Ändra sökning
Avgränsa sökresultatet
1234 151 - 196 av 196
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 151.
    Siddique, Waseem
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    El-Gabry, Lamyaa A.
    Shevchuk, Igor V.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Validation and analysis of numerical results for a two-pass trapezoidal channel with different cooling configurations of trailing edge2012Ingår i: Proceedings of the ASME Turbo Expo 2011, Vol 5, Parts A And B, American Society Of Mechanical Engineers , 2012, s. 1571-1581Konferensbidrag (Refereegranskat)
    Abstract [en]

    High inlet temperatures in a gas turbine lead to an increase in the thermal efficiency of the gas turbine. This results in the requirement of cooling of gas turbine blades/vanes. Internal cooling of the gas turbine blade/vanes with the help of two-pass channels is one of the effective methods to reduce the metal temperatures. Especially the trailing edge of a turbine vane is a critical area, where effective cooling is required. The trailing edge can be modeled as a trapezoidal channel. This paper describes the numerical validation of the heat transfer and pressure drop in a trapezoidal channel with and without orthogonal ribs at the bottom surface. A new concept of ribbed trailing edge has been introduced in this paper which presents a numerical study of several trailing edge cooling configurations based on the placement of ribs at different walls. The baseline geometries are two-pass trapezoidal channels with and without orthogonal ribs at the bottom surface of the channel. Ribs induce secondary flow which results in enhancement of heat transfer therefore for enhancement of heat transfer at the trailing edge, ribs are placed at the trailing edge surface in three different configurations: first without ribs at the bottom surface, then ribs at trailing edge surface in-line with the ribs at bottom surface and finally staggered ribs. Heat transfer and pressure drop is calculated at Reynolds number equal to 9400 for all configurations. Different turbulent models are used for the validation of the numerical results. For the smooth channel low-Re kappa-epsilon model, realizable kappa-epsilon model, the RNG kappa-omega model, low-Re kappa-omega model and SST kappa-omega models are compared, whereas for ribbed channel low-Re kappa-omega model and SST kappa-omega models are compared. The results show that the low-Re k-epsilon model, which predicts the heat transfer in outlet pass of the smooth channels with difference of +7%, underpredicts the heat transfer by -17% in case of ribbed channel compared to experimental data. Using the same turbulence model shows that the height of ribs used in the study is not suitable for inducing secondary flow. Also, the orthogonal rib does not strengthen the secondary flow rotational momentum. The comparison between the new designs for trailing edge shows that if pressure drop is acceptable, staggered arrangement is suitable for the outlet pass heat transfer. For the trailing edge wall, the thermal performancefor ribbed trailing edge only, was found about 8% better than other configurations.

  • 152.
    Siddique, Waseem
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    El-Gabry, Lamyaa
    American University in Cairo, Egypt.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Design of internally cooled trailing edge at engine similar conditions- A conjugate heat transfer problem2012Ingår i: ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, ASME Press, 2012, s. 1357-1372Konferensbidrag (Refereegranskat)
    Abstract [en]

    Gas turbines are operated at elevated temperatures as the thermal efficiency of the gas turbine is directly linked to the turbine inlet gas temperature. The different regions of the turbine blade require different means of cooling. This paper presents different designs of the two-pass trapezoidal channel which represents the trailing edge of a real engine. Engine similar boundary conditions are applied and conjugate heat transfer method is used to predict the wall temperatures. The aim is to design a cooling channel that through use of steam can reduce wall temperatures to below a target value while maintaining minimal pressure drop. The variations in design of a smooth two-pass channel were made to achieve the design target. These variations included installation of ribs at the walls, tapered divider wall, tilted divider wall and L-shaped divider wall to promote fluid impingement on the trailing wall. The results suggest that a channel with staggered ribs at the outlet pass, a tilted divider wall and impingement at the corner is the best arrangement for reducing wall temperatures below the target value; however, it has low overall aerothermal performance due to high pressure losses. A similar channel without impingement can yield acceptable results if a thermal barrier coating is applied or if a small corner of the tip-trailing edge is truncated to reduce material volume. This modification though can improve the thermal performance of the channel, is to result in higher profile and aerodynamics losses.

