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  • 1.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Scaling effects of a novel solar receiver for a micro gas-turbine based solar dish system2018In: International Journal of Solar Energy, ISSN 0142-5919, E-ISSN 1477-2752, Vol. 162, p. 248-264Article in journal (Refereed)
    Abstract [en]

    Laboratory-scale component testing in dedicated high-flux solar simulators is a crucial step in the developmentand scale-up of concentrating solar power plants. Due to different radiative boundary conditions available inhigh-flux solar simulators and full-scale power plants the temperature and stress profiles inside the investigatedreceivers differ between these two testing platforms. The main objective of this work is to present a systematicscaling methodology for solar receivers to guarantee that experiments performed in the controlled environmentof high-flux solar simulators yield representative results when compared to full-scale tests. In this work theeffects of scaling a solar air receiver from the integration into the OMSoP full-scale micro gas-turbine based solardish system to the KTH high-flux solar simulator are investigated. Therefore, Monte Carlo ray-tracing routines ofthe solar dish concentrator and the solar simulator are developed and validated against experimental characterizationresults. The thermo-mechanical analysis of the solar receiver is based around a coupled CFD/FEManalysislinked with stochastic heat source calculations in combination with ray-tracing routines. A geneticmulti-objective optimization is performed to identify suitable receiver configurations for testing in the solarsimulator which yield representative results compared to full-scale tests. The scaling quality is evaluated using aset of performance and scaling indicators. Based on the results a suitable receiver configuration is selected forfurther investigation and experimental evaluation in the KTH high-flux solar simulator.

  • 2.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental evaluation of a novel solar receiver for a micro gas-turbine based solar dish system in the KTH high-flux solar simulator2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 159, p. 184-195Article in journal (Refereed)
    Abstract [en]

    This work presents the experimental evaluation of a novel pressurized high-temperature solar air receiver for the integration into a micro gas-turbine solar dish system reaching an air outlet temperature of 800°C. The experiments are conducted in the controlled environment of the KTH high-flux solar simulator with well-defined radiative boundary conditions. Special focus is placed on providing detailed information to enable the validation of numerical models. The solar receiver performance is evaluated for a range of operating points and monitored using multiple point measurements. The porous absorber front surface temperature is measured continuously as it is one of the most critical components for the receiver performance and model validation. Additionally, pyrometer line measurements of the absorber and glass window are taken for each operating point. The experiments highlight the feasibility of volumetric solar receivers for micro gas-turbine based solar dish systems and no major hurdles were found. A receiver efficiency of 84.8% was reached for an air outlet temperature of 749°C. When using a lower mass flow, an air outlet temperature of 800°C is achieved with a receiver efficiency of 69.3%. At the same time, all material temperatures remain below permissible limits and no deterioration of the porous absorber is found.

  • 3.
    Arnaudo, Monica
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Zaalouk, O. A.
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Techno-economic Analysis of Integrated Energy Systems at Urban District Level - A Swedish Case Study2018In: Energy Procedia, Elsevier, 2018, p. 286-296Conference paper (Refereed)
    Abstract [en]

    Within the Nordic countries, distributed heat and power supply technologies, like domestic scale heat pumps and photovoltaics, are challenging the current centralized district energy infrastructure. An increasing number of customers decide to disconnect from the traditional heating network by comparing the bill to the potential economic savings which can be generated by a residential heat pump system. However, this approach can be considered valid only on a short-term perspective. This paper presents a new approach to compare the techno-economic performance of alternative technologies, based on their lifetime average cost of generation. The proposed analysis is able to determine the optimal energy infrastructure at urban district level. Within this solution, operators, city planners and users will have a solid reference for their decision making process on resources investment. From a first step analysis of a few Swedish case studies, it was found that a district heating based system is more techno-economically efficient compared to the distributed alternative. By comparing the district heating production cost to its final price, a significant profit margin for the utility was qualitatively highlighted. Thus, from a customer perspective, on the medium run, the district heating tariff can be adapted and the estimated savings from switching to a residential heat pump system can be nullified.

