| 1. |
- Strand, Torsten, et al.
(författare)
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On the Significance of Concentrated Solar Power R&D in Sweden
- 2011
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Ingår i: Proceedings of the World Renewable Energy Congress 2011, Linköping.
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 2. |
- Aichmayer, Lukas, et al.
(författare)
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Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants
- 2013
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Ingår i: Journal of engineering for gas turbines and power. - : ASME International. - 0742-4795 .- 1528-8919. ; 135:11, s. 113001-
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts, the combined pressure drop of the recuperator and receiver is more important. In terms of both electricity costs and carbon emissions, the internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20–35%.
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| 3. |
- Aichmayer, Lukas, et al.
(författare)
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Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants
- 2013
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Ingår i: Proceedings of the ASME Turbo Expo 2013. San Antonio, USA. June 3-7. - : ASME. - 9780791855188
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Konferensbidrag (refereegranskat)abstract
- Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts the combined pressure drop of the recuperator and receiver is more important. The internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated, in terms of both electricity costs and carbon emissions. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20 – 35%.
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| 4. |
- Arturo Manrique, Carrera, et al.
(författare)
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Catalytic Partial Oxidation of Natural Gas in Gas Turbine Applications
- 2013
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Ingår i: Proceedings of ASME Turbo Expo 2013. - 9780791855119
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The demands of emissions, combustion efficiency over a wider operational range, and fuel flexibility for industrial gas turbine applications are expected to increase in the coming years. Currently, it is common the use of a stabilizing piloting diffusion flame during part load operation, this flame is accountable for an important part of the thermal NOx emissions on partial load, and in some cases also at full load operation. On the other hand Catalytic Partial Oxidation (CPO) of natural gas is a technique used in petrochemical industry for the Fischer-Tropsch process and for H2 production, and is based in the production of Syn-Gas rich in H2 and CO.The present work explores the possibility to use the CPO of natural gas in industrial gas turbine applications, it is based in experiments performed between 5 and 13 bar using an arrangement of Rh based catalyst and CH4. The experiments were done at the Catalytic Combustion High Pressure Test Facility, at the Royal Institute of Technology (KTH) in Sweden. The gas produced leaves the CPO reactor between 700 and 850 °C and it is rich in H2 and CO. It was found that the most important parameter after reaching the light off temperature in the CPO reactor is the equivalence ratio Φ, which evidences the kinetically controlled regime in the Rh catalyst that depends on O2 availability. The H2/CO ratio is close to the theoretical value of 2 and the selectivity towards H2 and CO are 90% and 95% respectively while the CH4 conversion reached approximately 55%.Pressure on the other hand had a small negative influence in the tested pressure range and it is more relevant at richer fuel conditions (high equivalence ratios). The CPO process had shown that it is relatively easy to control the operation temperature of the catalyst. This temperature is kept below the maximum allowed by reducing the O2 availability.The high temperature Syn-Gas gas produced through CPO process could be burnt in the downstream of the catalysts steadily at flame temperatures below the thermal-NOx threshold. The CPO reactor could provide the flame stabilization function at a wide range of operational conditions, and replace the diffusion piloting flame. This approach could cope with NOx and CO emissions in a wider operational range and offers the possibility of using different fuels as the reaction controlling factor is O2 availability. Furthermore, an initial design of a possible combustion strategy downstream of the CPO reactor is also presented.
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| 5. |
- Arturo Manrique, Carrera, et al.
(författare)
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Staged Lean Catalytic Combustion of Gasified Biomass for Gas Turbine Applications : an Experimental Approach to Investigate Performance of Catalysts
- 2013
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Ingår i: Proceedings of ASME Turbo Expo 2013. - 9780791855133
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Emission demands for gas turbine utilization will become more stringent in the coming years. Currently different techniques are used to reach low levels of NOx emissions. One possible solution is the Staged Lean Catalytic Combustion. In this concept a catalysts arrangement is used to generate high temperature combustion gases. The high temperature gases could be used to feed a second combustion stage in which more fuel is injected.In this work a series of experiments were performed at the Catalytic Combustion High Pressure Test Facility at the Royal Institute of Technology (KTH) in Sweden. The fuel used was a simulated gasified biomass and the catalytic combustor consisted of an arrangement of different catalysts, e.g. bimetallic, hexaaluminates, and perovskites catalysts. These were used as, ignition catalyst, medium temperature catalyst and high temperature catalyst respectively.The tests were performed between 5 and 13.5 bar, and the overall conversion varied between 60% and 70% and the temperature of flue gases could reach 750°C and contains high level of oxygen. The determining factor to control the exit gas temperature was the richness of the mixture (λ value). On the other hand, the increased pressure had a moderate negative effect in the overall fuel conversion. This effect is stronger at leaner mixtures compared to richer ones. Moreover, λ value and also pressure affected the temperature distribution along the reactor.The utilization of a lean catalytic combustion approach makes possible the use of a post catalytic combustion. In this region additional fuel is injected to fully burn the exiting gases and increase the exit temperature to the desired levels. This staged lean catalytic combustion approach could resemble moderate levels exhaust gas recirculation techniques and/or high air temperature combustion and it is also briefly examined in the present work.
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| 6. |
- Baagherzadeh Hushmandi, Narmin, 1978-, et al.
