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  • 51.
    Laumert, Björn
    et al.
    KTH, Superseded Departments, Energy Technology.
    Mårtensson, H.
    Fransson, Torsten H.
    KTH, Superseded Departments, Energy Technology.
    Investigation of unsteady aerodynamic blade excitation mechanisms in a transonic turbine stage - Part II: Analytical description and quantification2002In: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 124, no 3, p. 419-428Article in journal (Refereed)
    Abstract [en]

    This paper presents a study of the blade pressure perturbation levels and the resulting blade forces in a high-pressure transonic turbine stage based on 3-D time dependent viscous computations. Globally, the blade pressure unsteadiness is quantified with the RMS of the pressure perturbations integrated in both time and along the blade surface. Operation point as well as spanwise variations are addressed. Locally, the relative strength of the pressure perturbation events on the vane and rotor blade surface is investigated. To obtain information about the relative strength of events related to the blade passing frequency and higher harmonics, the pressure field is Fourier decomposed in time at different radial positions along the blade arc-length. The amplitude peaks are then related to the pressure events in space-time maps. With the help of the observations and results from the blade pressure study, the radial variations of the unsteady blade force and torque acting on a constant span blade profile section are investigated. The connection between the first and second vane passing frequency pressure amplitudes on the rotor blade surface and the resulting force and the torque amplitudes for three selected blade modes was investigated in detail. In this investigation the pressure was integrated over defined rotor blade regions to quanti,, local force contributions. Spanwise as well as operation point variations are addressed.

  • 52.
    Laumert, Björn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mårtensson, Hans
    Volvo Aero Corporation.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aeroelasticity in Turbomachines2003Conference paper (Other academic)
  • 53.
    Laumert, Björn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mårtensson, Hans
    Volvo Aero Corporation.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Investigation of Unsteady Aerodynamic Blade Excitation Mechanism in Transonic Turbine Stages2002In: ASME paper GT-2002-30450, 2002Conference paper (Refereed)
  • 54.
    Laumert, Björn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mårtensson, Hans
    Volvo Aero Corporation.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Simulation of Rotor/Stator Interaction with a 4D Finite Volume Method2002In: ASME paper GT-2002-30601, 2002Conference paper (Refereed)
  • 55.
    Laumert, Björn
    et al.
    KTH, Superseded Departments, Energy Technology.
    Mårtensson, Hans
    Volvo Aero Corporation.
    Fransson, Torsten H.
    KTH, Superseded Departments, Energy Technology.
    Investigation of the Flowfield in the Transonic VKI Brite EURAM Turbine Stage with 3D Steady and Unsteadu N-S Computations2000In: ASME TURBO EXPO LAND SEA & AIR 2000, Munich, Germany, 2000, 2000Conference paper (Refereed)
  • 56.
    Laumert, Björn
    et al.
    Volvo Aero.
    Pettersson, Anders
    Volvo Aero.
    Östensen, Rosmarie
    Volvo Aero.
    The Vinci and TPX Turbine Demonstrator Programs: Latest Advances for the Next Generation European Launcher Engines2008Conference paper (Other academic)
  • 57.
    Mårtensson, Hans
    et al.
    Volvo Aero Corporation.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aeromechanical Aspects on Unsteady Flow in Turbines2003Conference paper (Refereed)
  • 58.
    Payaro, Albert
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Naik, Ankit Anurag
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Identification of Required Cost Reductions for CSP to Retain Its Competitive Advantage as Most Economically Viable Solar-Dispatchable Technology2018In: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS (SOLARPACES 2017) / [ed] Mancilla, R Richter, C, AMER INST PHYSICS , 2018, article id 040028-1Conference paper (Refereed)
    Abstract [en]

    The present study evaluates and compares the optimum configurations for both PV-batteries and molten salt tower concentrating solar power plants that minimize the levelized cost of electricity for a suitable location for deployment of both solar technologies nearby Ouarzazate, Morocco, when considering two capacity factor objectives, namely 50% and 85%, and cost-projections for 2020 and 2030. Required target cost reduction rates for each of the main blocks in the tower plant (i.e. the solar field, the storage and the power block) are identified for guaranteeing its competitive advantage as the most economically viable solar-only technology at both capacity factor objectives investigated. It is shown that the larger the capacity factor requirement is, the more competitive the solar thermal technology would be. Specifically, the case-study shows that for an 85% capacity factor objective, tower plants would be more competitive even when considering the most pessimistic and optimistic cost projections for the solar thermal and PV-batteries sub-components, respectively. Nevertheless, it was also determined that in order to ensure being the most competitive solar-only technology at a 50% capacity factor objective by 2030, the costs of the solar field of the solar tower plants should reach values as low as 20-50 (sic)/m(2), depending on the scenario, which means approximately a three to seven fold decrease of the costs as of 2017. At last, recommendations to solar thermal technology owners and developers are provided, and a short discussion regarding the viability and limitations of using battery electric storage systems for utility-scale solar plants is presented.

