different pressures. The possibility of extracting more energy from the economizer to replace part of the extracted steam increases the plant efficiency. The results show that very high efficiencies can be achieved without using multiple pressure-levels. [DOI: 10.1115/1.4004146]
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40.
  • Karlsson, Christer, et al. (författare)
  • Detection and interactive isolation of faults in steam turbines to support maintenance decisions
  • 2008
  • Ingår i: Simulation Modelling Practice and Theory. - : Elsevier BV. - 1569-190X .- 1878-1462. ; 16:10, s. 1689-1703
  • Tidskriftsartikel (refereegranskat)abstract
    • The maintenance of steam turbines is expensive, particularly if dismantling is required. A concept for the provision Of Support for the maintenance engineer in determining steam turbine status in relation to the recommended maintenance interval is presented here. The concept embodies an artificial neural network which is conditioned to recognise patterns known to be related to faults. The faults Simulated are not known to be recognized on-line and the concept is in an early stage of development, An example of a Bayesian network structure containing expert knowledge is proposed to be used, in a dialogue with the operator, to isolate the root causes of a number Of fault types. The aim is to be well informed about the statue of the turbine in order to take earlier and better informed maintenance actions. The detection procedure has been validated in a Simulation environment. (C) 2008 Elsevier B.V. All rights reserved.
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41.
  • Lejon, Marcus, 1986, et al. (författare)
  • Multidisciplinary Design of a Three Stage High Speed Booster
  • 2017
  • Ingår i: ASME Turbo Expo 2017: Turbine Technical Conference and Exposition. - : ASME Press. ; 2B-2017
  • Konferensbidrag (refereegranskat)abstract
    • The paper describes a multidisciplinary conceptual design of an axial compressor, targeting a three stage, high speed, high efficiency booster with a design pressure ratio of 2.8. The paper is outlined in a step wise manner starting from basic aircraft and engine thrust requirements, establishing the definition of the high speed booster interface points and its location in the engine. Thereafter, the aerodynamic 1D/2D design is carried out using the commercial throughflow tool SC90C. A number of design aspects are described, and the steps necessary to arrive at the final design are outlined. The SC90C based design is then carried over to a CFD based conceptual design tool AxCent, in which a first profiling is carried out based on a multiple circular arc blade definition. The design obtained at this point is referred to as the VINK compressor. The first stage of the compressor is then optimized using an in-house optimization tool, where the objective functions are evaluated from detailed CFD calculations. The design is improved in terms of efficiency and in terms of meeting the design criteria put on the stage in the earlier design phases. Finally, some aeromechanical design aspects of the first stage are considered. The geometry and inlet boundary conditions of the compressor are shared with the turbomachinery community on a public server. This is intended to be used as a test case for further optimization and analysis.
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42.
  • Lundbladh, Anders, 1964, et al. (författare)
  • High Power Density Work Extraction from Turbofan Exhaust Heat
  • 2015
  • Ingår i: ISABE-2015-20101.
  • Konferensbidrag (refereegranskat)abstract
    • Integration of steam and air bottoming cycles with a conventional transport category turbofan is discussed. A conceptual design of a turbofan with a steam bottoming cycle yielded a 5% efficiency improvement for realistic component performance, but the weight eliminated in principal all gain on an aircraft level. For an air bottoming cycle simplified core cycle simulations showed the potential for up to 8% efficiency improvement. A novel Exhaust Heated Bleed engine where the bottoming cycle is integrated with a conventional turbofan turbo machinery is proposed. Simulation of this engine for take-off, climb and cruise conditions shows a 3-7% efficiency benefit. A concept for an exhaust heat exchanger and a conceptual turbine design for the Bleed Turbine to convert the exhaust heat to shaft power are illustrated.
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43.