  • 4.
    Ayele, Getnet Tadesse
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. CNRS, UMR 6144, GEPEA, IMT Atlantique, F-44307 Nantes, France..
    Mabrouk, Mohamed Tahar
    CNRS, UMR 6144, GEPEA, IMT Atlantique, F-44307 Nantes, France..
    Haurant, Pierrick
    CNRS, UMR 6144, GEPEA, IMT Atlantique, F-44307 Nantes, France..
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH Royal Inst Technol, Dept Energy Technol, S-10044 Stockholm, Sweden..
    Lacarriere, Bruno
    CNRS, UMR 6144, GEPEA, IMT Atlantique, F-44307 Nantes, France..
    Optimal placement and sizing of heat pumps and heat only boilers in a coupled electricity and heating networks2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 182, p. 122-134Article in journal (Refereed)
    Abstract [en]

    Multi-energy systems are reported to have a better environmental and economic performance relative to the conventional, single-carrier, energy systems. Electrification of district heating networks using heat pumps and combined heat and power technologies is one such example. Due to lack of suitable modelling tools, however, the sizing and optimal placement of heat pumps is always done only from the heating network point of view which sometimes compromises the electricity network. This paper proposes an integrated optimization algorithm to overcome such limitation. A load flow model based on an extended energy hub approach is combined with a nested particle swarm optimization algorithm. A waste to energy combined heat and power plant, heat pumps (HPs), heat only boiler (HOB), solar photovoltaic, wind turbines and imports from the neighborhood grids are considered in the case studies. The results show that optimal placement and sizing of HPs and a HOB using the proposed methodology avoids an unacceptable voltage profiles and overloading of the electricity distribution network, which could arise while optimizing only from the heating network point of view. It also shows that up to 41.2% of the electric loss and 5% of the overall operating cost could be saved.

  • 5.
    Ayele, Getnet Tadesse
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mabrouk, Mohamed Tahar
    IMT Atlantique - DSEE - Département Systèmes énergétiques et environnement.
    Haurant, Pierrick
    IMT Atlantique - DSEE - Département Systèmes énergétiques et environnement.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Lacarrière, Bruno
    IMT Atlantique - DSEE - Département Systèmes énergétiques et environnement.
    Santarelli, Massimo
    Polito - Politecnico di Torino.
    Exergy analysis and thermo-economic optimization of a district heating network with solar- photovoltaic and heat pumps2019In: Proceedings of the 32nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems / [ed] Wojciech Stanek, Paweł Gładysz, Sebastian Werle, Wojciech Adamczyk, 2019Conference paper (Refereed)
    Abstract [en]

    Electrification of district heating networks, especially using heat pumps, is widely recommended in literature. Installing heat pumps affects both electricity and heating networks. Due to lack of suitable modelling tools, size optimization of heat pumps in the heating network with the full consideration of the electric distribution network is not well addressed in literature. This paper presents an optimization of a district heating network consisting of solar photovoltaic and heat pumps with the consideration of the detail parameters of heating and electric distribution networks. An extended energy hub approach is used to model the energy system. Exergy and energy analyses are applied to identify and isolate lossy branches in a meshed heating network. Both methods resulted into the same reduced topology. Particle swarm optimization is then applied on the reduced topology in order to find out the most economical temperature profiles and size of distributed heat pumps. The thermo-economic results are found to be highly influenced by the heat demand distribution, the power loss in both electric and heat distribution network, the cost of generation, the temperature limits and the coupling effect of the heat pumps.

  • 6. Benmakhlouf, Y.
    et al.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Wallmander, J.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A methodology to assess the market potential and identify most promising business cases for small scale CSP plants with thermal energy storage2019In: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, Vol. 2126, article id 130001Conference paper (Refereed)
    Abstract [en]

    This study presents a methodology to quantify the market potential for a novel distributed CSP technology with thermal energy technology. The system in question relies on the Stirling engine for power production, which is fed by heat collected from a heliostat field and stored in an integrated latent heat storage unit. Selected countries in the MENA region are investigated to identify best prospective business cases for such a technology. With a global market potential above 40 GW in the whole MENA, industrial sectors such as mining and cement hold the best prospects in terms of market share. The achievable costs of generation vary depending on the DNI of the sites considered but prove to be lower compared with conventional distributed generation (diesel gensets or PV-BEES). However, several countries in the MENA, although having high DNI resource, still offer low electricity utility prices to industrial customers for distributed CSP to become competitive with on-grid electricity procurement. A scenario analysis coupled with a multi criteria selection of the optimal business case quantifies the amount of subsidies necessary to reach competitiveness.