  • 59.
    Ragnolo, Gianmarco
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Strand, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Technoeconomic Design of a Micro Gas-Turbine for a Solar Dish System2014In: Proceedings of the International SolarPACES Conference 2014. Beijing, China. September 16-19, Elsevier, 2014Conference paper (Refereed)
    Abstract [en]

    An integrated approach for the design of a custom-tailored hybrid solar MGT with an integrated solar receiver for the use in a small-scale solar dish unit is presented in order to overcome the inherent limitations of adapting a MGT in the desired power range to solar operation. The resulting MGT-dish equipped with the ‘optimal’ MGT shows a nominal conversion efficiency of 29.6%. Then, a thermoeconomic analysis of the entire system is performed to evaluate and compare the economic and environmental performance of the MGT-dish with a Dish-Stirling system. From an economical point of view the MGT-dish outperforms the dish-Stirling with LCoEs as low as 15.3€cts/kWhel compared to 22.4€cts/kWhel.

  • 60.
    Saha, Ranjan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mamaev, Boris
    Siemens LLC Energy Oil & Gas Design Department, Russia.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Influence of Prehistory and Leading Edge Contouring on Aero Performance of a Three-Dimensional Nozzle Guide Vane2014In: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 136, no 7, p. 071014-1-071014-10Article in journal (Refereed)
    Abstract [en]

    Experiments are conducted to investigate the effect of the prehistory in the aerodynamic performance of a three-dimensional nozzle guide vane with a hub leading edge contouring. The performance is determined with two pneumatic probes (five hole and three hole) concentrating mainly on the end wall. The investigated vane is a geometrically similar gas turbine vane for the first stage with a reference exit Mach number of 0.9. Results are compared for the baseline and filleted cases for a wide range of operating exit Mach numbers from 0.5 to 0.9. The presented data includes loading distributions, loss distributions, fields of exit flow angles, velocity vector, and vorticity contour, as well as mass-averaged loss coefficients. The results show an insignificant influence of the leading edge fillet on the performance of the vane. However, the prehistory (inlet condition) affects significantly in the secondary loss. Additionally, an oil visualization technique yields information about the streamlines on the solid vane surface, which allows identifying the locations of secondary flow vortices, stagnation line, and saddle point.

  • 61.
    Saha, Ranjan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mamaev, Boris
    Siemens LLC Energy Oil & Gas Design Department, Rusia.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Influence of pre-history and leading edge contouring on aero-performance of a 3D nozzle guide vane2013In: Proceedings of the ASME Gas Turbine India Conference -2013- ; presented at ASME 2013 Gas Turbine India Conference, December 5-6, 2013, Bangalore, India, ASME Press, 2013Conference paper (Refereed)
    Abstract [en]

    Experiments are conducted to investigate the effect of the pre-history in the aerodynamic performance of a threedimensional nozzle guide vane with a hub leading edge contouring. The performance is determined with two pneumatic probes (5 hole and 3 hole) concentrating mainly on the endwall. The investigated vane is a geometrically similar gas turbine vane for the first stage with a reference exit Mach number of 0.9. Results are compared for the baseline and filleted cases for a wide range of operating exit Mach numbers from 0.5 to 0.9. The presented data includes loading distributions, loss distributions, fields of exit flow angles, velocity vector and vorticity contour, as well as, mass-averaged loss coefficients. The results show an insignificant influence of the leading edge fillet on the performance of the vane. However, the pre-history (inlet condition) affects significantly in the secondary loss. Additionally, an oil visualization technique yields information about the streamlines on the solid vane surface which allows identifying the locations of secondary flow vortices, stagnation line and saddle point.

  • 62.
    Sandoz, Raphael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Air-Based Bottoming-Cycles for Water-Free Hybrid Solar Gas-Turbine Power Plants2013In: Proceedings of the ASME TurboExpo 2013, 2013Conference paper (Refereed)
    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-off 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.

  • 63.
    Sandoz, Raphael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Air-Based Bottoming-Cycles for Water-Free Hybrid Solar Gas-Turbine Power Plants2013In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 135, no 10, p. 101701-Article in journal (Refereed)
    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.

  • 64. Spelling, J.
    et al.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermoeconomic evaluation of solar thermal and photovoltaic hybridization options for combined-cycle power plants2014In: Proceedings of the ASME Turbo Expo, ASME Press, 2014Conference paper (Refereed)
    Abstract [en]

    The hybridization of combined-cycle power plants with solar energy is an attractive means of reducing carbon dioxide 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 thermoeconomic study has been performed for three different hybrid power plant configurations, including both solar thermal and photovoltaic hybridization options. Solar photovoltaic combined-cycle power plants were shown to be able to integrate up to 63 % solar energy on an annual basis, whereas hybrid gas-turbine combined-cycle 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 configuration has been shown to be economically unattractive. Copyright

  • 65.
    Spelling, James
    et al.
    IMDEA Energy Institute, High Temperature Processes Unit, Móstoles, Spain.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermoeconomic Evaluation of a Novel Utility-Scale Hybrid Solar Dish Micro Gas-Turbine Power Plant2015In: Proceedings of the ASME Turbo Expo 2015. Montreal, Canada. June 15-19, ASME Press, 2015Conference paper (Refereed)
    Abstract [en]