  • Mondejar, Maria, et al. (författare)
  • Aerodynamic considerations in the thermodynamic analysis of organic Rankine cycles
  • 2014
  • Ingår i: [Host publication title missing]. ; 2, s. 002-016
  • Konferensbidrag (refereegranskat)abstract
    • Due to the increasing interest of producing power from renewable and non-conventional resources, organic Rankine cycles are finding their place in today’s thermal energy mix. The main influencers on the efficiency of an organic Rankine cycle are the working fluid and the expander. Therefore most of the research done up to date turns around the selection of the best performance working media and the optimization of the expansion unit design. However, few studies consider the interaction of the working fluids in the turbine design, and how this fact can affect the overall thermodynamic cycle analysis. In this work we aim at including the aerodynamic behavior of the working fluids and their effect on the turbine efficiency in the thermodynamic analysis of an organic Rankine cycle. To that end, we proposed a method for the estimation of the characteristics of an axial in-flow turbine in an organic Rankine cycle simulation model. The code developed for the characterization of the turbine behavior under the working fluid properties evaluated the irreversibilities associated to the aerodynamic losses in the turbine. The organic Rankine cycle was analyzed by using IPSEpro process simulator. A set of candidate working fluids composed of selected organofluorines and organochlorines was chosen for the analysis. The thermophysical properties of the fluids were estimated with the equations of state implemented in Refprop. Results on the energy and exergy overall performances of the cycle were analyzed for a case study with standard source and sink temperatures. For each fluid the number of stages and geometry of the turbine were optimized. It was observed that some working fluids that could initially be considered as advantageous from a thermodynamic point of view, had an unfavorable impact on the turbine efficiency, thus increasing the irreversibilities of the cycle. We concluded that if the influence of the working fluid on the turbine performance is underestimated, the real performance of the organic Rankine cycle could show unexpected deviations from the theoretical results.
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44.
  • Mondejar, Maria E., et al. (författare)
  • Quasi-steady state simulation of an organic Rankine cycle for waste heat recovery in a passenger vessel
  • 2017
  • Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 185:Special Issue Part 2, s. 1324-1335
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work we present the quasi-steady state simulation of a regenerative organic Rankine cycle (ORC)integrated in a passenger vessel, over a standard round trip. The study case is the M/S Birka Stockholmcruise ship, which covers a daily route between Stockholm (Sweden) and Mariehamn (Finland).Experimental data of the exhaust gas temperatures, engine loads, and electricity demand on board werelogged over a period of four weeks. These data where used as inputs for a simulation model of an ORC forwaste heat recovery of the exhaust gases. A quasi-steady state simulation was carried out on an offdesignmodel, based on optimized design conditions, to estimate the average net power production ofthe ship over a round trip. The maximum net power production of the ORC during the round trip wasestimated to supply approximately 22% of the total power demand on board. The results showed apotential for ORC as a solution for the maritime transport sector to accomplish the new and morerestrictive regulations on emissions, and to reduce the total fuel consumption.
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45.
  • Mondejar, Maria, et al. (författare)
  • Study of the on-route operation of a waste heat recovery system in a passenger vessel
  • 2015
  • Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 75, s. 1646-1653, s. 1646-1653
  • Tidskriftsartikel (refereegranskat)abstract
    • Waste heat recovery systems for power generation are gaining interest among the marine transport sector as a solution to accomplish the upcoming more restrictive regulations on emissions, and to reduce the total fuel consumption. In this paper we evaluate how a waste heat recovery system based on a regenerative organic Rankine cycle (rORC) could improve the performance of a passenger vessel. The case study is based on the M/S Birka Stockholm cruise ship, which covers a daily route between Stockholm (Sweden) and Mariehamn (Finland). Experimental data on exhaust gas temperatures, fuel consumption and electricity demand on board were logged for a period of four weeks. Based on the results of a fluid and configuration optimization performed in a previous work, an off-design model of a rORC working with benzene was used to estimate the net power production of the rORC at the different load conditions during a port-to-port trip of the vessel. The power generation curve of the rORC over time was compared to that of the electricity demand of the ship. Results showed that the rORC could provide up to 16 % of the total power demand. However, this value should be corrected if the auxiliary engines load is reduced as a consequence of the partial coverage of the electricity demand by the ORC.
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46.
  • Noor, Hina, et al. (författare)
  • INVESTIGATION OF ONE-DIMENSIONAL TURBINE DESIGN PARAMETERS WITH RELATION TO COOLING PARAMETERS FOR A HIGH PRESSURE INDUSTRIAL GAS TURBINE STAGE
  • 2011
  • Ingår i: 9TH EUROPEAN CONFERENCE ON TURBOMACHINERY. - : EUROPEAN TURBOMACHINERY SOC-EUROTURBO. ; , s. 557-568
  • Konferensbidrag (refereegranskat)abstract
    • This parametric study describes the effects of design parameters on coolant consumption and performance loss of the first stage of a high pressure industrial gas turbine. The Lund University Axial Turbine (LUAX-T) tool is employed to develop a better coupling between design parameters, cooling air and aerodynamic losses. From the performed design study; a lower stage reaction degree decreases the rotor coolant requirement, mainly due to a resulting decrease in rotor inlet temperature. However, a low reaction degree increases the cooling losses for the vane, which is because of a direct proportion between the mixing losses and the local Mach number. Based on the performed calculations and loss predictions, a range of design parameters is recommended for first stage of a gas turbine, while considering the influence of this choice on the next stage. The loss calculated for the stator blade has been calibrated against existing experimental data.