  • 153.
    Siddique, Waseem
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    El-Gabry, Lamyaa
    American University in Cairo, Egypt.
    Shevchuk, Igor
    MBtech Group GmbH & Co. KGaA, Germany..
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Validation and Analysis of Numerical Results for a Two-Pass Trapezoidal Channel With Different Cooling Configurations of Trailing Edge2012Ingår i: Journal of turbomachinery, ISSN 0889-504X, E-ISSN 1528-8900, Vol. 135, nr 1, s. 011027-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High inlet temperatures in a gas turbine lead to an increase in the thermal efficiency of the gas turbine. This results in the requirement of cooling of gas turbine blades/vanes. Internal cooling of the gas turbine blade/vanes with the help of two-pass channels is one of the effective methods to reduce the metal temperatures. In particular, the trailing edge of a turbine vane is a critical area, where effective cooling is required. The trailing edge can be modeled as a trapezoidal channel. This paper describes the numerical validation of the heat transfer and pressure drop in a trapezoidal channel with and without orthogonal ribs at the bottom surface. A new concept of ribbed trailing edge has been introduced in this paper which presents a numerical study of several trailing edge cooling configurations based on the placement of ribs at different walls. The baseline geometries are two-pass trapezoidal channels with and without orthogonal ribs at the bottom surface of the channel. Ribs induce secondary flow which results in enhancement of heat transfer; therefore, for enhancement of heat transfer at the trailing edge, ribs are placed at the trailing edge surface in three different configurations: first without ribs at the bottom surface, then ribs at the trailing edge surface in-line with the ribs at the bottom surface, and finally staggered ribs. Heat transfer and pressure drop is calculated at Reynolds number equal to 9400 for all configurations. Different turbulent models are used for the validation of the numerical results. For the smooth channel low-Re k-e model, realizable k-e model, the RNG k-ω model, low-Re k-ω model, and SST k-ω models are compared, whereas for ribbed channel, low-Re k-e model and SST k-ω models are compared. The results show that the low-Re k-e model, which predicts the heat transfer in outlet pass of the smooth channels with difference of +7%, underpredicts the heat transfer by -17% in case of ribbed channel compared to experimental data. Using the same turbulence model shows that the height of ribs used in the study is not suitable for inducing secondary flow. Also, the orthogonal rib does not strengthen the secondary flow rotational momentum. The comparison between the new designs for trailing edge shows that if pressure drop is acceptable, staggered arrangement is suitable for the outlet pass heat transfer. For the trailing edge wall, the thermal performance for the ribbed trailing edge only was found about 8% better than other configurations.

  • 154.
    Siddique, Waseem
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    El-Gabry, Lamyaa
    American University in Cairo; Egypt.
    Shevchuk, Igor
    MBtech Group GmbH & Co. Germany.
    Hushmandi, Narmin B.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Flow structure, heat transfer and pressure drop in varying aspect ratio two-pass rectangular smooth channels2012Ingår i: Heat and Mass Transfer, ISSN 0947-7411, E-ISSN 1432-1181, Vol. 48, nr 5, s. 735-748Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two-pass channels are used for internal cooling in a number of engineering systems e.g., gas turbines. Fluid travelling through the curved path, experiences pressure and centrifugal forces, that result in pressure driven secondary motion. This motion helps in moving the cold high momentum fluid from the channel core to the side walls and plays a significant role in the heat transfer in the channel bend and outlet pass. The present study investigates using Computational Fluid Dynamics (CFD), the flow structure, heat transfer enhancement and pressure drop in a smooth channel with varying aspect ratio channel at different divider-to-tip wall distances. Numerical simulations are performed in two-pass smooth channel with aspect ratio W-in/H = 1:3 at inlet pass and W-out/H = 1:1 at outlet pass for a variety of divider-to-tip wall distances. The results show that with a decrease in aspect ratio of inlet pass of the channel, pressure loss decreases. The divider-to-tip wall distance (W-el) not only influences the pressure drop, but also the heat transfer enhancement at the bend and outlet pass. With an increase in the divider-to-tip wall distance, the areas of enhanced heat transfer shifts from side walls of outlet pass towards the inlet pass. To compromise between heat transfer and pressure drop in the channel, W-el/H = 0.88 is found to be optimum for the channel under study.

  • 155.
    Siddique, Waseem
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    El-Gabry, Lamyaa A.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Improved Design of Internally Cooled Trailing Edge at Engine Similar Conditions: A Conjugate Heat Transfer Problem2012Ingår i: Proceedings of the Asme Turbo Expo, NEW YORK: AMER SOC MECHANICAL ENGINEERS , 2012, s. 1357-1372Konferensbidrag (Refereegranskat)
    Abstract [en]

    Gas turbines are operated at elevated temperatures as the thermal efficiency of the gas turbine is directly linked to the turbine inlet gas temperature. The different regions of the turbine blade require different means of cooling. This paper presents different designs of the two-pass trapezoidal channel which represents the trailing edge of a real engine. Engine similar boundary conditions are applied and conjugate heat transfer method is used to predict the wall temperatures. The aim is to design a cooling channel that through use of steam can reduce wall temperatures to below a target value while maintaining minimal pressure drop. The variations in design of a smooth two-pass channel were made to achieve the design target. These variations included installation of ribs at the walls, tapered divider wall, tilted divider wall and L-shaped divider wall to promote fluid impingement on the trailing wall. The results suggest that a channel with staggered ribs at the outlet pass, a tilted divider wall and impingement at the corner is the best arrangement for reducing wall temperatures below the target value; however, it has low overall aerothermal performance due to high pressure losses. A similar channel without impingement can yield acceptable results if a thermal barrier coating is applied or if a small corner of the tip-trailing edge is truncated to reduce material volume. This modification though can improve the thermal performance of the channel, is to result in higher profile and aerodynamics losses.