    A novel solar power plant concept is presented, based on the use of a coupled network of hybrid solar-dish micro gas-turbines, driving a centralized heat recovery steam generator and steam-cycle, thereby seeking to combine the high collector efficiency of the solar dish with the high conversion efficiency of a combined-cycle power block. To explore the potential of the concept, its performance has been compared against a more conventional solar dish farm based on recuperated micro gas-turbines. Multi-objective optimization has been used to identify Pareto-optimal designs and examine the trade-offs between minimizing capital costs and maximizing performance. The micro gas-turbine combined-cycle layout has been shown to be promising for utility-scale applications, reducing electricity costs by 5–10%, depending on the degree of solar integration; this novel power plant layout also reduces emissions through increased conversion efficiency of the power block. However, at smaller plant sizes (outputs below 18 MWe), more traditional recuperated solar dish farms remain the most viable option.

  • 66.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guedez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Thermo-Economic Study of Storage Integration in Hybrid Solar Gas-Turbine Power Plants2015In: Journal of solar energy engineering, ISSN 0199-6231, E-ISSN 1528-8986, Vol. 137, no 1Article in journal (Refereed)
    Abstract [en]

    A thermo-economic simulation model of a hybrid solar gas-turbine (HSGT) power plant with an integrated storage unit has been developed, allowing determination of the thermodynamic and economic performance. Designs were based around two representative industrial gas-turbines: a high efficiency machine and a low temperature machine. In order to examine the trade-offs that must be made, multi-objective thermo-economic analysis was performed, with two conflicting objectives: minimum investment costs and minimum specific carbon dioxide (CO2) emissions. It was shown that with the integration of storage, annual solar shares above 85% can be achieved by HSGT systems. The levelized electricity cost (LEC) for the gas-turbine system as this level of solar integration was similar to that of parabolic trough plants, allowing them to compete directly in the solar power market. At the same time, the water consumption of the gas-turbine system is significantly lower than contemporary steam-cycle based solar thermal power plants.

  • 67.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guedez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    The Value of Storage in Hybrid Solar Gas-Turbine Power Plants2012In: Proceedings of the International SolarPACES Conference 2012, Marrakesh, 2012Conference paper (Refereed)
    Abstract [en]

    A thermoeconomic simulation model of a hybrid solar gas-turbine power plant with an integrated storage unit has been developed, allowing determination of the thermodynamic and economic performance. Designs were based around two representative industrial gas-turbines: a high efficiency machine and a low temperature machine. In order to examine the trade-offs that must be made, multi-objective thermo-economic analysis was performed, with two conflicting objectives: minimum investment costs and minimum specific CO2 emissions. It was shown that with the integration of storage, annual solar shares above 85% can be achieved by hybrid solar gas-turbine systems. The levelised electricity cost for the gas-turbine system as this level of solar integration was similar to that of parabolic trough plants, allowing them to compete directly in the solar power market. At the same time, the water consumption of the gas-turbine system is significantly lower than contemporary steam-cycle based solar thermal power plants.

  • 68.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermo-economic evaluation of solar thermal and photovoltaic hybridization options for combined-cycle power plants2015In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, no 3, p. 031801-Article in journal (Refereed)
    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.

  • 69.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Comparative Thermoeconomic Study of Hybrid Solar Gas-Turbine Power Plants2013In: Proceedings of the ASME Turbo Expo, 2013Conference paper (Refereed)
    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 as well as 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 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.

  • 70.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Comparative Thermoeconomic Study of Hybrid Solar Gas-Turbine Power Plants2014In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 136, no 1, p. 011801-Article in journal (Refereed)
    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.

  • 71.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Thermoeconomic Study of Low-Temperature Intercooled-Recuperated Cycles for Pure-Solar Gas-Turbine Applications2012In: Journal of solar energy engineering, ISSN 0199-6231, E-ISSN 1528-8986, Vol. 134, no 4, p. 041015-Article in journal (Refereed)
    Abstract [en]

    A dynamic model of a megawatt-scale low-temperature intercooled-recuperated solar gas-turbine power plant has been developed in order to allow determination of the thermodynamic and economic performance. The model was then used for multi-objective thermoeconomic optimization of both the power plant performance and cost, using a population-based algorithm. In order to examine the trade-offs that must be made and identify optimal' plant sizes and operating conditions, two conflicting objectives were considered, namely minimum investment costs and maximum annual electricity production. Levelized electricity costs from a 65 MWe power plant operating at 950°C are predicted to be below 130 USD/MWhe, competitive with other solar thermal power technologies. Optimal plant sizes and configurations have been identified.

  • 72.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Advanced Hybrid Solar Tower Combined-Cycle Power Plants2014In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 49, p. 1207-1217Article in journal (Refereed)
    Abstract [en]

    Hybrid solar gas-turbine technology is a promising alternative to conventional solar thermal power plants. In order to increase the economic viability of the technology, advanced power plant concepts can be envisioned, with the integration of thermal energy storage and combined-cycle power blocks. In order to pinpoint the most promising configurations, 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. Advanced solar hybrid combined-cycle power plants provide a 60% reduction in electricity costs compared to parabolic trough power plants. Furthermore, a 22% reduction in costs and a 32% reduction in CO2 emissions are achieved relative to a combination of parabolic trough and combined-cycle power plants.

