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Xin Li - One of the best experts on this subject based on the ideXlab platform.

  • energy and exergy analysis of Solar power Tower plants
    Applied Thermal Engineering, 2011
    Co-Authors: Chao Xu, Zhifeng Wang, Xin Li
    Abstract:

    Establishing the renewable electricity contribution from Solar thermal power Systems based on energy analysis alone cannot legitimately be complete unless the exergy concept becomes a part of that analysis. This paper presents a theoretical framework for the energy analysis and exergy analysis of the Solar power Tower System using molten salt as the heat transfer fluid. Both the energy losses and exergy losses in each component and in the overall System are evaluated to identify the causes and locations of the thermodynamic imperfection. Several design parameters including the direct normal irradiation (DNI), the concentration ratio, and the type of power cycle are also tested to evaluate their effects on the energy and exergy performance. The results show that the maximum exergy loss occurs in the receiver System, followed by the heliostat field System, although main energy loss occurs in the power cycle System. The energy and exergy efficiencies of the receiver and the overall System can be increased by increasing the DNI and the concentration ratio, but that increment in the efficiencies varies with the values of DNI and the concentration ratio. It is also found that the overall energy and exergy efficiencies of the Solar Tower System can be increased to some extent by integrating advanced power cycles including reheat Rankine cycles and supercritical Rankine cycles.

  • energy and exergy analysis of Solar power Tower plants
    Applied Thermal Engineering, 2011
    Co-Authors: Chao Xu, Zhifeng Wang, Xin Li
    Abstract:

    Establishing the renewable electricity contribution from Solar thermal power Systems based on energy analysis alone cannot legitimately be complete unless the exergy concept becomes a part of that analysis. This paper presents a theoretical framework for the energy analysis and exergy analysis of the Solar power Tower System using molten salt as the heat transfer fluid. Both the energy losses and exergy losses in each component and in the overall System are evaluated to identify the causes and locations of the thermodynamic imperfection. Several design parameters including the direct normal irradiation (DNI), the concentration ratio, and the type of power cycle are also tested to evaluate their effects on the energy and exergy performance. The results show that the maximum exergy loss occurs in the receiver System, followed by the heliostat field System, although main energy loss occurs in the power cycle System. The energy and exergy efficiencies of the receiver and the overall System can be increased by increasing the DNI and the concentration ratio, but that increment in the efficiencies varies with the values of DNI and the concentration ratio. It is also found that the overall energy and exergy efficiencies of the Solar Tower System can be increased to some extent by integrating advanced power cycles including reheat Rankine cycles and supercritical Rankine cycles.

Paolo Silva - One of the best experts on this subject based on the ideXlab platform.

  • preliminary assessment of sco2 cycles for power generation in csp Solar Tower plants
    Applied Energy, 2017
    Co-Authors: Marco Binotti, Marco Astolfi, Stefano Campanari, Giampaolo Manzolini, Paolo Silva
    Abstract:

    Abstract This work discusses a preliminary thermodynamic assessment of three different supercritical CO 2 (sCO 2 ) power cycles applied to a high temperature Solar Tower System, with maximum temperatures up to 800 °C. The thermal power is transferred from the Solar receiver to the power block through KCl-MgCl 2 molten salts as heat transfer fluid, therefore an indirect cycle configuration is considered assuming a surrounded field as the one of GemaSolar plant. The most promising cycle configuration in terms of Solar-to-electric efficiency is selected, optimizing the cycle turbine inlet temperature to achieve the best compromise between cycle and receiver performance: the highest efficiency at design conditions is achieved by the Recompression with Main Compression Intercooling (RMCI) configuration with a Solar to electric efficiency of 24.5% and a maximum temperature of 750 °C. The yearly energy yield of the proposed power plant is estimated with a simplified approach and results in the range of 18.4%: the performance decay from design to average yearly conditions is mostly due to the optical and thermal efficiencies reduction (−10.8% and −16.4%, respectively).

  • preliminary assessment of sco2 power cycles for application to csp Solar Tower plants
    Energy Procedia, 2017
    Co-Authors: Marco Binotti, Marco Astolfi, Stefano Campanari, Giampaolo Manzolini, Paolo Silva
    Abstract:

    Abstract This work presents a preliminary thermodynamic assessment of three different supercritical CO2 (sCO2) power cycles integrated in a high temperature Solar Tower System, working up to 800 °C. An indirect cycle configuration is considered with KCl-MgCl2 molten salt as heat transfer fluid (HTF) in the Solar receiver and a two tanks thermal energy storage (TES) System. The most promising cycle configuration is selected, optimizing the cycle turbine inlet temperature to achieve the best compromise between cycle and receiver efficiency. An estimate of the yearly energy yield of the proposed power plant is finally performed, indicating the possibility of reaching Solar-to-electric efficiency of about 17.5%.