  • 156.
    Siddique, Waseem
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Shevchuk, Igor
    MBtech Group GmbH & Co. KGaA, Germany..
    El-Gabry, Lamyaa
    American University in Cairo, Egypt.
    Hushmandi, Narmin B.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    On flow structure, heat transfer and pressure drop in varying aspect ratio two-pass rectangular channel with ribs at 45 degrees2013Ingår i: Heat and Mass Transfer, ISSN 0947-7411, E-ISSN 1432-1181, Vol. 49, nr 5, s. 679-694Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To increase the thermal efficiency of gas turbines, inlet temperature of gas is increased. This results in the requirement of cooling of gas turbine blades and vanes. Internal cooling of gas turbine blades and vanes is one of several options. Two-pass channels are provided with ribs to enhance heat transfer at the expense of an increased pressure drop. The space in the blade is limited and requires channels with small aspect ratios. Numerical simulations have been performed to investigate heat transfer, flow field and pressure loss in a two-pass channel equipped with 45A degrees ribs with aspect ratio (W-in/H) equal to 1:3 in the inlet pass and 1:1 in the outlet pass with both connected together with a 180A degrees bend. The results are compared with a higher aspect ratio channel (W-in/H = 1:2, inlet pass). In the ribbed channel, a decrease in pressure drop was observed with a decrease in the aspect ratio of the channel. The smaller aspect ratio channel not only allows using more cooling channels in the blade, but also results in more heat transfer enhancement. The divider-to-tip wall distance (W-el) has influence on the pressure drop, as well as on the heat transfer enhancement at the bend and outlet pass. Heat transfer decreases with decrease in aspect ratio of the inlet pass of the two-pass channel. With increase in divider-to-tip wall distance, heat transfer tries to attain a constant value.

  • 157.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    A Comparative Thermoeconomic Study of Hybrid Solar Gas-Turbine Power Plants2013Ingår i: Proceedings of the ASME Turbo Expo, 2013Konferensbidrag (Refereegranskat)
    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.

  • 158.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    A Comparative Thermoeconomic Study of Hybrid Solar Gas-Turbine Power Plants2014Ingår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 136, nr 1, s. 011801-Artikel i tidskrift (Refereegranskat)
    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.

  • 159.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    A Thermoeconomic Study of Low-Temperature Intercooled-Recuperated Cycles for Pure-Solar Gas-Turbine Applications2012Ingår i: Journal of solar energy engineering, ISSN 0199-6231, E-ISSN 1528-8986, Vol. 134, nr 4, s. 041015-Artikel i tidskrift (Refereegranskat)
    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.

  • 160.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Advanced Hybrid Solar Tower Combined-Cycle Power Plants2014Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 49, s. 1207-1217Artikel i tidskrift (Refereegranskat)
    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.

  • 161.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Optimal Gas-Turbine Design For Hybrid Solar Power Plant Operation2012Ingår i: Proceedings of the ASME Turbo Expo 2012, Vol 6, ASME Press, 2012, s. 249-259Konferensbidrag (Refereegranskat)
    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.

  • 162.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Optimal Gas-Turbine Design for Hybrid Solar Power Plant Operation2012Ingår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 134, nr 9Artikel i tidskrift (Refereegranskat)
    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.

  • 163.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Russ, Matthias
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    A Thermoeconomic Study of Hybrid Solar Gas-Turbine Power Plants2011Ingår i: Proceedings of the International SolarPACES Conference 2011, Granada, 2011Konferensbidrag (Refereegranskat)
    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.

  • 164.
    Spelling, James
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Russ, Matthias
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    A Thermoeconomic Study of Low-Temperature Intercooled-Recuperated Cycles for Pure-Solar Gas-Turbine Applications2011Ingår i: Proceedings of the International SolarPACES Conference 2011, Granada, 2011Konferensbidrag (Refereegranskat)
    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.

  • 165.
    Strand, Torsten
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    On the Significance of Concentrated Solar Power R&D in Sweden2011Ingår i: Proceedings of the World Renewable Energy Congress 2011, Linköping, 2011Konferensbidrag (Refereegranskat)
    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.

  • 166.
    Tomyak, Roman
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Kazachkov, Ivan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Case study tool as interactive learning material in computerized educational system2010Konferensbidrag (Övrigt vetenskapligt)
  • 167.
    Tomyak, Roman
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Kazachkov, Ivan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Case study tools in the multimedia interactive teaching-learning platform for energy technology2010Ingår i: Applied computer science, 9789604742257, 2010, s. 156-162Konferensbidrag (Refereegranskat)
    Abstract [en]

    The tools called case study are normally presented in the computerized educational (CompEdu) platform as short pages with popups giving precise short introduction into some narrow subject. The CompEdu is based on the multimedia interactive presentation of a slide show of lecturing material in a non-conventional way where the material is presented in a progressive and concise way ensuring the coverage of large portions of material in shortest number of pages. In this paper, some recent results in the development of case studies by different subjects with emphasize of the new combustion systems are presented and discussed. Also some methodological aspects and features are discussed concerning their advantages for intensive and easy (pleasant) form of teaching-learning using computerized system developed at EGI/KTH.

  • 168.
    Udomsri, Seksan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Martin, Andrew
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Municipal Solid Waste Management and Waste to Energy Alternatives in Thailand2005Ingår i: International Conference on Engineering for Waste Treatment (WasteEng05), 2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Rapid expansion of industry, urbanization and increasing population, especially in large cities likeBangkok, has dramatically increased the amount of municipal solid waste (MSW) generated inThailand. However, issues related to sound municipal solid waste management – including recycling programs, waste reduction, and disposal – have not been addressed adequately. Landfilling is currently the most popular form of waste disposal for some 14 million tons of waste annually, although the majority of facilities do not employ modern techniques like landfill gas recovery. It is clear that there is a pressing need to develop and deploy new alternatives in order to minimize the environmental impacts at all links in the municipal solid waste chain. Waste to energy facilities can play a key role in ensuring a swift and economically viable shift to improved municipal solid waste management inThailandand other areas ofAsia. In addition, positive environmental benefits can be achieved in parallel (i.e. reduction of greenhouse gas emissions via minimizing open dumping and expansion of a biomass-based electricity production method). The objective of this work is to investigate municipal solid waste management and electric power production through incineration of municipal solid waste inThailand. This paper contains a survey of current municipal solid waste management practices along with the current energy situation inThailand. The energy recovery potential of municipal solid waste is analyzed by investigating various types of incineration technologies. In particular hybrid dual-fuel cycles, which integrate municipal solid waste and high-quality fuels like natural gas in an innovative fashion, are considered to be promising solutions. Results show that there is significant potential for environmental and waste management improvements via municipal solid waste incineration.