  • 73.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Optimal Gas-Turbine Design For Hybrid Solar Power Plant Operation2012In: Proceedings of the ASME Turbo Expo 2012, Vol 6, ASME Press, 2012, p. 249-259Conference paper (Refereed)
    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 MW, 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.

  • 74.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Optimal Gas-Turbine Design for Hybrid Solar Power Plant Operation2012In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 134, no 9Article in journal (Refereed)
    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.

  • 75.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Russ, Matthias
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Thermoeconomic Study of Hybrid Solar Gas-Turbine Power Plants2011In: Proceedings of the International SolarPACES Conference 2011, Granada, 2011Conference paper (Refereed)
    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. Designs were based around two representative gas-turbines: a high efficiency machine and a low temperature machine. In order to examine the trade-offs that must be made, multi-objective thermo-economic analysis was performed, with two conflicting objectives: minimum investment costs and minimum specific CO2 emissions. At current fuel prices, gas-turbine solarisation was shown to result in only a small increase in levelised electricity costs at moderate solar shares. In the future, with higher fuel prices and carbon taxes, it was shown that electricity from hybrid solar gas-turbines could be cheaper than from fossil-only gas-turbines.

  • 76.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Russ, Matthias
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Thermoeconomic Study of Low-Temperature Intercooled-Recuperated Cycles for Pure-Solar Gas-Turbine Applications2011In: Proceedings of the International SolarPACES Conference 2011, Granada, 2011Conference paper (Refereed)
    Abstract [en]

    A dynamic model of a megawatt-scale low-temperature intercooled-recuperated solar gas-turbine power plant has been developed in order to allow determination of the thermodynamic and economic performance. The model was then used for multi-objective thermo-economic optimisation of both the power plant performance and cost, using a population-based algorithm. In order to examine the trade-offs that must be made and identify ‘optimal’ plant sizes and operating conditions, two conflicting objectives were considered, namely minimum investment costs and maximum annual electricity production. Levelised electricity costs from a 50 – 60 MWe power plant are predicted to be below 150 USD/MWhe, competitive with other solar thermal power technologies, and optimal plant sizes and configurations have been identified.

  • 77.
    Strand, Torsten
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    On the Significance of Concentrated Solar Power R&D in Sweden2011In: Proceedings of the World Renewable Energy Congress 2011, Linköping, 2011Conference paper (Refereed)
    Abstract [en]

    Concentrated Solar Power (CSP) is an emerging renewable energy technology that has the potential to provide a major part of European energy needs at competitive cost levels. Swedish industry is strongly involved in CSP-based energy production either in the form of growing providers on the European energy market or as developers and producers of key components for CSP power plants. The growing industrial interest is reflected and accompanied by state of the art research in this field at the Department of Energy Technology at KTH. In the present paper the main challenges and opportunities for CSP R&D are presented and linked to the industrial environment and interests in Sweden. Related to these challenges, an overview of the latest research activities and results at the Department of Energy Technology is given with examples concerning CSP plant operation and optimisation, techno- economic cycle studies and high temperature solar receiver development.

  • 78.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ellakany, Farid
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guedez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Genrup, Magnus
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermo-Economic Study on the Implementation of Steam Turbine Concepts for Flexible Operation on a Direct Steam Generation Solar Tower Power Plant2016In: SOLARPACES 2015: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, American Institute of Physics (AIP), 2016, article id 060005Conference paper (Refereed)
    Abstract [en]

    Among concentrating solar power technologies, direct steam generation solar tower power plants represent a promising option. These systems eliminate the usage of heat transfer fluids allowing for the power block to be run at greater operating temperatures and therefore further increasing the thermal efficiency of the power cycle. On the other hand, the current state of the art of these systems does not comprise thermal energy storage as there are no currently available and techno-economically feasible storage integration options. This situation makes direct steam generation configurations even more susceptible to the already existing variability of operating conditions due to the fluctuation of the solar supply. In the interest of improving the annual performance and competitiveness of direct steam generation solar tower systems, the present study examines the influence of implementing two flexibility enhancing concepts which control the steam flow to the turbine as a function of the incoming solar irradiation. The proposed concepts were implemented in a reference plant model previously developed by the authors. Then, a multi-objective optimization was carried out in order to understand which configurations of the steam turbine concepts yield reductions of the levelized cost of electricity at a lower investment costs when compared to the reference model. Results show that the implementation of the proposed strategies can enhance the thermo-economic performance of direct steam generation systems by yielding a reduction of up to 9.2% on the levelized cost of electricity, mainly due to allowing 20% increase in the capacity factor, while increasing the investment costs by 7.8%.