  • 7. Christoph, Richter
    et al.
    Ferruzza, Davide
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Dinter, Frank
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Haglind, Fredrik
    Identification of optimum molten salts for use as heat transfer fluids in parabolic trough CSP plants. A techno-economic comparative optimization2017In: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616Article in journal (Refereed)
    Abstract [en]

    Parabolic trough power plants using thermal oil as heat transfer fluid are the most mature concentrating solar power technology and state of the art. To further increase their efficiency and lower costs, molten salts can be used as heat transfer fluid. This results in higher operating temperature differences for improved cycle efficiencies and enables direct thermal energy storage at lower costs due to omission of the oil-to-salt heat exchanger and the need for smaller storage sizes. As a variety of salts are available to choose from, this study uses a multi-objective optimization to identify the most suitable heat transfer fluid for three locations in South Africa, Spain and Chile. The lowest values for the levelized costs of electricity (LCOE) can be found in Chile using Solar Salt as heat transfer fluid (75.0 $/MWhe). Generally, Solar Salt offers the lowest LCOE values followed by thermal oil and Hitec. The results also suggest that the choice of the heat transfer fluid is dependent on the direct normal irradiance (DNI) at each location. Thermal oil is competitive with Solar Salt in small systems at locations with low DNI values, whereas Hitec can be cheaper than thermal oil in large systems at locations with high DNI. Furthermore, it is also investigated at which freeze alert temperature set point the activation of the freeze protection system is optimal. The results indicate that this temperature should be chosen close to the solar field inlet temperature for small systems, while it can be lowered significantly for large systems to reduce electricity consumption from the freeze protection system.

  • 8. Ferruzza, D.
    et al.
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Haglind, F.
    Impact of steam generator start-up limitations on the performance of a parabolic trough solar power plant2018In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 169, p. 255-263Article in journal (Refereed)
    Abstract [en]

    Concentrating solar power plants are an attractive option in the renewable energy generation market. The possibility of integrating relatively cheap forms of energy storage makes them a desirable solution when power generation must be readily available at any time of the day. Solar power plants typically start-up and shut down every day, so in order to maximize their profitability, it is necessary to increase their flexibility in transient operation and to initiate power generation as rapidly as possible. Two of the key components are the steam generator and steam turbine and the rates at which they can reach operational speed are limited by thermo-mechanical constraints. This paper presents an analysis of the effects of the thermal stress limitations of the steam generator and steam turbine on the power plant start-up, and quantifies their impact on the economy of the system. A dynamic model of a parabolic trough power plant was developed and integrated with a logic controller to identify start-up limitations, and subsequently the dynamic model was integrated in a techno-economic tool previously developed by the authors. The plant was analysed under two different operating strategies, namely solar-driven and peak-load. The results indicate that for steam generator hot start-ups, a 1.5% increase in peak-load electricity production would be achieved by doubling the maximum allowable heating rate of the evaporator. No useful increase would be achieved by increasing the rates beyond a limit of 7–8 K/min, as the turbine would then be the main limiting component during start-up. Similar conclusions can be drawn for the solar-driven case, for which the solar field and the energy source availability would pose the major constraint when starting up the steam generator system.