  • 169.
    Udomsri, Seksan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Martin, Andrew
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Possibilities for Municipal Solid Waste Incineration and Gas Turbine Hybrid Dual-Fueled Cycles in Thailand2006Ingår i: A and WM, Annual International Conference on Incineration and Thermal Treatment Technologies, IT3, 2006, s. 11-24Konferensbidrag (Refereegranskat)
    Abstract [en]

    The energy sector is one of the most sensitive base industries inThailandsince almost half of the total energy supply relies on imported sources. Of these, fossil fuels currently dominate electricity production. Exploring underutilized fuels like municipal solid waste (MSW) are vital towards securing a sustainable energy supply while minimizing greenhouse gas emissions. Moreover, a shift from MSW landfilling to incineration, if done with proper environmental controls, can also have positive benefits. This paper investigates the opportunities and potential for new MSW power plants with a focus on theBangkokregion, which produces up to 5 million tons of MSW per year. The energy recovery potential from MSW is analyzed by investigating various types of incineration technologies. In particular hybrid dual-fuel cycles, which integrate MSW and high-quality fuels like natural gas in an innovative fashion, are considered to be promising solutions. Study of plant performance in terms of efficiency and natural gas consumption from different power plant configurations are analyzed. An economic evaluation has been performed in this work to demonstrate the economic impact of the systems under consideration. Preliminary results show that MSW incineration has the potential to cover 8% ofThailand’s electricity; this amount is sufficient to meet the growth of national electrical consumption during a seven year span. InBangkokonly, power production via conventional incineration of MSW can achieve up to 2 TWh of electricity per year and this amount can be increased up to 3 TWh/yr if hybrid power plants employing integrated natural gas-fired topping cycles are employed. The maximum electrical efficiency increased by up to nearly 5% points for all hybrid cycles with natural gas to MSW fuel ratios of 0.3-0.4 NG. All proposed cycles (conventional and hybrid) are economically viable. The economic evaluation results also reveal that hybrid dual-fueled cycles are more economically acceptable compared to other alternatives.

  • 170.
    Udomsri, Seksan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Martin, Andrew
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Possibilities for Various Energy Applications from Municipal Solid Waste Incineration in Bangkok and Hanoi: Combined Heat, Cooling and Power Generation (CHCP) in Southeast Asia2008Ingår i: Proceedings of i-CIPEC2008 - 5th International Conference on Combustion, Incineration/Pyrolysis and Emission Control, 2008, s. 103-109Konferensbidrag (Refereegranskat)
    Abstract [en]

    Increasingly intensive efforts are underway for employing renewable energy resources, especially when oil prices are unpredictable like today. Southeast Asia, which features large populations and expansive economies, already has a high energy demand and will grow even more in the future. Biomass is an important renewable energy source in this region, and Municipal Solid Waste (MSW) is an excellent candidate in this context. With industrialization, there has been an increase in the amount of MSW, particularly in large cities like Bangkok and Hanoi. While the need for a complete sustainable energy solution is crucial, solid waste management is also critical for these cities. Energy recovery from flue gases in thermal treatment plants is an integral part of MSW management for many industrialized nations. Often cogeneration can be employed for both enhancing the plant profitability and increasing the overall energy yield. However, it is normally difficult to justify traditional cogeneration in tropical locations since there is little need for the heat produced. The implementation of heat-driven cooling processes like absorption chillers is extremely attractive in this setting. In this paper, the energy applications from MSW in tropical urban areas have been investigated. Also investigated are the opportunities and potentials for various types of MSW power plants for providing both electricity and cooling in an innovative fashion. Results show that there is significant potential for various energy applications i.e. electricity, heatingand cooling from MSW in Southeast Asia. For example, electricity production via conventional incineration of MSW can achieve up to 2TWh per year in Bangkok and nearly this same amount in Hanoi. For heat-driven cooling, absorption chillers provide significant potential to replace electrically driven cooling: such systems are capable of providing 77 MWcooling and 22 MWel from CHP plant using MSW incineration. Heat driven chillers are also capable of reducing the fuel consumption per unit of cooling in comparison with conventional cooling technology: absorption chillers consume 0.78 MWfuel/MWcooling while distributed compression chillersconsume 2.06 MWfuel/MWcooling. If an MSW power plant coupled with heat- driven cooling is to be implemented, the system can save 118 MW of NG (60 MW of electricity) from thermal power plant.