  • 79.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ferruzza, D.
    Seeger, F.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Analysis of plant performance with improved turbine flexibility: Test case on a parabolic trough configuration2018In: AIP Conference Proceedings, American Institute of Physics Inc. , 2018Conference paper (Refereed)
    Abstract [en]

    Parabolic trough configurations account for 95% of the current installed concentrating solar power (CSP) capacity. Certainly this technology is considered as the most mature among other CSP types. However, regardless of its maturity, the pursuit of cost competitiveness with respect to fossil fuels and other renewables is still a dire need. One way to maximize profitability and improve performance is flexibility through fast starts. In this regard, the steam turbine has been identified as a key limiting component to the start-up process. This work focuses on analyzing the influence of steam turbine start-up parameters on the overall annual performance of a CSP plant. For this, a detailed parabolic trough power plant (PTPP) performance model was developed including a control strategy to account for turbine transient start-up constraints. The PTPP model was developed in accordance to the latest state-of-the-art of the technology. As such, the first part of the results consisted of validation studies of the model with respect to the actual power plant. The results obtained in this regard showed that the model correlates to the rated performance of the power plant with maximum errors of 12% and of 14% to the dynamic operation of the power plant. The second part of this work consisted of using the validated model in a series of sensitivity studies concerning the variation of different turbine start-up parameters. Results showed that improvements of up to 1.8% in the annual electricity production are possible with only 0.3% increase in fuel consumption.

  • 80.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Genrup, Magnus
    Lund University.
    Jöcker, Markus
    Siemens Industrial Turbomachinery.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Operational Improvements for Start-up Time Reduction in solar Steam Turbines2014In: PROCEEDINGS OF THE ASME TURBO EXPO: Paper No. GT2014-27065 Volume05C, New York: ASME , 2014Conference paper (Refereed)
    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 lifing 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 temperatures and showed significant improvements on the start-up times of the turbine.

  • 81.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Genrup, Magnus
    Lund University.
    Jöcker, Markus
    Siemens Industrial Turbomachinery.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Operational Improvements for Startup Time Reduction in Solar Steam Turbines2015In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, no 4, article id 042604Article in journal (Refereed)
    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.

  • 82.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guedez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Impact of Increasing Steam Turbine Flexibility on the Annual Performance of a Direct Steam Generation Tower Power Plant2014In: Energi Procedia, Beijing, 2014, Vol. 69, p. 1171-1180Conference paper (Refereed)
    Abstract [en]

    Among concentrating solar power technologies, solar tower power plants currently represent one of the most promising ones. Compared to parabolic trough configurations, tower systems enable considerable efficiency gains as higher concentration ratios can be achieved. Direct steam generation systems, in particular, eliminate the usage of heat transfer fluids allowing for the power block to be run at greater operating temperatures and therefore further increasing the thermal efficiency of the power cycle. On the other hand, the current state of the art of these systems does not comprise thermal energy storage. Although it has been shown that the integration of storage potentially enhances the economic viability and profitability of the plants, there are no currently available and techno-economically feasible storage integration options for the case of direct steam generation towers.

    The lack of storage adds to the already existing variability of operating conditions that all concentrating power plants endure due to the fluctuating nature of the solar supply. This situation is more prominent for the case of direct steam generation systems; leading up to multiple start-ups during a 24h period if the weather conditions are not optimal. In the interest of improving the annual performance and competitiveness of direct steam generation concentrating solar power plants, it is desirable for the plant to achieve fast start-up times to harness the solar energy as soon as possible. The start-up speed of the whole plant is limited by the thermal inertia of certain key components, one of which is the steam turbine.

    This paper studies the potential for power plant performance improvement through the increase of steam turbine flexibility at the time of start-up. The methodology consisted of performing sensitivity studies on the annual operation of a power plant while considering different scenarios of turbine operational modifications. For each study, the corresponding power plant performance indicators were evaluated and compared to the base case without modifications. It is shown that gains of up to 7% in total power plant electric output and reductions in turbine maintenance periods can be achieved as a result of the implemented operational improvements. 

  • 83.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Jöcker, M.
    Paul, S.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Differential expansion sensitivity studies during steam turbine start-up2015In: Proceedings of the ASME Turbo Expo, ASME Press, 2015, Vol. 8Conference paper (Refereed)
    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 start-up 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 thermo mechanical properties. Then, the range of applicability of the model was validated by a two-fold comparison with a higher order finite element 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 inter-casing 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 towards further understanding the differential expansion during start and establishing future clearance control strategies during turbine transient operation.

  • 84.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Jöcker, M.
    Paul, S.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Differential Expansion Sensitivity Studies during Steam Turbine Startup2015In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 6, article id GTP-15-1419Article in journal (Refereed)
    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.

  • 85.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Improving concentrating solar power plant performance by increasing steam turbine flexibility at start-up2018In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 165, p. 10-18Article in journal (Refereed)
    Abstract [en]

    Among concentrating solar power technologies, solar tower power plants currently represent one of the most promising ones. Direct steam generation systems, in particular, eliminate the usage of heat transfer fluids allowing for the power block to be run at greater operating temperatures and therefore further increasing the thermal efficiency of the power cycle. On the other hand, the current state of the art of these systems does not comprise thermal energy storage. The lack of storage adds to the already existing variability of operating conditions that all concentrating power plants endure due to the fluctuating nature of the solar supply. One way of improving this situation is increasing the operating flexibility of power block components to better adapt to the varying levels of solar irradiance. In particular, it is desirable for the plant to achieve fast start-up times in order to be available to harness as much solar energy as possible. However, the start-up speed of the whole plant is limited by the thermal inertia of certain key components, one of which is the steam turbine. This paper studies the potential for power plant performance improvement through the increase of steam turbine flexibility at the time of start-up. This has been quantified by carrying out power plant techno-economic studies in connection with steam turbine thermo-mechanic behavior analysis. Different turbine flexibility investigations involving the use of retrofitting measures to keep the turbine warmer during offline periods or changing the operating map of the turbine have been tested through multi-objective optimization considering annual power performance and operating costs. Results show that reductions of up to 11% on the levelized cost of electricity are possible through the implementation of these measures.