  • 9.
    Ferruzza, Davide
    et al.
    Tech Univ Denmark, Dept Mech Engn, Nils Koppels Alle,Bldg 403, DK-2800 Lyngby, Denmark..
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Haglind, Fredrik
    Tech Univ Denmark, Dept Mech Engn, Nils Koppels Alle,Bldg 403, DK-2800 Lyngby, Denmark..
    Optimal start-up operating strategies for gas-boosted parabolic trough solar power plants2018In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 176, p. 589-603Article in journal (Refereed)
    Abstract [en]

    Concentrating solar power plants are taking an increasing share in the renewable energy generation market. Parabolic trough is one of such technologies and the most commercially mature. However, this technology still suffers from technical challenges that need to be addressed. As these power plants experience daily start-up procedures, the optimal performance in transient operation needs to be considered. This paper presents a performance based modelling tool for a gas-boosted parabolic trough power plant. The objective of the paper is to define an optimal operational strategy of the power plant start-up procedure with the aim of minimizing its fuel consumption while at the same time maximizing its electric energy output, taking into account all the thermo-mechanical constraints involved in the procedure. Heating rate constraints of the steam generator and the booster heater, and the steam turbine start-up schedule were considered. The simulation model was developed based on a power plant located near Abu Dhabi, and was validated against real operational data with a maximum integral relative deviation of 4.3% for gross electric energy production. A multi-objective optimization was performed for a typical operating week during winter and spring weather conditions. The results suggest that in order to minimize the fuel consumption and at the same time maximize the electric energy production, an evaporator heating rate of 6 K/min is an optimal value both for winter and spring conditions.

  • 10.
    Gan, Philipe Gunawan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, Cologne, 51147, Germany.
    Monnerie, N.
    Brendelberger, S.
    Roeb, M.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Sattler, C.
    Modeling, simulation and economic analysis of CSP-driven solar fuel plant for diesel and gasoline production2019In: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, article id 180009Conference paper (Refereed)
    Abstract [en]

    The present research focuses on modeling of solar thermal driven fuel production plant with CO2 and H2O as raw materials to produce synthetic gas (syngas) which is converted into hydrocarbons through Fischer-Tropsch process either with Fe and Co catalyst to produce diesel, gasoline and kerosene. The solar reactor uses cerium oxide (CeO2) as a metal-redox and operates at 1773 K and 1300 K for reduction and oxidation step respectively under non-stoichiometric condition. The plant is analyzed by performing a quasi-steady state simulation under boundary condition that the Fischer-Tropsch reactor should operate with the capacity factor of 0.95 or 8350 hours annually. A storage tank is used to store and regulate the flow of syngas going into the Fischer-Tropsch reactor. Sensitivity analysis is carried out, particularly on solar reactor conversion and solid-to-solid heat exchanger efficiency. Another sensitivity analysis is to combine PV and CSP as the external electricity source. The production cost is finally calculated using annuity method with constant discount rate.

  • 11.
    Garrido, Jorge
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Abou-Taouk, A.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Characterization of a Stirling cavity receiver performance in the KTH high-flux solar simulator and comparison with real Dish-Stirling data2018In: AIP Conference Proceedings, American Institute of Physics Inc. , 2018Conference paper (Refereed)
    Abstract [en]

    This paper presents the experimental results of the Cleanergy's C11S solar engine-generator tested in the KTH solar simulator. The paper focuses on the analysis of the thermal performance of the cavity receiver used in the C11S module. Multiple temperature measurements were taken on the tubes of the receiver, inside the cavity and on the internal surface of the cavity. These values allowed characterizing the temperature distribution all around the cavity receiver for the validation of thermal models and the estimation of the thermal losses. Moreover, this paper shows a comparison of the operating characteristics of the C11S module under the real operating conditions and the laboratory ones. It was observed that the temperatures of the receiver in the High Flux Solar Simulator (HFSS) resemble well the real temperatures. Thereby, the KTH solar lab provides proper irradiance levels to operate solar receivers at representative working conditions.

  • 12.
    Garrido, Jorge
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Abou-Taouk, Abdallah
    Cleanergy, Regnbagsgatan 6, S-41755 Gothenburg, Sweden..
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental and numerical performance analyses of a Dish-Stirling cavity receiver: Geometry and operating temperature studies2018In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 170, p. 913-923Article in journal (Refereed)
    Abstract [en]