  • 171.
    Udomsri, Seksan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Martin, Andrew
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Waste-to-Energy Alternative and Sustainable Energy Development in Thailand2006Ingår i: 2006 Thai-Europe Technology Transfer Conference, Ministry of Science and Technology and Office of Science and Technology, 2006Konferensbidrag (Refereegranskat)
  • 172.
    Udomsri, Seksan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Martin, Andrew
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Frostell, Björn
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi (flyttat 20130630).
    The Role of Municipal Solid Waste Incineration for Greenhouse Gas Mitigation in Southeast Asia2008Ingår i: Proceedings of SIDA Conference and Workshop in Uppsala: Meeting Global Challenges in Research Cooperation / [ed] Ingrid Karlsson, Kristina Röing de Nowina, 2008, s. 84-85Konferensbidrag (Övrigt vetenskapligt)
  • 173.
    Udomsri, Seksan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Martin, Andrew
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Frostell, Björn
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi (flyttat 20130630).
    The Role of Municipal Solid Waste Incineration for Greenhouse Gas Mitigation: Towards Sustainable Energy Systems in Southeast Asia2008Ingår i: Proceedings of SIDA Conference and Workshop in Uppsala - Meeting Global Challenges in Research Cooperation / [ed] Ingrid Karlsson and Kristina Röing de Nowina, 2008, s. 60-67Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an evaluation of the potential of municipal solid waste incinerationfor greenhouse gas mitigation and promotion of biomass-based electricity productionin a more sustainable direction in Southeast Asia. Beyond political and environmentalpressures, renewable energy sources are inherently attractive and have become a globalconcern. Resource constraints and rapid growth in world energy demand have alreadybrought oil prices over record levels. Developing countries – especially in high economicgrowth regions of Southeast Asia – often have strained resources and suffer as a result.Enhanced energy security and renewable energy development is high on the publicagenda in Thailand and other countries in Asia. Biomass and municipal solid waste(MSW) have widely been accepted as important renewable energy sources because theymay be used as carbon dioxide (CO2) mitigation concepts. Solid waste management hasbecome a crucial issue in Southeast Asia since the most popular form for waste disposalstill employs open dumping. The overall objective of this investigation is to promotesound MSW management practices including waste-to-energy (WTE) recovery, as wellas to promote an expansion of biomass-based electricity. The energy recovery potentialof MSW is analyzed by investigating various types of incineration technologies. Bothconventional and more advanced hybrid dual-fuel cycles are considered to evaluate cycleperformance (electrical efficiency), CO2 emission and economic aspects. Results show that there is significant potential for environmental and waste management improvements viaMSW incineration. In Bangkok only, power production via hybrid power plants employingintegrated natural gas-fired topping cycles can achieve up to 4 TWh and 10 TWhin 2008 and 2030, respectively. The reduction of CO2 emissions is even more attractivewhen hybrid dual-fuel cycles are combined. CO2 reductions of 670 and 1,800 thousandtons, respectively, can be met in comparison with current thermal power plants. Hybriddual-fuel cycle is somewhat more attractive as it has quite short payback period (5 years)in terms of economy comparison.

  • 174.
    Udomsri, Seksan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Martin, Andrew R.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Economic assessment and energy model scenarios of municipal solid waste incineration and gas turbine hybrid dual-fueled cycles in Thailand2010Ingår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 30, nr 7, s. 1414-1422Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Finding environmentally benign methods related to sound municipal solid waste (MSW) management is of highest priority in Southeast Asia. It is very important to study new approaches which can reduce waste generation and simultaneously enhance energy recovery. One concrete example of particular significance is the concept of hybrid dual-fuel power plants featuring MSW and another high-quality fuel like natural gas. The hybrid dual-fuel cycles provide significantly higher electrical efficiencies than a composite of separate single-fuel power plant (standalone gas turbine combined cycle and MSW incineration). Although hybrid versions are of great importance for energy conversion from MSW, an economic assessment of these systems must be addressed for a realistic appraisal of these technologies. This paper aims to further examine an economic assessment and energy model analysis of different conversion technologies. Energy models are developed to further refine the expected potential of MSW incineration with regards to energy recovery and environmental issues. Results show that MSW incineration can play role for greenhouse gas reduction, energy recovery and waste management. In Bangkok, the electric power production via conventional incineration and hybrid power plants can cover 2.5% and 8% of total electricity consumption, respectively. The hybrid power plants have a relative short payback period (5 years) and can further reduce the CO2 levels by 3% in comparison with current thermal power plants.

  • 175.
    Udomsri, Seksan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Petrov, Miroslav P.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Martin, Andrew R.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Clean energy conversion from municipal solid waste and climate change mitigation in Thailand: Waste management and thermodynamic evaluation2011Ingår i: Energy for Sustainable Development, ISSN 0973-0826, Vol. 15, nr 4, s. 355-364Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Enhanced energy security and renewable energy development are currently high on the public agenda in Southeast Asia, which features large populations and expansive economies. Biomass and Municipal Solid Waste (MSW) have widely been accepted as important locally-available renewable energy sources and represent one of the largest renewable energy sources worldwide. This article presents an evaluation of the potential of MSW incineration for climate change mitigation and promotion of biomass-based electricity production in a more sustainable direction in Thailand. The energy recovery potential of MSW is analyzed by investigating various types of incineration technologies. Both conventional technologies and more advanced hybrid dual-fuel cycles (which combine MSW and natural gas fuels) are considered in analyses covering cycle performance and CO(2) emissions. Results show that MSW incineration has the ability to lessen environmental impact associated with waste disposal, and it can contribute positively towards expanding biomass-based energy production in Thailand. Hybrid cycles can be proposed to improve system performance and overall electrical efficiency of conventional incineration. The hybrid cycle featuring parallel interconnection is somewhat more attractive in terms of efficiency improvement: electrical efficiency increases by 4% and CO(2) emission levels are reduced by 5-10% as compared to the reference incineration case. The reduction of greenhouse gas emissions is even more attractive when methane gas emitted fro m existing landfill sites is to be compared.