  • 86.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Improving Concentrating Solar Power Plant Performance by Increasing Steam Turbine Flexibility at Start-up2017In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257Article in journal (Refereed)
    Abstract [en]

    Among concentrating solar power technologies, solar tower power plants currentlyrepresent one of the most promising ones. Direct steam generationsystems, in particular, eliminate the usage of heat transfer uids allowing forthe power block to be run at greater operating temperatures and thereforefurther increasing the thermal eciency of the power cycle. On the otherhand, the current state of the art of these systems does not comprise thermalenergy storage. The lack of storage adds to the already existing variability ofoperating conditions that all concentrating power plants endure due to theuctuating nature of the solar supply. One way of improving this situationis increasing the operating exibility of power block components to betteradapt to the varying levels of solar irradiance.In particular, it is desirable for the plant to achieve fast start-up times inorder to be available to harness as much solar energy as possible. However,the start-up speed of the whole plant is limited by the thermal inertia ofcertain key components, one of which is the steam turbine. This paperstudies the potential for power plant performance improvement through theincrease of steam turbine exibility at the time of start-up. This has beenquantied by carrying out power plant techno-economic studies in connectionwith steam turbine thermo-mechanic behavior analysis. Dierent turbineexibility investigations involving the use of retrotting measures to keep theturbine warmer during oine periods or changing the operating map of the turbine have been tested through multi-objective optimization consideringannual power performance and operating costs. Results show that reductionsof up to 11% on the levelized cost of electricity are possible through theimplementation of these measures, which in turn has a favorable impact onpower plant protability.

  • 87.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Nilsson, Asa
    Jocker, Markus
    INVESTIGATION INTO THE THERMAL LIMITATIONS OF STEAM TURBINES DURING START-UP OPERATION2017In: PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2017, VOL 8, AMER SOC MECHANICAL ENGINEERS , 2017Conference paper (Refereed)
    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.

  • 88.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Lundqvist, Mårten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Haglind, F.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Towards prioritizing flexibility in the design and construction of concentrating solar power plants2017In: SOLARPACES 2016: International Conference on Concentrating Solar Power and Chemical Energy Systems, American Institute of Physics (AIP), 2017, article id 060005Conference paper (Refereed)
    Abstract [en]

    In the operation and maintenance of concentrating solar power plants, high operational flexibility is required in order to withstand the variability from the inherent solar fluctuations. However, during the development phases of a solar thermal plant, this important objective is overlooked as a relevant factor for cost reduction in the long term. This paper will show the value of including flexibility aspects in the design of a concentrating solar power plant by breaking down their potential favorable impact on the levelized cost of electricity (LCOE) calculations. For this, three scenarios to include flexibility as a design objective are analyzed and their potential impact on the LCOE is quantified. The scenarios were modeled and analyzed using a techno-economic model of a direct steam generation solar tower power plant. Sensitivity studies were carried out for each scenario, in which the level of improvement due to each scenario was compared to the base case. Then, the results obtained for each scenario were compared for similar levels of LCOE and flexibility improvements. In general, all scenarios were beneficial on power plant performance. Improvements on the LCOE in the range of 3-4% were obtained with different distributions of costs and annual electricity for each case.

  • 89.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Nilsson, Åsa
    Jöcker, Markus
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Investigation into the Thermal Limitations of Steam Turbines During Start-up Operation2017In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919Article in journal (Refereed)
    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.

  • 90.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Jöcker, Markus
    Siemens Industrial Turbomachinery.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Geometric Modularity in the Thermal Modeling of Solar Steam Turbines2014In: Proceedings of the SolarPACES 2013 International Conference, Elsevier, 2014, Vol. 49, p. 1737-1746Conference paper (Refereed)
    Abstract [en]

    To optimize the start-up schedules of steam turbines operating in concentrating solar power plants, accurate predictions of the temperatures within the turbine are required. In previous work by the authors, thermal models of steam turbines have been developed and validated for parabolic trough solar power plant applications. Building on these results, there is an interest to increase the adaptability of the models with respect to different turbine geometries due to the growing trend of having larger steam turbines in parabolic trough and solar tower power plants. In this work, a modular geometric approach has been developed and compared against both the previous modeling approach and 96h of measured data from an operational parabolic trough power plant. Results show a large degree of agreement with respect to the measured data in spite of the different detail levels. The new model allows for simple and fast prediction of the thermal behavior of different steam turbine sizes and geometries, which is expected to be of significant importance for future concentrating solar power plants.

