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  • ASME International  (4)
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  • ASME International  (4)
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  • 1
    Online Resource
    Online Resource
    ASME International ; 2010
    In:  Journal of Solar Energy Engineering Vol. 132, No. 4 ( 2010-11-01)
    In: Journal of Solar Energy Engineering, ASME International, Vol. 132, No. 4 ( 2010-11-01)
    Abstract: For clean and efficient electric power generation, the combination of solar power towers (SPTs) with ultrasupercritical steam cycle power plants could be the next development step. The methodology of the European concentrated solar thermal roadmap study was used to predict the annual performance and the cost reduction potential of this option applying tubular receivers with various appropriate high temperature heat transfer media (HTM). For the assessment, an analytical model of the heat transfer in a parametric 360 deg cylindrical and tubular central receiver was developed to examine the receiver’s efficiency characteristics. The receiver’s efficiency characteristics, which are based on different irradiation levels relative to the receiver’s design point, are, then, used to interpolate the receiver’s thermal efficiency in an hourly based annual calculation of one typical year that is defined by hourly based real measurements of the direct normal irradiance and the ambient temperature. Applying appropriate cost assumptions from literature, the levelized electricity costs (LEC) were estimated for each considered SPT concept and compared with the reference case, which is a scale-up of the state of the art molten salt concept. The power level of all compared concepts and the reference case is 50 MWel. The sensitivity of the specific cost assumptions for the LEC was evaluated for each concept variation. No detailed evaluation was done for the thermal storage but comparable costs were assumed for all cases. The results indicate a significant cost reduction potential of up to 15% LEC reduction in the liquid metal HTM processes. Due to annual performance based parametric studies of the number of receiver panels and storage capacity, the results also indicate the optimal values of these parameters concerning minimal LEC.
    Type of Medium: Online Resource
    ISSN: 0199-6231 , 1528-8986
    Language: English
    Publisher: ASME International
    Publication Date: 2010
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    ASME International ; 2014
    In:  Journal of Solar Energy Engineering Vol. 136, No. 2 ( 2014-05-01)
    In: Journal of Solar Energy Engineering, ASME International, Vol. 136, No. 2 ( 2014-05-01)
    Abstract: Increased receiver temperatures of solar tower power plants are proposed to decrease the plants levelized electricity costs (LEC) due to the utilization of supercritical steam power plants and thus higher overall plant efficiency. Related to elevated receiver temperatures preliminary concept studies show a distinct LEC reduction potential of the internal direct absorption receiver (IDAR), if it is compared to liquid in tube (LIT) or beam-down (BD) receiver types. The IDAR is characterized by a downward oriented aperture of a cylindrical cavity, whose internal lateral area is illuminated from the concentrator field and cooled by a liquid molten salt film. The objective is the further efficiency enhancement, as well as the identification and assessment of the technical critical aspects. For this a detailed fluid mechanic and thermodynamic receiver model of the novel receiver concept is developed to be able to analyze the IDAR's operating performance at full size receiver geometries. The model is used to analyze the open parameters concerning the feasibility, functionality and performance of the concept. Hence, different system management strategies are examined and assessed, which lead to the proposal of a cost optimized lead-concept. This concept involves a rotating receiver system with inclined absorber walls. The spatial arrangements of the absorber walls minimize thermal losses of the receiver and enhance film stability. The centrifugal forces acting on the liquid salt film are essential to realize the required system criteria, which are related to the maximal molten salt temperature, film stability and droplet ejection. Compared to the state of the art at a 200 MWel power level the IDAR concept can lead to a LEC reduction of up to 8%. The cost assumptions made for the assessment are quantified with sensitivity analysis.
    Type of Medium: Online Resource
    ISSN: 0199-6231 , 1528-8986
    Language: English
    Publisher: ASME International
    Publication Date: 2014
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    ASME International ; 2014
    In:  Journal of Solar Energy Engineering Vol. 136, No. 2 ( 2014-05-01)
    In: Journal of Solar Energy Engineering, ASME International, Vol. 136, No. 2 ( 2014-05-01)
    Abstract: The cost reduction potential of solar power towers (SPT) is an important issue concerning its market introduction. Raising the steam process temperature and pressure can lead to a cost reduction due to increased overall plant efficiency. Thus, for new receiver configurations, a supercritical steam cycle operated at 300 bar/600 °C/610 °C live steam conditions was assumed. The considered systems include innovative direct absorption receivers, either with conventional or beam down heliostat field layouts. For the beam down option, the receiver is assumed to be a cylindrical vessel with a flow-through porous absorber structure at the internal lateral area of the cylinder. The direct absorption receiver option consists of a cylindrical barrel with downwards oriented aperture, whose absorber structure at the internal lateral area is cooled by a molten salt film. For the assessment, CFD based methods are developed and able to examine the receiver efficiency characteristics. Based on the receiver thermal efficiency characteristics and the solar field characteristics, the annual performance is evaluated using hourly time series. The assessment methodology is based on the European Concentrated Solar Thermal Roadmap (ECOSTAR) study and enables the prediction of the annual performance and the levelized cost of electricity (LCOE). Applying appropriate cost assumptions from literature, the LCOE are estimated for each considered SPT concept and compared to tubular receiver concepts with molten salt and liquid metal cooling. The power level of the compared concepts and the reference case is 200 MWel. The sensitivity of the specific cost assumptions is analyzed. No detailed evaluation is done for the thermal storage, but comparable storage utilization and costs are assumed for all cases. At optimized plant parameters, the results indicate a LCOE reduction potential of up to 0.5% for beam down and of up to 7.2% for the direct absorption receiver compared to today's state of the art molten salt solar tower technology.
    Type of Medium: Online Resource
    ISSN: 0199-6231 , 1528-8986
    Language: English
    Publisher: ASME International
    Publication Date: 2014
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    ASME International ; 2011
    In:  Journal of Solar Energy Engineering Vol. 133, No. 4 ( 2011-11-01)
    In: Journal of Solar Energy Engineering, ASME International, Vol. 133, No. 4 ( 2011-11-01)
    Abstract: Boundary design of stratified hot water heat stores is important not only to minimize the thermal losses to the ambient but also to preserve the thermodynamic quality of the stored energy. A new method of characterization, which equivalently accounts for both these concerns, is applied in this paper to investigate into the boundary design of large-scale hot water heat stores. A variety of concepts related to general design of the containments, namely, the effects of the thermal conductivity and thickness of the container wall, are numerically analyzed. The design insights provided by the analysis are in good agreement with the corresponding experimental results for small-scale hot water heat stores found in the literature. Different ways of insulation application, differential application of the external insulation, and insulation of the top walls are further investigated to obtain ideas for the efficient use of the insulation material. The new characterization scheme proves to be an efficient tool to rank the performance of different boundary designs during storing process of large-scale stratified hot water heat stores and to provide valuable design insights.
    Type of Medium: Online Resource
    ISSN: 0199-6231 , 1528-8986
    Language: English
    Publisher: ASME International
    Publication Date: 2011
    Location Call Number Limitation Availability
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