    Higher performance cavity receivers are needed to increase the competitiveness of solar power plants. However, the design process needs to be improved with more relevant experimental and numerical analyses. Thereby, the performance of four different Dish-Stirling cavities is investigated experimentally analyzing the influence of the cavity aperture diameter and shape at various operating temperatures. Temperatures inside the cavity receiver were collected together with the electrical power produced by the engine-generator. Then, a thermal system simulation was modelled and a comprehensive multi-parameter and multi-operation validation was performed. To improve this validation, the temperature distribution across the receiver tubes was analyzed in order to relate temperatures on the irradiated region with the non-irradiated one, where thermocouples can measure. The simulations were later used to obtain cavity receiver efficiencies, temperatures and loss breakdowns. The results show that the cavity receiver must be studied in optimization processes in conjunction with the other system components. Moreover, the reverse-conical cavity was found to be more efficient than a nearly cylindrical shape. Regarding the cavity receiver thermal losses, radiation and natural convection present similar contributions in the system under study. Finally, it was found that thermocouples installed on a non-irradiated region can be used to obtain peak receiver temperatures if the measurements are rectified by a correction value proportional to the DNI.

  • 13.
    Garrido, Jorge
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Abou-Taouk, Abdallah
    Azelio, Regnbagsgatan 6, S-41755 Gothenburg, Sweden..
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental and numerical performance analyses of Dish-Stirling cavity receivers: Radiative property study and design2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 169, p. 478-488Article in journal (Refereed)
    Abstract [en]

    The solar receiver performance has a direct impact on the CSP power plant performance and, thereby, its levelized cost of electricity. Improved receiver designs supported by new advanced numerical tools and experimental validation campaigns directly help to make CSP technology more competitive. This paper presents an experimental and numerical investigation of the influence of the cavity receiver radiative properties and the thermal power input on the Dish-Stirling performance. Three cavity coatings are experimentally investigated: the original cavity material (Fiberfrax 140), Pyromark 2500 and Pyro-paint 634-ZO. Moreover, simulations validated with the experimental measurements are utilized to define a higher performance cavity receiver for the Eurodish system. The results indicate that the absorptivity of the cavity should be as low as possible to increase the receiver efficiency whereas the optimum emissivity depends on the operating temperatures. If the cavity temperature is lower than the absorber temperature, low emissivities are recommended and vice-versa. All material/coatings analyzed for the cavity provide similar receiver efficiencies, being Fiberfrax 140 slightly more efficient. Finally, a total receiver efficiency of 91.5% is reached by the proposed Eurodish cavity receiver when operating under the most favorable external conditions. 

  • 14.
    Garrido, Jorge
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Characterization of the KTH high-flux solar simulator combining three measurement methods2017In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 141, p. 2091-2099Article in journal (Refereed)
    Abstract [en]

    This paper presents the characterization of the first Fresnel lens-based High-Flux Solar Simulator (HFSS) showing the evaluation of the total thermal radiative power dependent on the aperture radius at the focal plane. This result can be directly applied to calculate the thermal power input into any solar receiver tested in the KTH HFSS. Three measurement setups were implemented and their results combined to assess and verify the characterization of the solar simulator: a thermopile sensor measuring radiative flux, a CMOS camera coupled with a Lambertian target to obtain flux maps, and a calorimeter to measure the total thermal power within an area of 300×300 mm. Finally, a Monte Carlo analysis was performed to calculate the total uncertainties associated to each setup and to combine them to obtain the simulator characterization. The final result shows a peak flux of 6.8 ± 0.35 MW/m2 with a thermal power of 14.7 ± 0.75 kW within an aperture of 180 mm in diameter at the focal plane, and a thermal-electrical conversion efficiency of 25.8 ± 0.3%. It was found very good repeatability and a stable energy output from the lamps during the experiments.

  • 15.
    Garrido, Jorge
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Sjöqvist, R.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Mechanical coupling behavior of a dish-Stirling receiver: Influence on the absorber tube stresses2019In: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, Vol. 2126, article id 050003Conference paper (Refereed)
    Abstract [en]

    The solar receiver tubes work under the highest temperatures and heat flux conditions, being their thermo-mechanical design critical to assure a safe and durable operation. Finite Element Analyses are traditionally utilized to assess the stresses for lifetime calculations. However, the real boundary conditions for these analyses are not well known yet. Thereby, this paper presents an experimental and numerical study to determine more realistic boundary conditions. Firstly, four deflection measurements are measured simultaneously by high-accuracy laser meters. Secondly, three types of boundary conditions are simulated trying to fit the experimental deflections: fixed, elastic and remote displacement. Finally, the stresses at critical regions are compared for each simulation. The results show that, unlike fixed support, remote displacement boundary conditions can obtain realistic deflection results but must be re-adjusted for each specific support, and elastic support fails to capture the manifold rotations. Using remote displacement stress results as reference for the case under study, fixed support leads to deviations in the stresses of at least 50% whilst elastic support can provide some similar stress results.