  • 91.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Vitrano, Andrea
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Utilization of a thermo-mechanical model coupled with multi-objective optimization to enhance the start-up process of solar steam turbines2018In: Proceedings of the ASME Turbo Expo, ASME Press, 2018, Vol. 8Conference paper (Refereed)
    Abstract [en]

    The need to mitigate the climate change has brought in the last years to a fast rise of renewable technologies. The inherent fluctuations of the solar resource make concentrating solar power technologies an application that demands full flexibility of the steam turbine component. A key aspect of this sought steam turbine flexibility is the capability for fast starts, in order to harvest the solar energy as soon as it is available. However, turbine start-up time is constrained by the risk of low cycle fatigue damage due to thermal stress, which may bring the machine to failure. Given that the thermal limitations related to fatigue are temperature dependent, a transient thermal analysis of the steam turbine during start process is thus necessary in order to improve the start-up operation. This work focuses on the calculation of turbine thermomechanical properties and the optimization of different start-up cases in order to identify the best solution in terms of guaranteeing reliable and fast start-ups. In order to achieve this, a finite element thermal model of a turbine installed in a concentrating solar power plant was developed and validated against measured data. Results showed relative errors of temperature evolutions below 2%, making valid the assumptions and simplifications made. Since there is trade-off between start-up speed and turbine lifetime consumption, the model was then implemented within a multi-objective optimization scheme in order to test and design faster start-ups while ensuring safe operation of the machine. Significant improvements came up in terms of start-up time reduction up to 30% less than the standard start-up process.

  • 92.
    Trevisan, Silvia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Bouzekri, H.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Initial design of a radial-flow high temperature thermal energy storage concept for air-driven CSP systems2019In: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, Vol. 2126, article id 200031Conference paper (Refereed)
    Abstract [en]

    The present work deals with the initial design and performance evaluation of a novel thermal energy storage concept consisting of a packed bed of rocks with a radial gas flow, suitable for the a generation of air-driven concentrating solar power plants. In doing so, this article also presents a state of the art of most promising packed bed concepts, highlighting their advantages and disadvantages, all considered in the design of the new proposed system. A thermomechanical model of the concept was developed and used in simulations to assess its behavior during both charging and discharging processes, as well as to evaluate the influence of critical design parameters. This same model was used to compare the technical performance of the concept against that of more conventional packed-beds with axial-flow. Results show that the novel concept is able to outperform the other systems by enabling a theoretical reduction of 46% and 50% in radiation losses and pressure drops, respectively, thus calling for future investigations, including an in-depth thermos-mechanical study and life-cycle analysis of the concept prior to building a lab-scale prototype.

  • 93.
    Trevisan, Silvia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Preliminary assessment of integration of a packed bed thermal energy storage in a Stirling - CSP system2019In: SolarPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems, American Institute of Physics (AIP), 2019, Vol. 2126, article id 200032Conference paper (Refereed)
    Abstract [en]

    The present work deals with the thermodynamic analysis of four different integration schemes for a packed bed thermal energy storage in a Stirling - CSP system. Simplified models for the different systems' configurations have been developed and analyzed in steady and transient working conditions. Particularly, a parallel and serial connection between the power and the storage unit have been compared, showing a trade-off between the contemporaneity of power production and storage and the usefulness of the storage itself accordingly to the working temperature constraints for the power unit. It is shown that a closed parallel system configuration is the most promising solution as it allows for a longer production during night time and an higher net energy production, it is therefore worth of further investigations.

  • 94.
    Trollheden, Stefan
    et al.
    Volvo Aero.
    Laumert, Björn
    Volvo Aero.
    Brodin, Staffan
    Volvo Aero.
    Pettersson, Anders
    Volvo Aero.
    Turbine Technologies for Future Cryogenic ELV Engines2006In: AIAA 57th International Astronautical Congress, IAC 2006, 2006, p. 6157-6167Conference paper (Refereed)
    Abstract [en]

    Volvo Aero has developed the turbines for the Hydrogen and Oxygen turbopumps for the Vulcain and Vulcain 2 engines used for Ariane 5. For the new European upper stage engine, Vinci, Volvo Aero has maintained the same responsibility for the turbines as during the Vulcain development. In Europe there are presently a number of technology programs to prepare and mature new technologies, for example the Vinci demo and the Vulcain X program. This paper presents the effort at Volvo Aero to prepare the turbine technology for the next cryogenic ELV engines. The requirements on engine, turbopump and turbines will be described. Potential new concepts which meet the new requirements will be discussed for GG and Expander cycle engines. Also the need for new method development to increase the accuracy of turbine behavior as well as decreasing development risks will be presented. Furthermore a demonstration program for a new generation turbine for the Hydrogen Turbopump, TPX, will be presented and also the Vinci demo program.

  • 95.
    Wang, Wujun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Development of a Fresnel lens based high-flux solar simulator2017In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 144, p. 436-444Article in journal (Refereed)
    Abstract [en]

    In this paper, a Fresnel lens based high flux solar simulator (HFSS) is developed for concentrating solar power research and high temperature material testing. In this design, each commercially available 7 kW(e) xenon-arc lamp is coupled with a silicone-on-glass Fresnel lenses as the optical concentrator, and 12 lamp-lens units are distributed in a circular array. In total, the power of the solar simulator can reach 84 kWe. A ray tracing model has been developed based on the real arc-emitter shape and the Fresnel lens optics for predicting the optical performance of the HFSS design. The testing result shows that the ray tracing model can predict the flux distribution on the focal plane accurately but a bit conservative in the center region. The flux distribution on the focal plane appears axisymmetric with a peak flux of 7.22 MW/m(2), and 19.7 kW of radiative power in total is delivered on a 280 mm diameter target. (C) 2017 Elsevier Ltd. All rights reserved.