(författare)
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Effects of multiblocking and axial gap distance on performance of partial admission turbines : A numerical analysis
- 2011
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Ingår i: Journal of turbomachinery. - : ASME International. - 0889-504X .- 1528-8900. ; 133:3, s. 031028-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the effects of axial gap distance between the first stage stator and rotor blades and multiblocking on aerodynamics and performance of partial admission turbines are analyzed numerically. The selected test case is a two stage axial steam turbine with low reaction blades operating with compressed air. The multiblocking effect is studied by blocking the inlet annulus of the turbine in a single arc and in two opposing blocked arcs, each having the same admission degree. The effect of axial gap distance between the first stage stator and rotor blades is studied while varying the axial gap by 20% compared with the design gap distance. Finally, full admission turbine is modeled numerically for comparison. Performance of various computational cases showed that the first stage efficiency of the two stage partial admission turbine with double blockage was better than that of the single blockage turbine; however, the extra mixing losses of the double blockage turbine caused the efficiency to deteriorate in the downstream stage. It was shown that the two stage partial admission turbine with smaller axial gap than the design value had better efficiency of the first stage due to lower main flow and leakage flow interactions; however, the efficiency at the second stage decreased faster compared with the other cases. Numerical computations showed that the parameters, which increased the axial force of the first stage rotor wheel for the partial admission turbine, were longer blocked arc, single blocked arc, and reduced axial gap distance between the first stage stator and rotor blades.
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| 7. |
- Baagherzadeh Hushmandi, Narmin, 1978-
(författare)
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Numerical Analysis of Partial Admission in Axial Turbines
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- HTML clipboard Numerical analysis of partial admission in axial turbines is performed in this work. Geometrical details of an existing two stage turbine facility with low reaction blades is used for this purpose. For validation of the numerical results, experimental measurements of one partial admission configuration at design point was used. The partial admission turbine with single blockage had unsymmetrical shape; therefore the full annulus of the turbine had to be modeled numerically. The numerical grid included the full annulus geometry together with the disc gaps and rotor shrouds. Importance of various parameters in accurate modeling of the unsteady flow field of partial admission turbines was assessed. Two simpler models were selected to study the effect of accurate modeling of radial distribution of flow parameters. In the first numerical model, the computational grid was two dimensional and the radial distribution of flow parameters was neglected. The second case was three-dimensional and full blades’ span height was modeled but the leakage flows at disc cavity and rotor shroud were neglected. Detailed validation of the results from various computational models with the experimental data showed that modeling of the leakage flow at disc cavities and rotor shroud of partial admission turbines has substantial importance in accuracy of numerical computations. Comparison of the results from two computational models with varying inlet extension showed that modeling of the inlet cone has considerable importance in accuracy of results but with increased computational cost. Partial admission turbine with admission degree of ε = 0.524 in one blocked arc and two opposing blocked arcs were tested. Results showed that blocking the inlet annulus in one single arc produce better overall efficiency compared to the two blocked arc model. Effect of varying axial gap distance between the first stage stator and rotor rows was also tested numerically for the partial admission turbine with admission degree of ε = 0.726. Results showed higher efficiency for the reduced axial gap model. Computations showed that the main flow leave the blade path down to the disc cavity and re-enter into the flow channel downstream the blockage, this flow would pass the rotor with very low efficiency. First stage rotor blades are subject to large unsteady forces due to the non-uniform inlet flow. Plotting the unsteady forces of first stage rotor blades for partial admission turbine with single blockage showed that the blades experience large changes in magnitude and direction while traveling along the circumference. Unsteady forces of first stage rotor blades were plotted in frequency domain using Fourier transform. The largest amplitudes caused by partial admission were at first and second multiples of rotational frequency due to the existence of single blockage and change in the force direction. Results obtained from the numerical computations showed that the discs have nonuniform pressure distribution especially in the first stage of partial admission turbines. The axial force of the first rotor wheel was considerably higher when the axial gap distance was reduced between the first stage stator and rotor rows. The commercial codes used in this work are ANSYS ICEM-CFD 11.0 as mesh generator and FLUENT 6.3 as flow solver.
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| 8. |
- Baagherzadeh Hushmandi, Narmin, et al.
(författare)
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Unsteady Forces of Rotor Blades in Full and Partial Admission Turbines
- 2011
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Ingår i: Journal of turbomachinery. - : ASME International. - 0889-504X .- 1528-8900. ; 133:4, s. 041017-1-041017-12
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Tidskriftsartikel (refereegranskat)abstract
- A numerical and experimental study of partial admission in a low reaction two-stage axial air test turbine is performed in this paper. In order to model one part load configuration, corresponding to zero flow in one of the admission arcs, the inlet was blocked at one segmental arc, at the leading edge of the first stage guide vanes. Due to the unsymmetrical geometry, the full annulus of the turbine was modeled numerically. The computational domain contained the shroud and disk cavities. The full admission turbine configuration was also modeled for reference comparisons. Computed unsteady forces of the first stage rotor blades showed cyclic change both in magnitude and direction while moving around the circumference. Unsteady forces of first stage rotor blades were plotted in the frequency domain using Fourier analysis. The largest amplitudes caused by partial admission were at first and second multiples of rotational frequency due to the existence of single blockage and change in the force direction. Unsteady forces of rotating blades in a partial admission turbine could cause unexpected failures in operation; therefore, knowledge about the frequency content of the unsteady force vector and the related amplitudes is vital to the design process of partial admission turbine blades. The pressure plots showed that the nonuniformity in the static pressure field decreases considerably downstream of the second stage's stator row, while the nonuniformity in the dynamic pressure field is still large. The numerical results between the first stage's stator and rotor rows showed that the leakage flow leaves the blade path down into the disk cavity in the admitted sector and re-enters downstream of the blocked channel. This process compensates for the sudden pressure drop downstream of the blockage but reduces the momentum of the main flow.
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| 9. |
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| 10. |
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