  • 176.
    Vogt, Damian
    et al.
    KTH, Tidigare Institutioner, Energiteknik.
    Fransson, Torsten
    KTH, Tidigare Institutioner, Energiteknik.
    A Technique for Using Recessed-Mounted Pressure Transducers to Measure Unsteady Pressure2004Konferensbidrag (Refereegranskat)
  • 177.
    Vogt, Damian
    et al.
    KTH, Tidigare Institutioner, Energiteknik.
    Fransson, Torsten
    KTH, Tidigare Institutioner, Energiteknik.
    Effect of Blade Mode Shape on the Aeroelastic Stability of a LPT Cascade2004Konferensbidrag (Refereegranskat)
  • 178.
    Vogt, Damian
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Turbomachinery Aeroelasticity Analyses: Everyday Business or Exceptional Challenge?2011Konferensbidrag (Refereegranskat)
  • 179.
    Vogt, Damian
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fridh, Jens
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    CHARACTERIZATION AND FIRST APPLICATION OF A THIN-FILM ELECTRET UNSTEADY PRESSURE MEASUREMENT TECHNIQUE2008Ingår i: XIX Biannual Symposium on Measuring Techniques in Turbomachinery: Transonic and Supersonic Flow in Cascades and Turbomachines, Brussels: Von Karman Institute for Fluid Dynamics , 2008, s. 1-5Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    A new thin-film electret unsteady pressure measurement technique for application in turbomachine aerodynamical experiments is under investigation. The technique is based on a layered sensor comprising a permanently polarized foil in the center. Changes in foil thickness due to variation in pressure result in a potential difference, which is used as measurement signal. The investigated technique presents a cost attractive alternative for unsteady pressure measurement instrumentation. Low signal levels however put severe requirements to acquisition and the treatment of the signals, especially when reducing the sensor area. First measurements have been performed with a 2.5x2.5mm sensor. The signals have been correlated to Kulite data and good agreement has been found. A characterization of the technique as well a description of the first tests in relevant flow is presented in the paper.

  • 180.
    Vogt, Damian
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fridh, Jens
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Design and Construction of a New Modular Wind Tunnel System2006Konferensbidrag (Refereegranskat)
  • 181.
    Vogt, Damian
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Glodic, Nenad
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    The Effect of Unsteady Aerodynamic Asymmetric Perturbations on the Mode Shape Sensitivity of an Oscillating LPT Cascade2009Konferensbidrag (Refereegranskat)
  • 182.
    Vogt, Damian M.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Experimental investigation of mode shape sensitivity of an oscillating low-pressure turbine cascade at design and off-design conditions2007Ingår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 129, nr 2, s. 530-541Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 183.
    Vogt, Damian M.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Experimental investigation of mode shape sensitivity of an oscillating LPT cascade at design and off-design conditions2006Ingår i: Proceedings of the ASME Turbo Expo 2006, Vol 5, Pts A and B, 2006, s. 1151-1163Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 184.
    Vogt, Damian M.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten H.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Podcasting the whiteboard: - A new way of teaching engineers2012Ingår i: ASME Turbo Expo 2012: Turbine Technical Conference and Exposition: Volume 3: Cycle Innovations; Education; Electric Power; Fans and Blowers; Industrial and Cogeneration, ASME Press, 2012, s. 525-536Konferensbidrag (Refereegranskat)
    Abstract [en]

    The education of engineers largely relies on traditional classroom teaching in which a teacher instructs a subject using a variety of techniques ranging from the traditional blackboard (nowadays also whiteboard), over overhead to computer-based presentations. In order to deepen knowledge and get hands-on experience, students are often given practical exercises or case studies to perform, be it individually or in group in the form of a seminar. It is experienced that black-(or white) board based lectures are having an advantage over overheads / slide shows as knowledge is built up instantaneously at a natural pace rather than confronting students with pages of prepared material. The present paper presents a new technique herein referred to as "podcasted whiteboard lectures" in which lectures are given in a traditional lecture hall setup but with having the teacher lecturing by means of an electronic whiteboard. A key advantage of this technique is that it can be recorded and made available to students afterwards, which is here done using podcasting. It is experienced that the technique is very efficient for maximizing the students' learning experience as one is given the possibility to follow a subject ubiquitous and at preferred pace. Another advantage is that animations and simulations can be integrated right into the lecture and into the same medium used for lecturing. The technique is thereby equally applicable to campus as well as distance-based teaching.

  • 185.
    Vogt, Damian
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mårtensson, H
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Direct Calculation of Aerodynamic Influence Coefficients Using a Commercial CFD Solver2007Konferensbidrag (Refereegranskat)
  • 186.
    Vogt, Damian
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mårtensson, H.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Experimental and Numerical Study of Unsteady Aerodynamics in an Oscillating Low-Pressure Turbine Cascade of Annular Sector Shape2006Konferensbidrag (Refereegranskat)
  • 187.
    Vogt, Damian
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mårtensson, H.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Validation of a Three-Dimensional Flutter Prediction Tool2005Konferensbidrag (Refereegranskat)
  • 188. Wang, K.
    et al.
    Wang, S.
    Guo, X.
    Luo, Z.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Comparison of pyrolysis characteristics of degreased and synthesized Mongolian Pine2010Ingår i: 2nd International Symposium on Aqua Science, Water Resource and Low Carbon Energy, American Institute of Physics (AIP), 2010, s. 221-224Konferensbidrag (Refereegranskat)
    Abstract [en]