  • 96.
    Wang, Wujun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Design and Validation of a Low-cost High-flux Solar Simulator using Fresnel Lens Concentrators2013In: Proceedings of the SolarPACES 2013 International Conference, Elsevier, 2013, p. 2221-2230Conference paper (Refereed)
    Abstract [en]

    A systematic design procedure for a high flux solar simulator is presented in this paper. The 84 kWe solar simulator is based on an array of 12 commercially available xenon-arc lamps (each 7 kWe) coupled with silicone-on-glass Fresnel lenses as the optical concentrator. A ray-tracing model of the xenon lamp has been developed based on the real emitter shape and the Fresnel lens optics; simulations performed using a non-sequential Monte Carlo technique have been validated against experimental test data. The results show that 19.7 kW of radiative power is delivered on a 20 cm diameter target with and a peak flux of 6.73 MW/m2 and an electricity to radiative power efficiency of 23.4%. This research facility will be used as an experimental platform for high flux solar receiver and thermochemical reactor research, as well as for advanced high-temperature material testing.

  • 97.
    Wang, Wujun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Bo, Wang
    Li, Lifeng
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Strand, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    The effect of nozzle arrangement to the thermal performance of impinging receiverManuscript (preprint) (Other academic)
  • 98. Wang, Wujun
    et al.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    An axial type impinging receiver2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 162, p. 318-334Article in journal (Refereed)
    Abstract [en]

    An axial type impinging receiver has been developed for a solar dish-Brayton system. By using selective reflection cavity surfaces as a secondary concentrator, the solar irradiation is reflected and concentrated on a cylindrical absorber that is located in the center of the cavity. A modified inverse design method was applied for quickly finding possible cavity receiver designs, and a numerical conjugate heat transfer model combined with a ray-tracing model was utilized for studying the detailed performance of the impinging receivers. The ray-tracing results show that the flux distribution on the cavity and absorber surfaces can be efficiently adjusted to meet the design requirements by changing the absorber diameter, the cavity diameter, the cavity length and the offset length. A candidate receiver design was selected for detailed numerical studies, and the results show that the average outlet air temperature and the radiative-to-thermal efficiency can reach 801.1 °C and 82.8% at a DNI level of 800 W/m2. The temperature differences on the absorber can be controlled within 122.7 °C for DNI level of 800 W/m2, and 126.4 °C for DNI level of 1000 W/m2. Furthermore, the structure is much simpler than a typical radial impinging design. 

  • 99.
    Wang, Wujun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Effect of cavity surface material on the concentrated solar flux distribution for an impinging receiver2017In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 161, p. 177-182Article in journal (Refereed)
    Abstract [en]

    In this paper, the effects of cavity surface materials on the radiative flux distribution of solar cavity receivers have been studied with the help of a ray-tracing methodology. Three metallic substrate materials (Inconel 600, austenitic stainless steel 253 MA and Kanthal APM) and two coating materials (Pyromark® 2500 coating and YSZ TBC coating) were selected as the candidate cavity surface materials. The results show that the flux distribution and the total optical efficiency are much more sensitive to the absorptivity on the cylindrical surface than on the bottom. By using high absorptivity coating on the cylindrical surface and low absorptivity coating on the bottom, the radiative flux on the bottom can be controlled at a low level, and it can help to reduce the cavity length for an impinging receiver with jets on the cylindrical surface. Furthermore, the radiative flux distribution on the cylindrical surface can also be tailored to meet various design requirements by applying different coating designs on the cylindrical surface.

  • 100.
    Wang, Wujun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Simulate a ‘Sun’ for Solar Research: A Literature Review of Solar Simulator Technology2014Report (Other academic)
    Abstract [en]

    The solar simulator is the key facility for indoor research of solar PV cells, solar heat collectors, space craft and CSP systems. This paper classifies the four types of solar simulators based on their characteristics and their design objects: space solar simulator, standard PV cell testing solar simulator, collector testing solar simulator and high-flux solar simulator. The review of solar simulator developments is mainly based on the developments of light sources and optical concentrators. The light source is the most important component for a solar simulator design; carbon arc lamp, metal halide arc lamp, quartz tungsten halogen lamp, xenon arc lamp, mercury xenon lamp, argon arc lamp and light-emitting diode lamp (LED) are used to be chosen as the light sources to meet the various requirements for the design objects. The optical concentrator is another key component; ellipsoidal reflector, compound parabolic concentrator (CPC), light cone, hyperboloid concentrator, parabolic dish concentrator and Fresnel lens are also reviewed in this paper. Finally, the near future developments of these four type solar simulators are discussed based on the requirements of research and the available technology of light sources and optical concentrators.

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