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47.
  •  
48.
  • Noor, Hina, et al. (författare)
  • Selection of one-dimensional design parameter 'reaction degree' for 1 st stage of a cooled gas turbine
  • 2012
  • Ingår i: Proc. ASME Turbo Expo. - 9780791844748 ; , s. 2345-2354
  • Konferensbidrag (refereegranskat)abstract
    • The recommendations available today in open literature for the choice of design parameter such as flow coefficient, stage loading and reaction degree incorporates mainly the influence of aerodynamics loss on efficiency. However, it is difficult to find the recommendation relating the influence of not only the aerodynamics loss but also cooling mass flow and cooling losses on varying most influential design parameters. In this paper, preliminary design and performance guidelines are presented for a cooled turbine stage using the 1D design tool LUAXT. The intention is to provide recommendations on the selection of design parameters, mainly reaction degree, which is found to be highly influenced by not only the aerodynamics loss but also the cooling mass flow and cooling loss such as in 1st stage of a High Pressure Turbines (HPT). The One-Dimensional (1D) design methods used to perform this task are verified and validated against experimental test data. A comparison of different loss models has been performed to provide most accurate outcomes for certain tested ranges. Based on the outcomes of this study, 'Craig & Cox' loss model has been considered to perform subsequent investigations for HPT design and performance estimation while formulating a parametric study. From this study, the design recommendations for the selection of performance parameter reaction degree are developed for cooled turbines. The results shows that for a HPT 1st stage, the recommended reaction degree range of 0.20 to 0.37 seems to provide the optimum stage design when chosen for stage loading in between 1.40 to 1.80 along with the stator exit flow angle in range of 74° to 78°.
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49.
  • Nyberg, Björn, et al. (författare)
  • Aerodynamic Analysis of a Humid Air Turbine Expander
  • 2012
  • Ingår i: ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. ; 3, s. 217-225
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents a reduced-order through-flow expander design for the Humid Air Turbine (HAT) also called the Evaporative Gas Turbine (EvGT). The HAT cycle is an innovative gas turbine cycle that uses humid air to enhance efficiency and power output. This means that there will be a higher water vapour content in the exhaust gases than for a simple cycle. This high water content affects the design of the HAT expander. The design of a wet expander is presented and compared with the results obtained with an expander working under dry exhaust gas conditions. The study was conducted using the reduced-order turbine design tool LUAX-T, developed at Lund University, which is freely available for academic use upon request. LUAX-T allows a flow-path analysis of the expander by specifying important flow-path parameters such as blade root stress and wall-hade angle. The HAT cycle enables cooling flow to the expander under different conditions and design differences for three different options are presented. The first cooling air bleeding point evaluated is the original position, where air is bled from the compressor discharge. The second position is just before the humidification tower, where the air has been cooled down to a low temperature. The third position is just after the humidification tower, where the air has been humidified thus changing its thermodynamic properties. Results in this paper shows that there is a need for an additional turbine stage in a humid expander compared to a dry expander. There are also results indicating that the compressor power can be reduced depending on which cooling strategy is used which can yield an increased total efficiency for a HAT cycle.
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50.
  • Orbay, Raik, et al. (författare)
  • Off-design performance investigation of a low calorific value gas fired generic type single-shaft gas turbine
  • 2007
  • Ingår i: Proceedings of the ASME Turbo Expo. ; 2, s. 733-741
  • Konferensbidrag (refereegranskat)abstract
    • When low calorific value gases are fired, the performance and stability of gas turbines may deteriorate due to a large amount of inert ballast and changes in working fluid properties. Since it is rather rare to have custom-built gas turbines for low Lower Heating Value (LHV) operation, the engine will be forced to operate outside its design envelope. This, in turn, poses limitations to usable fuel choices. Typical restraints are decrease in Wobbe-index and surge- and flutter-margins for turbomachinery. In this study, an advanced performance deck has been used to quantify the impact of firing low-LHV gases in a generic type gas turbine. A single-shaft gas turbine characterized by a compressor and an expander map is considered. Emphasis has been put on predicting the off-design behavior. The combustor is discussed and related to previous experiments which include investigation of flammability limits, Wobbe-index, flame position, etc. The computations show that at constant turbine inlet temperature (TIT), the shaft power and the pressure ratio will increase, however the surge margin will decrease. Possible design changes in the component level are also discussed. Aerodynamic issues (and necessary modifications) that can pose severe limitations on the gas turbine compressor- and turbine sections are discussed. Typical methods for axial turbine capacity adjustment are presented and discussed. Copyright © 2007 by ASME.
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