Zhifeng Wang - One of the best experts on this subject based on the ideXlab platform.

  • simulations of reflected sun beam traces over a target plane for an azimuth elevation tracking heliostat with fixed geometric error sources
    Solar Energy, 2013
    Co-Authors: Minghuan Guo, Zhifeng Wang, Feihu Sun
    Abstract:

    Abstract For a heliostat with geometric errors, the reflected central Solar ray from the mirror surface center forms a curved error trace on the target plane during the day rather than staying fixed on one target point. A general azimuth–elevation tracking angle formula has been developed for a heliostat with a mirror-pivot offset and other typical geometric errors. This tracking angle formula is re-rewritten here as a series of easily solved expressions. This azimuth–elevation tracking angle formula is then used in a new complete geometric model of the sun-beam tracking errors for an azimuth–elevation tracking heliostat to simulate the sun beam tracking error trace on the target plane for a heliostat with fixed geometric errors. Here, the analysis is for a point sun and a point heliostat (or the heliostat considered as a small optical flat). The mirror surface center is defined as the orthogonal projection of the heliostat pivot on the mirror surface plane. The reflected sun-beam centre in the target plane is defined as the intersection of the mirror-surface-centre reflected central Solar ray with the target plane. Due to a position tracking error in the target plane depending on the position and the orientation of the specific target plane, the position tracking error is further converted to the angular tracking error in the reflection direction to facilitate evaluation of the heliostat tracking performance. Simulations for the artificial #78 heliostat in the Beijing Solar Tower System on June 21st are shown to illustrate this heliostat tracking error model. This heliostat tracking error model can be used to reveal the effect of various geometrical errors in pedestal tilt etc. on the location of the beam at the target, and thus is useful in setting limits on the various geometrical errors. Essentially this paper allows one to estimate the offset of the reflected Solar beam centre due to specific geometrical tracking errors, once the beam centre is computed by some other means. It also allows one to determine a limit on each error or set of errors which are allowable for a given purpose.

  • energy and exergy analysis of Solar power Tower plants
    Applied Thermal Engineering, 2011
    Co-Authors: Chao Xu, Zhifeng Wang, Xin Li
    Abstract:

    Establishing the renewable electricity contribution from Solar thermal power Systems based on energy analysis alone cannot legitimately be complete unless the exergy concept becomes a part of that analysis. This paper presents a theoretical framework for the energy analysis and exergy analysis of the Solar power Tower System using molten salt as the heat transfer fluid. Both the energy losses and exergy losses in each component and in the overall System are evaluated to identify the causes and locations of the thermodynamic imperfection. Several design parameters including the direct normal irradiation (DNI), the concentration ratio, and the type of power cycle are also tested to evaluate their effects on the energy and exergy performance. The results show that the maximum exergy loss occurs in the receiver System, followed by the heliostat field System, although main energy loss occurs in the power cycle System. The energy and exergy efficiencies of the receiver and the overall System can be increased by increasing the DNI and the concentration ratio, but that increment in the efficiencies varies with the values of DNI and the concentration ratio. It is also found that the overall energy and exergy efficiencies of the Solar Tower System can be increased to some extent by integrating advanced power cycles including reheat Rankine cycles and supercritical Rankine cycles.

  • energy and exergy analysis of Solar power Tower plants
    Applied Thermal Engineering, 2011
    Co-Authors: Chao Xu, Zhifeng Wang, Xin Li
    Abstract:

    Establishing the renewable electricity contribution from Solar thermal power Systems based on energy analysis alone cannot legitimately be complete unless the exergy concept becomes a part of that analysis. This paper presents a theoretical framework for the energy analysis and exergy analysis of the Solar power Tower System using molten salt as the heat transfer fluid. Both the energy losses and exergy losses in each component and in the overall System are evaluated to identify the causes and locations of the thermodynamic imperfection. Several design parameters including the direct normal irradiation (DNI), the concentration ratio, and the type of power cycle are also tested to evaluate their effects on the energy and exergy performance. The results show that the maximum exergy loss occurs in the receiver System, followed by the heliostat field System, although main energy loss occurs in the power cycle System. The energy and exergy efficiencies of the receiver and the overall System can be increased by increasing the DNI and the concentration ratio, but that increment in the efficiencies varies with the values of DNI and the concentration ratio. It is also found that the overall energy and exergy efficiencies of the Solar Tower System can be increased to some extent by integrating advanced power cycles including reheat Rankine cycles and supercritical Rankine cycles.