    In order to study the influence of components' cross-interaction on biomass pyrolysis, research of degreased and synthesized Mongolian Pine (MP) was performed on a thermogravimetric analyzer coupled with a Fourier transform infrared spectroscopy (TG-FTIR) and the fast pyrolysis device. Compared with synthesized MP, the thermal behavior of degreased MP is much closer to the original and the degreased MP produces less aldehydes, alcohols or phenols and acids due to the cross-interactions of components. Synthesized MP has lower bio-oil yield and higher gas production than the degreased one. And the contents of furfural, acetic acid and levoglucosan change with the kind of samples obviously due to the intense cross-interactions of components.

  • 189. Wang, Shurong
    et al.
    Liu, Qian
    Wang, Kaige
    Guo, Xiujuan
    Luo, Zhongyang
    Cen, Kefa
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Study on Catalytic Pyrolysis of Manchurian Ash for Production of Bio-Oil2010Ingår i: International Journal of Green Energy, ISSN 1543-5075, E-ISSN 1543-5083, Vol. 7, nr 3, s. 300-309Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pyrolysis of Manchurian ash (Fraxinus mandshurica Rupr.) sawdust with four zeolite molecular sieve catalysts was performed on a thermogravimetric analyzer coupled with a Fourier transform infrared spectrometer. Pyrolysis of pure Manchurian ash and three main components, viz. cellulose, xylan, lignin, was also carried out as reference. The four zeolite catalysts investigated in this study (viz. HZSM-5, H-, USY and Na-Y) all catalyze the dehydration reaction, restrain the release of volatiles, and obviously promote the final residue yields. Y-type catalysts show the most evident catalytic effect, such as restraining the formation of aldehydes, acids, and ethers, and promoting that of isoalkanes and aromatics. The preferred catalyst should have both high activity for deoxygenating and selectivity for hydrocarbon production.

  • 190. Wang, Shurong
    et al.
    Wang, Kaige
    Liu, Qian
    Gu, Yueling
    Luo, Zhongyang
    Cen, Kefa
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Comparison of the pyrolysis behavior of lignins from different tree species2009Ingår i: Biotechnology Advances, ISSN 0734-9750, E-ISSN 1873-1899, Vol. 27, nr 5, s. 562-567Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the increasing importance of biomass pyrolysis. little is known about the pyrolysis behavior of lignin-one of the main components of biomass-due to its structural complexity and the difficulty in its isolation. In the present study, we extracted lignins from Manchurian ash (Fraxinus mandschurica) and Mongolian Scots pine (Pinus sylvestris var. mongolica) using the Bjorkman procedure, which has little effect on the structure of lignin. Fourier transform infrared (FTIR) spectrometry was used to characterize the microstructure of the Bjorkman lignins, i.e., milled wood lignins (MWLs), from the different tree species. The pyrolysis characteristics of MWLs were investigated using a thermogravimetric analyzer, and the release of the main volatile and gaseous products of pyrolysis were detected by FTIR spectroscopy. During the pyrolysis process, MWLs underwent thermodegradation over a wide temperature range. Manchurian ash MWL showed a much higher thermal degradation rate than Mongolian Scots pine MWL in the temperature range from 290-430 degrees C. High residue yields were achieved at 37 wt.% for Mongolian Scots pine MWL and 26 wt.% for Manchurian ash MWL. In order to further investigate the mechanisms of lignin pyrolysis, we also analyzed the FTIR profiles for the main pyrolysis products (CO2, CO, methane, methanol, phenols and formaldehyde) and investigated the variation in pyrolysis products between the different MWLs.

  • 191.
    Wang, Wujun
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Aichmayer, Lukas
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Design and Validation of a Low-cost High-flux Solar Simulator using Fresnel Lens Concentrators2013Ingår i: Proceedings of the SolarPACES 2013 International Conference, Elsevier, 2013, s. 2221-2230Konferensbidrag (Refereegranskat)
    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.

  • 192.
    Wei, Bo
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fakhrai, Reza
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Saadatfar, Bahram
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Mohan, Gowtham
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    The design of a solar-driven catalytic reactor for CO2 conversions2014Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 57, s. 2752-2761Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The solar energy has been employed to provide the heat for CO2 conversions for several years except for its use on power generation, since it is one of the most common renewable energy resources and the total amount is enormous; However, the dominant method is to concentrate solar rays directly on reactants, relying on the design and quality of the receivers a lot. The operation and maintenance of the receivers require extra attention due to the delicate structure of the receivers and the potential contamination on the lenses from the chemical reactions. To steer clear of the shortcoming, a solar-driven catalytic reactor has been designed and analyzed in this article. The reactor drives the endothermic reactions with the heat source of hot gases, which are produced in solar receivers upriver, thus the flexible and necessary operations on the catalytic reactor could be peeled off from the solar receiver, and the potential contamination on the optical components in the solar receiver could be avoided. The design processes and details are described, the heat performance is simulated and analyzed, and efficiencies are theoretically calculated in this article. The solar-driven catalytic reactor exhibits the possibility of the practical use of solar energy in CO2 conversion and recycle.