  • 16.
    Guédez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Garcia, Jose Angel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Martin, Fernando
    AF Aries Energia, Paseo Castellana 130,3th Floor, Madrid 28046, Spain..
    Wiesenberg, Ralf
    AF Aries Energia, Paseo Castellana 130,3th Floor, Madrid 28046, Spain..
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Integrated Solar Combined Cycles vs Combined Gas Turbine to Bottoming Molten Salt Tower Plants - A Techno-economic Analysis2018In: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS (SOLARPACES 2017) / [ed] Mancilla, R Richter, C, AMER INST PHYSICS , 2018, article id 180006-1Conference paper (Refereed)
    Abstract [en]

    The present work deals with the techno-economic analysis of a novel combined power cycle consisting of a molten-salt solar tower power plant with storage supported by additional heat provided from the exhaust of a topping gas-turbine unit. A detailed model has been elaborated using in house simulation tools that simultaneously encompass meteorological, demand and required dispatch data. A range of possible designs are evaluated for a suitable location with both good solar resource and vast natural gas resources in order to show the trade-offs between the objectives of achieving low carbon-intensive and economically competitive designs. These were compared against more conventional integrated solar combined cycles of equivalent capacity factors. It is shown that the novel concept is worth further investigating as it is able to outperform the more conventional cycle while simultaneously offering additional flexibility to grid-operators.

  • 17.
    Hansson, Linus
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Larchet, Kevin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Development and implementation of a dynamic TES dispatch control component in a PV-CSP techno-economic performance modelling tool2017In: AIP Conference Proceedings, American Institute of Physics (AIP), 2017, Vol. 1850, article id 160013Conference paper (Refereed)
    Abstract [en]

    The dispatchability offered by thermal energy storage (TES) in concentrated solar power (CSP) and solar hybrid plants based on such technology presents the most important difference compared to power generation based only on photovoltaics (PV). This has also been one reason for recent hybridization efforts of the two technologies and the creation of Power Purchase Agreement (PPA) payment schemes based on offering higher payment multiples during daily hours of higher (peak or priority) demand. Recent studies involving plant-level thermal energy storage control strategies are however to a large extent based on pre-determined approaches, thereby not taking into account the actual dynamics of thermal energy storage system operation. In this study, the implementation of a dynamic dispatch strategy in the form of a TRNSYS controller for hybrid PV-CSP plants in the power-plant modelling tool DYESOPT is presented. In doing this it was attempted to gauge the benefits of incorporating a day-ahead approach to dispatch control compared to a fully pre-determined approach determining hourly dispatch only once prior to annual simulation. By implementing a dynamic strategy, it was found possible to enhance technical and economic performance for CSP-only plants designed for peaking operation and featuring low values of the solar multiple. This was achieved by enhancing dispatch control, primarily by taking storage levels at the beginning of every simulation day into account. The sequential prediction of the TES level could therefore be improved, notably for evaluated plants without integrated PV, for which the predicted storage levels deviated less than when PV was present in the design. While also featuring dispatch performance gains, optimal plant configurations for hybrid PV-CSP was found to present a trade-off in economic performance in the form of an increase in break-even electricity price when using the dynamic strategy which was offset to some extent by a reduction in upfront investment cost. An increase in turbine starts for the implemented strategy however highlights that this is where further improvements can be made.

  • 18.
    Payaro, Albert
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Naik, Ankit Anurag
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Identification of Required Cost Reductions for CSP to Retain Its Competitive Advantage as Most Economically Viable Solar-Dispatchable Technology2018In: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS (SOLARPACES 2017) / [ed] Mancilla, R Richter, C, AMER INST PHYSICS , 2018, article id 040028-1Conference paper (Refereed)
    Abstract [en]

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

  • 19.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ferruzza, D.
    Seeger, F.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Analysis of plant performance with improved turbine flexibility: Test case on a parabolic trough configuration2018In: AIP Conference Proceedings, American Institute of Physics Inc. , 2018Conference paper (Refereed)
    Abstract [en]

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

  • 20.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Improving concentrating solar power plant performance by increasing steam turbine flexibility at start-up2018In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 165, p. 10-18Article in journal (Refereed)
    Abstract [en]

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

  • 21.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Improving Concentrating Solar Power Plant Performance by Increasing Steam Turbine Flexibility at Start-up2017In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257Article in journal (Refereed)
    Abstract [en]

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

  • 22.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Nilsson, Asa
    Jocker, Markus
    INVESTIGATION INTO THE THERMAL LIMITATIONS OF STEAM TURBINES DURING START-UP OPERATION2017In: PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2017, VOL 8, AMER SOC MECHANICAL ENGINEERS , 2017Conference paper (Refereed)
    Abstract [en]

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

  • 23.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Vitrano, Andrea
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Utilization of a thermo-mechanical model coupled with multi-objective optimization to enhance the start-up process of solar steam turbines2018In: Proceedings of the ASME Turbo Expo, ASME Press, 2018, Vol. 8Conference paper (Refereed)
    Abstract [en]

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

  • 24.
    Trevisan, Silvia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Bouzekri, H.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Initial design of a radial-flow high temperature thermal energy storage concept for air-driven CSP systems2019In: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, Vol. 2126, article id 200031Conference paper (Refereed)
    Abstract [en]

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

  • 25.
    Trevisan, Silvia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Preliminary assessment of integration of a packed bed thermal energy storage in a Stirling - CSP system2019In: SolarPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems, American Institute of Physics (AIP), 2019, Vol. 2126, article id 200032Conference paper (Refereed)
    Abstract [en]

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

  • 26. Wang, Wujun
    et al.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    An axial type impinging receiver2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 162, p. 318-334Article in journal (Refereed)
    Abstract [en]

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

  • 27.
    Wang, Wujun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Malmquist, Anders
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Transient performance of an impinging receiver: An indoor experimental study2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 158, p. 193-200Article in journal (Refereed)
    Abstract [en]

    The impinging receiver is a new member of the cavity solar receiver family. In this paper, the transient performance of a prototype impinging receiver has been studied with the help of a Fresnel lens based solar simulator and an externally fired micro gas turbine. The impinging receiver can offer an air outlet temperature of 810 °C at an absorber temperature of 960 °C. The radiative-to-thermal efficiency is measured to be 74.1%. The absorber temperature uniformity is good but high temperature differences have been detected during the ‘cold startup’ process. The temperature changing rate of the receiver is within 3 °C/s for the startup process and 4 °C/s for the shut-down process. In order to avoid quenching effects caused by the impinging jets, the micro gas turbine should be turned off to stop the airflow when the radiative power is off. 

  • 28.
    Wang, Wujun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Malmquist, Anders
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Comparison of potential control strategies for an impinging receiver based dish-Brayton system when the solar irradiation exceeds its design value2018In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 169, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Potential control strategies for an impinging receiver based dish-Brayton system have been presented for protecting the key components from the risks of overheating when the solar irradiation exceeds its design value. Two of them are selected for a detailed study: changing the effective diameter of the shading device and changing the inlet temperature. A rope-pulley shading device is developed for controlling the shading area in the center of the dish, and the change of the inlet temperature is achieved by applying a bypass at the cold side of the recuperator for reducing the heat transfer rate. Both control strategies can manage the peak temperature on the absorber surface within 1030 °C with an outlet temperature fluctuation between −4.1 and 15.1 °C, so that the impinging receiver can work for long time at any solar direct normal irradiance value. Furthermore, the temperature differences on the absorber surface are between 137.1 °C and 163.8 °C. The cases that are achieved by changing the shield effective diameter are significantly lower (11–26 °C) than the corresponding cases that are achieved by changing the inlet temperature.

1 - 28 of 28
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