Chao Xu - One of the best experts on this subject based on the ideXlab platform.

  • energy and exergy analysis of Solar power Tower plants
    Applied Thermal Engineering, 2011
    Co-Authors: Chao Xu, Zhifeng Wang, Xin Li
    Abstract:

    Establishing the renewable electricity contribution from Solar thermal power Systems based on energy analysis alone cannot legitimately be complete unless the exergy concept becomes a part of that analysis. This paper presents a theoretical framework for the energy analysis and exergy analysis of the Solar power Tower System using molten salt as the heat transfer fluid. Both the energy losses and exergy losses in each component and in the overall System are evaluated to identify the causes and locations of the thermodynamic imperfection. Several design parameters including the direct normal irradiation (DNI), the concentration ratio, and the type of power cycle are also tested to evaluate their effects on the energy and exergy performance. The results show that the maximum exergy loss occurs in the receiver System, followed by the heliostat field System, although main energy loss occurs in the power cycle System. The energy and exergy efficiencies of the receiver and the overall System can be increased by increasing the DNI and the concentration ratio, but that increment in the efficiencies varies with the values of DNI and the concentration ratio. It is also found that the overall energy and exergy efficiencies of the Solar Tower System can be increased to some extent by integrating advanced power cycles including reheat Rankine cycles and supercritical Rankine cycles.

  • energy and exergy analysis of Solar power Tower plants
    Applied Thermal Engineering, 2011
    Co-Authors: Chao Xu, Zhifeng Wang, Xin Li
    Abstract:

    Establishing the renewable electricity contribution from Solar thermal power Systems based on energy analysis alone cannot legitimately be complete unless the exergy concept becomes a part of that analysis. This paper presents a theoretical framework for the energy analysis and exergy analysis of the Solar power Tower System using molten salt as the heat transfer fluid. Both the energy losses and exergy losses in each component and in the overall System are evaluated to identify the causes and locations of the thermodynamic imperfection. Several design parameters including the direct normal irradiation (DNI), the concentration ratio, and the type of power cycle are also tested to evaluate their effects on the energy and exergy performance. The results show that the maximum exergy loss occurs in the receiver System, followed by the heliostat field System, although main energy loss occurs in the power cycle System. The energy and exergy efficiencies of the receiver and the overall System can be increased by increasing the DNI and the concentration ratio, but that increment in the efficiencies varies with the values of DNI and the concentration ratio. It is also found that the overall energy and exergy efficiencies of the Solar Tower System can be increased to some extent by integrating advanced power cycles including reheat Rankine cycles and supercritical Rankine cycles.

Weidong Huang - One of the best experts on this subject based on the ideXlab platform.

  • an analytical solution for the Solar flux density produced by a round focusing heliostat
    Renewable Energy, 2019
    Co-Authors: Weidong Huang, Liang Yu, Peng Hu
    Abstract:

    Abstract This paper presents an analytical solution for calculation of flux density distribution on the image plane of a round spherical heliostat which is deduced from the convolution-based integration method. The two-dimensional integration for flux density calculation is converted to a one-dimensional integration and solved as a function, thereby reducing the amount of calculation and obtaining fast computation. The flux density on the receiver plane can be calculated through projection even if the distance between the heliostat and receiver is not equal to the focal length of the heliostat. The ray tracing and numerical method are applied to validate the accuracy of the analytical method which shows the analytical method can be applied to most heliostats for Solar Tower System with a faster calculation speed than SolTrace code, and the error source is analyzed, which is inversely proportional to the cube of the focal length f and is proportional to the biquadrate of the heliostat radius R0. It is proved that a radially symmetric Solar flux density distribution on the image plane is produced by a round spherical heliostat, which is so far the only radially symmetric Solar flux density distribution formed by the heliostat when the incident angle is not 0.

  • Solar flux density calculation for a heliostat with an elliptical gaussian distribution source
    Applied Energy, 2016
    Co-Authors: Weidong Huang
    Abstract:

    The calculation of Solar flux density is a key work for the design and optimization of Solar Tower System. Because of the great amount of calculation, the source distribution is often regarded as a radial distribution, which is not consistent with the reality. This paper presents a new method to calculate the flux density distribution by a focusing heliostat with an elliptical Gaussian distribution source. The two-dimensional convolution integration is proposed and converted into a one-dimensional integration. We use the Gauss-Legendre integration method to reduce the amount of calculation and accelerate the speed of integration. This method can be used to calculate the Solar flux at image and receiver plane by most of the heliostat. It needs only 0.1% time of the ray tracing method for calculating the efficiency of the heliostat. It can be applied for design optimization of the Solar heliostat field which is superior to the present methods in both accuracy and computation requirements.