  • 193.
    Wei, Bo
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Saadatfar, Bahram
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fakhrai, Reza
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Review on the two-step-conversion of CO2 driven by solar energy2013Ingår i: The Journal of Macro Trends in Energy and Sustainability, ISSN 2333-0511, Vol. 1, nr 1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The catalytic conversions of CO2 and H2O emerge as an attractive way to recycle CO2 and H2O to provide synthesis gas as an alternative fuel. Two-step-conversion method with catalysts shows a better performance among different techniques for converting CO2. Solar energy is highly interesting for researchers since it is renewable, feasible and abundant. This article reviews the different aspects of two-step-conversion of CO2 driven by solar energy, including the catalysts used for conversions, and the conversion systems with solar energy. The article focuses on ceria (CeO2) as the promising catalyst, and the looping circulating fluidized bed as the reactors for conversion systems with the prospect. The factors affecting the gas-solid interaction in fluidization are also reviewed. As the conclusion, the two-step conversion of CO2 driven by solar energy appears competitive and ceria gets advantages among the involved catalysts.

  • 194.
    Zhang, Xiaoxiang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Jayasuriya, Jeevan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fakhraie, Reza
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Evaluation of reduced kinetics in simulation of gasified biomass gas combustion2013Ingår i: ASME Turbo Expo 2013: Turbine Technical Conference and Exposition: Volume 1B: Combustion, Fuels and Emissions, ASME Press, 2013, Vol. 1B, s. V01BT04A045-Konferensbidrag (Refereegranskat)
    Abstract [en]

    It is essentially important to use appropriate chemical kinetic models in the simulation process of gas turbine combustion. To integrate the detailed kinetics into complex combustion simulations has proven to be a computationally expensive task with tens to thousands of elementary reaction steps. It has been suggested that an appropriate simplified kinetics which are computationally efficient could be used instead. Therefore reduced kinetics are often used in CFD simulation of gas turbine combustion. At the same time, simplified kinetics for specific fuels and operation conditions need to be carefully selected to fulfill the accuracy requirements. The applicability of several simplified kinetics for premixed Gasified Biomass Gas (GBG) and air combustion are evaluated in this paper. The current work is motivated by the growing demand of gasified biomass gas (GBG) fueled combustion. Even though simplified kinetic schemes developed for hydrocarbon combustions are published by various researchers, there is little research has been found in literature to evaluate the ability of the simplified chemical kinetics for the GBG combustion. The numerical Simulation tool "CANTERA" is used in the current study for the comparison of both detailed and simplified chemical kinetics. A simulated gas mixture of CO/H2/CH4/CO2/N2 is used for the current evaluation, since the fluctuation of GBG components may have an unpredictable influence on the simulation results. The laminar flame speed has an important influence with flame stability, extinction limits and turbulent flame speed, here it is chosen as an indicator for validation. The simulation results are compared with the experimental data from the previous study [1] which is done by our colleagues. Water vapour which has shown a dilution effect in the experimental study are also put into concern for further validation. As the results indicate, the reduced kinetics which are developed for hydrocarbon or hydrogen combustion need to be highly optimized before using them for GBG combustion. Further optimization of the reduced kinetics is done for GBG and moderate results are achieved using the optimized kinetics compared with the detailed combustion kinetics.

  • 195.
    Zhang, Xiaoxiang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Jayasuriya, Jeevan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Kinetic Evaluation of the Laminar Flame Speed for Biomass Derived Gas CombustionManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The gas composition derived from gasification of biomass has been used in gasturbine combustion to achieve higher energy efficiency. However, there is an essential requirement to better understand the combustion characteristics of biomass derived gas before it can be used in the existing combustion facilities. A quantified study of the laminar flame speed of biomass derived gas combustionis presented in this paper. The study was carried out based on the kinetic model of the biomass derived gas flame and the results are compared with the experimental data from the our laboratory and various literatures. The laminarflame speed of the biomass derived gas was evaluated through a range of initial temperature (298 K - 398 K) and pressure (1 atm - 10 atm), as well as with various gas compositions. An empirical relationship for estimating the laminarflame speed has been derived for a composition of typical biomass derived gas. Furthermore, the evaluation of laminar flame speeds with various compositions have been carried out through numerical calculations and results were compared with experimental data from previous studies. The hydrogen concentration in gas composition has shown an essential importance for the laminarflame speed variation.

  • 196.
    Zhang, Xiaoxiang
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Jayasuriya, Jeevan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Kinetic Study on Ignition Delay Time of Biomass Derived Gas CombustionManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The ignition delay time is one of the fundamental characteristics of a combustionprocess and has an essential effect on the performance of the combustion process. In the current study, a kinetic study on auto iginition delaytime is carried out for biomass derived gas combustion. A gas mixture of CO/H2/CO2/CH4/N2 is used to represent the typical composition from a biomass gasification process. The gas mixture is mixed with air under a certain range of operating conditions. A pressure range from 1 – 32 atm and an initial temperature range from 900 K to 1250 K were considered in the current study.The correlation between the ignition delay time and the operating conditions (pressures, initial temperatures and equivalence ratio) was derived for the biomass derived gas based on the kinetic calculations and published experimental data. The empirical correlation was obtained for the gas mixture ofCO/H2/CO2/CH4/N2/air and the gas mixture of CO/H2/O2/Ar. The influence of fuel compositions of the ignition delay time has also been discussed within this study. However, the influence of composition variation shown in the current study was not significant and was difficult to be cross-validated by various experimental data.

1234 151 - 196 av 196
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf